cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.3453470.v1
title: Lithological controls on igneous intrusion-induced ground deformation

description: Ground deformation commonly precedes volcanic eruptions, although its relationship to underlying intrusion networks is complex. We use 3D seismic reflection data to examine the link between a saucer-shaped sill and an overlying forced fold formed at the contemporaneous palaeosurface. Our results highlight a disparity in size between the sill and fold, which we attribute to accommodation of magma by overburden uplift and fluid expulsion from the host rock. Sill transgression occurred in response to plastic deformation of the host rock and did not produce seismically resolvable uplift. Inversion models of ground deformation should therefore acknowledge host rock behaviour during intrusion.
DOI: 10.6084/m9.figshare.3453467
title: Along-strike variations in the composition of sandstones derived from the uplifting western Greater Caucasus: causes and implications for reservoir quality prediction in the Eastern Black Sea

description: Oligo-Miocene outcrops along the southern margin of the western Greater Caucasus preserve a record of sediments shed from the range into the northern and central parts of the Eastern Black Sea. Sandstones in the Russian western Caucasus are significantly more quartz-rich than those located farther SE in western Georgia. The latter contain appreciably more mudstone and volcanic rock fragments. Oligo-Miocene turbidite systems derived from the Russian western Caucasus in the Tuapse Trough and central Eastern Black Sea may therefore form better-quality reservoirs at shallow to moderate depths than sediments derived from west Georgian volcaniclastic sources in the easternmost part of the basin. Palynomorph analysis indicates sediment derivation predominantly from Jurassic and Cretaceous strata in the Russian western Caucasus and from Eocene strata, and an increasing proportion of Cretaceous strata upsection, in western Georgia. An Eocene volcaniclastic source is proposed for the increased rock fragment component in west Georgian sandstones. Eocene volcaniclastic rocks are no longer exposed in the Greater Caucasus, but similar rocks form the inverted fill of the Adjara–Trialet Basin farther south in the Lesser Caucasus. The former presence of a northern strand of this basin in the west Georgian Caucasus is supported by earlier thermochronological work.
DOI: 10.6084/m9.figshare.3453464
title: A Hf-isotope perspective on continent formation in the south Peruvian Andes

description: Convergent continental margins are the primary host of both growth and loss of continental crust. Continental growth largely occurs via subduction-driven magmatism, whereas continental loss largely occurs via subduction erosion and sediment subduction. Because the latter typically involves partial recycling into magmas, both growth and loss of continental crust can be represented in the magmatic record. The degree of crustal recycling can be estimated from the initial Hf isotope signatures in both magmatic and detrital zircon grains. Recent insights into the geodynamic evolution of the Peruvian margin, in combination with a new dataset of Hf isotopic data on zircon from the Carboniferous to Early Cretaceous, enable us to (1) compare the geodynamic history of the southern Peruvian margin with its Hf isotopic evolution, and (2) quantify the crustal growth between 500 and 135 Ma. The data exhibit a correlation with trends in isotope composition v. time and reflect the dominantly extensional regime that prevailed from the onset of subduction from 530 Ma to <em>c.</em> 135 Ma. This study demonstrates that the Peruvian margin experienced continental growth with juvenile input to arc magmatism of 30–45% on average, and illustrates the use of U–Pb and Hf isotopes in zircon as a tool to trace episodes of crustal growth through time.
DOI: 10.6084/m9.figshare.3453461
title: Neoarchaean crustal growth by combined arc–plume action: evidence from the Kadiri Greenstone Belt, eastern Dharwar craton, India

