cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.3453902.v1
title: The impact of oxidation on spore and pollen chemistry

description: Sporomorphs (pollen and spores) have an outer wall composed of sporopollenin. Sporopollenin chemistry contains both a signature of ambient ultraviolet-B flux and taxonomic information, but it is currently unknown how sensitive this is to standard palynological processing techniques. Oxidation in particular is known to cause physical degradation to sporomorphs, and it is expected that this should have a concordant impact on sporopollenin chemistry. Here, we test this by experimentally oxidizing <em>Lycopodium</em> (clubmoss) spores using two common oxidation techniques: acetolysis and nitric acid. We also carry out acetolysis on eight angiosperm (flowering plant) taxa to test the generality of our results. Using Fourier Transform infrared (FTIR) spectroscopy, we find that acetolysis removes labile, non-fossilizable components of sporomorphs, but has a limited impact upon the chemistry of sporopollenin under normal processing durations. Nitric acid is more aggressive and does break down sporopollenin and reorganize its chemical structure, but when limited to short treatments (i.e. ≤10 min) at room temperature sporomorphs still contain most of the original chemical signal. These findings suggest that when used carefully oxidation does not adversely affect sporopollenin chemistry, and that palaeoclimatic and taxonomic signatures contained within the sporomorph wall are recoverable from standard palynological preparations.
DOI: 10.6084/m9.figshare.3453890
title: Distribution of mafic sills in the Transvaal Supergroup, northeastern South Africa

description: Systematic measured profiles on a regional scale are used to document the distribution of noritic and amphibolitic sills (787 in total) in the largely sedimentary latest Archaean–early Proterozoic succession of the Transvaal Supergroup in northeastern South Africa. An aggregate thickness of over 2.2 km of sills intruded this 12 km thick succession. The proportion of sill to sill plus sedimentary rock increases upward (average 16%), towards the overlying mafic phase of the Bushveld Complex. The average thickness of sills is 34 m, but increases in the same sense. The emplacement level of the Bushveld Complex transgresses across some 5 km of the stratigraphy of the upper formations of the Transvaal Supergroup. A node of maximum intensity of noritic sill intrusion is developed in these uppermost strata adjacent to the location where the transgressive relationship is most pronounced. The structural styles of the Transvaal Supergroup strata influence intensity of sill intrusion. Other factors being equal, maximum intrusion intensity is associated with areas of shallow homoclinal dip (&lt;20°) and minimum intensity with areas of steeper dip and folding. A lithological control on sill emplacement is also documented, with quartzite- and shale-dominated formations being more heavily intruded than dolomite and basaltic lava.
DOI: 10.6084/m9.figshare.3453890.v1
title: Distribution of mafic sills in the Transvaal Supergroup, northeastern South Africa

description: Systematic measured profiles on a regional scale are used to document the distribution of noritic and amphibolitic sills (787 in total) in the largely sedimentary latest Archaean–early Proterozoic succession of the Transvaal Supergroup in northeastern South Africa. An aggregate thickness of over 2.2 km of sills intruded this 12 km thick succession. The proportion of sill to sill plus sedimentary rock increases upward (average 16%), towards the overlying mafic phase of the Bushveld Complex. The average thickness of sills is 34 m, but increases in the same sense. The emplacement level of the Bushveld Complex transgresses across some 5 km of the stratigraphy of the upper formations of the Transvaal Supergroup. A node of maximum intensity of noritic sill intrusion is developed in these uppermost strata adjacent to the location where the transgressive relationship is most pronounced. The structural styles of the Transvaal Supergroup strata influence intensity of sill intrusion. Other factors being equal, maximum intrusion intensity is associated with areas of shallow homoclinal dip (&lt;20°) and minimum intensity with areas of steeper dip and folding. A lithological control on sill emplacement is also documented, with quartzite- and shale-dominated formations being more heavily intruded than dolomite and basaltic lava.
DOI: 10.6084/m9.figshare.3453884
title: The Fram Slide off Svalbard: a submarine landslide on a low-sedimentation-rate glacial continental margin

