Some geodynamic models focus on the role of mantle upwellings and decompression melting to understand the origins of plains volcanism. Reese et al. (2007) suggest that the lithosphere has thickened over the last 1 Ga, causing a decrease in melting consistent with the impact crater population and resurfacing history. Smrekar and Sotin (2012) focused on modeling the formation of mantle plumes capable of producing the hotspots. As discussed above, available thermal emissivity data from VIRTIS, as well as Magellan radar emissivity measurements, suggest that recent, large-scale volcanism is confined to hotspot/mantle plume settings. If this observation is borne out by future missions, it may turn out that tiny amounts of volatiles from the lower mantle are required to enable decompression melting in mantle plumes. Localized upwelling confined to the upper mantle may not be capable of crossing the solidus today due to desiccation of the upper mantle by prior, widespread melting (e.g., Smrekar and Sotin, 2012). This hypothesis is potentially consistent with the interpretation of Ar isotope data as indicating that Venus' interior volatiles are ~25% outgassed (e.g., Kaula, 1999; O'Rourke and Korenga, 2015), if the upper mantle represents ~25% of the total mantle volume.

## 5.1.2 Lava Channels

Models of canali and sinuous rilles mainly focus on explaining their observed morphology, e.g., meander wavelengths, from Magellan radar images. Kargel et al. (1994) applied a scaling law, which describes the relationship between the meander wavelength and discharge at bank-full stage for streams on Earth, to estimate lava volumes required to form canali. These authors also calculated the duration of the lava flows from a simple estimate of how quickly canali meander could migrate, and found that a typical canale could form from ~10¹³ to 10¹⁵ m³ of lava, which could cover up to ~2.5 × 10⁶ km² with ~500-m thick flows. If the lava contained ~50 vol% carbonate minerals, the degassed CO₂ would have between 0.05% and 5% of the total mass of the present-day atmosphere. Perhaps older “generations” of canali once existed, contributing even more CO₂ to the atmosphere, but are not visible on the modern surface. Currently, Venus' atmosphere contains nearly as much carbon as exists in Earth's lithosphere and atmosphere (e.g., Lécuyer et al. 2000). However, studies have not yet fully elucidated how crustal or mantle differentiation on Venus could have produced huge volumes of carbonatite lava.

Few studies have attempted to estimate the depth profiles of lava channels on Venus because of the difficulty in making these estimates from the ~10–30 km horizontal footprint of Magellan altimetry data (Ford et al. 1993), which is substantially wider than the widths of most channels. However, post-Magellan studies have used radar clinometry at Baltis Vallis (Oshigami and Namiki, 2007) and six sinuous rilles and two valley networks (Oshigami et al. 2009) to obtain depth profiles that were resolved along the length of the channel.

One-dimensional models of channel formation by thermal erosion have been developed for application to Venus and other planets (e.g., Huppert and Sparks, 1985; Williams et al., 2001; Honda, 2005). Briefly, these models solve the heat balance for a lava flow to determine how far it can travel before solidifying given ground slope, the properties of the substrate, and lava composition, rheology, and thickness. For a certain type of lava, the thickness of the flow is adjusted to reproduce the observed length of the channel. The depth of the channel at the source is divided by the predicted vertical erosion rate to determine the effective duration of the lava flow. Oshigami et al. (2009) used this type of model to estimate that basaltic lava flows with initial thicknesses of ~2–6 m and durations of ~6–25 months could explain the lengths and depth profiles of six sinuous rilles, assuming present-day surface temperatures. The total lava volume associated with a typical sinuous rille on Venus is thus ~10¹² m³, ~1–3 orders of magnitude less than that suggested for a typical canale.
Some geodynamic models focus on the role of mantle upwellings and decompression melting to understand the origins of plains volcanism. Reese et al. (2007) suggest that the lithosphere has thickened over the last 1 Ga, causing a decrease in melting consistent with the impact crater population and resurfacing history. Smrekar and Sotin (2012) focused on modeling the formation of mantle plumes capable of producing the hotspots. As discussed above, available thermal emissivity data from VIRTIS, as well as Magellan radar emissivity measurements, suggest that recent, large-scale volcanism is confined to hotspot/mantle plume settings. If this observation is borne out by future missions, it may turn out that tiny amounts of volatiles from the lower mantle are required to enable decompression melting in mantle plumes. Localized upwelling confined to the upper mantle may not be capable of crossing the solidus today due to desiccation of the upper mantle by prior, widespread melting (e.g., Smrekar and Sotin, 2012). This hypothesis is potentially consistent with the interpretation of Ar isotope data as indicating that Venus' interior volatiles are ~25% outgassed (e.g., Kaula, 1999; O'Rourke and Korenga, 2015), if the upper mantle represents ~25% of the total mantle volume.

## 5.1.2 Lava Channels

Models of canali and sinuous rilles mainly focus on explaining their observed morphology, e.g., meander wavelengths, from Magellan radar images. Kargel et al. (1994) applied a scaling law, which describes the relationship between the meander wavelength and discharge at bank-full stage for streams on Earth, to estimate lava volumes required to form canali. These authors also calculated the duration of the lava flows from a simple estimate of how quickly canali meander could migrate, and found that a typical canale could form from ~10¹³ to 10¹⁵ m³ of lava, which could cover up to ~2.5 × 10⁶ km² with ~500-m thick flows. If the lava contained ~50 vol% carbonate minerals, the degassed CO₂ would have between 0.05% and 5% of the total mass of the present-day atmosphere. Perhaps older “generations” of canali once existed, contributing even more CO₂ to the atmosphere, but are not visible on the modern surface. Currently, Venus' atmosphere contains nearly as much carbon as exists in Earth's lithosphere and atmosphere (e.g., Lécuyer et al. 2000). However, studies have not yet fully elucidated how crustal or mantle differentiation on Venus could have produced huge volumes of carbonatite lava.

Few studies have attempted to estimate the depth profiles of lava channels on Venus because of the difficulty in making these estimates from the ~10–30 km horizontal footprint of Magellan altimetry data (Ford et al. 1993), which is substantially wider than the widths of most channels. However, post-Magellan studies have used radar clinometry at Baltis Vallis (Oshigami and Namiki, 2007) and six sinuous rilles and two valley networks (Oshigami et al. 2009) to obtain depth profiles that were resolved along the length of the channel.

One-dimensional models of channel formation by thermal erosion have been developed for application to Venus and other planets (e.g., Huppert and Sparks, 1985; Williams et al., 2001; Honda, 2005). Briefly, these models solve the heat balance for a lava flow to determine how far it can travel before solidifying given ground slope, the properties of the substrate, and lava composition, rheology, and thickness. For a certain type of lava, the thickness of the flow is adjusted to reproduce the observed length of the channel. The depth of the channel at the source is divided by the predicted vertical erosion rate to determine the effective duration of the lava flow. Oshigami et al. (2009) used this type of model to estimate that basaltic lava flows with initial thicknesses of ~2–6 m and durations of ~6–25 months could explain the lengths and depth profiles of six sinuous rilles, assuming present-day surface temperatures. The total lava volume associated with a typical sinuous rille on Venus is thus ~10¹² m³, ~1–3 orders of magnitude less than that suggested for a typical canale.
Existing modelling studies of lava channels on Venus have several limitations. First, they assume that Venus' surface temperature has remained constant, but it could have been higher or lower in the past. Second, models of sinuous rilles have not tested lava compositions other than Earth-like basalt. Third, no erosion models have been applied to canali. Since some proposed canali-forming lava compositions (e.g., carbonatite) have a lower melting temperature than the eroded substrate (i.e., basalt), mechanical erosion is likely more important than thermal erosion. Analogous models have been applied to the erosion of bedrock by water in attempts to calculate the discharge rates and volumes required to produce fluvial channels on Mars (e.g., Kleinhans 2005). Developing hybrid mechanical and thermal models of lava on Venus would be very useful for studies of channel formation. Measurements of the depth profiles of all channels, the grain sizes of the flow deposits and surrounding material, and any flow thicknesses via stratigraphy would provide key inputs to these models. Finally, any new information about the composition of surface material would help discriminate between models that feature different types of lavas and substrate materials.

### 5.1.3 Volcanic Rises

Volcanic rises are one of the few feature types for which there is an almost universally agreed formation mechanism: hotspots. The ten or so large volcanic rises on Venus are characterized by broad topographic swells, large positive gravity anomalies, and the presence of large volcanoes or coronae (e.g., McGill 1994), all of which are characteristic features of hotspots on Earth (see Sect. 2.1.2). Models of the interaction of plumes with the lithosphere seek to produce similar topographic uplift and gravity signatures (Kiefer and Hager, 1991) and de-compression melting (Smrekar and Parmentier, 1996) consistent with the presence of large volcanoes. These studies indicate a thermal lithospheric thickness of 100 to 150 km and upwellings from the core–mantle boundary that are consistent with hotspot characteristics. Modelling the initiation of mantle plumes at the core–mantle boundary as well as the observed number of hotspots (e.g., Smrekar and Sotin, 2012) provides important information about mantle convective processes, as discussed in Rolf et al. 2022 (this collection).

As described in Sect. 3.2, more recent modelling work focuses on the lithosphere flexure associated with large volcano emplacement. McGovern and Solomon (1997) noted the lack of flexural induced moats and extensional faults around large (>100 km diameter) volcanoes on Venus. They then used flexural models to calculate the volumes of extrusive lava flows required to fill the expected (but not observed) flexural moat. McGovern and Solomon (1997) concluded that large volcanoes and the filled moat are one structurally coherent volcanic unit, unlike those on Earth and Mars that are partially filled by mass wasting or edifice collapse. The interaction of stresses—related to magma chamber growth and magma ascent, plus lithosphere flexure from the growing edifice—favour lateral subsurface flow as edifices grow, creating oblate magma chambers and promoting dyking (e.g., Galgana et al., 2011; McGovern and Solomon, 1998; McGovern et al. 2013, 2014).

### 5.1.4 Coronae and Novae

The wide range of corona characteristics (Sect. 2.1.3) have spawned numerous interpretations and models. Most of these modelling studies succeed in recreating at least some of the corona fracture annulus, topographic profiles, and/or gravity signatures, and point to a progression of topographic shapes over time.

Early work on corona formation focused on their generally circular shape, topography, and associated volcanism to conclude that some form of mantle upwelling must be involved
Existing modelling studies of lava channels on Venus have several limitations. First, they assume that Venus' surface temperature has remained constant, but it could have been higher or lower in the past. Second, models of sinuous rilles have not tested lava compositions other than Earth-like basalt. Third, no erosion models have been applied to canali. Since some proposed canali-forming lava compositions (e.g., carbonatite) have a lower melting temperature than the eroded substrate (i.e., basalt), mechanical erosion is likely more important than thermal erosion. Analogous models have been applied to the erosion of bedrock by water in attempts to calculate the discharge rates and volumes required to produce fluvial channels on Mars (e.g., Kleinhans 2005). Developing hybrid mechanical and thermal models of lava on Venus would be very useful for studies of channel formation. Measurements of the depth profiles of all channels, the grain sizes of the flow deposits and surrounding material, and any flow thicknesses via stratigraphy would provide key inputs to these models. Finally, any new information about the composition of surface material would help discriminate between models that feature different types of lavas and substrate materials.

### 5.1.3 Volcanic Rises

Volcanic rises are one of the few feature types for which there is an almost universally agreed formation mechanism: hotspots. The ten or so large volcanic rises on Venus are characterized by broad topographic swells, large positive gravity anomalies, and the presence of large volcanoes or coronae (e.g., McGill 1994), all of which are characteristic features of hotspots on Earth (see Sect. 2.1.2). Models of the interaction of plumes with the lithosphere seek to produce similar topographic uplift and gravity signatures (Kiefer and Hager, 1991) and de-compression melting (Smrekar and Parmentier, 1996) consistent with the presence of large volcanoes. These studies indicate a thermal lithospheric thickness of 100 to 150 km and upwellings from the core–mantle boundary that are consistent with hotspot characteristics. Modelling the initiation of mantle plumes at the core–mantle boundary as well as the observed number of hotspots (e.g., Smrekar and Sotin, 2012) provides important information about mantle convective processes, as discussed in Rolf et al. 2022 (this collection).

As described in Sect. 3.2, more recent modelling work focuses on the lithosphere flexure associated with large volcano emplacement. McGovern and Solomon (1997) noted the lack of flexural induced moats and extensional faults around large (>100 km diameter) volcanoes on Venus. They then used flexural models to calculate the volumes of extrusive lava flows required to fill the expected (but not observed) flexural moat. McGovern and Solomon (1997) concluded that large volcanoes and the filled moat are one structurally coherent volcanic unit, unlike those on Earth and Mars that are partially filled by mass wasting or edifice collapse. The interaction of stresses—related to magma chamber growth and magma ascent, plus lithosphere flexure from the growing edifice—favour lateral subsurface flow as edifices grow, creating oblate magma chambers and promoting dyking (e.g., Galgana et al., 2011; McGovern and Solomon, 1998; McGovern et al. 2013, 2014).

### 5.1.4 Coronae and Novae

The wide range of corona characteristics (Sect. 2.1.3) have spawned numerous interpretations and models. Most of these modelling studies succeed in recreating at least some of the corona fracture annulus, topographic profiles, and/or gravity signatures, and point to a progression of topographic shapes over time.

Early work on corona formation focused on their generally circular shape, topography, and associated volcanism to conclude that some form of mantle upwelling must be involved
(Barsukov et al. 1986; Basilevsky 1986). A common proposition is that coronae form in response to stresses developed above an upwelling mantle plume or diapir, followed by gravitational relaxation or collapse due to magma withdrawal (e.g., Stofan et al. 1991, 1992; Janes et al. 1992; Squyres et al., 1992; Koch, 1994; Koch and Manga 1996 Grindrod and Hoogenboom, 2006; Gerya, 2014; Gülcher et al. 2020, 2023). Smrekar and Stofan (1997) introduced the first 2D numerical model incorporating plume-induced delamination, wherein lithospheric downwelling occurs at the edges of the laterally spreading plume head. These plume-induced delamination models were better at predicting the observed corona topographies than previous modelling, and placed the varying corona topographies into an evolutionary sequence (Smrekar and Stofan 1997; 1999). Some larger coronae may possess delamination or subduction, described below.

An additional class of models relies on volcanic construction to form coronae. Dombarod et al. (2007) argued that partial melting above transient mantle plumes that impinge only on the base of the thermal lithosphere can cause magmatic loading of the crust above. Subsequent lateral crustal flow may cause surface deformation, producing the elevated rim surrounding an interior depression commonly observed at coronae, as first described in a simple model by Stofan et al. (1991). McGovern et al. (2013) suggested that the vertical loads exerted on the lithosphere by large volcanoes could influence magma ascent pathways from the mantle to the surface, which in the case of low elastic thickness may produce annular ridges of volcanic material at the surface, matching the topographic signatures of some coronae. Moreover, for higher values of elastic thickness (~10–40 km), volcanoes are predicted to form instead of coronae. However, as discussed above, many larger coronae have elastic thickness of ~20–40 km.

The first study to use two-phase flow to model the pressure-release melting process at coronae shows that topographic rims can be produced by uplift above the buoyant melt concentrations (Schools and Smrekar 2024). This model also predicts high strain rate shearing that indicates the location of fracturing at rims. This model shows good agreement with a recent study of the shape of corona rim topography and the relationship to fracture locations (Sabbeth et al. 2024). This model creates rims at an early rather than late stage of evolution, suggesting an alternate evolutionary sequence to prior models.

The first 3D numerical study on corona formation involved thermal mantle plume impingement into warm and thin Venusian lithosphere (Gerya, 2014), assuming a thin elastic lithosphere (Anderson and Smrekar 2006). The results of this study suggest that plume-induced convection in a weak, ductile crust may be a plausible origin for some small-to-moderate sized (<200 km) coronae on Venus. This process may be analogous to those believed responsible for the formation of ancient terrestrial gneiss complexes (Campbell and Hill, 1988). Gerya (2014) noted that the first stage of uplift over a plume predicts radial fracturing, similar to ‘novae’ that are sometimes associated with coronae. Indeed, some prior studies did suggest that novae represent either an early stage or a “failed” corona (e.g., Janes and Squyres 1995; Stofan et al., 1997; Krassilnikov and Head 2003). Ernst et al. (2003) describe numerous radiating fracture patterns on Venus that they compare to dyke swarms on Earth. Gülcher et al. (2020) expanded on 3D numerical studies of plume-induced corona formation, defining different plume–lithosphere interaction scenarios possible at large coronae, such as lithospheric delamination, subduction (see Sect. 2.1.3), and an underplated plume, dependent on lithospheric and mantle plume properties. Gülcher et al. (2023) model lateral variations in crustal and/or lithospheric thicknesses to create asymmetric coronae with a prolonged tectonic and magmatic lifetime to develop, highlighting the importance of lateral variations in lithospheric properties for geodynamics on Venus.
(Barsukov et al. 1986; Basilevsky 1986). A common proposition is that coronae form in response to stresses developed above an upwelling mantle plume or diapir, followed by gravitational relaxation or collapse due to magma withdrawal (e.g., Stofan et al. 1991, 1992; Janes et al. 1992; Squyres et al., 1992; Koch, 1994; Koch and Manga 1996 Grindrod and Hoogenboom, 2006; Gerya, 2014; Gülcher et al. 2020, 2023). Smrekar and Stofan (1997) introduced the first 2D numerical model incorporating plume-induced delamination, wherein lithospheric downwelling occurs at the edges of the laterally spreading plume head. These plume-induced delamination models were better at predicting the observed corona topographies than previous modelling, and placed the varying corona topographies into an evolutionary sequence (Smrekar and Stofan 1997; 1999). Some larger coronae may possess delamination or subduction, described below.

An additional class of models relies on volcanic construction to form coronae. Dombarod et al. (2007) argued that partial melting above transient mantle plumes that impinge only on the base of the thermal lithosphere can cause magmatic loading of the crust above. Subsequent lateral crustal flow may cause surface deformation, producing the elevated rim surrounding an interior depression commonly observed at coronae, as first described in a simple model by Stofan et al. (1991). McGovern et al. (2013) suggested that the vertical loads exerted on the lithosphere by large volcanoes could influence magma ascent pathways from the mantle to the surface, which in the case of low elastic thickness may produce annular ridges of volcanic material at the surface, matching the topographic signatures of some coronae. Moreover, for higher values of elastic thickness (~10–40 km), volcanoes are predicted to form instead of coronae. However, as discussed above, many larger coronae have elastic thickness of ~20–40 km.

The first study to use two-phase flow to model the pressure-release melting process at coronae shows that topographic rims can be produced by uplift above the buoyant melt concentrations (Schools and Smrekar 2024). This model also predicts high strain rate shearing that indicates the location of fracturing at rims. This model shows good agreement with a recent study of the shape of corona rim topography and the relationship to fracture locations (Sabbeth et al. 2024). This model creates rims at an early rather than late stage of evolution, suggesting an alternate evolutionary sequence to prior models.

The first 3D numerical study on corona formation involved thermal mantle plume impingement into warm and thin Venusian lithosphere (Gerya, 2014), assuming a thin elastic lithosphere (Anderson and Smrekar 2006). The results of this study suggest that plume-induced convection in a weak, ductile crust may be a plausible origin for some small-to-moderate sized (<200 km) coronae on Venus. This process may be analogous to those believed responsible for the formation of ancient terrestrial gneiss complexes (Campbell and Hill, 1988). Gerya (2014) noted that the first stage of uplift over a plume predicts radial fracturing, similar to ‘novae’ that are sometimes associated with coronae. Indeed, some prior studies did suggest that novae represent either an early stage or a “failed” corona (e.g., Janes and Squyres 1995; Stofan et al., 1997; Krassilnikov and Head 2003). Ernst et al. (2003) describe numerous radiating fracture patterns on Venus that they compare to dyke swarms on Earth. Gülcher et al. (2020) expanded on 3D numerical studies of plume-induced corona formation, defining different plume–lithosphere interaction scenarios possible at large coronae, such as lithospheric delamination, subduction (see Sect. 2.1.3), and an underplated plume, dependent on lithospheric and mantle plume properties. Gülcher et al. (2023) model lateral variations in crustal and/or lithospheric thicknesses to create asymmetric coronae with a prolonged tectonic and magmatic lifetime to develop, highlighting the importance of lateral variations in lithospheric properties for geodynamics on Venus.
Alternatively, models involving lithospheric downwelling with no associated mantle plume, such Rayleigh-Taylor instabilities, may also account for some of the topographic characteristics of coronae (e.g., Tackley and Stevenson, 1991; Grindrod and Hoogenboom, 2006; Hoogenboom and Houseman 2006). In these models, the nominal instability is caused by a dense mantle lithospheric layer over a less dense asthenosphere. A hybrid hypothesis involves the interaction between a mantle upwelling associated with large rifts and an adjacent downwelling instability, which may account for the spatial association of coronae with rift zones (Piskorz et al. 2014).

Since many different corona formation models can reproduce at least some of the key corona features, and both up- and downwelling of different sizes are common within the mantle convection regimes that may prevail within Venus (see Rolf et al. 2022, this collection), there may be multiple plausible formation scenarios for the diversity of observed coronae. Additionally, different corona morphologies may also represent different stages in their evolution. In particular, Gülcher et al. (2020) found that the topographic profile displayed by a corona may be completely isostatically inverted when an active plume interacting with the lithosphere cools down and fully crystallizes over time. These authors' analysis reveals that observed coronae on Venus may fall on a spectrum between early-stage ("active") and late-stage ("inactive") structures. However, different evolutionary sequences are possible (e.g., Schools and Smrekar 2024).

## 5.2 Formation of Tectonic Features

A key aspect of all modelling efforts to date is that subduction under Venusian conditions seems to be short-lived and, in contrast to modelling investigations under Earth-like conditions (e.g. Gerya et al. 2015; Baes et al., 2016), self-sustaining subduction zone does not develop on Venus. The exact conditions and behaviour of slab break-up is model- and condition dependent. For example, in the analogue models of Davaille et al. (2017), the slab separates into segments due to tearing caused by the brittle elasto-plastic behaviour of the lithosphere, while in the numerical models of Gülcher et al. (2020, 2023) the slab can coherently neck and detach, or tear into multiple segments that will caused directional slab retreat and detachment, based on the rheological parameters used. Moreover, the densification of slab material by eclogitization parameterized in the models seems to be a key factor in driving crustal recycling into the deeper mantle (Gülcher et al. 2023).

### 5.2.1 Rifts and Radiating Fracture Networks

Stoddard and Jurdy (2012) compared topographic profiles of selected rifts and hotspots on Earth and Venus. They calculated correlation coefficients between each topographic profile along a rift and the average of all profiles from that rift. These correlation coefficients were much higher for terrestrial rifts than Venusian rifts—the latter appeared most similar to terrestrial slow spreading rifts. Ghail (2015) found that the topographic profile across Venusian rifts are consistent with different rates of extension below a thermally-induced crustal detachment. Tectonic fractures characterize 'slower' rifts (e.g., Diana Chasma), while 'faster' rifts (e.g., Parga Chasma) host large numbers of coronae.

As discussed in Sect. 3.2, Venus possesses over 100 giant radial fracture systems, with an average radius of ~325 km and a maximum of >2000 km (e.g., Grosfils and Head 1994a, 1994b). Moreover, more such systems are likely to be found with future, higher-resolution radar imagery (Ernst et al. 2003). Early studies noted the similarity of the radial fractures to radial dyke swarms on Earth (McKenzie et al. 1992; Grosfils and Head 1994a, 1994b;
Alternatively, models involving lithospheric downwelling with no associated mantle plume, such Rayleigh–Taylor instabilities, may also account for some of the topographic characteristics of coronae (e.g., Tackley and Stevenson, 1991; Grindrod and Hoogenboom, 2006; Hoogenboom and Houseman 2006). In these models, the nominal instability is caused by a dense mantle lithospheric layer over a less dense asthenosphere. A hybrid hypothesis involves the interaction between a mantle upwelling associated with large rifts and an adjacent downwelling instability, which may account for the spatial association of coronae with rift zones (Piskorz et al. 2014).

Since many different corona formation models can reproduce at least some of the key corona features, and both up- and downwelling of different sizes are common within the mantle convection regimes that may prevail within Venus (see Rolf et al. 2022, this collection), there may be multiple plausible formation scenarios for the diversity of observed coronae. Additionally, different corona morphologies may also represent different stages in their evolution. In particular, Gülcher et al. (2020) found that the topographic profile displayed by a corona may be completely isostatically inverted when an active plume interacting with the lithosphere cools down and fully crystallizes over time. These authors’ analysis reveals that observed coronae on Venus may fall on a spectrum between early-stage (“active”) and late-stage (“inactive”) structures. However, different evolutionary sequences are possible (e.g., Schools and Smrekar 2024).

## 5.2 Formation of Tectonic Features

A key aspect of all modelling efforts to date is that subduction under Venusian conditions seems to be short-lived and, in contrast to modelling investigations under Earth-like conditions (e.g. Gerya et al. 2015; Baes et al., 2016), self-sustaining subduction zone does not develop on Venus. The exact conditions and behaviour of slab break-up is model- and condition dependent. For example, in the analogue models of Davaille et al. (2017), the slab separates into segments due to tearing caused by the brittle elasto-plastic behaviour of the lithosphere, while in the numerical models of Gülcher et al. (2020, 2023) the slab can coherently neck and detach, or tear into multiple segments that will caused directional slab retreat and detachment, based on the rheological parameters used. Moreover, the densification of slab material by eclogitization parameterized in the models seems to be a key factor in driving crustal recycling into the deeper mantle (Gülcher et al. 2023).

### 5.2.1 Rifts and Radiating Fracture Networks

Stoddard and Jurdy (2012) compared topographic profiles of selected rifts and hotspots on Earth and Venus. They calculated correlation coefficients between each topographic profile along a rift and the average of all profiles from that rift. These correlation coefficients were much higher for terrestrial rifts than Venusian rifts—the latter appeared most similar to terrestrial slow spreading rifts. Ghail (2015) found that the topographic profile across Venusian rifts are consistent with different rates of extension below a thermally-induced crustal detachment. Tectonic fractures characterize ‘slower’ rifts (e.g., Diana Chasma), while ‘faster’ rifts (e.g., Parga Chasma) host large numbers of coronae.

As discussed in Sect. 3.2, Venus possesses over 100 giant radial fracture systems, with an average radius of ~325 km and a maximum of >2000 km (e.g., Grosfils and Head 1994a, 1994b). Moreover, more such systems are likely to be found with future, higher-resolution radar imagery (Ernst et al. 2003). Early studies noted the similarity of the radial fractures to radial dyke swarms on Earth (McKenzie et al. 1992; Grosfils and Head 1994a, 1994b;
Ernst et al. 1995), although some modelled their formation as faults formed from dome up-
lift from a mantle upwelling (Stofan et al., 1991; Janes et al. 1992; Cyr and Melosh 1993),
akin to novae formation. Conceptual and analytical models of the dyke formation mech-
anism (McKenzie et al. 1992; Grosfils and Head 1994a; Koenig and Pollard 1998) used
terrestrial field and modelling work to estimate surface stresses and resultant strains on the
Venus surface. Grindrod et al. (2005) found that the measured strain at four selected radial
fracture centres is too large to be solely uplift related and must be primarily dyke driven, but
concluded that the formation process is likely to be a combination of dyking and uplift. The
numerical model of Galgana et al. (2013) accounted for both flexural stress from lithosphere
uplift and the stress of magma chamber inflation. These authors found that edifice growth
creates compressive stresses that eventually halt magma ascent and force existing, ascending
dykes to grow laterally, thus becoming radial dykes. As previously discussed with corona
models, it is probable that similar features such as radial corona fracture systems may have
differing formation mechanisms dependent on emplacement conditions such as lithosphere
thickness or strain from regional tectonics, and no single formati

5.2.2 Plume-Induced Subduction

The edges of some large coronae have been proposed to be sites of subduction (e.g., McKen-
zie et al. 1992; Sandwell and Schubert 1992b; 1995), with the concept of plume-induced
subduction probably first described by Sandwell and Schubert (1992b) to explain coronae.
Subsequent focus in the terrestrial community on understanding the initiation of subduction
as the first step in developing plate tectonics led to a variety of models of plume-induced
subduction (e.g., Ueda et al. 2008; Burov and Cloetingh 2010; Gerya et al. 2015). These
models show how a long-lived, buoyant mantle plume can overcome the strength of and
thus penetrate the lithosphere. The plume head then intrudes between the upper crust and
dense mantle lithosphere, pushing the lithosphere downward into the asthenosphere, even-
tually initiating self-sustained subduction (Ueda et al. 2008; Stern and Gerya 2018).

Numerical explorations of this theory in 3D were undertaken to investigate subduction initiation by a thermal plume in the Archean on Earth (Gerya et al. 2015) and by a thermal-chemical plume on the modern Earth (Baes et al., 2016). Gerya et al. (2015) suggested that plume–lithosphere interactions on Archean Earth initiated subduction zones, which possibly led to the onset of plate tectonics. At a minimum, such complete breaks in the lithosphere are needed to allow individual plates to form. These workers proposed that a combination of three key physical factors is needed to trigger self-sustained, plume-induced subduction: a strong, negatively buoyant lithosphere, focused magmatic weakening leading to thinning of the lithosphere above the plume, and lubrication of the upper slab interface by hydrated crust (Gerya et al. 2015). The first and third factor may be (partially) absent on Venus (e.g. Huang et al. 2013). However, other means of weakening slab interfaces are possible in addition to hydrated crust, such as grain size reduction (Li and Gurnis 2023).

Gülcher et al. (2020) expanded on 3D numerical studies of plume-induced subduction, mapping out the dependency of different plume–lithosphere interaction scenarios on three key factors: plume buoyancy, lithospheric strength, and crustal thickness. Short-lived subduction episodes, leading to slab detachment, were identified in models that featured high plume buoyancy in combination with a low crust–mantle boundary temperature (by a relatively strong lithosphere through a colder lithosphere and/or a thin crust). For higher crust–mantle boundary temperatures (in that study found to be ~1100 K), lithospheric dripping developed instead of retreating slab segments. Follow-up work (Gülcher et al. 2023) on 3D plume-impingement upon laterally changing crustal thicknesses (i.e., lowland transitioning
Ernst et al. 1995), although some modelled their formation as faults formed from dome up-
lift from a mantle upwelling (Stofan et al., 1991; Janes et al. 1992; Cyr and Melosh 1993),
akin to novae formation. Conceptual and analytical models of the dyke formation mech-
anism (McKenzie et al. 1992; Grosfils and Head 1994a; Koenig and Pollard 1998) used
terrestrial field and modelling work to estimate surface stresses and resultant strains on the
Venus surface. Grindrod et al. (2005) found that the measured strain at four selected radial
fracture centres is too large to be solely uplift related and must be primarily dyke driven, but
concluded that the formation process is likely to be a combination of dyking and uplift. The
numerical model of Galgana et al. (2013) accounted for both flexural stress from lithosphere
uplift and the stress of magma chamber inflation. These authors found that edifice growth
creates compressive stresses that eventually halt magma ascent and force existing, ascending
dykes to grow laterally, thus becoming radial dykes. As previously discussed with corona
models, it is probable that similar features such as radial corona fracture systems may have
differing formation mechanisms dependent on emplacement conditions such as lithosphere
thickness or strain from regional tectonics, and no single formati

5.2.2 Plume-Induced Subduction

The edges of some large coronae have been proposed to be sites of subduction (e.g., McKen-
zie et al. 1992; Sandwell and Schubert 1992b; 1995), with the concept of plume-induced
subduction probably first described by Sandwell and Schubert (1992b) to explain coronae.
Subsequent focus in the terrestrial community on understanding the initiation of subduction
as the first step in developing plate tectonics led to a variety of models of plume-induced
subduction (e.g., Ueda et al. 2008; Burov and Cloetingh 2010; Gerya et al. 2015). These
models show how a long-lived, buoyant mantle plume can overcome the strength of and
thus penetrate the lithosphere. The plume head then intrudes between the upper crust and
dense mantle lithosphere, pushing the lithosphere downward into the asthenosphere, even-
tually initiating self-sustained subduction (Ueda et al. 2008; Stern and Gerya 2018).

Numerical explorations of this theory in 3D were undertaken to investigate subduction initiation by a thermal plume in the Archean on Earth (Gerya et al. 2015) and by a thermal-chemical plume on the modern Earth (Baes et al., 2016). Gerya et al. (2015) suggested that plume–lithosphere interactions on Archean Earth initiated subduction zones, which possibly led to the onset of plate tectonics. At a minimum, such complete breaks in the lithosphere are needed to allow individual plates to form. These workers proposed that a combination of three key physical factors is needed to trigger self-sustained, plume-induced subduction: a strong, negatively buoyant lithosphere, focused magmatic weakening leading to thinning of the lithosphere above the plume, and lubrication of the upper slab interface by hydrated crust (Gerya et al. 2015). The first and third factor may be (partially) absent on Venus (e.g. Huang et al. 2013). However, other means of weakening slab interfaces are possible in addition to hydrated crust, such as grain size reduction (Li and Gurnis 2023).

Gülcher et al. (2020) expanded on 3D numerical studies of plume-induced subduction, mapping out the dependency of different plume–lithosphere interaction scenarios on three key factors: plume buoyancy, lithospheric strength, and crustal thickness. Short-lived subduction episodes, leading to slab detachment, were identified in models that featured high plume buoyancy in combination with a low crust–mantle boundary temperature (by a relatively strong lithosphere through a colder lithosphere and/or a thin crust). For higher crust–mantle boundary temperatures (in that study found to be ~1100 K), lithospheric dripping developed instead of retreating slab segments. Follow-up work (Gülcher et al. 2023) on 3D plume-impingement upon laterally changing crustal thicknesses (i.e., lowland transitioning
into a plateau) confirmed the occurrence of a short-lived subduction arc on the lowland-side (thinned crust). Several key features of retreating subduction zones were reproduced in these 3D models, such as an outer rise surrounding a deep trench, a topographic feature observed at several Venusian coronae.

Theories of coronae formation involving plume-induced lithospheric subduction are supported by the successful reproduction of some of the tectonic features observed at several coronae margins in 3D analogue experiments (Davaille et al. 2017). They utilized analogue materials to represent the full range of structure and rheology for both the brittle lithosphere and convecting mantle, which is not achieved in numerical studies of corona formation. For example the lithosphere, which forms via drying of surface, has pervasive cracks that allow asymmetry to develop. In particular, this study is able to reproduce characteristic features observed at, for example, Artemis and Quetzalpetlal coronae, such as the arcuate outer rise surrounding a trench and rim. The outer rise of these coronae features extensional deformation, interpreted to result from bending of the subducting plate. Recent models of corona formation predict the locations of faulting where rims are flexed upward above buoyant partially molten regions at the base of the lithosphere (Schools and Smrekar 2024). In these models, topography surface faulting can be attributed to magmatic processes at depth due to plume evolution.

# 6 Is Venus the Archean Earth, Proterozoic Earth, or Something Completely Different?

Venus' apparent lack of modern Earth-like plate tectonics as well as its basaltic crust, mantle hotspots, and high surface temperature has led to tantalizing comparisons to Archean Earth (Morgan 1983; Hansen 2018; Harris and Bédard 2014). One challenge for assessing whether the Venus of today is a good representation of Earth of the past (i.e., Hadean and/or Archean) is that most of Earth's earliest history (i.e., 4.5-4.0 Ga) has been removed by plate tectonics, leaving primarily geochemical data from limited locations to piece together evidence of past processes. Similarly, very limited chemical data exist for Venus, and then only for a handful of locations. Venus and early Earth offer complementary, though very incomplete, views of the dominant processes on a pre-plate tectonic planet. Venus has been described as having vertical tectonics (Solomon and Head 1982; Phillips and Malin 1983; Morgan and Phillips 1983), dominated by mantle plumes. Similarly, Archean Earth was likely driven by vertical processes of mantle plume-initiated rifting and collision (Smithies et al., 2005a; Condie et al., 2016; Bédard 2018; Brown et al. 2020), and vertical return flow via lithospheric delamination (Johnson et al., 2014). As discussed below, this assumption is further supported by our understanding of Archean cratons and the known rock types and surface features of Venus (Hansen 2007, 2015, 2018; Harris and Bédard 2014, 2015).

## 6.1 Comparison with Archean Tectonic Systems

Little is known about the tectonic regime and development of the Archean (4.0–2.5 Ga) on Earth because the rock record is not widely exposed or preserved relative to younger terranes and cratons (Brown et al. 2020; Hawkesworth et al. 2020). There is debate on the timing of the initiation of plate tectonics and thus interpretations of a modern plate tectonic system cannot be robustly confirmed for the Archean (Condie and Kröner 2008; Stern 2008; Hamilton 2011, 1998). However, it is expected that the thermal regime under which the Archean crust developed had mantle potential temperatures ($T_p$) ~300–500 K higher than
into a plateau) confirmed the occurrence of a short-lived subduction arc on the lowland-side (thinned crust). Several key features of retreating subduction zones were reproduced in these 3D models, such as an outer rise surrounding a deep trench, a topographic feature observed at several Venusian coronae.

Theories of coronae formation involving plume-induced lithospheric subduction are supported by the successful reproduction of some of the tectonic features observed at several coronae margins in 3D analogue experiments (Davaille et al. 2017). They utilized analogue materials to represent the full range of structure and rheology for both the brittle lithosphere and convecting mantle, which is not achieved in numerical studies of corona formation. For example the lithosphere, which forms via drying of surface, has pervasive cracks that allow asymmetry to develop. In particular, this study is able to reproduce characteristic features observed at, for example, Artemis and Quetzalpetlal coronae, such as the arcuate outer rise surrounding a trench and rim. The outer rise of these coronae features extensional deformation, interpreted to result from bending of the subducting plate. Recent models of corona formation predict the locations of faulting where rims are flexed upward above buoyant partially molten regions at the base of the lithosphere (Schools and Smrekar 2024). In these models, topography surface faulting can be attributed to magmatic processes at depth due to plume evolution.

# 6 Is Venus the Archean Earth, Proterozoic Earth, or Something Completely Different?

Venus' apparent lack of modern Earth-like plate tectonics as well as its basaltic crust, mantle hotspots, and high surface temperature has led to tantalizing comparisons to Archean Earth (Morgan 1983; Hansen 2018; Harris and Bédard 2014). One challenge for assessing whether the Venus of today is a good representation of Earth of the past (i.e., Hadean and/or Archean) is that most of Earth's earliest history (i.e., 4.5-4.0 Ga) has been removed by plate tectonics, leaving primarily geochemical data from limited locations to piece together evidence of past processes. Similarly, very limited chemical data exist for Venus, and then only for a handful of locations. Venus and early Earth offer complementary, though very incomplete, views of the dominant processes on a pre-plate tectonic planet. Venus has been described as having vertical tectonics (Solomon and Head 1982; Phillips and Malin 1983; Morgan and Phillips 1983), dominated by mantle plumes. Similarly, Archean Earth was likely driven by vertical processes of mantle plume-initiated rifting and collision (Smithies et al., 2005a; Condie et al., 2016; Bédard 2018; Brown et al. 2020), and vertical return flow via lithospheric delamination (Johnson et al., 2014). As discussed below, this assumption is further supported by our understanding of Archean cratons and the known rock types and surface features of Venus (Hansen 2007, 2015, 2018; Harris and Bédard 2014, 2015).

## 6.1 Comparison with Archean Tectonic Systems

Little is known about the tectonic regime and development of the Archean (4.0–2.5 Ga) on Earth because the rock record is not widely exposed or preserved relative to younger terranes and cratons (Brown et al. 2020; Hawkesworth et al. 2020). There is debate on the timing of the initiation of plate tectonics and thus interpretations of a modern plate tectonic system cannot be robustly confirmed for the Archean (Condie and Kröner 2008; Stern 2008; Hamilton 2011, 1998). However, it is expected that the thermal regime under which the Archean crust developed had mantle potential temperatures ($T_p$) ~300–500 K higher than
ambient conditions today (1620 ± 50 K). There is almost no rock record for the Hadean (>4.0 Ga) as most of the information is inferred from detrital zircons, the Acasta gneiss, or isotopic model ages (Harrison 2009; O'Neil et al., 2012; Roth et al. 2014; O'Neil and Carlson, 2017; Reimink et al. 2020). Earth's Archean cratons are composed of two distinct belts or "terranes". One of these major terranes, the greenstone-granite belts, primarily record surficial rock sequences, whereas the other major terrane, the granulite-gneiss belts, record middle to lower crust metamorphic conditions (Condie 1981; Kröner 1985). Together, it is likely that greenstone-granite and granulite-gneiss belts represent a glimpse into the formation of primitive terrestrial crust or proto-continental crust (Smithies et al., 2005a; Thurston 2015; Bédard 2018).

Greenstone-granite belts are linear to curvilinear rock suites (i.e., ~10–25 km wide, ~100–300 km long, ~5–30 km thick). These dimensions are similar to those of the many tessera inliers distributed around Venus (e.g., Ivanov and Head, 2011). Terrestrial greenstone-granite belts have a characteristic stratigraphy of volcanic and volcaniclastic rocks, and sedimentary rocks accompanied by granitic rocks including tonalite-trondhjemite-granodiorite (TTG) suites (e.g., Condie 1981; Anhaeusser 2014; Thurston 2015). All greenstone belts are metamorphosed, but the degree (i.e., granulite, amphibolite, greenschist, prehnite-pumpellyite facies) and type (i.e. regional, contact, retrograde) of metamorphism are unique to each one. The volcanic suites are divided into an older subaqueous lower komatiite-tholeiitic basalt series and an upper, younger (by 3 to 30 Ma) bimodal sequence composed of tholeiitic basalt and calc-alkaline basalt, andesite, and rhyolite (Anhaeusser 2014; Thurston 2015). Greenstone belt formation and origin (i.e., a plate-tectonic origin or not) has yet to be resolved. However, they may be analogous to oceanic plateaus, volcanic arcs, ophiolites, or flood basalt suites that, at some level, may involve a mantle plume, particularly with respect to the eruption of the lower ultramafic-mafic volcanic series (de Wit and Ashwal, 1995; Smithies et al., 2005a; Bédard et al. 2003, 2013; Bédard 2006; Condie and Benn 2006; Anhaeusser 2014; Thurston 2015). The calc-alkaline nature of the upper silicic volcanic rocks is evidence that favours a volcanic arc-like origin, but similar rocks can be found in extensional tectonic settings since the calc-alkaline signature is a consequence of oxidizing magma conditions (Scott et al. 2002; Wyman et al. 2002; Arculus 2003; Smithies et al. 2005b; Bédard 2018). Modern (Cambrian to present) examples of greenstone-like belts exist and are associated with subduction and extensional tectonic settings but lack komatiitic rocks and banded-iron formations (Turner et al. 2014; Shellnutt and Dostal 2019).

At first glance, the topography of Venus resembles the continental and oceanic crustal dichotomy on Earth, in which tesserae are representative of 'continental' crust and the plains 'oceanic' crust (e.g. Smrekar et al. 2018). Near-infrared mapping spectrometer data suggest that, at least in one location, the plains and tesserae are compositionally different (Hashimoto et al. 2008; Mueller et al. 2008; Gilmore et al. 2015). Crustal thickness estimates indicate that plains are possibly ~10–20 km thick, whereas the tesserae may be ~65 km thick or more (see Sect. 3.1). These estimates are within the range of crustal thicknesses estimated for greenstone-granite belts and granulite-gneiss belts. The inferred compositional differences are consistent with the differences between terrestrial oceanic and continental crust. The major elemental composition of basalt measured at the Venera 14 landing site is very similar to olivine tholeiite of Archean greenstone belts, and the estimated primary melt compositions are ultramafic but not komatiitic (Shellnutt 2016, 2021). In comparison, the estimated composition of the rock at the Venera 8 landing site could be granodiorite/dacite and broadly resemble the calc-alkaline silicic rocks from the bimodal volcanic sequence of greenstone belts. However, uncertainty in its composition means that the Venera 8 rock could be lamprophyric (Nikolayeva 1990; Basilevsky et al. 1992; Kargel et al. 1993; Shellnutt 2019). Mantle
ambient conditions today (1620 ± 50 K). There is almost no rock record for the Hadean (>4.0 Ga) as most of the information is inferred from detrital zircons, the Acasta gneiss, or isotopic model ages (Harrison 2009; O'Neil et al., 2012; Roth et al. 2014; O'Neil and Carlson, 2017; Reimink et al. 2020). Earth's Archean cratons are composed of two distinct belts or "terranes". One of these major terranes, the greenstone-granite belts, primarily record surficial rock sequences, whereas the other major terrane, the granulite-gneiss belts, record middle to lower crust metamorphic conditions (Condie 1981; Kröner 1985). Together, it is likely that greenstone-granite and granulite-gneiss belts represent a glimpse into the formation of primitive terrestrial crust or proto-continental crust (Smithies et al., 2005a; Thurston 2015; Bédard 2018).

Greenstone-granite belts are linear to curvilinear rock suites (i.e., ~10–25 km wide, ~100–300 km long, ~5–30 km thick). These dimensions are similar to those of the many tessera inliers distributed around Venus (e.g., Ivanov and Head, 2011). Terrestrial greenstone-granite belts have a characteristic stratigraphy of volcanic and volcaniclastic rocks, and sedimentary rocks accompanied by granitic rocks including tonalite-trondhjemite-granodiorite (TTG) suites (e.g., Condie 1981; Anhaeusser 2014; Thurston 2015). All greenstone belts are metamorphosed, but the degree (i.e., granulite, amphibolite, greenschist, prehnite-pumpellyite facies) and type (i.e. regional, contact, retrograde) of metamorphism are unique to each one. The volcanic suites are divided into an older subaqueous lower komatiite-tholeiitic basalt series and an upper, younger (by 3 to 30 Ma) bimodal sequence composed of tholeiitic basalt and calc-alkaline basalt, andesite, and rhyolite (Anhaeusser 2014; Thurston 2015). Greenstone belt formation and origin (i.e., a plate-tectonic origin or not) has yet to be resolved. However, they may be analogous to oceanic plateaus, volcanic arcs, ophiolites, or flood basalt suites that, at some level, may involve a mantle plume, particularly with respect to the eruption of the lower ultramafic-mafic volcanic series (de Wit and Ashwal, 1995; Smithies et al., 2005a; Bédard et al. 2003, 2013; Bédard 2006; Condie and Benn 2006; Anhaeusser 2014; Thurston 2015). The calc-alkaline nature of the upper silicic volcanic rocks is evidence that favours a volcanic arc-like origin, but similar rocks can be found in extensional tectonic settings since the calc-alkaline signature is a consequence of oxidizing magma conditions (Scott et al. 2002; Wyman et al. 2002; Arculus 2003; Smithies et al. 2005b; Bédard 2018). Modern (Cambrian to present) examples of greenstone-like belts exist and are associated with subduction and extensional tectonic settings but lack komatiitic rocks and banded-iron formations (Turner et al. 2014; Shellnutt and Dostal 2019).