description: Submarine slope failures are a widespread, hazardous phenomenon on continental margins. The prevailing opinion links large submarine landslides along the glaciated NW European continental margins to overpressure generated by the alternation of rapidly deposited glacigenic and hemipelagic material. Here, we report a newly discovered large landslide complex off NW Svalbard. It differs from all known large slides off NW Europe, as the available data rule out that this slope failure resulted from rapid glacigenic deposition. This suggests that processes such as contour currents, tectonic faulting, and overpressure build-up related to the gas hydrate system must be considered for hazard assessment.
DOI: 10.6084/m9.figshare.3453875
title: Volcanic volumes associated with the Kenya Rift: recognition and correction of preservation biases

description: New eruptive volume estimates have been calculated for the Kenyan segment of the East African Rift. Since the initial publications of volume estimates for the Kenyan Rift, numerous age dates have been obtained for the region allowing for temporal analysis of eruptive volumes. Additionally, more recent available datasets allow for the independent testing of map-derived volumes. Newly calculated volumes from available seismic data indicate a total volume of <em>c.</em> 310 000 km<sup>3</sup>, which is significantly more than map-derived volumes found here or published previously. It is suggested that the map-based estimates are likely affected by biases against recognizing small volume events in the older record. Such events have been, however, the main driver of erupted volume over the last 5 Ma. A simple ratio-adjustment technique was developed to counter these biases and results in convergence of the volume estimates from the two independent datasets examined.
DOI: 10.6084/m9.figshare.3453875.v1
title: Volcanic volumes associated with the Kenya Rift: recognition and correction of preservation biases

description: New eruptive volume estimates have been calculated for the Kenyan segment of the East African Rift. Since the initial publications of volume estimates for the Kenyan Rift, numerous age dates have been obtained for the region allowing for temporal analysis of eruptive volumes. Additionally, more recent available datasets allow for the independent testing of map-derived volumes. Newly calculated volumes from available seismic data indicate a total volume of <em>c.</em> 310 000 km<sup>3</sup>, which is significantly more than map-derived volumes found here or published previously. It is suggested that the map-based estimates are likely affected by biases against recognizing small volume events in the older record. Such events have been, however, the main driver of erupted volume over the last 5 Ma. A simple ratio-adjustment technique was developed to counter these biases and results in convergence of the volume estimates from the two independent datasets examined.
DOI: 10.6084/m9.figshare.3453866
title: Silurian flysch successions of Ellesmere Island, Arctic Canada, and their significance to northern Caledonian palaeogeography and tectonics

description: Detrital zircon provenance studies of Silurian flysch units that underlie the Hazen and Clements Markham fold belts of Ellesmere Island, Arctic Canada, were conducted to evaluate models for northern Caledonian palaeogeography and tectonics. Llandovery flysch was deposited along an active plate margin and yields detrital zircons that require northern derivation from the adjacent Pearya terrane. If Pearya originated near Svalbard and NE Greenland, it was transported by strike-slip faults to Ellesmere Island by the Early Silurian. Wenlock to Ludlow turbidites yield Palaeozoic–Archaean detrital zircons with dominant age-groupings <em>c</em>. 650, 970, 1150, 1450 and 1650 Ma. These turbidite systems did not fill a flexural foreland basin in front of the East Greenland Caledonides, but rather an east–west-trending trough that was probably related to sinistral strike-slip faulting along the northern Laurentian margin. The data support provenance connections with the Svalbard Caledonides, especially Baltican-affinity rocks of SW Spitsbergen that were proximal to NE Greenland during the Baltica–Laurentia collision. Pridoli flysch has sources that include Pearya, the East Greenland Caledonides and the Canadian Shield. Devonian–Carboniferous molasse in Arctic Canada has analogous detrital zircon signatures, which implies recycling of Silurian flysch during mid-Palaeozoic (Ellesmerian) collisional tectonism or that some collisional blocks were of similar Baltican–Laurentian crustal affinities.
DOI: 10.6084/m9.figshare.3453866.v1
title: Silurian flysch successions of Ellesmere Island, Arctic Canada, and their significance to northern Caledonian palaeogeography and tectonics