At first glance, the topography of Venus resembles the continental and oceanic crustal dichotomy on Earth, in which tesserae are representative of 'continental' crust and the plains 'oceanic' crust (e.g. Smrekar et al. 2018). Near-infrared mapping spectrometer data suggest that, at least in one location, the plains and tesserae are compositionally different (Hashimoto et al. 2008; Mueller et al. 2008; Gilmore et al. 2015). Crustal thickness estimates indicate that plains are possibly ~10–20 km thick, whereas the tesserae may be ~65 km thick or more (see Sect. 3.1). These estimates are within the range of crustal thicknesses estimated for greenstone-granite belts and granulite-gneiss belts. The inferred compositional differences are consistent with the differences between terrestrial oceanic and continental crust. The major elemental composition of basalt measured at the Venera 14 landing site is very similar to olivine tholeiite of Archean greenstone belts, and the estimated primary melt compositions are ultramafic but not komatiitic (Shellnutt 2016, 2021). In comparison, the estimated composition of the rock at the Venera 8 landing site could be granodiorite/dacite and broadly resemble the calc-alkaline silicic rocks from the bimodal volcanic sequence of greenstone belts. However, uncertainty in its composition means that the Venera 8 rock could be lamprophyric (Nikolayeva 1990; Basilevsky et al. 1992; Kargel et al. 1993; Shellnutt 2019). Mantle
potential temperature estimates of Venusian basalts are variable: the rocks at the Venera 13 and Venera 14 sites are probably derived from a thermal regime similar to modern Earth, but estimates of the thermal regime for rocks at the Vega 2 landing site indicate an anomalously hot (2051 ± 167 K) regime (Lee et al. 2009; Weller and Duncan 2015; Shellnutt 2016).

There is debate on the precise composition of the tesserae, possible depositional processes, existence of a hydrosphere, formation of coronae, the mantle thermal regime, and the tectonic regime that was operating on ancient Venus. Recent studies indicate that the tesserae could be composed of mafic volcanic-sedimentary sequences rather than intermediate to silicic volcanic or plutonic rocks (Byrne et al. 2021). No *in situ* geochemical data exist for tesserae, and the high U (2.2 ± 0.7 ppm), Th (6.5 ± 2.2 ppm), and K₂O (4.0 ± 1.2 wt%) contents reported at the Venera 8 landing site could be indicative of a lamprophyre (alkali basalt) rather than a dacitic/syenitic rock (Basilevsky et al. 1992). It is possible that Venus had a hydrosphere during the Archean, but lithified sedimentary rocks (or their metamorphic equivalents) derived by mechanical weathering and chemical precipitation have not been verified (Florensky et al. 1977; Basilevsky et al. 1985). At present, the only evidence for the existence of sulphur-rich evaporites (e.g., gypsum, anhydrite) is the high SO₃ (4.7 ± 1.5 wt%) content measured at the Vega 2 landing site, but sulphates may form by weathering under current Venus conditions (Fegley and Prinn 1989; Fegley et al. 1997; Bullock and Grinspoon 2001; Dyar et al. 2021).

Earth's continental crust began to form during the Archean. One key reason why determining whether or not tesserae are true analogues of continents is that massive volumes of felsic crust require basaltic melt extraction from the mantle, ideally in the presence of water (e.g. Campbell 2002; Bonin 2012). Thus, tesserae may host the geochemical fingerprints of past water. This is a critical question not only for understanding the divergent evolution of Venus and Earth, but also for establishing Venus' potential habitability (Westall et al. 2023). Venus is the only other rocky body in the Solar System with a possible substantial volume of silicic crust (Shellnutt 2013; Wang et al. 2022). The formation and erosion of Earth's continental crust into the oceans is proposed to be the source of the elements needed for life to flourish (Duncan and Dasgupta 2017). In addition to the plume-induced subduction mechanism discussed above, some coronae types may form via delamination (Hoogenboom and Houseman 2006), possibly assisted by mantle flow due to extension (Piskorz et al. 2014). Moreover, Venus' large-scale ridge belts may be a result of compression above mantle downwelling (e.g. Zuber 1990). Thus, a variety of features on Venus may be indicative of crustal recycling and large-scale mantle melting.

Venus' high surface temperature creates a hot lithosphere and provides a thermal/mechanical analogue to conditions on early Earth. Davaille et al. (2017) argued that the apparent plume-induced subduction seen at features such as Artemis and Quetzelpetlatl Coronae are more likely to form under conditions of hot mantle and moderately thin lithosphere, as inferred for Venus today and Earth in the Archean. Hotter mantle temperatures allow for more buoyant plumes able to break a moderately strong lithosphere. The lithosphere cannot be too thin, or it will be too buoyant to subduct (e.g., Gülcher et al. 2020). Although many agree that subduction, which creates a complete break of the lithosphere, is the first step in plate tectonics, the evolution to mobile plates is not clear. Bercovici and Ricard (2014) suggested that the reason that Venus has developed subduction but has not yet developed Earth-like mobile plates is that breaks created by subduction are annealed over time due to the high temperatures, preventing the formation of large plates. This inference is consistent with the presence of many but moderately sized discrete blocks of lowland lithosphere, which appear to have jostled together since, at least in places, the emplacement of the locally youngest plains materials (Byrne et al. 2021).
potential temperature estimates of Venusian basalts are variable: the rocks at the Venera 13 and Venera 14 sites are probably derived from a thermal regime similar to modern Earth, but estimates of the thermal regime for rocks at the Vega 2 landing site indicate an anomalously hot (2051 ± 167 K) regime (Lee et al. 2009; Weller and Duncan 2015; Shellnutt 2016).

There is debate on the precise composition of the tesserae, possible depositional processes, existence of a hydrosphere, formation of coronae, the mantle thermal regime, and the tectonic regime that was operating on ancient Venus. Recent studies indicate that the tesserae could be composed of mafic volcanic-sedimentary sequences rather than intermediate to silicic volcanic or plutonic rocks (Byrne et al. 2021). No *in situ* geochemical data exist for tesserae, and the high U (2.2 ± 0.7 ppm), Th (6.5 ± 2.2 ppm), and K₂O (4.0 ± 1.2 wt%) contents reported at the Venera 8 landing site could be indicative of a lamprophyre (alkali basalt) rather than a dacitic/syenitic rock (Basilevsky et al. 1992). It is possible that Venus had a hydrosphere during the Archean, but lithified sedimentary rocks (or their metamorphic equivalents) derived by mechanical weathering and chemical precipitation have not been verified (Florensky et al. 1977; Basilevsky et al. 1985). At present, the only evidence for the existence of sulphur-rich evaporites (e.g., gypsum, anhydrite) is the high SO₃ (4.7 ± 1.5 wt%) content measured at the Vega 2 landing site, but sulphates may form by weathering under current Venus conditions (Fegley and Prinn 1989; Fegley et al. 1997; Bullock and Grinspoon 2001; Dyar et al. 2021).

Earth's continental crust began to form during the Archean. One key reason why determining whether or not tesserae are true analogues of continents is that massive volumes of felsic crust require basaltic melt extraction from the mantle, ideally in the presence of water (e.g. Campbell 2002; Bonin 2012). Thus, tesserae may host the geochemical fingerprints of past water. This is a critical question not only for understanding the divergent evolution of Venus and Earth, but also for establishing Venus' potential habitability (Westall et al. 2023). Venus is the only other rocky body in the Solar System with a possible substantial volume of silicic crust (Shellnutt 2013; Wang et al. 2022). The formation and erosion of Earth's continental crust into the oceans is proposed to be the source of the elements needed for life to flourish (Duncan and Dasgupta 2017). In addition to the plume-induced subduction mechanism discussed above, some coronae types may form via delamination (Hoogenboom and Houseman 2006), possibly assisted by mantle flow due to extension (Piskorz et al. 2014). Moreover, Venus' large-scale ridge belts may be a result of compression above mantle downwelling (e.g. Zuber 1990). Thus, a variety of features on Venus may be indicative of crustal recycling and large-scale mantle melting.

Venus' high surface temperature creates a hot lithosphere and provides a thermal/mechanical analogue to conditions on early Earth. Davaille et al. (2017) argued that the apparent plume-induced subduction seen at features such as Artemis and Quetzelpetlatl Coronae are more likely to form under conditions of hot mantle and moderately thin lithosphere, as inferred for Venus today and Earth in the Archean. Hotter mantle temperatures allow for more buoyant plumes able to break a moderately strong lithosphere. The lithosphere cannot be too thin, or it will be too buoyant to subduct (e.g., Gülcher et al. 2020). Although many agree that subduction, which creates a complete break of the lithosphere, is the first step in plate tectonics, the evolution to mobile plates is not clear. Bercovici and Ricard (2014) suggested that the reason that Venus has developed subduction but has not yet developed Earth-like mobile plates is that breaks created by subduction are annealed over time due to the high temperatures, preventing the formation of large plates. This inference is consistent with the presence of many but moderately sized discrete blocks of lowland lithosphere, which appear to have jostled together since, at least in places, the emplacement of the locally youngest plains materials (Byrne et al. 2021).
When and how modern (oceanic) plate tectonics started on Earth is debated. There are ad-
vocates for plate tectonics having always operated and those that think it began at ~3.2 Ga,
~2.5 Ga, ~1.0 Ga, or ~0.8 Ga (e.g., Condie and Kröner 2008; Stern 2008; Hamilton 2011,
1998; Kusky et al. 2018; Windley et al., 2021). The precise origin of greenstone-granite and
granulite-gneiss belts is still debated, and there are compelling arguments for and against the
operation of plate tectonic-related processes in their development (de Wit and Ashwal, 1995;
Anhaeusser 2014; Thurston 2015). Nevertheless, it appears that the generation of highly dif-
ferentiated continental crust was either absent, very slow, or stunted on Venus. Currently, the
continental crust represents ~41% of the surface area of the Earth and ~0.7% of its volume.
It has taken ~4.5 Ga to create this volume of continental crust; however, although the rate
of crustal growth throughout geologic time is uncertain (Honing and Spohn, 2016; Honing
et al., 2019; Hawkesworth et al. 2019, 2020), we do know that this rate has not been con-
stant. The three most common models for crustal growth are rapid development followed
by steady-state; continuous growth; or episodic growth (Fig. 13). There are a number of
uncertainties in these models, but perhaps the most important uncertainty is the timing of
the initiation of modern plate tectonics (Honing and Spohn, 2016; Condie 2018; Windley
et al. 2021). Assuming Venus is a close analogue of Earth and many fundamental planetary
properties (e.g., thermal structure, abundances of heat-producing elements) are proportional
to the size difference between the planets, then Venus' surface should have a similar area
and volume of continental crust as Earth does today. Under the assumption that tesserae are
similar to continental crust, then only ~7.3% of the surface area of Venus is continental crust
(Ivanov and Head 2011; James et al. 2013)—that is, only 17% to 20% of the expected con-
tinental crust is present on Venus taking into consideration differences in crustal thickness
estimates and that no crustal recycling occurred. According to different terrestrial crustal
growth models (Fig. 13), Earth produced 17% to 20% of its current continental crust during
one of three different time periods (Fig. 5): the Hadean to Eoarchean (~4.4–3.9 Ga); the
Mesoarchean to Neoarchean (~3.1–2.7 Ga); or the Paleoproterozoic (~2.4–2.1 Ga). Thus,
either the processes of crustal evolution on Venus have operated significantly more slowly
than on Earth, or the development of continental crust was arrested relatively early. Alterna-
tively, Ivanov and Head (1996) suggest that felsic crust could underlie as much as ~55% of
Venus and that there may be only a surface veneer of basalt (~2–4 km thick). If this is the
case, then Venus would have a larger surface area of continental crust than Earth.

Is Venus therefore analogous to Archean Earth? Possibly. However, our overall under-
standing of Venus' crustal evolution and overall geodynamics is in its infancy. A possible
Venusian hydrosphere is currently only speculation. New geologic, geochemical, and iso-
topic surface measurements are required to thoroughly investigate the possibility that Venus
can help us understand the nature and development of continental crust in the absence of
modern plate tectonics, which may be, in turn, analogous to the Archean Earth.

## 6.2 Comparison with Proterozoic Tectonic Systems

By the end of the Archean, Earth was certainly developing its present-day dynamics. But there were also important tectonic, hydro atmospheric, and biological shifts that occurred during the Proterozoic that laid the foundation of Earth's present habitability. It is during the Archean–Proterozoic transition that the planetary evolution of Earth and Venus may have diverged. There are suggestions that by the Neoarchean (2.8 to 2.5 Ga), horizontal tectonic processes responsible for collision and accretion of island-arc-like terranes was becoming increasingly dominant (Zegers and van Keken, 2001; O'Neill et al. 2016; Windley et al., 2021). Once Earth transitioned into the Paleoproterozoic (2.5 to 1.6 Ga), some geologic
When and how modern (oceanic) plate tectonics started on Earth is debated. There are ad-
vocates for plate tectonics having always operated and those that think it began at ~3.2 Ga,
~2.5 Ga, ~1.0 Ga, or ~0.8 Ga (e.g., Condie and Kröner 2008; Stern 2008; Hamilton 2011,
1998; Kusky et al. 2018; Windley et al., 2021). The precise origin of greenstone-granite and
granulite-gneiss belts is still debated, and there are compelling arguments for and against the
operation of plate tectonic-related processes in their development (de Wit and Ashwal, 1995;
Anhaeusser 2014; Thurston 2015). Nevertheless, it appears that the generation of highly dif-
ferentiated continental crust was either absent, very slow, or stunted on Venus. Currently, the
continental crust represents ~41% of the surface area of the Earth and ~0.7% of its volume.
It has taken ~4.5 Ga to create this volume of continental crust; however, although the rate
of crustal growth throughout geologic time is uncertain (Honing and Spohn, 2016; Honing
et al., 2019; Hawkesworth et al. 2019, 2020), we do know that this rate has not been con-
stant. The three most common models for crustal growth are rapid development followed
by steady-state; continuous growth; or episodic growth (Fig. 13). There are a number of
uncertainties in these models, but perhaps the most important uncertainty is the timing of
the initiation of modern plate tectonics (Honing and Spohn, 2016; Condie 2018; Windley
et al. 2021). Assuming Venus is a close analogue of Earth and many fundamental planetary
properties (e.g., thermal structure, abundances of heat-producing elements) are proportional
to the size difference between the planets, then Venus' surface should have a similar area
and volume of continental crust as Earth does today. Under the assumption that tesserae are
similar to continental crust, then only ~7.3% of the surface area of Venus is continental crust
(Ivanov and Head 2011; James et al. 2013)—that is, only 17% to 20% of the expected con-
tinental crust is present on Venus taking into consideration differences in crustal thickness
estimates and that no crustal recycling occurred. According to different terrestrial crustal
growth models (Fig. 13), Earth produced 17% to 20% of its current continental crust during
one of three different time periods (Fig. 5): the Hadean to Eoarchean (~4.4–3.9 Ga); the
Mesoarchean to Neoarchean (~3.1–2.7 Ga); or the Paleoproterozoic (~2.4–2.1 Ga). Thus,
either the processes of crustal evolution on Venus have operated significantly more slowly
than on Earth, or the development of continental crust was arrested relatively early. Alterna-
tively, Ivanov and Head (1996) suggest that felsic crust could underlie as much as ~55% of
Venus and that there may be only a surface veneer of basalt (~2–4 km thick). If this is the
case, then Venus would have a larger surface area of continental crust than Earth.

Is Venus therefore analogous to Archean Earth? Possibly. However, our overall under-
standing of Venus' crustal evolution and overall geodynamics is in its infancy. A possible
Venusian hydrosphere is currently only speculation. New geologic, geochemical, and iso-
topic surface measurements are required to thoroughly investigate the possibility that Venus
can help us understand the nature and development of continental crust in the absence of
modern plate tectonics, which may be, in turn, analogous to the Archean Earth.

## 6.2 Comparison with Proterozoic Tectonic Systems

By the end of the Archean, Earth was certainly developing its present-day dynamics. But there were also important tectonic, hydro atmospheric, and biological shifts that occurred during the Proterozoic that laid the foundation of Earth's present habitability. It is during the Archean–Proterozoic transition that the planetary evolution of Earth and Venus may have diverged. There are suggestions that by the Neoarchean (2.8 to 2.5 Ga), horizontal tectonic processes responsible for collision and accretion of island-arc-like terranes was becoming increasingly dominant (Zegers and van Keken, 2001; O'Neill et al. 2016; Windley et al., 2021). Once Earth transitioned into the Paleoproterozoic (2.5 to 1.6 Ga), some geologic
<figure><img src="image_15.png" /><figcaption>**Fig. 13** - Terrestrial crustal growth curves showing the models that constrain the volume of crust in the Earth's past independent of present-day age distributions (modified from Cawood et al. 2013). The intersections (arrows) of the terrestrial crustal growth curves are shown at 17–20 vol.% crust to highlight the time periods when the amount of tesserae on Venus may have reached its present state if it evolved along the same path as Earth</figcaption></figure>

features appeared (e.g., giant radiating mafic dyke swarms, anorthosite massifs, ophiolites) that were either rare or absent during the Archean.

A considerable proportion of the cratons that existed at the end of the Archean (~2.7–2.5 Ga) apparently amalgamated for the first time to form a supercontinent or multiple large continental blocks (Bleeker 2002; Pesonen et al., 2003). The emplacement of giant radiating mafic dyke swarms (e.g., Matachewan, Mistassini, Dharwar, Fort Frances, Kikkertavak, Black Range) and the possible existence of ophiolites at ~2.7–2.2 Ga indicates that a continent or continents broke up during the Early Paleoproterozoic (Cadman et al. 1993; Kusky et al. 2001; Ernst and Bleeker 2010; Sarma et al. 2020; Windley et al., 2021). Associated with these dykes are the correspondingly voluminous, and probably mantle plume-derived, flood basalt provinces that are collectively referred to as large igneous provinces (LIPs) (Ernst and Buchan 2001). The volcanic rocks of Paleoproterozoic LIPs are not commonly preserved due to erosion but their Neoproterozoic (~1.0–0.54 Ga old) and Phanerozoic (~0.54 Ga to present day) equivalents are better preserved. Archean giant radiating dyke swarms are rare. Their appearance during the latest Archean to earliest Paleoproterozoic marks a major shift in Earth's tectonic regime, becoming a common feature during the break-up of younger supercontinents (e.g., Rodinia, Pangea).

Complementary to the Paleoproterozoic dyke swarms and continental break-up events are well defined ophiolites that are within collisional and accretionary orogenic belts. The Purtuniq, Jormua, and Kandra ophiolites demonstrate that oceanic crust was obducted at active continental margin settings at ~2.0–1.8 Ga (Scott et al. 1992; Peltonen and Kontinen 2004; Kumar et al. 2010). At ~1.9–1.8 Ga, a major global orogenic cycle occurred that is evidenced by the number of contemporaneous orogenic belts (e.g., Trans-Hudson, Thelon, Svecofennian), followed by post-collisional granites and anorthosite massifs were emplacement into the roots of the old orogens and another cycle of plate break-up, collisional/accretion orogens, and post-orogenic magmatism (Nance et al. 2014; Mitchell et al.
<figure><img src="image_15.png" /><figcaption>**Fig. 13** - Terrestrial crustal growth curves showing the models that constrain the volume of crust in the Earth's past independent of present-day age distributions (modified from Cawood et al. 2013). The intersections (arrows) of the terrestrial crustal growth curves are shown at 17–20 vol.% crust to highlight the time periods when the amount of tesserae on Venus may have reached its present state if it evolved along the same path as Earth</figcaption></figure>

features appeared (e.g., giant radiating mafic dyke swarms, anorthosite massifs, ophiolites) that were either rare or absent during the Archean.

A considerable proportion of the cratons that existed at the end of the Archean (~2.7–2.5 Ga) apparently amalgamated for the first time to form a supercontinent or multiple large continental blocks (Bleeker 2002; Pesonen et al., 2003). The emplacement of giant radiating mafic dyke swarms (e.g., Matachewan, Mistassini, Dharwar, Fort Frances, Kikkertavak, Black Range) and the possible existence of ophiolites at ~2.7–2.2 Ga indicates that a continent or continents broke up during the Early Paleoproterozoic (Cadman et al. 1993; Kusky et al. 2001; Ernst and Bleeker 2010; Sarma et al. 2020; Windley et al., 2021). Associated with these dykes are the correspondingly voluminous, and probably mantle plume-derived, flood basalt provinces that are collectively referred to as large igneous provinces (LIPs) (Ernst and Buchan 2001). The volcanic rocks of Paleoproterozoic LIPs are not commonly preserved due to erosion but their Neoproterozoic (~1.0–0.54 Ga old) and Phanerozoic (~0.54 Ga to present day) equivalents are better preserved. Archean giant radiating dyke swarms are rare. Their appearance during the latest Archean to earliest Paleoproterozoic marks a major shift in Earth's tectonic regime, becoming a common feature during the break-up of younger supercontinents (e.g., Rodinia, Pangea).

Complementary to the Paleoproterozoic dyke swarms and continental break-up events are well defined ophiolites that are within collisional and accretionary orogenic belts. The Purtuniq, Jormua, and Kandra ophiolites demonstrate that oceanic crust was obducted at active continental margin settings at ~2.0–1.8 Ga (Scott et al. 1992; Peltonen and Kontinen 2004; Kumar et al. 2010). At ~1.9–1.8 Ga, a major global orogenic cycle occurred that is evidenced by the number of contemporaneous orogenic belts (e.g., Trans-Hudson, Thelon, Svecofennian), followed by post-collisional granites and anorthosite massifs were emplacement into the roots of the old orogens and another cycle of plate break-up, collisional/accretion orogens, and post-orogenic magmatism (Nance et al. 2014; Mitchell et al.
2021). The break-up and collision of cratons is indicative of the supercontinent cycle, which has become a defining characteristic of modern plate tectonics on Earth.

In comparison to Earth, the corresponding Proterozoic Eon of Venus was probably less geologically eventful. Per our current understanding, Venus appears not to have undergone the transition from a non-plate tectonic regime to a plate tectonic regime. Consequently, accretionary belts, island-arc terranes, ophiolites, and accretionary prisms are not expected to be found on Venus. Although collision-related mountains exist (e.g., Maxwell Montes) and underthrusting of crust probably occurred (Ansan and Vergely 1995; Davaille et al. 2017), the processes of proto-continental crust formation via the development of Earth-like subduction zones, their volcanic systems, and accretionary processes seemingly did not occur (Nimmo and McKenzie 1998). The converse of this is true as well: MORB-like oceanic crust did not develop either. From the Th/U ratios of Venusian basalt, it is likely that the overall internal heat budget generated by radioactive decay is the same as or similar to Earth (e.g., Steinberger et al. 2010; Armann and Tackley 2012; Taylor et al. 2018). Tonalite–trondhjemite–granodiorite suites, anorthosite, and post-collisional granite may be present within the crust of Venus as they do not require special geologic processes in order to form (Gilmore et al. 2015; Shellnutt and Manu Prasanth 2021; Wang et al. 2022). For example, anorthosite can be produced by crystallization and accumulation of plagioclase from a mafic parental magma, whereas post-collisional granite can develop after a period of compressive crustal stress. Since basalt and mountains generated by compressive stress are known to exist on Venus, it stands to reason that anorthosite and post-collisional granite could be present within the crust of Venus. Moreover, large, ore-bearing layered igneous complexes like the Bushveld intrusion or Great Dyke of Zimbabwe should be present as well, because they principally require large volumes of primitive mafic and ultramafic magma to differentiate. It is possible that some lobate or rounded smaller coronae of Venus are analogous to Bushveld-type complexes, but the Sudbury Igneous Complex-type intrusions may be unique to Earth since it was likely derived, in part, by bolide impact-induced melting (Therriault et al. 2002).

The major uncertainties in the Proterozoic evolution of Venus are the development of the atmosphere, hydrosphere, and biosphere. The current CO₂-rich atmosphere of Venus may or may not be primary, but it is likely that Venus lost a substantial amount of H₂ and without becoming O₂-rich like Earth (Donahue et al. 1997; Shaw 2008; Lammer et al. 2018). The evolution of Earth’s atmosphere is directly related to the hydrosphere and biosphere, since the evolution of anaerobic cyanobacteria likely increased the amount of oxygen, whereas their subsequent demise due to the conversion of atmospheric CH₄ to CO₂ and H₂O may have assisted, along with lower solar luminosity, in the development of the Paleoproterozoic glaciations and reduced photosynthesis until after glacial retreat (Kopp et al. 2005). Could a similar process have occurred on Venus only for it to revert back to a CO₂-rich atmosphere? It depends on whether there was a hydrosphere and if life (i.e., cyanobacteria) evolved to the point where photosynthesis started to change the composition of the atmosphere. Venus may have lost a huge quantity of water during its early evolution, and surface water might have been stable until as recently as one billion years ago (Donahue et al. 1997; Way et al., 2016; Way and Del Genio, 2020). If Venus did indeed have a vibrant, Earth-like hydrosphere until ~1 Ga, then prokaryotic and possibly early eukaryotic life could have evolved. Furthermore, a hydrosphere would have permitted the chemical precipitation of limestone, banded-iron formations, primary and secondary sulphate rocks, and the formation of hydrothermal and hydro-magmatic mineral deposits (sulphate materials, along with Fe-oxides and Fe-sulfides, might also result from likely weathering of current surface rocks, see Gilmore et al, 2023, this collection). Nevertheless, if there was a global hydrosphere, Venus did not sustain a tropopause ‘cold trap’, allowing the hydrosphere to evaporate and generating a significant
2021). The break-up and collision of cratons is indicative of the supercontinent cycle, which has become a defining characteristic of modern plate tectonics on Earth.

In comparison to Earth, the corresponding Proterozoic Eon of Venus was probably less geologically eventful. Per our current understanding, Venus appears not to have undergone the transition from a non-plate tectonic regime to a plate tectonic regime. Consequently, accretionary belts, island-arc terranes, ophiolites, and accretionary prisms are not expected to be found on Venus. Although collision-related mountains exist (e.g., Maxwell Montes) and underthrusting of crust probably occurred (Ansan and Vergely 1995; Davaille et al. 2017), the processes of proto-continental crust formation via the development of Earth-like subduction zones, their volcanic systems, and accretionary processes seemingly did not occur (Nimmo and McKenzie 1998). The converse of this is true as well: MORB-like oceanic crust did not develop either. From the Th/U ratios of Venusian basalt, it is likely that the overall internal heat budget generated by radioactive decay is the same as or similar to Earth (e.g., Steinberger et al. 2010; Armann and Tackley 2012; Taylor et al. 2018). Tonalite–trondhjemite–granodiorite suites, anorthosite, and post-collisional granite may be present within the crust of Venus as they do not require special geologic processes in order to form (Gilmore et al. 2015; Shellnutt and Manu Prasanth 2021; Wang et al. 2022). For example, anorthosite can be produced by crystallization and accumulation of plagioclase from a mafic parental magma, whereas post-collisional granite can develop after a period of compressive crustal stress. Since basalt and mountains generated by compressive stress are known to exist on Venus, it stands to reason that anorthosite and post-collisional granite could be present within the crust of Venus. Moreover, large, ore-bearing layered igneous complexes like the Bushveld intrusion or Great Dyke of Zimbabwe should be present as well, because they principally require large volumes of primitive mafic and ultramafic magma to differentiate. It is possible that some lobate or rounded smaller coronae of Venus are analogous to Bushveld-type complexes, but the Sudbury Igneous Complex-type intrusions may be unique to Earth since it was likely derived, in part, by bolide impact-induced melting (Therriault et al. 2002).

The major uncertainties in the Proterozoic evolution of Venus are the development of the atmosphere, hydrosphere, and biosphere. The current CO₂-rich atmosphere of Venus may or may not be primary, but it is likely that Venus lost a substantial amount of H₂ and without becoming O₂-rich like Earth (Donahue et al. 1997; Shaw 2008; Lammer et al. 2018). The evolution of Earth’s atmosphere is directly related to the hydrosphere and biosphere, since the evolution of anaerobic cyanobacteria likely increased the amount of oxygen, whereas their subsequent demise due to the conversion of atmospheric CH₄ to CO₂ and H₂O may have assisted, along with lower solar luminosity, in the development of the Paleoproterozoic glaciations and reduced photosynthesis until after glacial retreat (Kopp et al. 2005). Could a similar process have occurred on Venus only for it to revert back to a CO₂-rich atmosphere? It depends on whether there was a hydrosphere and if life (i.e., cyanobacteria) evolved to the point where photosynthesis started to change the composition of the atmosphere. Venus may have lost a huge quantity of water during its early evolution, and surface water might have been stable until as recently as one billion years ago (Donahue et al. 1997; Way et al., 2016; Way and Del Genio, 2020). If Venus did indeed have a vibrant, Earth-like hydrosphere until ~1 Ga, then prokaryotic and possibly early eukaryotic life could have evolved. Furthermore, a hydrosphere would have permitted the chemical precipitation of limestone, banded-iron formations, primary and secondary sulphate rocks, and the formation of hydrothermal and hydro-magmatic mineral deposits (sulphate materials, along with Fe-oxides and Fe-sulfides, might also result from likely weathering of current surface rocks, see Gilmore et al, 2023, this collection). Nevertheless, if there was a global hydrosphere, Venus did not sustain a tropopause ‘cold trap’, allowing the hydrosphere to evaporate and generating a significant
volume of evaporites (i.e., carbonates, sulphates, halites). If all these events took place, how could the atmosphere become CO₂-rich again? The mostly likely explanation would be the devolatilization of carbonate and/or evaporite rocks due to contact metamorphism associated with magmatism (c.f., Aarnes et al. 2011; Pang et al. 2013). The possible implications of a Venusian hydrosphere are profound but purely speculative without evidence for chemically precipitated sedimentary rocks, glaciations, or hydro-magmatic mineral deposits. Although it is possible that Venus and Earth were similar during the Archean, they must have diverged by the Proterozoic. However, it is possible that life on both planets evolved in parallel until the loss of the Venusian hydrosphere.

# 7 Knowledge Gaps and Measurements Required to Fill Them

Venus is the least geologically understood of the terrestrial planetary bodies of the inner Solar System. Enormous knowledge gaps remain (Treiman 2007; Glaze et al., 2018). The thick, cloudy atmosphere of Venus is a formidable challenge to remote sensing of the surface, motivating the need for surface or near-surface measurements. New missions will greatly advance our understanding and lead to new questions about the evolution of Venus through time (Widemann et al. 2023, this collection, and references therein). Additionally, fundamental geophysical techniques of seismology, electromagnetic sounding, heat flow, and magnetometry have yet to be exploited for interrogating the interior.

## 7.1 Geochemistry

Venera landers provided in situ data at four sites, providing images, atmospheric composition, wind speed, temperature, and the composition of surface materials. Major elemental compositions were reported at three sites, and Th, U, K contents at two others, with the Vega 2 site providing the only measurements of both major and trace elemental compositions (Surkov et al. 1984, 1986; Kargel et al. 1993).

First-order geochemical measurements of the surface rocks and regolith are needed. Advances in X-ray fluorescence spectrometry, particle X-ray spectrometry, Mössbauer spectrometry, and sample preparation, as well as the development of laser-induced breakdown spectrometry (LIBS) and remote micro-imager (RMI) technology, permit smaller equipment to be included in surface landers (e.g., Gorevan et al. 2003; Treiman 2007; Clegg et al. 2009; Wiens et al. 2012). The measurement accuracy and precision of the various techniques would be a substantial improvement over the data reported from the Venera and Vega probes (c.f., Treiman 2007). The elements that can be measured range from major elements (Si, Ti, Al, Fe, Mg, Ca, Na, K, P) to many trace elements (Li, Sr, Rb, Mn). Depending on the rock type (ultramafic, mafic, felsic) additional elements (e.g., Ni, Cr, V) may be of a suitable concentration for measurements. The key problem with Venus is the harsh surface conditions (93 bars, 740 K), and any spectrometer would have to be properly prepared to overcome these extreme environmental conditions.

Of critical importance are the landing sites. The Venera and Vega probes landed at equatorial to tropical latitudes within 2 km of the mean planetary radius in eastern Aphrodite Terra and eastern to southeastern Beta Regio (Kargel et al. 1993). If possible, suitable landing sites should be considered across the various landscapes of Venus (in tesserae, coronae, and hotspots). The highland regions of Ishtar Terra, Aphrodite Terra, Beta Regio, and Lada Terra should be prioritized as likely preserving the oldest rocks and the greatest diversity of lithologies and compositions (e.g., Hashimoto et al. 2008; Gilmore et al. 2015,
volume of evaporites (i.e., carbonates, sulphates, halites). If all these events took place, how could the atmosphere become CO₂-rich again? The mostly likely explanation would be the devolatilization of carbonate and/or evaporite rocks due to contact metamorphism associated with magmatism (c.f., Aarnes et al. 2011; Pang et al. 2013). The possible implications of a Venusian hydrosphere are profound but purely speculative without evidence for chemically precipitated sedimentary rocks, glaciations, or hydro-magmatic mineral deposits. Although it is possible that Venus and Earth were similar during the Archean, they must have diverged by the Proterozoic. However, it is possible that life on both planets evolved in parallel until the loss of the Venusian hydrosphere.

# 7 Knowledge Gaps and Measurements Required to Fill Them

Venus is the least geologically understood of the terrestrial planetary bodies of the inner Solar System. Enormous knowledge gaps remain (Treiman 2007; Glaze et al., 2018). The thick, cloudy atmosphere of Venus is a formidable challenge to remote sensing of the surface, motivating the need for surface or near-surface measurements. New missions will greatly advance our understanding and lead to new questions about the evolution of Venus through time (Widemann et al. 2023, this collection, and references therein). Additionally, fundamental geophysical techniques of seismology, electromagnetic sounding, heat flow, and magnetometry have yet to be exploited for interrogating the interior.

## 7.1 Geochemistry

Venera landers provided in situ data at four sites, providing images, atmospheric composition, wind speed, temperature, and the composition of surface materials. Major elemental compositions were reported at three sites, and Th, U, K contents at two others, with the Vega 2 site providing the only measurements of both major and trace elemental compositions (Surkov et al. 1984, 1986; Kargel et al. 1993).

First-order geochemical measurements of the surface rocks and regolith are needed. Advances in X-ray fluorescence spectrometry, particle X-ray spectrometry, Mössbauer spectrometry, and sample preparation, as well as the development of laser-induced breakdown spectrometry (LIBS) and remote micro-imager (RMI) technology, permit smaller equipment to be included in surface landers (e.g., Gorevan et al. 2003; Treiman 2007; Clegg et al. 2009; Wiens et al. 2012). The measurement accuracy and precision of the various techniques would be a substantial improvement over the data reported from the Venera and Vega probes (c.f., Treiman 2007). The elements that can be measured range from major elements (Si, Ti, Al, Fe, Mg, Ca, Na, K, P) to many trace elements (Li, Sr, Rb, Mn). Depending on the rock type (ultramafic, mafic, felsic) additional elements (e.g., Ni, Cr, V) may be of a suitable concentration for measurements. The key problem with Venus is the harsh surface conditions (93 bars, 740 K), and any spectrometer would have to be properly prepared to overcome these extreme environmental conditions.

Of critical importance are the landing sites. The Venera and Vega probes landed at equatorial to tropical latitudes within 2 km of the mean planetary radius in eastern Aphrodite Terra and eastern to southeastern Beta Regio (Kargel et al. 1993). If possible, suitable landing sites should be considered across the various landscapes of Venus (in tesserae, coronae, and hotspots). The highland regions of Ishtar Terra, Aphrodite Terra, Beta Regio, and Lada Terra should be prioritized as likely preserving the oldest rocks and the greatest diversity of lithologies and compositions (e.g., Hashimoto et al. 2008; Gilmore et al. 2015,
2017; Treiman et al. 2016; Gilmore and Head 2018; Byrne et al. 2021; Resor et al. 2021). From the surface rocks and regolith, a number of important processes and geologic conditions can potentially be investigated, including crustal differentiation, magma crystallization and mineral chemistry, lava viscosity, eruptive temperature, formation of magmatic mineral deposits, mantle source composition, mantle redox conditions, mantle potential temperature, depositional environment, metamorphic facies (pressure, temperature, $fO_2$), stress and strain rates, as well as investigations of whether any evidence exists in support of ancient hydrological cycles, phreatomagmatic eruptions, hydro-magmatic and hydrothermal mineral deposits, water composition, paleoenvironment, and biosphere development. Clarity on any or all of these facets of Venus geology and geophysics would offer a huge advancement in our understanding of the interior properties and development of the planet.

Of equal importance to basic surface geochemistry, but technologically problematic to measure, is the isotopic systematics of Venusian rocks. Light and heavy stable isotopes (e.g., H, O, C, S, Fe, Zn, Mo) and radiogenic isotopes (e.g., Sr, Nd, Pb, Hf, Os) are invaluable for addressing the interior and surficial development of a planetary body. The stable isotopes offer insight into mass-dependent fractionation, primarily of atmosphere-lithosphere interactions that involve the hydrosphere, biosphere, mantle volatile budget, and climate, and can also be useful for assessing mantle evolution and mineral deposits (e.g., Hoefs 2009). The radiogenic isotopes of Venusian rocks offer insight to planetary accretion, interior differentiation of the core, mantle, and crust, and secular mantle and crust evolution (e.g., Faure 2001). Most of the isotopic systems require the application of relatively intense laboratory preparation prior to measurement and would not be practical for a surface lander. The return of surface samples or the identification of Venusian rocks in the meteorite collection are currently the only viable means to measure some or all of the stable and radiogenic isotopic systems. However, there are breakthroughs in the measurement of some radiogenic isotopes by in situ laser (~20–50 mm beam size) ablation methods (Bolea-Fernandez et al. 2016; Spencer et al. 2020). Sr and Hf isotopes can be measured with a suitable degree of accuracy by in situ methods with minimal sample preparation but rely on the presence of Rb-Sr- and Lu-Hf-rich silicate minerals such as feldspar (KAlSi₃O₈–NaAlSi₃O₈–CaAl₂Si₂O₈) and zircon (ZrSiO₄). If the in-situ measurement of Sr (⁸⁷Sr/⁸⁶Sr) and Hf (¹⁷⁶Hf/¹⁷⁷Hf, ¹⁷⁶Lu/¹⁷⁷Hf) isotopic ratios can be achieved by a lander, such measurements would provide a major advance in the understanding of planetary accretion and internal differentiation of Venus.

Perhaps the most ambitious and desirable measurement that can be achieved is radioisotopic geochronology of rocks and minerals from the surface (e.g., Coleman et al. 2012; Cohen et al., 2019). Crater retention and distribution, and relative geologic relationships, are the only methods for estimating the average surface age (<1 Ga) and general stratigraphy (e.g., Strom et al. 1994; Ivanov and Head 2015), in which, for example, tesserae are usually regarded as older than the plains (e.g., Basilevsky and Head, 2002; Gilmore and Head 2018). However, radiometric dating is the only method that can return a measure of the absolute age of a rock. Over the past twenty years, in situ geochronology has exploded in the geologic literature and, on Earth, is a common, reliable, affordable, and low-intensity sample preparation method of choice (Spencer et al., 2016). Under ideal circumstances, a rock sample from Venus would be necessary for mineral separation and measurement but, it may be feasible to measure the isotopic ratios directly with minimal sample preparation by in situ methods. Specifically, U–Pb dating of zircon, a common accessory mineral of granitic rocks, can provide a robust measurement of the ²⁰⁷Pb/²⁰⁶Pb, ²⁰⁷Pb/²³⁵U, and ²⁰⁶Pb/²³⁸U ratios with an uncertainty in the range ~2–4% (Spencer et al., 2016). Another possibility is the application of the Rb/Sr isochron method on minerals (e.g., feldspar, biotite, amphibole, pyroxene) using the measured ⁸⁷Sr/⁸⁶Sr ratio and Rb and Sr concentrations to estimate the ⁸⁷Rb/⁸⁶Sr ratio.
2017; Treiman et al. 2016; Gilmore and Head 2018; Byrne et al. 2021; Resor et al. 2021). From the surface rocks and regolith, a number of important processes and geologic conditions can potentially be investigated, including crustal differentiation, magma crystallization and mineral chemistry, lava viscosity, eruptive temperature, formation of magmatic mineral deposits, mantle source composition, mantle redox conditions, mantle potential temperature, depositional environment, metamorphic facies (pressure, temperature, $fO_2$), stress and strain rates, as well as investigations of whether any evidence exists in support of ancient hydrological cycles, phreatomagmatic eruptions, hydro-magmatic and hydrothermal mineral deposits, water composition, paleoenvironment, and biosphere development. Clarity on any or all of these facets of Venus geology and geophysics would offer a huge advancement in our understanding of the interior properties and development of the planet.

Of equal importance to basic surface geochemistry, but technologically problematic to measure, is the isotopic systematics of Venusian rocks. Light and heavy stable isotopes (e.g., H, O, C, S, Fe, Zn, Mo) and radiogenic isotopes (e.g., Sr, Nd, Pb, Hf, Os) are invaluable for addressing the interior and surficial development of a planetary body. The stable isotopes offer insight into mass-dependent fractionation, primarily of atmosphere-lithosphere interactions that involve the hydrosphere, biosphere, mantle volatile budget, and climate, and can also be useful for assessing mantle evolution and mineral deposits (e.g., Hoefs 2009). The radiogenic isotopes of Venusian rocks offer insight to planetary accretion, interior differentiation of the core, mantle, and crust, and secular mantle and crust evolution (e.g., Faure 2001). Most of the isotopic systems require the application of relatively intense laboratory preparation prior to measurement and would not be practical for a surface lander. The return of surface samples or the identification of Venusian rocks in the meteorite collection are currently the only viable means to measure some or all of the stable and radiogenic isotopic systems. However, there are breakthroughs in the measurement of some radiogenic isotopes by in situ laser (~20–50 mm beam size) ablation methods (Bolea-Fernandez et al. 2016; Spencer et al. 2020). Sr and Hf isotopes can be measured with a suitable degree of accuracy by in situ methods with minimal sample preparation but rely on the presence of Rb-Sr- and Lu-Hf-rich silicate minerals such as feldspar (KAlSi₃O₈–NaAlSi₃O₈–CaAl₂Si₂O₈) and zircon (ZrSiO₄). If the in-situ measurement of Sr (⁸⁷Sr/⁸⁶Sr) and Hf (¹⁷⁶Hf/¹⁷⁷Hf, ¹⁷⁶Lu/¹⁷⁷Hf) isotopic ratios can be achieved by a lander, such measurements would provide a major advance in the understanding of planetary accretion and internal differentiation of Venus.

Perhaps the most ambitious and desirable measurement that can be achieved is radioisotopic geochronology of rocks and minerals from the surface (e.g., Coleman et al. 2012; Cohen et al., 2019). Crater retention and distribution, and relative geologic relationships, are the only methods for estimating the average surface age (<1 Ga) and general stratigraphy (e.g., Strom et al. 1994; Ivanov and Head 2015), in which, for example, tesserae are usually regarded as older than the plains (e.g., Basilevsky and Head, 2002; Gilmore and Head 2018). However, radiometric dating is the only method that can return a measure of the absolute age of a rock. Over the past twenty years, in situ geochronology has exploded in the geologic literature and, on Earth, is a common, reliable, affordable, and low-intensity sample preparation method of choice (Spencer et al., 2016). Under ideal circumstances, a rock sample from Venus would be necessary for mineral separation and measurement but, it may be feasible to measure the isotopic ratios directly with minimal sample preparation by in situ methods. Specifically, U–Pb dating of zircon, a common accessory mineral of granitic rocks, can provide a robust measurement of the ²⁰⁷Pb/²⁰⁶Pb, ²⁰⁷Pb/²³⁵U, and ²⁰⁶Pb/²³⁸U ratios with an uncertainty in the range ~2–4% (Spencer et al., 2016). Another possibility is the application of the Rb/Sr isochron method on minerals (e.g., feldspar, biotite, amphibole, pyroxene) using the measured ⁸⁷Sr/⁸⁶Sr ratio and Rb and Sr concentrations to estimate the ⁸⁷Rb/⁸⁶Sr ratio.
ratio (Coleman et al. 2012; Bolea-Fernandez et al. 2016). Although the uncertainty of the Rb/Sr isochron method makes it less reliable, it would be useful (i.e., better than ±100 Ma) and in situ Rb/Sr geochronology may be more practical because the potential target minerals are common in mafic to silicic rocks. Regardless, the first step in the application of in situ geochronology methods would be the positive identification of differentiated igneous rocks (i.e., intermediate to silicic) by surface geochemical remote sensing.

## 7.2 Seismology

A better knowledge of Venus' seismicity would majorly improve our understanding of rock rheology, deformation mechanisms, and Venus geotherms, as well as help us constrain estimates of crustal thickness, mantle viscosity, and core properties. As described above, Venus' young surface has a wide range of volcanic and tectonic features capable of producing substantial seismicity. The spatial distribution of seismic events related to tectonic features, like faults and volcanoes, is much more homogeneous on Venus than on other planets, due in part to the extremely limited erosion. Seismicity estimates have assumed an intraplate level of seismic activity because Venus lacks Earth-like plate tectonics. As expected, this approach leads to a lower predicted rate of activity than on Earth (e.g., Stofan et al., 1993; Stevenson et al. 2015). Sources of uncertainty come from the limited constraints on heat flow and rock rheology discussed above. Lognonné and Johnson (2007) predicted >100 quakes >Mw5 per year, with a maximum seismic moment magnitude of ~6.5 based on analogy to terrestrial intraplate activity. This low maximum quake magnitude calculation assumed a thickness of the seismogenic layer to be 30 km. Knapmeyer et al. (2006) estimated seismicity on Mars based on extensive (albeit hillshade-based) mapping of surface faults and their conversion into quake magnitudes. This approach, which has large error bars, predicts a range of seismicity consistent with seismic data from the InSight mission (Giardini et al. 2020). Sabbath et al. (2023) applied a similar approach to a specific fault type on Venus, predicting an order of magnitude higher level of seismicity at Venus than InSight measured in Cerberus Fossae on Mars. This estimate was based on fault lengths. Future high-resolution topography would allow fault throw to be measured as well, providing greater fidelity to this approach. Seismic sources due to meteoroid impacts are likely to be rare because the thick atmosphere destroys impactors that produce craters less than a few kilometres in diameter (e.g., Zahnle 1992; Korycansky and Zahnle 2005). Airbursts due to impactor disruption and breakup in the thick Venus atmosphere could help provoke a seismic signal, although an impactor large enough to airburst in the lower atmosphere is statistically unlikely to hit Venus in the next several decades (e.g., McKinnon et al. 1997).