description: Detrital zircon provenance studies of Silurian flysch units that underlie the Hazen and Clements Markham fold belts of Ellesmere Island, Arctic Canada, were conducted to evaluate models for northern Caledonian palaeogeography and tectonics. Llandovery flysch was deposited along an active plate margin and yields detrital zircons that require northern derivation from the adjacent Pearya terrane. If Pearya originated near Svalbard and NE Greenland, it was transported by strike-slip faults to Ellesmere Island by the Early Silurian. Wenlock to Ludlow turbidites yield Palaeozoic–Archaean detrital zircons with dominant age-groupings <em>c</em>. 650, 970, 1150, 1450 and 1650 Ma. These turbidite systems did not fill a flexural foreland basin in front of the East Greenland Caledonides, but rather an east–west-trending trough that was probably related to sinistral strike-slip faulting along the northern Laurentian margin. The data support provenance connections with the Svalbard Caledonides, especially Baltican-affinity rocks of SW Spitsbergen that were proximal to NE Greenland during the Baltica–Laurentia collision. Pridoli flysch has sources that include Pearya, the East Greenland Caledonides and the Canadian Shield. Devonian–Carboniferous molasse in Arctic Canada has analogous detrital zircon signatures, which implies recycling of Silurian flysch during mid-Palaeozoic (Ellesmerian) collisional tectonism or that some collisional blocks were of similar Baltican–Laurentian crustal affinities.
DOI: 10.6084/m9.figshare.3453863
title: 0.3 byr of drainage stability along the Palaeozoic palaeo-Pacific Gondwana margin; a detrital zircon study

description: The palaeo-Pacific margin of Gondwana in the present-day south–central Andes is marked by tectonic activity related to subduction and terrane accretion. We present detrital zircon U–Pb data encompassing the Palaeozoic era in northern Chile and northwestern Argentina. Cathodoluminescence images reveal dominantly magmatic zircon barely affected by abrasion and displaying only one growth phase. The main age clusters for these zircon grains are Ediacaran to Palaeozoic with an additional peak at 1.3–0.9 Ga and they can be correlated with ‘Grenvillian’ age, and the Brasiliano, Pampean, and Famatinian orogenies. The zircon data reveal main transport from the nearby Ordovician Famatinian arc and related rocks. The Silurian sandstone units are more comparable with Cambrian units, with Brasiliano and Transamazonian ages (2.2–1.9 Ga) being more common, because the Silurian deposits were situated within or east of the (extinct) Famatinian arc. Hence, the arc acted as a transport barrier throughout Palaeozoic time. The complete suite of zircon ages does not record the accretions of exotic terranes or the Palaeozoic glacial periods. We conclude that the transport system along the palaeo-Pacific margin of Gondwana remained stable for <em>c</em>. 0.3 byr and that provenance data do not necessarily reflect the interior of a continent. Hence, inherited geomorphological features must be taken into account when detrital mineral ages are interpreted.
DOI: 10.6084/m9.figshare.3453863.v1
title: 0.3 byr of drainage stability along the Palaeozoic palaeo-Pacific Gondwana margin; a detrital zircon study

description: The palaeo-Pacific margin of Gondwana in the present-day south–central Andes is marked by tectonic activity related to subduction and terrane accretion. We present detrital zircon U–Pb data encompassing the Palaeozoic era in northern Chile and northwestern Argentina. Cathodoluminescence images reveal dominantly magmatic zircon barely affected by abrasion and displaying only one growth phase. The main age clusters for these zircon grains are Ediacaran to Palaeozoic with an additional peak at 1.3–0.9 Ga and they can be correlated with ‘Grenvillian’ age, and the Brasiliano, Pampean, and Famatinian orogenies. The zircon data reveal main transport from the nearby Ordovician Famatinian arc and related rocks. The Silurian sandstone units are more comparable with Cambrian units, with Brasiliano and Transamazonian ages (2.2–1.9 Ga) being more common, because the Silurian deposits were situated within or east of the (extinct) Famatinian arc. Hence, the arc acted as a transport barrier throughout Palaeozoic time. The complete suite of zircon ages does not record the accretions of exotic terranes or the Palaeozoic glacial periods. We conclude that the transport system along the palaeo-Pacific margin of Gondwana remained stable for <em>c</em>. 0.3 byr and that provenance data do not necessarily reflect the interior of a continent. Hence, inherited geomorphological features must be taken into account when detrital mineral ages are interpreted.
DOI: 10.6084/m9.figshare.3453860
title: Chronology, petrogenesis and heat sources for successive Carboniferous magmatic events in the Southern–Central Variscan Vosges Mts (NE France)