Although long duration, in-situ seismic measurements would be ideal, Venus' surface temperature motivates a range of possible methods, including orbital searches for atmospheric airglow or balloon-born infrasound measurements (Stevenson et al. 2015). If present, aerial platforms could detect infrasound from explosive volcanism (e.g., Brissaud et al. 2021; Garcia et al. 2022; Rossi et al. 2023). Pyroclastic flows, likely from explosive volcanism (e.g., Ganesh et al. 2021), appear to be rare but indicate that such eruptions have occurred on Venus (e.g., Campbell et al. 2017; Ganesh et al. 2022). See also a review of future seismic investigations and concepts in Widemann et al. 2023, Sect. 10 (This collection).

## 7.3 Electromagnetic Sounding

Future missions could use electromagnetic (EM) sounding to probe properties of the lithosphere that influence volcanic and tectonic processes. Grimm et al. (2012) proposed exploiting Schumann resonances at ~10–40 Hz to determine the depth profiles of conductivity and
ratio (Coleman et al. 2012; Bolea-Fernandez et al. 2016). Although the uncertainty of the Rb/Sr isochron method makes it less reliable, it would be useful (i.e., better than ±100 Ma) and in situ Rb/Sr geochronology may be more practical because the potential target minerals are common in mafic to silicic rocks. Regardless, the first step in the application of in situ geochronology methods would be the positive identification of differentiated igneous rocks (i.e., intermediate to silicic) by surface geochemical remote sensing.

## 7.2 Seismology

A better knowledge of Venus' seismicity would majorly improve our understanding of rock rheology, deformation mechanisms, and Venus geotherms, as well as help us constrain estimates of crustal thickness, mantle viscosity, and core properties. As described above, Venus' young surface has a wide range of volcanic and tectonic features capable of producing substantial seismicity. The spatial distribution of seismic events related to tectonic features, like faults and volcanoes, is much more homogeneous on Venus than on other planets, due in part to the extremely limited erosion. Seismicity estimates have assumed an intraplate level of seismic activity because Venus lacks Earth-like plate tectonics. As expected, this approach leads to a lower predicted rate of activity than on Earth (e.g., Stofan et al., 1993; Stevenson et al. 2015). Sources of uncertainty come from the limited constraints on heat flow and rock rheology discussed above. Lognonné and Johnson (2007) predicted >100 quakes >Mw5 per year, with a maximum seismic moment magnitude of ~6.5 based on analogy to terrestrial intraplate activity. This low maximum quake magnitude calculation assumed a thickness of the seismogenic layer to be 30 km. Knapmeyer et al. (2006) estimated seismicity on Mars based on extensive (albeit hillshade-based) mapping of surface faults and their conversion into quake magnitudes. This approach, which has large error bars, predicts a range of seismicity consistent with seismic data from the InSight mission (Giardini et al. 2020). Sabbath et al. (2023) applied a similar approach to a specific fault type on Venus, predicting an order of magnitude higher level of seismicity at Venus than InSight measured in Cerberus Fossae on Mars. This estimate was based on fault lengths. Future high-resolution topography would allow fault throw to be measured as well, providing greater fidelity to this approach. Seismic sources due to meteoroid impacts are likely to be rare because the thick atmosphere destroys impactors that produce craters less than a few kilometres in diameter (e.g., Zahnle 1992; Korycansky and Zahnle 2005). Airbursts due to impactor disruption and breakup in the thick Venus atmosphere could help provoke a seismic signal, although an impactor large enough to airburst in the lower atmosphere is statistically unlikely to hit Venus in the next several decades (e.g., McKinnon et al. 1997).

Although long duration, in-situ seismic measurements would be ideal, Venus' surface temperature motivates a range of possible methods, including orbital searches for atmospheric airglow or balloon-born infrasound measurements (Stevenson et al. 2015). If present, aerial platforms could detect infrasound from explosive volcanism (e.g., Brissaud et al. 2021; Garcia et al. 2022; Rossi et al. 2023). Pyroclastic flows, likely from explosive volcanism (e.g., Ganesh et al. 2021), appear to be rare but indicate that such eruptions have occurred on Venus (e.g., Campbell et al. 2017; Ganesh et al. 2022). See also a review of future seismic investigations and concepts in Widemann et al. 2023, Sect. 10 (This collection).

## 7.3 Electromagnetic Sounding

Future missions could use electromagnetic (EM) sounding to probe properties of the lithosphere that influence volcanic and tectonic processes. Grimm et al. (2012) proposed exploiting Schumann resonances at ~10–40 Hz to determine the depth profiles of conductivity and
temperature within the lithosphere. If the lithosphere is dry as expected, then EM sounding could probe depths of hundreds of kilometres on Venus. If the lithosphere is wet (i.e., with hundreds of ppm H₂O), then sounding would be limited to depths of <20 km—but the discovery of a wet lithosphere would be a major result by itself. Speculatively, EM sounding could also search for molten salt aquifers as proposed by Kargel et al. (1994). An aerial platform could perform EM sounding with instruments such as magnetometers and electrometers at ~55-km altitudes in the clouds (e.g., Wilson et al. 2012; Cutts et al. 2022). However, no previous mission has confirmed the presence of Schumann resonances.

On Earth, frequent lightning discharges (tens each second) dump so much EM energy below the ionosphere that Schumann resonances exist always around the globe (e.g., Grimm et al. 2012). Observations of whistler waves from Venus Express and Pioneer Venus Orbiter have been claimed to reveal that lightning happens on Venus several times more often than on Earth (e.g., Hart et al. 2022). However, these whistlers might have a non-lightning origin (George et al. 2023). Recently, the Parker Solar Probe mission observed whistlers at Venus during a gravity assist and measured their direction of propagation for the first time. Whereas lightning-generated whistlers would propagate outwards from the atmosphere, the observed whistlers travelled towards Venus from its nightside magnetotail (George et al. 2023). Multiple processes can produce whistlers at Venus, but no existing measurement provides proof of lightning. Long-duration observations from an orbiter would provide much better statistical constraints on the rate of lightning-derived whistlers.

Lightning could be absent or extremely rare on Venus (see also Lorenz 2018 for a comprehensive review). The Akatsuki mission (Lorenz et al. 2019; Takahashi et al. 2020) and earlier ground-based observations (Hansell et al., 1995) have identified <10 optical flashes total that are potentially attributable to lightning, yielding a rate of only a few flashes per hour on all of Venus—less than 10⁻⁵ times the rate of cloud-based lightning on Earth. Other processes may have produced some or all of these flashes, including meteors (e.g., Blaske et al. 2023) and instrument artifacts (Lorenz et al. 2018), meaning that the rate of cloud-level lightning on Venus could be (nearly) zero. In principle, explosive volcanism and/or aeolian processes on the surface could generate lightning, albeit likely not at high rates (e.g., Lorenz et al. 2018). Unlike lightning in the clouds, near-surface lightning probably would create EM signals but not optical flashes detectable via remote observation. Ultimately, our ignorance about the EM environment below the ionosphere is profound and coupled to our struggles to understand and explore volcanism on Venus generally.

## 7.4 Magnetometry

Crustal remanent magnetism has revealed the history of volcanism and tectonics on other terrestrial planets. Most notably, scientists found “smoking gun” evidence for plate tectonics in the 1950s in the form of “stripes” of magnetized crust painted with alternating polarities outwards from spreading centres in the seafloor. As described in the introductory article of this collection (O’Rourke et al. 2023, this collection), no mission has so far discovered any crustal remanent magnetism on Venus. However, the detection limits are so weak that huge amounts of magnetized crust could await detection (O’Rourke et al. 2019)—for example, equivalent to the magnetic anomalies detected in the crusts of Mercury, Mars, Earth, and the Moon. As with EM sounding, we cannot promise to use crustal magnetometry to study volcanism and tectonics at Venus. Perhaps Venus never had a strong, global magnetic field that would enable lava or magma to acquire remnant magnetization. Maybe surface temperatures were higher in the recent past (e.g., Bullock and Grinspoon 2001; Warren and Kite 2023), which would have demagnetized any magnetized rocks in the crust. Again, as for
temperature within the lithosphere. If the lithosphere is dry as expected, then EM sounding could probe depths of hundreds of kilometres on Venus. If the lithosphere is wet (i.e., with hundreds of ppm H₂O), then sounding would be limited to depths of <20 km—but the discovery of a wet lithosphere would be a major result by itself. Speculatively, EM sounding could also search for molten salt aquifers as proposed by Kargel et al. (1994). An aerial platform could perform EM sounding with instruments such as magnetometers and electrometers at ~55-km altitudes in the clouds (e.g., Wilson et al. 2012; Cutts et al. 2022). However, no previous mission has confirmed the presence of Schumann resonances.

On Earth, frequent lightning discharges (tens each second) dump so much EM energy below the ionosphere that Schumann resonances exist always around the globe (e.g., Grimm et al. 2012). Observations of whistler waves from Venus Express and Pioneer Venus Orbiter have been claimed to reveal that lightning happens on Venus several times more often than on Earth (e.g., Hart et al. 2022). However, these whistlers might have a non-lightning origin (George et al. 2023). Recently, the Parker Solar Probe mission observed whistlers at Venus during a gravity assist and measured their direction of propagation for the first time. Whereas lightning-generated whistlers would propagate outwards from the atmosphere, the observed whistlers travelled towards Venus from its nightside magnetotail (George et al. 2023). Multiple processes can produce whistlers at Venus, but no existing measurement provides proof of lightning. Long-duration observations from an orbiter would provide much better statistical constraints on the rate of lightning-derived whistlers.

Lightning could be absent or extremely rare on Venus (see also Lorenz 2018 for a comprehensive review). The Akatsuki mission (Lorenz et al. 2019; Takahashi et al. 2020) and earlier ground-based observations (Hansell et al., 1995) have identified <10 optical flashes total that are potentially attributable to lightning, yielding a rate of only a few flashes per hour on all of Venus—less than 10⁻⁵ times the rate of cloud-based lightning on Earth. Other processes may have produced some or all of these flashes, including meteors (e.g., Blaske et al. 2023) and instrument artifacts (Lorenz et al. 2018), meaning that the rate of cloud-level lightning on Venus could be (nearly) zero. In principle, explosive volcanism and/or aeolian processes on the surface could generate lightning, albeit likely not at high rates (e.g., Lorenz et al. 2018). Unlike lightning in the clouds, near-surface lightning probably would create EM signals but not optical flashes detectable via remote observation. Ultimately, our ignorance about the EM environment below the ionosphere is profound and coupled to our struggles to understand and explore volcanism on Venus generally.

## 7.4 Magnetometry

Crustal remanent magnetism has revealed the history of volcanism and tectonics on other terrestrial planets. Most notably, scientists found “smoking gun” evidence for plate tectonics in the 1950s in the form of “stripes” of magnetized crust painted with alternating polarities outwards from spreading centres in the seafloor. As described in the introductory article of this collection (O’Rourke et al. 2023, this collection), no mission has so far discovered any crustal remanent magnetism on Venus. However, the detection limits are so weak that huge amounts of magnetized crust could await detection (O’Rourke et al. 2019)—for example, equivalent to the magnetic anomalies detected in the crusts of Mercury, Mars, Earth, and the Moon. As with EM sounding, we cannot promise to use crustal magnetometry to study volcanism and tectonics at Venus. Perhaps Venus never had a strong, global magnetic field that would enable lava or magma to acquire remnant magnetization. Maybe surface temperatures were higher in the recent past (e.g., Bullock and Grinspoon 2001; Warren and Kite 2023), which would have demagnetized any magnetized rocks in the crust. Again, as for
EM sounding, an aerial platform could characterize the magnetic environment below the ionosphere of Venus for the first time—and determine if measurements that are so powerful on Earth and other planets are applicable to Venus.

## 7.5 In Situ Heat Flow

Heat-flow data would provide valuable new information on local thermal gradients and, coupled with crustal thickness and thermal evolution models, the abundance and distribution of radiogenic elements. Heat flow is also a key discriminator between different modes of mantle convection (see Rolf et al. 2022, this collection). One approach is to measure the heat coming out of the interior with a flux plate (e.g., Kremic et al. 2020). However, scientists have inferred small (~1 K) diurnal surface temperature variations from remote observations of thermal emission (e.g., Mueller et al. 2008) and global climate models (e.g., Lebonnois et al. 2018). Such small changes in surface temperature could be problematic for the flux plate approach, but these estimates could change after future measurements of surface brightness temperature, acquired from orbit. Analyses could compensate for the effects of these variations if a long enough baseline of surface temperature could be made (i.e., over multiple Venus days). Alternatively, subsurface drilling could deploy a more traditional heat flow probe (Widemann et al. 2023, this collection, and references therein). As for surface seismology, the engineering challenge of drilling is considerable. Given the high scientific value of heat flow measurements to understanding the planet's interior evolution, new technologies to enable this kind of science investigation are important to develop.

## 8 Conclusion

In this article, we have explored how Venus' tectonic and volcanic processes provide essential insights on Venus' evolution, as any rocky body's crustal layer provides a complex archive for the planet's long term evolution. A primary constraint on the interpretation of geologic processes on another planet is the size and spatial distribution of impact craters, the study of tectonic processes that removed older terrains, which remains controversial. Our understanding of current processes and surface structures effectively provides boundary conditions for extrapolating back into Venus' geologic and convective history: the size, type and distribution of volcanic features provide a window into interior processes such as upwelling/downwelling, melting and mantle temperature. We have introduced the fact that a completely stagnant lid does not provide sufficient heat loss, leading to the idea that Venus has either cycled between a stagnant lid and past plate tectonic regimes, or has undergone regional equilibrium resurfacing: these different interpretations address the fundamental role that both the mean surface age and local variability play in framing the long-term geologic evolution of Venus, and in interpreting interior properties.

Tectonic features provide separate constraints on the rheology, thickness of the lithosphere, and the origin and magnitude of driving stress fields. Gravity data provide further information on the thickness of the crust, the lithosphere, and subsurface density variations due to processes such as mantle upwellings. The goal of this review work has been not to provide a single view, but rather to represent a range of possible interpretations, the constraints available from current data, and to outline specific needs for future datasets. Global mapping of the tessera terrain shows that most tessera margins are embayed by plains, thus establishing the tessera as the oldest materials in a proposed global stratigraphic column. Their composition has not yet been measured directly, but that of some tessera exposures
EM sounding, an aerial platform could characterize the magnetic environment below the ionosphere of Venus for the first time—and determine if measurements that are so powerful on Earth and other planets are applicable to Venus.

## 7.5 In Situ Heat Flow

Heat-flow data would provide valuable new information on local thermal gradients and, coupled with crustal thickness and thermal evolution models, the abundance and distribution of radiogenic elements. Heat flow is also a key discriminator between different modes of mantle convection (see Rolf et al. 2022, this collection). One approach is to measure the heat coming out of the interior with a flux plate (e.g., Kremic et al. 2020). However, scientists have inferred small (~1 K) diurnal surface temperature variations from remote observations of thermal emission (e.g., Mueller et al. 2008) and global climate models (e.g., Lebonnois et al. 2018). Such small changes in surface temperature could be problematic for the flux plate approach, but these estimates could change after future measurements of surface brightness temperature, acquired from orbit. Analyses could compensate for the effects of these variations if a long enough baseline of surface temperature could be made (i.e., over multiple Venus days). Alternatively, subsurface drilling could deploy a more traditional heat flow probe (Widemann et al. 2023, this collection, and references therein). As for surface seismology, the engineering challenge of drilling is considerable. Given the high scientific value of heat flow measurements to understanding the planet's interior evolution, new technologies to enable this kind of science investigation are important to develop.

## 8 Conclusion

In this article, we have explored how Venus' tectonic and volcanic processes provide essential insights on Venus' evolution, as any rocky body's crustal layer provides a complex archive for the planet's long term evolution. A primary constraint on the interpretation of geologic processes on another planet is the size and spatial distribution of impact craters, the study of tectonic processes that removed older terrains, which remains controversial. Our understanding of current processes and surface structures effectively provides boundary conditions for extrapolating back into Venus' geologic and convective history: the size, type and distribution of volcanic features provide a window into interior processes such as upwelling/downwelling, melting and mantle temperature. We have introduced the fact that a completely stagnant lid does not provide sufficient heat loss, leading to the idea that Venus has either cycled between a stagnant lid and past plate tectonic regimes, or has undergone regional equilibrium resurfacing: these different interpretations address the fundamental role that both the mean surface age and local variability play in framing the long-term geologic evolution of Venus, and in interpreting interior properties.

Tectonic features provide separate constraints on the rheology, thickness of the lithosphere, and the origin and magnitude of driving stress fields. Gravity data provide further information on the thickness of the crust, the lithosphere, and subsurface density variations due to processes such as mantle upwellings. The goal of this review work has been not to provide a single view, but rather to represent a range of possible interpretations, the constraints available from current data, and to outline specific needs for future datasets. Global mapping of the tessera terrain shows that most tessera margins are embayed by plains, thus establishing the tessera as the oldest materials in a proposed global stratigraphic column. Their composition has not yet been measured directly, but that of some tessera exposures
can be inferred from both NIR and radar observations. The generation of such large amounts of felsic melt could require both water and a lithospheric recycling mechanism for formation, and thus possibly must have formed during a more habitable era, assuming the tesserae are igneous in origin.

Volcanic and tectonic constraints on the evolution of Venus are therefore particularly important to our understanding of terrestrial planets' habitability, providing a natural laboratory to understand its evolution in time. A renaissance in Venus exploration is underway with ESA's EnVision orbiter mission, NASA's VERITAS orbiter and the DAVINCI in-situ probe missions all going to Venus by the early 2030s. VERITAS's payload is composed of two instruments crafted to study Venus' surface coupled with a radio science investigation to measure the gravity field. The two instruments are an X-band interferometric synthetic aperture radar, VISAR, and a fourteen-band infrared spectrometer, VEM (Smrekar et al., 2022a). DAVINCI's Venus Descent Imager (VenDI), a near-IR descent-imaging system will deliver clear, high contrast, high SNR images, providing the first geologic constraints on the tesserae surface environment at 2–200 m length scales (Garvin et al., 2022). EnVision's suite of investigations will perform targeted surface imaging as well as polarimetric and stereo imaging, radiometry, and altimetry, a subsurface radar that will sound the upper crust in search of material boundaries, and a suite of three spectrometers operating in the UV and Near- and Short Wave-IR (Widemann et al. 2023, this collection). Together, the three missions will fundamentally improve our understanding of the planet's long term history, current activity and evolutionary path.

## Declarations

**Competing Interests** The authors have no competing interests to declare that are relevant to the content of this article and no funding was received to assist with the preparation of this manuscript.

**Open Access** This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

## References

Aarnes I, Fristad F, Planke S, Svensen H (2011) The impact of host-rock composition on devolatilization of sedimentary rocks during contact metamorphism around mafic sheet intrusions. Geochem Geophys Geosyst 12:Q10019. https://doi.org/10.1029/2011GC003636

Adams AC, Stegman DR, Smrekar SE, Tackley PJ (2022) Regional-scale lithospheric recycling on Venus via peel-back delamination. J Geophys Res, Planets 127:e2022JE007460. https://doi.org/10.1029/2022JE007460

Addington EA (2001) A stratigraphic study of small volcano clusters on Venus. Icarus 149(1):16–36. https://doi.org/10.1006/icar.2000.6529

Airey MW, Mather TA, Pyle DM, Glaze LS, Ghail RC, Wilson CF (2015) Explosive volcanic activity on Venus: the roles of volatile contribution, degassing, and external environment. Planet Space Sci 113–114:33–48. https://doi.org/10.1016/j.pss.2015.01.009

Aittola M, Kostama VP (2002) Chronology of the formation process of Venusian novae and the associated coronae. J Geophys Res, Planets 107(E11):22–1–22–26. https://doi.org/10.1029/2001JE001528

Anderson FS, Smrekar SE (1999) Tectonic effects of climate change on Venus. J Geophys Res 104(E12):30743–30756. https://doi.org/10.1029/1999JE001082
can be inferred from both NIR and radar observations. The generation of such large amounts of felsic melt could require both water and a lithospheric recycling mechanism for formation, and thus possibly must have formed during a more habitable era, assuming the tesserae are igneous in origin.

Volcanic and tectonic constraints on the evolution of Venus are therefore particularly important to our understanding of terrestrial planets' habitability, providing a natural laboratory to understand its evolution in time. A renaissance in Venus exploration is underway with ESA's EnVision orbiter mission, NASA's VERITAS orbiter and the DAVINCI in-situ probe missions all going to Venus by the early 2030s. VERITAS's payload is composed of two instruments crafted to study Venus' surface coupled with a radio science investigation to measure the gravity field. The two instruments are an X-band interferometric synthetic aperture radar, VISAR, and a fourteen-band infrared spectrometer, VEM (Smrekar et al., 2022a). DAVINCI's Venus Descent Imager (VenDI), a near-IR descent-imaging system will deliver clear, high contrast, high SNR images, providing the first geologic constraints on the tesserae surface environment at 2–200 m length scales (Garvin et al., 2022). EnVision's suite of investigations will perform targeted surface imaging as well as polarimetric and stereo imaging, radiometry, and altimetry, a subsurface radar that will sound the upper crust in search of material boundaries, and a suite of three spectrometers operating in the UV and Near- and Short Wave-IR (Widemann et al. 2023, this collection). Together, the three missions will fundamentally improve our understanding of the planet's long term history, current activity and evolutionary path.

## Declarations

**Competing Interests** The authors have no competing interests to declare that are relevant to the content of this article and no funding was received to assist with the preparation of this manuscript.

**Open Access** This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

## References

Aarnes I, Fristad F, Planke S, Svensen H (2011) The impact of host-rock composition on devolatilization of sedimentary rocks during contact metamorphism around mafic sheet intrusions. Geochem Geophys Geosyst 12:Q10019. https://doi.org/10.1029/2011GC003636

Adams AC, Stegman DR, Smrekar SE, Tackley PJ (2022) Regional-scale lithospheric recycling on Venus via peel-back delamination. J Geophys Res, Planets 127:e2022JE007460. https://doi.org/10.1029/2022JE007460

Addington EA (2001) A stratigraphic study of small volcano clusters on Venus. Icarus 149(1):16–36. https://doi.org/10.1006/icar.2000.6529

Airey MW, Mather TA, Pyle DM, Glaze LS, Ghail RC, Wilson CF (2015) Explosive volcanic activity on Venus: the roles of volatile contribution, degassing, and external environment. Planet Space Sci 113–114:33–48. https://doi.org/10.1016/j.pss.2015.01.009

Aittola M, Kostama VP (2002) Chronology of the formation process of Venusian novae and the associated coronae. J Geophys Res, Planets 107(E11):22–1–22–26. https://doi.org/10.1029/2001JE001528

Anderson FS, Smrekar SE (1999) Tectonic effects of climate change on Venus. J Geophys Res 104(E12):30743–30756. https://doi.org/10.1029/1999JE001082
Anderson FS, Smrekar SE (2006) Global mapping of crustal and lithospheric thickness on Venus. J Geophys Res, Planets 111:E08006. https://doi.org/10.1029/2004JE002395

Anhaeusser CR (2014) Archaean greenstone belts and associated granitic rocks – a review. J Afr Earth Sci 100:684–732. https://doi.org/10.1016/j.jafrearsci.2014.07.019

Ansan V, Vergely P (1995) Evidence of vertical and horizontal motions on Venus: Maxwell Montes. Earth Moon Planets 69:285–310. https://doi.org/10.1007/BF00643789

Arculus RJ (2003) Use and abuse of the terms calcalkaline and calcalkalic. J Petrol 44:929–935. https://doi.org/10.1093/petrology/44.5.929

Armann M, Tackley PJ (2012) Simulating the thermochemical magmatic and tectonic evolution of Venus’s mantle and lithosphere: Two-dimensional models. J Geophys Res, Planets 117(E12). https://doi.org/10.1029/2012JE004231

Bachmann O, Bergantz GW (2008) Deciphering magma chamber dynamics from styles of compositional zoning in large silicic ash flow sheets. Rev Mineral Geochem 69(1):651–674. https://doi.org/10.2138/rmg.2008.69.17

Baes M, Gerya T, Sobolev SV (2016) 3-D thermo-mechanical modeling of plume-induced subduction initiation. Earth Planet Sci Lett 453:193–203. https://doi.org/10.1016/j.epsl.2016.08.023

Baker VR, Komatsu G, Parker TJ, Gulick VC, Kargel JS, Lewis JS (1992) Channels and valleys on Venus: preliminary analysis of Magellan data. J Geophys Res, Planets 97(E8):13421–13444. https://doi.org/10.1029/92JE00927

Banerdt WB (1986) Support of long-wavelength loads on Venus and implications for internal structure. J Geophys Res, Solid Earth 91(B1):403–419. https://doi.org/10.1029/JB091iB01p00403

Barsukov VL, Basilevsky AT, Burba GA, Bobinna NN, Kryuchkov VP, Kuzmin RO, Nikolaeva OV, Pronin AA, Ronca LB, Chernaya IM, Shashkina VP, Garanin AV, Kushky ER, Markov MS, Sukhanov AL, Kotelnikov VA, Rzhiga ON, Petrov GM, Alexandrov YN, Sidorenko AI, Bogomolov AF, Skrypnik GI, Bergman MY, Kudrin LV, Bokshtein IM, Kronrod MA, Chochia PA, Tyuflin YS, Kadnichansky SA, Akim EL (1986) The geology and geomorphology of the Venus surface as revealed by the radar images obtained by Veneras 15 and 16. J Geophys Res, Solid Earth 91(B4):378–398. https://doi.org/10.1029/JB091iB04p0D378

Basilevsky AT, Head JW (1996) Evidence for rapid and widespread emplacement of volcanic plains on Venus: stratigraphic studies in the Baltis Vallis region. Geophys Res Lett 23(12):1497–1500. https://doi.org/10.1029/96GL00975

Basilevsky AT, Head JW (2002) Venus: timing and rates of geologic activity. Geology 30(11):1015–1018. https://doi.org/10.1130/0091-7613(2002)030<1015:VTAROG>2.0.CO;2

Basilevsky AT, Kuzmin RO, Nikolaeva OV, Pronin AA, Ronca LB, Avduevsky VS, Uspensky GR, Chere-mukhina ZP, Semenchenko VV, Ladygin VM (1985) The surface of Venus as revealed by the Venera landings: part II. Geol Soc Am Bull 96(1):137–144. https://doi.org/10.1130/0016-7606(1985)96<137:TSOVAR>2.0.CO;2

Basilevsky AT, Nikolaeva OV, Weitz CM (1992) Geology of the Venera 8 landing site region from Magellan data: morphological and geochemical considerations. J Geophys Res, Planets 97:16315–16335. https://doi.org/10.1029/92JE01557

Bédard JH (2006) A catalytic delamination-driven model for coupled genesis of Archaean crust and sub-continental lithospheric mantle. Geochim Cosmochim Acta 70(5):1188–1214. https://doi.org/10.1016/j.gca.2005.11.008

Bédard JH (2018) Stagnant lids and mantle overturns: implications for Archaean tectonics, magmagenesis, crustal growth, mantle evolution, and the start of plate tectonics. Geosci Front 9(1):19–49. https://doi.org/10.1016/j.gsf.2017.01.005

Bédard JH, Brouillette P, Madore L, Berclaz A (2003) Archaean cratonization and deformation in the northern Superior Province, Canada: an evaluation of plate tectonic versus vertical tectonic models. Precambrian Res 127:61–87. https://doi.org/10.1016/S0301-9268(03)00181-5

Bédard JH, Harris LB, Thurston PC (2013) The hunting of the snArc. Precambrian Res 229:20–48. https://doi.org/10.1016/j.precamres.2012.04.001

Bercovici D, Ricard Y (2014) Generation of plate tectonics with two-phase grain-damage and pinning: source-sink model and toroidal flow. Earth Planet Sci Lett 365:275–288. https://doi.org/10.1016/j.epsl.2013.02.002

Bilotti F, Suppe J (1999) The global distribution of wrinkle ridges on Venus. Icarus 139(1):137–157. https://doi.org/10.1006/icar.1999.6092

Bindschadler DL, Parmentier EM (1990) Mantle flow tectonics: the influence of a ductile lower crust and implications for the formation of topographic uplands on Venus. J Geophys Res, Solid Earth 95(B13):21329–21344. https://doi.org/10.1029/JB095iB13p21329

Bindschadler DL, Schubert G, Kaula WM (1992) Coldspots and hotspots: global tectonics and mantle dynamics of Venus. J Geophys Res, Planets 97(E8):13495–13532. https://doi.org/10.1029/92JE01165
Anderson FS, Smrekar SE (2006) Global mapping of crustal and lithospheric thickness on Venus. J Geophys Res, Planets 111:E08006. https://doi.org/10.1029/2004JE002395

Anhaeusser CR (2014) Archaean greenstone belts and associated granitic rocks – a review. J Afr Earth Sci 100:684–732. https://doi.org/10.1016/j.jafrearsci.2014.07.019

Ansan V, Vergely P (1995) Evidence of vertical and horizontal motions on Venus: Maxwell Montes. Earth Moon Planets 69:285–310. https://doi.org/10.1007/BF00643789

Arculus RJ (2003) Use and abuse of the terms calcalkaline and calcalkalic. J Petrol 44:929–935. https://doi.org/10.1093/petrology/44.5.929

Armann M, Tackley PJ (2012) Simulating the thermochemical magmatic and tectonic evolution of Venus’s mantle and lithosphere: Two-dimensional models. J Geophys Res, Planets 117(E12). https://doi.org/10.1029/2012JE004231

Bachmann O, Bergantz GW (2008) Deciphering magma chamber dynamics from styles of compositional zoning in large silicic ash flow sheets. Rev Mineral Geochem 69(1):651–674. https://doi.org/10.2138/rmg.2008.69.17

Baes M, Gerya T, Sobolev SV (2016) 3-D thermo-mechanical modeling of plume-induced subduction initiation. Earth Planet Sci Lett 453:193–203. https://doi.org/10.1016/j.epsl.2016.08.023

Baker VR, Komatsu G, Parker TJ, Gulick VC, Kargel JS, Lewis JS (1992) Channels and valleys on Venus: preliminary analysis of Magellan data. J Geophys Res, Planets 97(E8):13421–13444. https://doi.org/10.1029/92JE00927

Banerdt WB (1986) Support of long-wavelength loads on Venus and implications for internal structure. J Geophys Res, Solid Earth 91(B1):403–419. https://doi.org/10.1029/JB091iB01p00403

Barsukov VL, Basilevsky AT, Burba GA, Bobinna NN, Kryuchkov VP, Kuzmin RO, Nikolaeva OV, Pronin AA, Ronca LB, Chernaya IM, Shashkina VP, Garanin AV, Kushky ER, Markov MS, Sukhanov AL, Kotelnikov VA, Rzhiga ON, Petrov GM, Alexandrov YN, Sidorenko AI, Bogomolov AF, Skrypnik GI, Bergman MY, Kudrin LV, Bokshtein IM, Kronrod MA, Chochia PA, Tyuflin YS, Kadnichansky SA, Akim EL (1986) The geology and geomorphology of the Venus surface as revealed by the radar images obtained by Veneras 15 and 16. J Geophys Res, Solid Earth 91(B4):378–398. https://doi.org/10.1029/JB091iB04p0D378

Basilevsky AT, Head JW (1996) Evidence for rapid and widespread emplacement of volcanic plains on Venus: stratigraphic studies in the Baltis Vallis region. Geophys Res Lett 23(12):1497–1500. https://doi.org/10.1029/96GL00975

Basilevsky AT, Head JW (2002) Venus: timing and rates of geologic activity. Geology 30(11):1015–1018. https://doi.org/10.1130/0091-7613(2002)030<1015:VTAROG>2.0.CO;2

Basilevsky AT, Kuzmin RO, Nikolaeva OV, Pronin AA, Ronca LB, Avduevsky VS, Uspensky GR, Chere-mukhina ZP, Semenchenko VV, Ladygin VM (1985) The surface of Venus as revealed by the Venera landings: part II. Geol Soc Am Bull 96(1):137–144. https://doi.org/10.1130/0016-7606(1985)96<137:TSOVAR>2.0.CO;2

Basilevsky AT, Nikolaeva OV, Weitz CM (1992) Geology of the Venera 8 landing site region from Magellan data: morphological and geochemical considerations. J Geophys Res, Planets 97:16315–16335. https://doi.org/10.1029/92JE01557

Bédard JH (2006) A catalytic delamination-driven model for coupled genesis of Archaean crust and sub-continental lithospheric mantle. Geochim Cosmochim Acta 70(5):1188–1214. https://doi.org/10.1016/j.gca.2005.11.008

Bédard JH (2018) Stagnant lids and mantle overturns: implications for Archaean tectonics, magmagenesis, crustal growth, mantle evolution, and the start of plate tectonics. Geosci Front 9(1):19–49. https://doi.org/10.1016/j.gsf.2017.01.005

Bédard JH, Brouillette P, Madore L, Berclaz A (2003) Archaean cratonization and deformation in the northern Superior Province, Canada: an evaluation of plate tectonic versus vertical tectonic models. Precambrian Res 127:61–87. https://doi.org/10.1016/S0301-9268(03)00181-5

Bédard JH, Harris LB, Thurston PC (2013) The hunting of the snArc. Precambrian Res 229:20–48. https://doi.org/10.1016/j.precamres.2012.04.001

Bercovici D, Ricard Y (2014) Generation of plate tectonics with two-phase grain-damage and pinning: source-sink model and toroidal flow. Earth Planet Sci Lett 365:275–288. https://doi.org/10.1016/j.epsl.2013.02.002

Bilotti F, Suppe J (1999) The global distribution of wrinkle ridges on Venus. Icarus 139(1):137–157. https://doi.org/10.1006/icar.1999.6092

Bindschadler DL, Parmentier EM (1990) Mantle flow tectonics: the influence of a ductile lower crust and implications for the formation of topographic uplands on Venus. J Geophys Res, Solid Earth 95(B13):21329–21344. https://doi.org/10.1029/JB095iB13p21329

Bindschadler DL, Schubert G, Kaula WM (1992) Coldspots and hotspots: global tectonics and mantle dynamics of Venus. J Geophys Res, Planets 97(E8):13495–13532. https://doi.org/10.1029/92JE01165
Bjonnes E, Johnson BC, Evans AJ (2021) Estimating Venusian thermal conditions using multiring basin morphology. Nat Astron 5:498–502. https://doi.org/10.1038/s41550-020-01289-6

Blaske CH, O'Rourke JG, Desch SJ, Borrelli ME (2023) Meteors may masquerade as lightning in the atmosphere of Venus. J Geophys Res, Planets 128(9):e2023JE007914. https://doi.org/10.1029/2023JE007914

Bleeker W (2002) The late Archean record: a puzzle in ca. 35 pieces. Lithos 71:99–134. https://doi.org/10.1016/j.lithos.2003.07.003

Bolea-Fernandez E, Van Malderen SJM, Balcaen L, Resano M, Vanhaecke F (2016) Laser ablation-tandem ICP-mass spectrometry (LA-ICP-MS/MS) for direct Sr isotopic analysis of solid samples with high Rb/Sr ratios. J Anal At Spectrom 31:464–472. https://doi.org/10.1039/C5JA00404G

Bondarenko NV, Head JW, Ivanov MA (2010) Present-day volcanism on Venus: evidence from microwave radiometry. Geophys Res Lett 37(23). https://doi.org/10.1029/2010GL045233

Bonin B (2012) Extra-terrestrial igneous granites and related rocks: a review of their occurrence and petrogenesis. Lithos 153:3–24. https://doi.org/10.1016/j.lithos.2012.04.007

Borrelli ME, O'Rourke JG, Smrekar SE, Ostberg CM (2021) A global survey of lithospheric flexure at steep-sided domical volcanoes on Venus reveals intermediate elastic thicknesses. J Geophys Res, Planets 126(7):e2020JE006756. https://doi.org/10.1029/2020JE006756

Brian AW, Stofan ER, Guest JE, Smrekar SE (2004) Laufey Regio: a newly discovered topographic rise on Venus. J Geophys Res, Planets 109(E7). https://doi.org/10.1029/2002JE002010

Bridges NT (1997) Ambient effects on basalt and rhyolite lavas under Venusian, subaerial, and subaqueous conditions. J Geophys Res, Planets 102(E4):9243–9255. https://doi.org/10.1029/97JE00390

Brissaud Q, Krishnamoorthy S, Jackson JM, Bowman DC, Komjathy A, Cutts JA, Zhan Z, Pauken MT, Izraelevitz JS, Walsh GJ (2021) The first detection of an earthquake from a balloon using its acoustic signature. Geophys Res Lett 48(12):e2021GL093013. https://doi.org/10.1029/2021GL093013

Brossier JF, Gilmore MS, Toner K (2020) Low radar emissivity signatures on Venus volcanoes and coronae: new insights on relative composition and age. Icarus 343:113693. https://doi.org/10.1016/j.icarus.2020.113693

Brown CD, Grimm RE (1995) Tectonics of Artemis Chasma: a Venusian “Plate” boundary. Icarus 117(2):219–249. https://doi.org/10.1006/icar.1995.1155

Brown CD, Grimm RE (1996) Lithospheric rheology and flexure at Artemis Chasma, Venus. J Geophys Res 101(E5):12697–12708. https://doi.org/10.1029/96JE00834

Brown CD, Grimm RE (1997) Tessera deformation and the contemporaneous thermal state of the plateau highlands. Venus, Earth and Planetary Science Letters 147(1):1–10. https://doi.org/10.1016/S0012-821X(97)00007-1

Brown CD, Grimm RE (1999) Recent tectonic and lithospheric thermal evolution of Venus. Icarus 139(1):40–48. https://doi.org/10.1006/icar.1999.6083

Brown M, Johnson T, Gardiner NJ (2020) Plate tectonics and the Archean Earth. Annu Rev Earth Planet Sci 48:291–320. https://doi.org/10.1146/annurev-earth-081619-052705

Bullock MA, Grinspoon DH (2001) The recent evolution of climate on Venus. Icarus 150:19–37. https://doi.org/10.1006/icar.2000.6570

Burov E, Cloetingh S (2010) Plume-like upper mantle instabilities drive subduction initiation. Geophys Res Lett 37(3). https://doi.org/10.1029/2009GL041535

Byrne PK, Krishnamoorthy S (2022) Estimates on the frequency of volcanic eruptions on Venus. J Geophys Res, Planets 127:e2021JE007040. https://doi.org/10.1029/2021JE007040

Byrne PK, Ghail RC, Gilmore MS, Şengör AMC, Klimczak C, Senske DA, Whitten JL, Khawja S, Ernst RE, Solomon SC (2021) Venus tesserae feature layered, folded, and eroded rocks. Geology 49:81–85. https://doi.org/10.1130/G47940.1

Cadman AC, Heaman L, Tarney J, Wardle R, Krogh TE (1993) U-Pb geochronology and geochemical variation within two Proterozoic mafic dyke swarms. Labrador Canad J Earth Sci 30:1490–1504. https://doi.org/10.1139/e93-128

Campbell IH (2002) Implications of the Nb/U, Th/U and Sm/Nd in plume magmas for the relationship between continental and oceanic crust formation and the development of depleted mantle. Geochim Cosmochim Acta 66(9):1651–1661. https://doi.org/10.1016/S0016-7037(01)00856-0

Campbell IH, Hill RI (1988) A two-stage model for the formation of the granite-greenstone terrains of the Kalgoorlie-Norseman area, Western Australia. Earth Planet Sci Lett 90(1):11–25. https://doi.org/10.1016/0012-821X(88)90107-0

Campbell IH, Taylor SR (1983) No water, no granites - no oceans, no continents. Geophys Res Lett 10(11):1061–1064. https://doi.org/10.1029/GL010i011p01061

Campbell BA, Campbell DB, Morgan GA, Carter LM, Nolan MC, Chandler JF (2015) Evidence for crater ejecta on Venus tessera terrain from Earth-based radar images. Icarus 250:123–130. https://doi.org/10.1016/j.icarus.2014.11.025
Bjonnes E, Johnson BC, Evans AJ (2021) Estimating Venusian thermal conditions using multiring basin morphology. Nat Astron 5:498–502. https://doi.org/10.1038/s41550-020-01289-6

Blaske CH, O'Rourke JG, Desch SJ, Borrelli ME (2023) Meteors may masquerade as lightning in the atmosphere of Venus. J Geophys Res, Planets 128(9):e2023JE007914. https://doi.org/10.1029/2023JE007914

Bleeker W (2002) The late Archean record: a puzzle in ca. 35 pieces. Lithos 71:99–134. https://doi.org/10.1016/j.lithos.2003.07.003

Bolea-Fernandez E, Van Malderen SJM, Balcaen L, Resano M, Vanhaecke F (2016) Laser ablation-tandem ICP-mass spectrometry (LA-ICP-MS/MS) for direct Sr isotopic analysis of solid samples with high Rb/Sr ratios. J Anal At Spectrom 31:464–472. https://doi.org/10.1039/C5JA00404G

Bondarenko NV, Head JW, Ivanov MA (2010) Present-day volcanism on Venus: evidence from microwave radiometry. Geophys Res Lett 37(23). https://doi.org/10.1029/2010GL045233

Bonin B (2012) Extra-terrestrial igneous granites and related rocks: a review of their occurrence and petrogenesis. Lithos 153:3–24. https://doi.org/10.1016/j.lithos.2012.04.007

Borrelli ME, O'Rourke JG, Smrekar SE, Ostberg CM (2021) A global survey of lithospheric flexure at steep-sided domical volcanoes on Venus reveals intermediate elastic thicknesses. J Geophys Res, Planets 126(7):e2020JE006756. https://doi.org/10.1029/2020JE006756

Brian AW, Stofan ER, Guest JE, Smrekar SE (2004) Laufey Regio: a newly discovered topographic rise on Venus. J Geophys Res, Planets 109(E7). https://doi.org/10.1029/2002JE002010

Bridges NT (1997) Ambient effects on basalt and rhyolite lavas under Venusian, subaerial, and subaqueous conditions. J Geophys Res, Planets 102(E4):9243–9255. https://doi.org/10.1029/97JE00390

Brissaud Q, Krishnamoorthy S, Jackson JM, Bowman DC, Komjathy A, Cutts JA, Zhan Z, Pauken MT, Izraelevitz JS, Walsh GJ (2021) The first detection of an earthquake from a balloon using its acoustic signature. Geophys Res Lett 48(12):e2021GL093013. https://doi.org/10.1029/2021GL093013

Brossier JF, Gilmore MS, Toner K (2020) Low radar emissivity signatures on Venus volcanoes and coronae: new insights on relative composition and age. Icarus 343:113693. https://doi.org/10.1016/j.icarus.2020.113693

Brown CD, Grimm RE (1995) Tectonics of Artemis Chasma: a Venusian “Plate” boundary. Icarus 117(2):219–249. https://doi.org/10.1006/icar.1995.1155

Brown CD, Grimm RE (1996) Lithospheric rheology and flexure at Artemis Chasma, Venus. J Geophys Res 101(E5):12697–12708. https://doi.org/10.1029/96JE00834

Brown CD, Grimm RE (1997) Tessera deformation and the contemporaneous thermal state of the plateau highlands. Venus, Earth and Planetary Science Letters 147(1):1–10. https://doi.org/10.1016/S0012-821X(97)00007-1

Brown CD, Grimm RE (1999) Recent tectonic and lithospheric thermal evolution of Venus. Icarus 139(1):40–48. https://doi.org/10.1006/icar.1999.6083

Brown M, Johnson T, Gardiner NJ (2020) Plate tectonics and the Archean Earth. Annu Rev Earth Planet Sci 48:291–320. https://doi.org/10.1146/annurev-earth-081619-052705

Bullock MA, Grinspoon DH (2001) The recent evolution of climate on Venus. Icarus 150:19–37. https://doi.org/10.1006/icar.2000.6570

Burov E, Cloetingh S (2010) Plume-like upper mantle instabilities drive subduction initiation. Geophys Res Lett 37(3). https://doi.org/10.1029/2009GL041535

Byrne PK, Krishnamoorthy S (2022) Estimates on the frequency of volcanic eruptions on Venus. J Geophys Res, Planets 127:e2021JE007040. https://doi.org/10.1029/2021JE007040

Byrne PK, Ghail RC, Gilmore MS, Şengör AMC, Klimczak C, Senske DA, Whitten JL, Khawja S, Ernst RE, Solomon SC (2021) Venus tesserae feature layered, folded, and eroded rocks. Geology 49:81–85. https://doi.org/10.1130/G47940.1

Cadman AC, Heaman L, Tarney J, Wardle R, Krogh TE (1993) U-Pb geochronology and geochemical variation within two Proterozoic mafic dyke swarms. Labrador Canad J Earth Sci 30:1490–1504. https://doi.org/10.1139/e93-128

Campbell IH (2002) Implications of the Nb/U, Th/U and Sm/Nd in plume magmas for the relationship between continental and oceanic crust formation and the development of depleted mantle. Geochim Cosmochim Acta 66(9):1651–1661. https://doi.org/10.1016/S0016-7037(01)00856-0

Campbell IH, Hill RI (1988) A two-stage model for the formation of the granite-greenstone terrains of the Kalgoorlie-Norseman area, Western Australia. Earth Planet Sci Lett 90(1):11–25. https://doi.org/10.1016/0012-821X(88)90107-0

Campbell IH, Taylor SR (1983) No water, no granites - no oceans, no continents. Geophys Res Lett 10(11):1061–1064. https://doi.org/10.1029/GL010i011p01061

Campbell BA, Campbell DB, Morgan GA, Carter LM, Nolan MC, Chandler JF (2015) Evidence for crater ejecta on Venus tessera terrain from Earth-based radar images. Icarus 250:123–130. https://doi.org/10.1016/j.icarus.2014.11.025
Campbell BA, Morgan GA, Whitten JL, Carter LM, Glaze LS, Campbell DB (2017) Pyroclastic flow deposits on Venus as indicators of renewed magmatic activity. J Geophys Res, Planets 122(7):1580–1596. https://doi.org/10.1002/2017JE005299

Carter LM, Gilmore MS, Ghail RC, Byrne PK, Smrekar SE, Ganey TM, Izenberg N (2023) Sedimentary processes on Venus. Space Sci Rev 219:85. https://doi.org/10.1007/s11214-023-01033-2

Cawood PA, Hawkesworth CJ, Dhuime B (2013) The continental record and the generation of continental crust. Geol Soc Am Bull 125(1–2):14–32. https://doi.org/10.1130/B30722.1