description: Plutonic bodies of the Central and Southern Vosges Mts can be assigned to two major early Carboniferous magmatic events: a Visean Mg–K event (<em>c.</em> 345 and 340–336 Ma) and a younger S-type event (329–322 Ma). New petrological, geochemical and Sr–Nd isotopic data highlight the existence of two groups of Mg–K intrusions that might be related to the nature of their primary magma sources; that is, CHUR-like and enriched mantle, which interacted with juvenile and mature crustal material, respectively. The differences between these two groups are explained by a geodynamic scenario involving deep subduction and relamination of the Saxothuringian continental crust under the Moldanubian continent. The relaminated radiogenic Saxothuringian material is thought to have been responsible for dehydration melting of both subducted crust and underlying metasomatized mantle, thereby generating the Mg–K magma subsequently emplaced at middle crustal depth. During their ascent, the mafic magmas interacted with crustally derived felsic melts. Significantly later (<em>c</em>. 10–15 myr) a widespread mid-crustal anatexis occurred, generating voluminous granite intrusions from mixed crustal sources (paragneisses and/or immature felsic–intermediate metaigneous rocks mixed with Mg–K plutons). The principal heat source for such a major melting event is related to the presence of Mg–K plutons rich in heat-producing elements, which were responsible, after the time lag specified, for a temperature increase at mid-crustal levels by <em>in situ</em> radiogenic heat production. The current study underlines the importance of deep continental crust subduction and relamination for the magmatism and development of collisional orogens.
DOI: 10.6084/m9.figshare.3453860.v1
title: Chronology, petrogenesis and heat sources for successive Carboniferous magmatic events in the Southern–Central Variscan Vosges Mts (NE France)

description: Plutonic bodies of the Central and Southern Vosges Mts can be assigned to two major early Carboniferous magmatic events: a Visean Mg–K event (<em>c.</em> 345 and 340–336 Ma) and a younger S-type event (329–322 Ma). New petrological, geochemical and Sr–Nd isotopic data highlight the existence of two groups of Mg–K intrusions that might be related to the nature of their primary magma sources; that is, CHUR-like and enriched mantle, which interacted with juvenile and mature crustal material, respectively. The differences between these two groups are explained by a geodynamic scenario involving deep subduction and relamination of the Saxothuringian continental crust under the Moldanubian continent. The relaminated radiogenic Saxothuringian material is thought to have been responsible for dehydration melting of both subducted crust and underlying metasomatized mantle, thereby generating the Mg–K magma subsequently emplaced at middle crustal depth. During their ascent, the mafic magmas interacted with crustally derived felsic melts. Significantly later (<em>c</em>. 10–15 myr) a widespread mid-crustal anatexis occurred, generating voluminous granite intrusions from mixed crustal sources (paragneisses and/or immature felsic–intermediate metaigneous rocks mixed with Mg–K plutons). The principal heat source for such a major melting event is related to the presence of Mg–K plutons rich in heat-producing elements, which were responsible, after the time lag specified, for a temperature increase at mid-crustal levels by <em>in situ</em> radiogenic heat production. The current study underlines the importance of deep continental crust subduction and relamination for the magmatism and development of collisional orogens.
DOI: 10.6084/m9.figshare.3453854
title: Chapter 20 Provenance, timing of sedimentation and metamorphism of metasedimentary rock suites from the Southern Granulite Terrane, India