Chantel J, Manthilake G, Andrault D, Novella D, Yu T, Wang YB (2016) Experimental evidence supports mantle partial melting in the asthenosphere. Experimental evidence supports mantle partial melting in the asthenosphere. Sci Adv 2, e1600246. https://doi.org/10.1126/sciadv.1600246. 2016

Christiansen RL (2005) Post-Laramide Tectonomagmatics of the U.S. Cordillera. Geochimica et Cosmochimica Acta Supplement 69(10). Supplement, 2005, A136

Christiansen EH, McCurry M (2008) Contrasting origins of Cenozoic silicic volcanic rocks from the western Cordillera of the United States. Bull Volcanol 70:251–267. https://doi.org/10.1007/s00445-007-0138-1

Clegg SM, Sklute E, Dyar MD, Barefield JE, Wiens RC (2009) Multivariate analysis of remote laser-induced breakdown spectroscopy spectra using partial least squares, principal component analysis, and related techniques. Spectrochim Acta, Part B, At Spectrosc 64(1):79–88. https://doi.org/10.1016/j.sab.2008.10.045

Cohen BA, Malespin CA, Farley KA, Martin PE, Cho Y, Mahaffy PR (2019) In situ geochronology on Mars and the development of future instrumentation. Astrobiology 19(11):1303–1314. https://doi.org/10.1089/ast.2018.1871

Coleman M, Hecht M, Hurowitz J, Neidholdt E, Polk J, Sinha MP, Sturhahn W, Zimmerman W (2012) In situ geochronology as a mission-enabling technology. In: 2012 IEEE aerospace conference, pp 1–8. https://doi.org/10.1109/AERO.2012.6187053

Condie KC (1981) Archean greenstone belts. Dev Precambrian Geol 3:1–434

Condie KC (2018) A planet in transition: the onset of plate tectonics on Earth between 3 and 2 Ga? Geosci Front 9(1):51–60. https://doi.org/10.1016/j.gsf.2016.09.001

Condie KC, Benn K (2006) Archean geodynamics: similar to or different from modern geodynamics? In: Benn K, Mareschal J-C, Condie KC (eds) Archean geodynamics and environments. Geophysical monograph series, vol 164, pp 47–59

Condie KC, Kröner A (2008) When did plate tectonics begin? Evidence from the geologic record. In: Condie KC, Pease V (eds) When did plate tectonics begin on planet Earth? Spec Pap Geol Soc Am, vol 440, pp 281–294

Condie KC, Aster RC van Hunen J (2016) A great thermal divergence in the mantle beginning 2.5 Ga: geochemical constraints from greenstone basalts and komatiites. Geosci Front 7(4):543–553. https://doi.org/10.1016/j.gsf.2016.01.006

Conrad JW, Nimmo F (2023) Constraining characteristic morphological wavelengths for Venus using Baltis Vallis. Geophys Res Lett 50(10):e2022GL101268. https://doi.org/10.1029/2022GL101268

Cordier D, Bonhommeau DA, Port S, Chevrier V, Lebonnois S, García-Sánchez F (2019) The physical origin of the Venus low atmosphere chemical gradient. Astrophys J 880:2. https://doi.org/10.3847/1538-4357/ab27bd

Crumpler LS, Head JW, Aubele JC (1993) Relation of major volcanic center concentration on Venus to global tectonic patterns. Science 261(5121):591–595. https://doi.org/10.1126/science.261.5121.591

Crumpler LS, Aubele JC, Senske DA, Keddie ST, Magee KP, Head JW (1997) Volcanoes and centers of volcanism on Venus. In: Bougher SW, Hunten DM, Phillips RJ (eds) Venus II. University of Arizona Press, Tucson, pp 697–756

Crumpler LS, Aubele JC (2000) Volcanism on Venus. In: Sigurdsson H et al (eds) Encyclopedia of volcanoes. Academic Press, New York, pp 727–770

Cutts J, Baines K, Dorsky L, Frazier W, Izraelevitz J, Krishnamoorthy S et al (2022) Exploring the clouds of Venus: science driven Aerobot missions to our sister planet. In: 2022 IEEE aerospace conference (AERO), pp 1–20. https://doi.org/10.1109/AERO53065.2022.9843740

Cyr KE, Melosh HJ (1993) Tectonic patterns and regional stresses near Venusian coronae. Icarus 102(2):175–184. https://doi.org/10.1006/icar.1993.1042

Davaille A, Smrekar SE, Tomlinson S (2017) Experimental and observational evidence for plume-induced subduction on Venus. Nat Geosci 10(5):349–355. https://doi.org/10.1038/ngeo2928

Dawson JB (1962) Sodium Carbonate Lavas from Oldoinyo Lengai. Tanganyika Nat 195(4846):1075–1076. https://doi.org/10.1038/1951075a0

Dawson JB, Pinkerton H, Norton GE, Pyle DM (1990) Physicochemical properties of alkali carbonatite lavas: data from the 1988 eruption of Oldoinyo Lengai. Tanzania Geol 18(3):260–263. https://doi.org/10.1130/0091-7613(1990)018<0260:PPOACL>2.3.CO;2

de WitMJ, Ashwal LD (1995) Greenstone belts: what are they? S Afr J Geol 98:505–520
Campbell BA, Morgan GA, Whitten JL, Carter LM, Glaze LS, Campbell DB (2017) Pyroclastic flow deposits on Venus as indicators of renewed magmatic activity. *J Geophys Res, Planets* 122(7):1580–1596. https://doi.org/10.1002/2017JE005299

Carter LM, Gilmore MS, Ghail RC, Byrne PK, Smrekar SE, Ganey TM, Izenberg N (2023) Sedimentary processes on Venus. *Space Sci Rev* 219:85. https://doi.org/10.1007/s11214-023-01033-2

Cawood PA, Hawkesworth CJ, Dhuime B (2013) The continental record and the generation of continental crust. *Geol Soc Am Bull* 125(1–2):14–32. https://doi.org/10.1130/B30722.1

Chantel J, Manthilake G, Andrault D, Novella D, Yu T, Wang YB (2016) Experimental evidence supports mantle partial melting in the asthenosphere. *Experimental evidence supports mantle partial melting in the asthenosphere*. *Sci Adv* 2, e1600246. https://doi.org/10.1126/sciadv.1600246. 2016

Christiansen RL (2005) Post-Laramide Tectonomagmatics of the U.S. Cordillera. *Geochimica et Cosmochimica Acta* Supplement 69(10). Supplement, 2005, A136

Christiansen EH, McCurry M (2008) Contrasting origins of Cenozoic silicic volcanic rocks from the western Cordillera of the United States. *Bull Volcanol* 70:251–267. https://doi.org/10.1007/s00445-007-0138-1

Clegg SM, Sklute E, Dyar MD, Barefield JE, Wiens RC (2009) Multivariate analysis of remote laser-induced breakdown spectroscopy spectra using partial least squares, principal component analysis, and related techniques. *Spectrochim Acta, Part B, At Spectrosc* 64(1):79–88. https://doi.org/10.1016/j.sab.2008.10.045

Cohen BA, Malespin CA, Farley KA, Martin PE, Cho Y, Mahaffy PR (2019) In situ geochronology on Mars and the development of future instrumentation. *Astrobiology* 19(11):1303–1314. https://doi.org/10.1089/ast.2018.1871

Coleman M, Hecht M, Hurowitz J, Neidholdt E, Polk J, Sinha MP, Sturhahn W, Zimmerman W (2012) In situ geochronology as a mission-enabling technology. In: 2012 IEEE aerospace conference, pp 1–8. https://doi.org/10.1109/AERO.2012.6187053

Condie KC (1981) Archean greenstone belts. *Dev Precambrian Geol* 3:1–434

Condie KC (2018) A planet in transition: the onset of plate tectonics on Earth between 3 and 2 Ga? *Geosci Front* 9(1):51–60. https://doi.org/10.1016/j.gsf.2016.09.001

Condie KC, Benn K (2006) Archean geodynamics: similar to or different from modern geodynamics? In: Benn K, Mareschal J-C, Condie KC (eds) Archean geodynamics and environments. *Geophysical monograph series*, vol 164, pp 47–59

Condie KC, Kröner A (2008) When did plate tectonics begin? Evidence from the geologic record. In: Condie KC, Pease V (eds) When did plate tectonics begin on planet Earth? *Spec Pap Geol Soc Am*, vol 440, pp 281–294

Condie KC, Aster RC van Hunen J (2016) A great thermal divergence in the mantle beginning 2.5 Ga: geochemical constraints from greenstone basalts and komatiites. *Geosci Front* 7(4):543–553. https://doi.org/10.1016/j.gsf.2016.01.006

Conrad JW, Nimmo F (2023) Constraining characteristic morphological wavelengths for Venus using Baltis Vallis. *Geophys Res Lett* 50(10):e2022GL101268. https://doi.org/10.1029/2022GL101268

Cordier D, Bonhommeau DA, Port S, Chevrier V, Lebonnois S, García-Sánchez F (2019) The physical origin of the Venus low atmosphere chemical gradient. *Astrophys J* 880:2. https://doi.org/10.3847/1538-4357/ab27bd

Crumpler LS, Head JW, Aubele JC (1993) Relation of major volcanic center concentration on Venus to global tectonic patterns. *Science* 261(5121):591–595. https://doi.org/10.1126/science.261.5121.591

Crumpler LS, Aubele JC, Senske DA, Keddie ST, Magee KP, Head JW (1997) Volcanoes and centers of volcanism on Venus. In: Bougher SW, Hunten DM, Phillips RJ (eds) Venus II. University of Arizona Press, Tucson, pp 697–756

Crumpler LS, Aubele JC (2000) Volcanism on Venus. In: Sigurdsson H et al (eds) *Encyclopedia of volcanoes*. Academic Press, New York, pp 727–770

Cutts J, Baines K, Dorsky L, Frazier W, Izraelevitz J, Krishnamoorthy S et al (2022) Exploring the clouds of Venus: science driven Aerobot missions to our sister planet. In: 2022 IEEE aerospace conference (AERO), pp 1–20. https://doi.org/10.1109/AERO53065.2022.9843740

Cyr KE, Melosh HJ (1993) Tectonic patterns and regional stresses near Venusian coronae. *Icarus* 102(2):175–184. https://doi.org/10.1006/icar.1993.1042

Davaille A, Smrekar SE, Tomlinson S (2017) Experimental and observational evidence for plume-induced subduction on Venus. *Nat Geosci* 10(5):349–355. https://doi.org/10.1038/ngeo2928

Dawson JB (1962) Sodium Carbonate Lavas from Oldoinyo Lengai. *Tanganyika Nat* 195(4846):1075–1076. https://doi.org/10.1038/1951075a0

Dawson JB, Pinkerton H, Norton GE, Pyle DM (1990) Physicochemical properties of alkali carbonatite lavas: data from the 1988 eruption of Oldoinyo Lengai. *Tanzania Geol* 18(3):260–263. https://doi.org/10.1130/0091-7613(1990)018<0260:PPOACL>2.3.CO;2

de Wit MJ, Ashwal LD (1995) Greenstone belts: what are they? *S Afr J Geol* 98:505–520
D'Incecco P, Müller N, Helbert J, D'Amore M (2017) Idunn Mons on Venus: location and extent of recently active lava flows. *Planet Space Sci* 136:25-33. https://doi.org/10.1016/j.pss.2016.12.002

Dombard AJ, Johnson CL, Richards MA, Solomon SC (2007) A magmatic loading model for coronae on Venus. *J Geophys Res, Planets* 112(E4). https://doi.org/10.1029/2006JE002731

Donahue TM, Grinspoon DH, Hartle RE, Hodges RR (1997) Ion/neutral escape of hydrogen and deuterium: evolution of water. In: Bougher SW, Hunten DM, Phillips RJ (eds) Venus II. Univ. Arizona Press, Tucson, pp 385-414

Duncan M, Dasgupta R (2017) Rise of Earth's atmospheric oxygen controlled by efficient subduction of organic carbon. *Nat Geosci* 10:387-392. https://doi.org/10.1038/ngeo2939

Dyar MD, Helbert J, Marturilli A, Müller NT, Kappel D (2020) Probing Venus surface iron contents with six-band visible near-infrared spectroscopy from orbit. *Geophys Res Lett* 47(23):e2020GL090497. https://doi.org/10.1029/2020GL090497

Dyar MD, Helbert J, Cooper RC, Sklute EC, Marurilli A, Mueller NT, Kappel D, Smrekar SE (2021) Surface weathering on Venus: constraints from kinetic, spectroscopic, and geochemical data. *Icarus* 358:114139. https://doi.org/10.1016/j.icarus.2020.114139

Elkins-Tanton LT, Smrekar SE, Hess PC, Parmentier EM (2007) Volcanism and volatile recycling on a one-plate planet: Applications to Venus. *J Geophys Res, Planets* 112(E4). https://doi.org/10.1029/2006JE002793

Ernst R, Bleeker W (2010) Large igneous provinces (LIPs), giant dyke swarms, and mantle plumes: significance for break-up events within Canada and adjacent regions from 2.5 Ga to the present. *Can J Earth Sci* 47:695-739. https://doi.org/10.1139/E10-025

Ernst RE, Buchan KL (2001) Large mafic magmatic events through time and links to mantle plume heads. In: Buchan RE, Buchan KL (eds) Mantle plumes: their identification through time. Spec Pap Geol Soc Am, vol 352, pp 483-575. https://doi.org/10.1130/0-8137-2352-3.483

Ernst RE, Head JW, Parfitt E, Grosfils E, Wilson L (1995) Giant radiating dyke swarms on Earth and Venus. *Earth-Sci Rev* 39(1):1-58. https://doi.org/10.1016/0012-8252(95)00017-5

Ernst RE, Grosfils EB, Mège D (2001) Giant Dike Swarms: Earth, Venus, and Mars. *Annu Rev Earth Planet Sci* 29:489-534. https://doi.org/10.1146/annurev.earth.29.1.489

Ernst RE, Dosnoyers DW, Head JW, Grosfils EB (2003) Graben-fissure systems in Guinevere Planitia and Beta Regio (264°-312°E, 24°-60°N), Venus, and implications for regional stratigraphy and mantle plumes. *Icarus* 164:282-316. https://doi.org/10.1016/S0019-1035(03)00126-X

Fagereng Å, Biggs J (2019) New perspectives on 'geological strain rates' calculated from both naturally deformed and actively deforming rocks. *J Struct Geol* 125:100-110. https://doi.org/10.1016/j.jsg.2018.10.004

Faure G (2001) Origin of igneous rocks: the isotopic evidence. Springer, Heidelberg

Fegley B Jr, Prinn RG (1989) Estimation of the rate of volcanism on Venus from reaction rate measurements. *Nature* 337:55-58. https://doi.org/10.1038/337055a0

Fegley B (2003) Venus. In: Holland HD, Turekian KK (eds) Treatise on geochemistry, vol 1. Elsevier, Amsterdam, pp 487-507. https://doi.org/10.1016/b0-08-043751-6/01150-6

Fegley B, Klingelhofer G, Lodders K, Widemann T (1997) Geochemistry of surface-atmosphere interactions on Venus. In: Bougher SW, Hunten DM, Phillips RJ (eds) Venus II. University of Arizona Press, Tucson, pp 591-636

Filiberto J (2014) Magmatic diversity on Venus: constraints from terrestrial analog crystallization experiments. *Icarus* 231:131-136. https://doi.org/10.1016/j.icarus.2013.12.003

Filiberto J, Trang D, Treiman AH, Gilmore MS (2020) Present-day volcanism on Venus as evidenced from weathering rates of olivine. *Sci Adv* 6(1):eaaax7445. https://doi.org/10.1126/sciadv.aax7445

Florensky CP, Ronca LB, Basilevsky AT, Burba GA, Nikolaeva OV, Pronin AA, Trakhtman AM, Volkov VP, Zazetsky VV (1977) The surface of Venus as revealed by Soviet Venera 9 and 10. *Geol Soc Am Bull* 88(11):1537-1545. https://doi.org/10.1130/0016-7606(1977)88<1537:TSOVAR>2.0.CO;2

Flynn ITW, Chevrel MO, Ramsey MS (2023) Adaptation of a thermorheological lava flow model for Venus conditions. *J Geophys Res, Planets* 128(7):e2022JE007710. https://doi.org/10.1029/2022JE007710

Ford JP, Plaut JJ, Weitz CM, Farr TG, Senske DA, Stofan ER, Michaels G, Parker TJ (1993) Guide to Magellan image interpretation. JPL Publ 93(24)

Galgana GA, McGovern PJ, Grosfils EB (2011) Evolution of large Venusian volcanoes: Insights from coupled models of lithospheric flexure and magma reservoir pressurization. *Journal of Geophysical Research Planets* 116(E3). https://doi.org/10.1029/2010JE003654

Galgana GA, Grosfils EB, McGovern PJ (2013) Radial dike formation on Venus: insights from models of uplift, flexure and magmatism. *Icarus* 225(1):538-547. https://doi.org/10.1016/j.icarus.2013.04.020

Ganesh I, McGuire LA, Carter LM (2021) Modeling the dynamics of dense pyroclastic flows on Venus: insights into pyroclastic eruptions. *J Geophys Res, Planets* 126(9):e2021JE006943. https://doi.org/10.1029/2021JE006943
D'Inecco P, Müller N, Helbert J, D'Amore M (2017) Idunn Mons on Venus: location and extent of recently active lava flows. *Planet Space Sci* 136:25-33. https://doi.org/10.1016/j.pss.2016.12.002

Dombard AJ, Johnson CL, Richards MA, Solomon SC (2007) A magmatic loading model for coronae on Venus. *J Geophys Res, Planets* 112(E4). https://doi.org/10.1029/2006JE002731

Donahue TM, Grinspoon DH, Hartle RE, Hodges RR (1997) Ion/neutral escape of hydrogen and deuterium: evolution of water. In: Bougher SW, Hunten DM, Phillips RJ (eds) Venus II. Univ. Arizona Press, Tucson, pp 385-414

Duncan M, Dasgupta R (2017) Rise of Earth's atmospheric oxygen controlled by efficient subduction of organic carbon. *Nat Geosci* 10:387-392. https://doi.org/10.1038/ngeo2939

Dyar MD, Helbert J, Marturilli A, Müller NT, Kappel D (2020) Probing Venus surface iron contents with six-band visible near-infrared spectroscopy from orbit. *Geophys Res Lett* 47(23):e2020GL090497. https://doi.org/10.1029/2020GL090497

Dyar MD, Helbert J, Cooper RC, Sklute EC, Marurilli A, Mueller NT, Kappel D, Smrekar SE (2021) Surface weathering on Venus: constraints from kinetic, spectroscopic, and geochemical data. *Icarus* 358:114139. https://doi.org/10.1016/j.icarus.2020.114139

Elkins-Tanton LT, Smrekar SE, Hess PC, Parmentier EM (2007) Volcanism and volatile recycling on a one-plate planet: Applications to Venus. *J Geophys Res, Planets* 112(E4). https://doi.org/10.1029/2006JE002793

Ernst R, Bleeker W (2010) Large igneous provinces (LIPs), giant dyke swarms, and mantle plumes: significance for break-up events within Canada and adjacent regions from 2.5 Ga to the present. *Can J Earth Sci* 47:695-739. https://doi.org/10.1139/E10-025

Ernst RE, Buchan KL (2001) Large mafic magmatic events through time and links to mantle plume heads. In: Buchan RE, Buchan KL (eds) Mantle plumes: their identification through time. Spec Pap Geol Soc Am, vol 352, pp 483-575. https://doi.org/10.1130/0-8137-2352-3.483

Ernst RE, Head JW, Parfitt E, Grosfils E, Wilson L (1995) Giant radiating dyke swarms on Earth and Venus. *Earth-Sci Rev* 39(1):1-58. https://doi.org/10.1016/0012-8252(95)00017-5

Ernst RE, Grosfils EB, Mège D (2001) Giant Dike Swarms: Earth, Venus, and Mars. Annu Rev Earth Planet Sci 29:489-534. https://doi.org/10.1146/annurev.earth.29.1.489

Ernst RE, Dosnoyers DW, Head JW, Grosfils EB (2003) Graben-fissure systems in Guinevere Planitia and Beta Regio (264°-312°E, 24°-60°N), Venus, and implications for regional stratigraphy and mantle plumes. *Icarus* 164:282-316. https://doi.org/10.1016/S0019-1035(03)00126-X

Fagereng Å, Biggs J (2019) New perspectives on 'geological strain rates' calculated from both naturally deformed and actively deforming rocks. *J Struct Geol* 125:100-110. https://doi.org/10.1016/j.jsg.2018.10.004

Faure G (2001) Origin of igneous rocks: the isotopic evidence. Springer, Heidelberg

Fegley B Jr, Prinn RG (1989) Estimation of the rate of volcanism on Venus from reaction rate measurements. *Nature* 337:55-58. https://doi.org/10.1038/337055a0

Fegley B (2003) Venus. In: Holland HD, Turekian KK (eds) Treatise on geochemistry, vol 1. Elsevier, Amsterdam, pp 487-507. https://doi.org/10.1016/b0-08-043751-6/01150-6

Fegley B, Klingelhofer G, Lodders K, Widemann T (1997) Geochemistry of surface-atmosphere interactions on Venus. In: Bougher SW, Hunten DM, Phillips RJ (eds) Venus II. University of Arizona Press, Tucson, pp 591-636

Filiberto J (2014) Magmatic diversity on Venus: constraints from terrestrial analog crystallization experiments. *Icarus* 231:131-136. https://doi.org/10.1016/j.icarus.2013.12.003

Filiberto J, Trang D, Treiman AH, Gilmore MS (2020) Present-day volcanism on Venus as evidenced from weathering rates of olivine. *Sci Adv* 6(1):eaaax7445. https://doi.org/10.1126/sciadv.aax7445

Florensky CP, Ronca LB, Basilevsky AT, Burba GA, Nikolaeva OV, Pronin AA, Trakhtman AM, Volkov VP, Zazetsky VV (1977) The surface of Venus as revealed by Soviet Venera 9 and 10. *Geol Soc Am Bull* 88(11):1537-1545. https://doi.org/10.1130/0016-7606(1977)88<1537:TSOVAR>2.0.CO;2

Flynn ITW, Chevrel MO, Ramsey MS (2023) Adaptation of a thermorheological lava flow model for Venus conditions. *J Geophys Res, Planets* 128(7):e2022JE007710. https://doi.org/10.1029/2022JE007710

Ford JP, Plaut JJ, Weitz CM, Farr TG, Senske DA, Stofan ER, Michaels G, Parker TJ (1993) Guide to Magellan image interpretation. JPL Publ 93(24)

Galgana GA, McGovern PJ, Grosfils EB (2011) Evolution of large Venusian volcanoes: Insights from coupled models of lithospheric flexure and magma reservoir pressurization. *Journal of Geophysical Research Planets* 116(E3). https://doi.org/10.1029/2010JE003654

Galgana GA, Grosfils EB, McGovern PJ (2013) Radial dike formation on Venus: insights from models of uplift, flexure and magmatism. *Icarus* 225(1):538-547. https://doi.org/10.1016/j.icarus.2013.04.020

Ganesh I, McGuire LA, Carter LM (2021) Modeling the dynamics of dense pyroclastic flows on Venus: insights into pyroclastic eruptions. *J Geophys Res, Planets* 126(9):e2021JE006943. https://doi.org/10.1029/2021JE006943
Ganesh I, Carter LM, Henz TN (2022) Radar backscatter and emissivity models of proposed pyroclastic density current deposits on Venus. J Geophys Res, Planets 127(10):e2022JE007318. https://doi.org/10.1029/2022JE007318

Garcia RF, Klotz A, Hertzog A, Martin R, Gérier S, Kassarian E, Bordereau J, Venel S, Mimoun D (2022) Infrasound from large earthquakes recorded on a network of balloons in the stratosphere. Geophys Res Lett 49(15):e2022GL098844. https://doi.org/10.1029/2022GL098844

Garvin JB, Getty SA, Arney GN, Johnson NM, Kohler E, Schwer KO, Sekerak M, Bartels A, Saylor RS, Elliott VE, Goodloe CS, Garrison MB, Cottini V, Izenberg N, Lorenz R, Malespin CA, Ravine M, Webster CR, Atkinson DH, Aslam S, Atreya S, Bos BJ, Brinckerhoff WB, Campbell B, Crisp D, Filiberto JR, Forget F, Gilmore M, Gorius N, Grinspoon D, Hofmann AE, Kane SR, Kiefer W, Lebonnois S, Mahaffy PR, Pavlov A, Trainer M, Zahnle KJ, Zolotov M (2022) Revealing the mysteries of Venus: the DAVINCI mission. Planet Sci J 3:117. https://doi.org/10.3847/psj/ac63c2

George H, Malaspina DM, Goodrich K, Ma Y, Ramstad R, Connor D, Bale SD, Curry S (2023) Non-lightning-generated whistler waves in near-Venus space. Geophys Res Lett 50(19):e2023GL105426. https://doi.org/10.1029/2023GL105426

Gerya T (2014) Precambrian geodynamics: concepts and models. Gondwana Res 25:442–463. https://doi.org/10.1016/j.gr.2012.11.008

Gerya TV, Stern RJ, Baes M, Sobolev S, Whattam SA (2015) Plate tectonics on the Earth triggered by plume-induced subduction initiation. Nature 527:221–225. https://doi.org/10.1038/nature15752

Ghail RC (2002) Structure and evolution of southeast Thetis Regio. J Geophys Res, Planets 107(E8):4–1–4–7. https://doi.org/10.1029/2001JE001514

Ghail RC (2015) Rheological and petrological implications for a stagnant lid regime on Venus. Planet Space Sci 113–114:2–9. https://doi.org/10.1016/j.pss.2015.02.005

Ghent RR, Hansen VL (1999) Structural and kinematic analysis of eastern Ovda Regio, Venus: implications for crustal Plateau formation. Icarus 139(1):116–136. https://doi.org/10.1006/icar.1999.6085

Ghent RR, Tibuleac IM (2002) Ribbon spacing in Venusian tessera: implications for layer thickness and thermal state. Geophys Res Lett 29(20):61. https://doi.org/10.1029/2002GL015994

Giardini D, Lognonné P, Banerdt WB et al (2020) The seismicity of Mars. Nat Geosci 13:205–212. https://doi.org/10.1038/s41561-020-0539-8

Gilmore MS, Head JW (2000) Sequential deformation of plains at the margins of Alpha Regio, Venus: implications for tessera formation. Meteorit Planet Sci 35(4):667–687. https://doi.org/10.1111/j.1945-5100.2000.tb01451.x

Gilmore MS, Head JW (2018) Morphology and deformational history of Tellus Regio, Venus: evidence for assembly and collision. Planet Space Sci 154:5–20. https://doi.org/10.1016/j.pss.2018.02.001

Gilmore MS, Ivanov MA, Head JW, Basilevsky AT (1997) Duration of tessera deformation on Venus. J Geophys Res, Planets 102(E6):13357–13368. https://doi.org/10.1029/97JE00965

Gilmore MS, Collins GC, Ivanov MA, Marinangeli L, Head JW (1998) Style and sequence of extensional structures in tessera terrain. Venus J Geophys Res Planets 103(E7):16813–16840. https://doi.org/10.1029/98JE01322

Gilmore MS, Mueller N, Helbert J (2015) VIRTIS emissivity of Alpha Regio, Venus, with implications for tessera composition. Icarus 254:350–361. https://doi.org/10.1016/j.icarus.2015.04.008

Gilmore M, Treiman A, Helbert J, Smrekar S (2017) Venus surface composition constrained by observation and experiment. Space Sci Rev 212(3–4):1511–1540

Gilmore MS, Dyar MD, Mueller N et al (2023) Mineralogy of the Venus Surface. Space Sci Rev 219:52. https://doi.org/10.1007/s11214-023-00988-6

Glaze LS, Stofan ER, Smrekar SE, Baloga SM (2002) Insights into corona formation through statistical analyses. J Geophys Res, Planets 107(E12):18–1–18–12. https://doi.org/10.1029/2002JE001904

Glaze LS, Wilson CF, Zasova LV, Nakamura M, Limaye S (2018) Future of Venus research and exploration. Space Sci Rev 214:89. https://doi.org/10.1007/s11214-018-0528-z

Global Volcanism Program (2023). [Database] Volcanoes of the World (v. 5.1.5; 15 Dec 2023). Distributed by Smithsonian Institution, compiled by Venzke, E. https://doi.org/10.5479/si.GVP.VOTW5-2023.5.1

Gorevan SP, Myrick T, Davis K, Chau JJ, Bartlett P, Mukherjee S, Anderson R, Squyres SW, Arvidson RE, Madsen MB, Bertelsen P, Goetz W, Binau CS, Richter L (2003) Rock Abrasion Tool: Mars Exploration Rover mission. J Geophys Res, Planets 108(E12). https://doi.org/10.1029/2003JE002061

Griffiths RW, Campbell IH (1990) Stirring and structure in mantle starting plumes. Earth Planet Sci Lett 99(1–2):66–78. https://doi.org/10.1016/0012-821X(90)90071-5

Grimm RE, Hess PC (1997) The crust of Venus. In: Venus II. University of Arizona Press, Tucson, pp 1205–1244

Grimm RE, Barr AC, Harrison KP, Stillman DE, Neal KL, Vincent MA, Delory GT (2012) Aerial electromagnetic sounding of the lithosphere of Venus. Icarus 217(2):462–473. https://doi.org/10.1016/j.icarus.2011.07.021
Ganesh I, Carter LM, Henz TN (2022) Radar backscatter and emissivity models of proposed pyroclastic density current deposits on Venus. J Geophys Res, Planets 127(10):e2022JE007318. https://doi.org/10.1029/2022JE007318

Garcia RF, Klotz A, Hertzog A, Martin R, Gérier S, Kassarian E, Bordereau J, Venel S, Mimoun D (2022) Infrasound from large earthquakes recorded on a network of balloons in the stratosphere. Geophys Res Lett 49(15):e2022GL098844. https://doi.org/10.1029/2022GL098844

Garvin JB, Getty SA, Arney GN, Johnson NM, Kohler E, Schwer KO, Sekerak M, Bartels A, Saylor RS, Elliott VE, Goodloe CS, Garrison MB, Cottini V, Izenberg N, Lorenz R, Malespin CA, Ravine M, Webster CR, Atkinson DH, Aslam S, Atreya S, Bos BJ, Brinckerhoff WB, Campbell B, Crisp D, Filiberto JR, Forget F, Gilmore M, Gorius N, Grinspoon D, Hofmann AE, Kane SR, Kiefer W, Lebonnois S, Mahaffy PR, Pavlov A, Trainer M, Zahnle KJ, Zolotov M (2022) Revealing the mysteries of Venus: the DAVINCI mission. Planet Sci J 3:117. https://doi.org/10.3847/psj/ac63c2

George H, Malaspina DM, Goodrich K, Ma Y, Ramstad R, Connor D, Bale SD, Curry S (2023) Non-lightning-generated whistler waves in near-Venus space. Geophys Res Lett 50(19):e2023GL105426. https://doi.org/10.1029/2023GL105426

Gerya T (2014) Precambrian geodynamics: concepts and models. Gondwana Res 25:442–463. https://doi.org/10.1016/j.gr.2012.11.008

Gerya TV, Stern RJ, Baes M, Sobolev S, Whattam SA (2015) Plate tectonics on the Earth triggered by plume-induced subduction initiation. Nature 527:221–225. https://doi.org/10.1038/nature15752

Ghail RC (2002) Structure and evolution of southeast Thetis Regio. J Geophys Res, Planets 107(E8):4–1–4–7. https://doi.org/10.1029/2001JE001514

Ghail RC (2015) Rheological and petrological implications for a stagnant lid regime on Venus. Planet Space Sci 113–114:2–9. https://doi.org/10.1016/j.pss.2015.02.005

Ghent RR, Hansen VL (1999) Structural and kinematic analysis of eastern Ovda Regio, Venus: implications for crustal Plateau formation. Icarus 139(1):116–136. https://doi.org/10.1006/icar.1999.6085

Ghent RR, Tibuleac IM (2002) Ribbon spacing in Venusian tessera: implications for layer thickness and thermal state. Geophys Res Lett 29(20):61. https://doi.org/10.1029/2002GL015994

Giardini D, Lognonné P, Banerdt WB et al (2020) The seismicity of Mars. Nat Geosci 13:205–212. https://doi.org/10.1038/s41561-020-0539-8

Gilmore MS, Head JW (2000) Sequential deformation of plains at the margins of Alpha Regio, Venus: implications for tessera formation. Meteorit Planet Sci 35(4):667–687. https://doi.org/10.1111/j.1945-5100.2000.tb01451.x

Gilmore MS, Head JW (2018) Morphology and deformational history of Tellus Regio, Venus: evidence for assembly and collision. Planet Space Sci 154:5–20. https://doi.org/10.1016/j.pss.2018.02.001

Gilmore MS, Ivanov MA, Head JW, Basilevsky AT (1997) Duration of tessera deformation on Venus. J Geophys Res, Planets 102(E6):13357–13368. https://doi.org/10.1029/97JE00965

Gilmore MS, Collins GC, Ivanov MA, Marinangeli L, Head JW (1998) Style and sequence of extensional structures in tessera terrain. Venus J Geophys Res Planets 103(E7):16813–16840. https://doi.org/10.1029/98JE01322

Gilmore MS, Mueller N, Helbert J (2015) VIRTIS emissivity of Alpha Regio, Venus, with implications for tessera composition. Icarus 254:350–361. https://doi.org/10.1016/j.icarus.2015.04.008

Gilmore M, Treiman A, Helbert J, Smrekar S (2017) Venus surface composition constrained by observation and experiment. Space Sci Rev 212(3–4):1511–1540

Gilmore MS, Dyar MD, Mueller N et al (2023) Mineralogy of the Venus Surface. Space Sci Rev 219:52. https://doi.org/10.1007/s11214-023-00988-6

Glaze LS, Stofan ER, Smrekar SE, Baloga SM (2002) Insights into corona formation through statistical analyses. J Geophys Res, Planets 107(E12):18–1–18–12. https://doi.org/10.1029/2002JE001904

Glaze LS, Wilson CF, Zasova LV, Nakamura M, Limaye S (2018) Future of Venus research and exploration. Space Sci Rev 214:89. https://doi.org/10.1007/s11214-018-0528-z

Global Volcanism Program (2023). [Database] Volcanoes of the World (v. 5.1.5; 15 Dec 2023). Distributed by Smithsonian Institution, compiled by Venzke, E. https://doi.org/10.5479/si.GVP.VOTW5-2023.5.1

Gorevan SP, Myrick T, Davis K, Chau JJ, Bartlett P, Mukherjee S, Anderson R, Squyres SW, Arvidson RE, Madsen MB, Bertelsen P, Goetz W, Binau CS, Richter L (2003) Rock Abrasion Tool: Mars Exploration Rover mission. J Geophys Res, Planets 108(E12). https://doi.org/10.1029/2003JE002061

Griffiths RW, Campbell IH (1990) Stirring and structure in mantle starting plumes. Earth Planet Sci Lett 99(1–2):66–78. https://doi.org/10.1016/0012-821X(90)90071-5

Grimm RE, Hess PC (1997) The crust of Venus. In: Venus II. University of Arizona Press, Tucson, pp 1205–1244

Grimm RE, Barr AC, Harrison KP, Stillman DE, Neal KL, Vincent MA, Delory GT (2012) Aerial electromagnetic sounding of the lithosphere of Venus. Icarus 217(2):462–473. https://doi.org/10.1016/j.icarus.2011.07.021
Grindrod PM, Hoogenboom T (2006) Venus: the corona conundrum. Astron Geophys 47(3):3.16–3.21.
https://doi.org/10.1111/j.1468-4004.2006.47316.x

Grindrod PM, Nimmo F, Stofan ER, Guest JE (2005) Strain at radially fractured centers on Venus. J Geophys Res, Planets 110(E12):E12002. https://doi.org/10.1029/2005JE002416

Grindrod PM, Stofan ER, Guest JE (2010) Volcanism and resurfacing on Venus at the full resolution of Magellan SAR data. Geophys Res Lett 37(15). https://doi.org/10.1029/2010GL043424

Grosfils E, Head JW (1994a) Emplacement of a radiating dike swarm in western Vinmara Planitia, Venus: interpretation of the regional stress field orientation and subsurface magmatic configuration. Earth Moon Planets 66:153–171. https://doi.org/10.1007/BF00644129

Grosfils E, Head JW (1994b) The global distribution of giant radiating dike swarms on Venus: implications for the global stress state. Geophys Res Lett 21(8):701–704. https://doi.org/10.1029/94GL00592

Grosfils E, Aubele J, Crumpler L, Gregg T, Sakimoto S (2000) Volcanism on Earth's Seafloor and Venus. In: Zimbelman JR, Gregg TKP (eds) Environmental effects on volcanic eruptions: from deep oceans to deep space

Guest JE, Stofan ER (1999) A new view of the stratigraphic history of Venus. Icarus 139(1):55–66. https://doi.org/10.1006/icar.1999.6091

Gülcher AJP, Gerya TV, Montési LGJ, Munch J (2020) Corona structures driven by plume-lithosphere interactions and evidence for ongoing plume activity on Venus. Nat Geosci 13(8):547–554. https://doi.org/10.1038/s41561-020-0606-1

Gülcher AJP, Yu T-Y, Gerya TV (2023) Tectono-magmatic evolution of asymmetric coronae on Venus: topographic classification and 3D thermo-mechanical modeling. J Geophys Res, Planets 123(1):e2023JE007978. https://doi.org/10.1029/2023JE007978

Hahn RM, Byrne PK (2022) Kernel density analysis of volcanoes on Venus at varying spatial scales. Lun Planet Sci Conf 53:2437

Hamilton WB (1998) Archean magmatism and deformation were not products of plate tectonics. Precambrian Res 91(1–2):143–179. https://doi.org/10.1016/S0301-9268(98)00042-4

Hamilton WB (2011) Plate tectonics began in Neoproterozoic time, and plumes from deep mantle have never operated. Lithos 123:1–20. https://doi.org/10.1016/j.lithos.2010.12.007

Hamilton VE, Stofan ER (1996) The geomorphology and evolution of Hecate Chasma, Venus. Icarus 121(1):171–194. https://doi.org/10.1006/icar.1996.0077

Hansell SA, Wells WK, Hunten DH (1995) Optical detection of lightning on Venus. Icarus 117(2):345–351. https://doi.org/10.1006/icar.1995.1160

Hansen VL (2007) Venus: a thin-lithosphere analog for early Earth? In: Van Kranendonk MJ, Smithies RH, Bennett VC (eds) Earth's oldest rocks, developments in Precambrian geology 15, pp 987–1012

Hansen VL (2015) Impact origin of Archean cratons. Lithosphere 7(5):563–578. https://doi.org/10.1130/L371.1

Hansen VL (2018) Global tectonic evolution of Venus, from exogenic to endogenic over time, and implications for early Earth processes. Philos Trans R Soc A376:20170412. https://doi.org/10.1098/rsta.2017.0412

Hansen VL, Phillips RJ (1993) Tectonics and volcanism of eastern Aphrodite Terra, Venus: no subduction, no spreading. Science 260(5107):526–530. https://doi.org/10.1126/science.260.5107.526

Hansen VL, Willis JA (1996) Structural analysis of a sampling of tesserae: implications for Venus geodynamics. Icarus 123(2):296–312. https://doi.org/10.1006/icar.1996.0159

Hansen VL, Banks BK, Ghent RR (1999) Tessera terrain and crustal plateaus, Venus. Geology 27(12):1071–1074. https://doi.org/10.1130/0091-7613(1999)027<1071:TTACPV>2.3.CO;2

Hansen VL, Phillips RJ, Willis JJ, Ghent RR (2000) Structures in tessera terrain, Venus: issues and answers. J Geophys Res, Planets 105(E2):4087–4368. https://doi.org/10.1029/1999JE001137

Harris LB, Bédard JH (2014) Crustal evolution and deformation in a non-plate-tectonic Archaean Earth: comparisons with Venus. In: Dilek Y, Furnes H (eds) Evolution of Archean crust and early life, modern approaches in solid Earth sciences, pp 215–291

Harris LB, Bédard JH (2015) Interactions between continent-like 'drift' rifting and mantle flow on Venus: gravity interpretations and Earth analogues. In: Plattz T, Massironi M, Byrne PK, Hiesinger H (eds) Volcanism and tectonism across the inner solar system. Geologic society of London special publication, vol 401, pp 327–356

Harrison TM (2009) The hadean crust: evidence from >4 Ga zircons. Annu Rev Earth Planet Sci 37:479–505. https://doi.org/10.1146/annurev.earth.031208.100151

Hart RA, Russell CT, Zhang T (2022) Statistical study of lightning-generated whistler-mode waves observed by Venus Express. Icarus 380:114993. https://doi.org/10.1016/j.icarus.2022.114993

Hashimoto GL, Roos-Serote M, Sugita S, Gilmore MS, Kamp LW, Carlson RW, Baines K-H (2008) Felsic highland crust on Venus suggested by Galileo near-infrared mapping spectrometer data. J Geophys Res, Planets 113:E00B24. https://doi.org/10.1029/2008JE003134
Grindrod PM, Hoogenboom T (2006) Venus: the corona conundrum. Astron Geophys 47(3):3.16–3.21.
https://doi.org/10.1111/j.1468-4004.2006.47316.x

Grindrod PM, Nimmo F, Stofan ER, Guest JE (2005) Strain at radially fractured centers on Venus. J Geophys Res, Planets 110(E12):E12002. https://doi.org/10.1029/2005JE002416

Grindrod PM, Stofan ER, Guest JE (2010) Volcanism and resurfacing on Venus at the full resolution of Magellan SAR data. Geophys Res Lett 37(15). https://doi.org/10.1029/2010GL043424

Grosfils E, Head JW (1994a) Emplacement of a radiating dike swarm in western Vinmara Planitia, Venus: interpretation of the regional stress field orientation and subsurface magmatic configuration. Earth Moon Planets 66:153–171. https://doi.org/10.1007/BF00644129

Grosfils E, Head JW (1994b) The global distribution of giant radiating dike swarms on Venus: implications for the global stress state. Geophys Res Lett 21(8):701–704. https://doi.org/10.1029/94GL00592

Grosfils E, Aubele J, Crumpler L, Gregg T, Sakimoto S (2000) Volcanism on Earth's Seafloor and Venus. In: Zimbelman JR, Gregg TKP (eds) Environmental effects on volcanic eruptions: from deep oceans to deep space

Guest JE, Stofan ER (1999) A new view of the stratigraphic history of Venus. Icarus 139(1):55–66. https://doi.org/10.1006/icar.1999.6091

Gülcher AJP, Gerya TV, Montési LGJ, Munch J (2020) Corona structures driven by plume-lithosphere interactions and evidence for ongoing plume activity on Venus. Nat Geosci 13(8):547–554. https://doi.org/10.1038/s41561-020-0606-1

Gülcher AJP, Yu T-Y, Gerya TV (2023) Tectono-magmatic evolution of asymmetric coronae on Venus: topographic classification and 3D thermo-mechanical modeling. J Geophys Res, Planets 123(1):e2023JE007978. https://doi.org/10.1029/2023JE007978

Hahn RM, Byrne PK (2022) Kernel density analysis of volcanoes on Venus at varying spatial scales. Lun Planet Sci Conf 53:2437

Hamilton WB (1998) Archean magmatism and deformation were not products of plate tectonics. Precambrian Res 91(1–2):143–179. https://doi.org/10.1016/S0301-9268(98)00042-4

Hamilton WB (2011) Plate tectonics began in Neoproterozoic time, and plumes from deep mantle have never operated. Lithos 123:1–20. https://doi.org/10.1016/j.lithos.2010.12.007

Hamilton VE, Stofan ER (1996) The geomorphology and evolution of Hecate Chasma, Venus. Icarus 121(1):171–194. https://doi.org/10.1006/icar.1996.0077

Hansell SA, Wells WK, Hunten DH (1995) Optical detection of lightning on Venus. Icarus 117(2):345–351. https://doi.org/10.1006/icar.1995.1160

Hansen VL (2007) Venus: a thin-lithosphere analog for early Earth? In: Van Kranendonk MJ, Smithies RH, Bennett VC (eds) Earth's oldest rocks, developments in Precambrian geology 15, pp 987–1012

Hansen VL (2015) Impact origin of Archean cratons. Lithosphere 7(5):563–578. https://doi.org/10.1130/L371.1

Hansen VL (2018) Global tectonic evolution of Venus, from exogenic to endogenic over time, and implications for early Earth processes. Philos Trans R Soc A376:20170412. https://doi.org/10.1098/rsta.2017.0412

Hansen VL, Phillips RJ (1993) Tectonics and volcanism of eastern Aphrodite Terra, Venus: no subduction, no spreading. Science 260(5107):526–530. https://doi.org/10.1126/science.260.5107.526

Hansen VL, Willis JA (1996) Structural analysis of a sampling of tesserae: implications for Venus geodynamics. Icarus 123(2):296–312. https://doi.org/10.1006/icar.1996.0159

Hansen VL, Banks BK, Ghent RR (1999) Tessera terrain and crustal plateaus, Venus. Geology 27(12):1071–1074. https://doi.org/10.1130/0091-7613(1999)027<1071:TTACPV>2.3.CO;2

Hansen VL, Phillips RJ, Willis JJ, Ghent RR (2000) Structures in tessera terrain, Venus: issues and answers. J Geophys Res, Planets 105(E2):4087–4368. https://doi.org/10.1029/1999JE001137

Harris LB, Bédard JH (2014) Crustal evolution and deformation in a non-plate-tectonic Archaean Earth: comparisons with Venus. In: Dilek Y, Furnes H (eds) Evolution of Archean crust and early life, modern approaches in solid Earth sciences, pp 215–291

Harris LB, Bédard JH (2015) Interactions between continent-like 'drift' rifting and mantle flow on Venus: gravity interpretations and Earth analogues. In: Plattz T, Massironi M, Byrne PK, Hiesinger H (eds) Volcanism and tectonism across the inner solar system. Geologic society of London special publication, vol 401, pp 327–356

Harrison TM (2009) The hadean crust: evidence from >4 Ga zircons. Annu Rev Earth Planet Sci 37:479–505. https://doi.org/10.1146/annurev.earth.031208.100151

Hart RA, Russell CT, Zhang T (2022) Statistical study of lightning-generated whistler-mode waves observed by Venus Express. Icarus 380:114993. https://doi.org/10.1016/j.icarus.2022.114993

Hashimoto GL, Roos-Serote M, Sugita S, Gilmore MS, Kamp LW, Carlson RW, Baines K-H (2008) Felsic highland crust on Venus suggested by Galileo near-infrared mapping spectrometer data. J Geophys Res, Planets 113:E00B24. https://doi.org/10.1029/2008JE003134