description: The Southern Granulite Terrane of India exposes remnants of an interbanded sequence of orthoquartzite–metapelite–calcareous rocks across the enigmatic Palghat–Cauvery Shear Zone (PCSZ), which has been interpreted as a Pan-African terrane boundary representing the eastward extension of the Betsimisaraka Suture Zone of Madagascar. Zircon U–Pb geochronology of metasedimentary rocks from both sides of the PCSZ shows that the precursor sediments of these rocks were sourced from the Dharwar Craton and the adjoining parts of the Indian shield. The similarity of the provenance and the vestiges of Grenvillian-age orogenesis in some metasedimentary rocks contradict an interpretation that the PCSZ is a Pan-African terrane boundary. The lithological association and the likely basin formation age of the metasedimentary rocks of the Southern Granulite Terrane show remarkable similarity to the rock assemblage and timing of sedimentation of the Palaeoproterozoic to Neoproterozoic shallow-marine deposits of the Purana basins lying several hundred kilometres north of this terrane. Integrating the existing geological information, it is postulated that the shallow-marine sediments were deposited on a unified land-mass consisting of a large part of Madagascar and the Indian shield that existed before Neoproterozoic time, part of which was later involved in the Pan-African orogeny.
DOI: 10.6084/m9.figshare.3453854.v1
title: Chapter 20 Provenance, timing of sedimentation and metamorphism of metasedimentary rock suites from the Southern Granulite Terrane, India

description: The Southern Granulite Terrane of India exposes remnants of an interbanded sequence of orthoquartzite–metapelite–calcareous rocks across the enigmatic Palghat–Cauvery Shear Zone (PCSZ), which has been interpreted as a Pan-African terrane boundary representing the eastward extension of the Betsimisaraka Suture Zone of Madagascar. Zircon U–Pb geochronology of metasedimentary rocks from both sides of the PCSZ shows that the precursor sediments of these rocks were sourced from the Dharwar Craton and the adjoining parts of the Indian shield. The similarity of the provenance and the vestiges of Grenvillian-age orogenesis in some metasedimentary rocks contradict an interpretation that the PCSZ is a Pan-African terrane boundary. The lithological association and the likely basin formation age of the metasedimentary rocks of the Southern Granulite Terrane show remarkable similarity to the rock assemblage and timing of sedimentation of the Palaeoproterozoic to Neoproterozoic shallow-marine deposits of the Purana basins lying several hundred kilometres north of this terrane. Integrating the existing geological information, it is postulated that the shallow-marine sediments were deposited on a unified land-mass consisting of a large part of Madagascar and the Indian shield that existed before Neoproterozoic time, part of which was later involved in the Pan-African orogeny.
DOI: 10.6084/m9.figshare.3453851
title: The zircon archive of continent formation through time

description: The strong resilience of the mineral zircon and its ability to host a wealth of isotopic information make it the best deep-time archive of Earth's continental crust. Zircon is found in most felsic igneous rocks, can be precisely dated and can fingerprint magmatic sources; thus, it has been widely used to document the formation and evolution of continental crust, from pluton- to global-scale. Here, we present a review of major contributions that zircon studies have made in terms of understanding key questions involving the formation of the continents. These include the conditions of continent formation on early Earth, the onset of plate tectonics and subduction, the rate of crustal growth through time and the governing balance of continental addition v. continental loss, and the role of preservation bias in the zircon record.
DOI: 10.6084/m9.figshare.3453851.v1
title: The zircon archive of continent formation through time

description: The strong resilience of the mineral zircon and its ability to host a wealth of isotopic information make it the best deep-time archive of Earth's continental crust. Zircon is found in most felsic igneous rocks, can be precisely dated and can fingerprint magmatic sources; thus, it has been widely used to document the formation and evolution of continental crust, from pluton- to global-scale. Here, we present a review of major contributions that zircon studies have made in terms of understanding key questions involving the formation of the continents. These include the conditions of continent formation on early Earth, the onset of plate tectonics and subduction, the rate of crustal growth through time and the governing balance of continental addition v. continental loss, and the role of preservation bias in the zircon record.
DOI: 10.6084/m9.figshare.3453848
title: Effect of diagenetic recrystallization on the strength of planktonic foraminifer tests under compression

description: We present the results of experiments to measure the brittle failure of fossil planktonic foraminifer tests under compression. We compare two upper Eocene species of contrasting morphology, <em>Cribrohantkenina inflata</em> (Howe, 1928) and <em>Turborotalia cerroazulensis</em> (Cole, 1928) in both well-preserved material from the Kilwa Group of Tanzania and recrystallized material from ODP Site 865, central Pacific Ocean. Well-preserved tests were several times stronger than recrystallized tests. <em>Turborotalia cerroazulensis</em> was stronger than <em>C. inflata</em> in both the well-preserved and recrystallized material.