description: Field and geochemical studies combined with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U–Pb dating set important constraints on the timing and petrogenesis of volcanic rocks of the Neoarchaean Kadiri greenstone belt and the mechanism of crust formation in the eastern Dharwar craton (EDC). The volcanic rocks are divided into three suites: tholeiitic basalts, calc-alkaline high-Mg# andesites and dominant dacites–rhyolites. The basalts (pillowed in places) show flat rare earth element (REE) and primordial mantle-normalized trace element patterns, but have minor negative Nb and Ta anomalies. They are interpreted as mantle plume-related oceanic plateau basalts whose source contained minor continental crustal input. The andesites are characterized by high Mg# (0.66–0.52), Cr and Ni, with depletion of high-field strength elements (HFSE) and enrichment of light REE (LREE) and large-ion lithophile elements (LILE). They were probably derived from a metasomatized mantle wedge overlying a subducted slab in a continental margin subduction zone. The dacites–rhyolites are silicic rocks (SiO<sub>2</sub>=61–72 wt%) with low Cr and Ni, K<sub>2</sub>O/Na<sub>2</sub>O mostly 0.5–1.1, highly fractionated REE patterns, enrichments of LILE and distinctly negative HFSE anomalies. One rhyolite sample yielded a zircon U–Pb age of 2353±32 Ma. This suite is similar to potassic adakites and is explained as the product of deep melting of thickened crust in the arc with a significant older crustal component. Collision between a continental margin arc with an oceanic plateau followed by slab break-off, upwelling of hot asthenosphere and extensive crustal reworking in a sustained compressional regime is proposed for the geodynamic evolution of the area. This is in corroboration with the scenario of EDC as a Neoarchaean hot orogen as suggested recently by some workers.
DOI: 10.6084/m9.figshare.3453461.v1
title: Neoarchaean crustal growth by combined arc–plume action: evidence from the Kadiri Greenstone Belt, eastern Dharwar craton, India

description: Field and geochemical studies combined with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U–Pb dating set important constraints on the timing and petrogenesis of volcanic rocks of the Neoarchaean Kadiri greenstone belt and the mechanism of crust formation in the eastern Dharwar craton (EDC). The volcanic rocks are divided into three suites: tholeiitic basalts, calc-alkaline high-Mg# andesites and dominant dacites–rhyolites. The basalts (pillowed in places) show flat rare earth element (REE) and primordial mantle-normalized trace element patterns, but have minor negative Nb and Ta anomalies. They are interpreted as mantle plume-related oceanic plateau basalts whose source contained minor continental crustal input. The andesites are characterized by high Mg# (0.66–0.52), Cr and Ni, with depletion of high-field strength elements (HFSE) and enrichment of light REE (LREE) and large-ion lithophile elements (LILE). They were probably derived from a metasomatized mantle wedge overlying a subducted slab in a continental margin subduction zone. The dacites–rhyolites are silicic rocks (SiO<sub>2</sub>=61–72 wt%) with low Cr and Ni, K<sub>2</sub>O/Na<sub>2</sub>O mostly 0.5–1.1, highly fractionated REE patterns, enrichments of LILE and distinctly negative HFSE anomalies. One rhyolite sample yielded a zircon U–Pb age of 2353±32 Ma. This suite is similar to potassic adakites and is explained as the product of deep melting of thickened crust in the arc with a significant older crustal component. Collision between a continental margin arc with an oceanic plateau followed by slab break-off, upwelling of hot asthenosphere and extensive crustal reworking in a sustained compressional regime is proposed for the geodynamic evolution of the area. This is in corroboration with the scenario of EDC as a Neoarchaean hot orogen as suggested recently by some workers.
DOI: 10.6084/m9.figshare.3453458
title: Application of till geochemical and indicator mineral data to the interpretation of the thick till sequence at Muhos, northern Finland

description: Recent drilling at Muhos, northern Finland has revealed an exceptionally thick Quaternary sediment cover, overlying the unmetamorphosed Neoproterozoic Muhos Siltstone Formation in the Oulujoki River Valley. Here we report preliminary petrographical, geochemical and heavy mineral results from four till units from the Muhos drill-core. The drilling site is located at 27 m asl, <em>c.</em> 1 km south of Oulujoki River and 30 km SE from the city of Oulu and the present shore of the Bothnian Bay of the Baltic Sea. The drilling at this site was performed with a GM 200 GTT drilling platform using 1 -m long sample tubes (HDPV, diameter 5 cm) inside the stainless steel cover tubes. The coring penetrated down to the siltstone bedrock 54 m below the ground surface and the sediment core recovery was over 75%. The sedimentary sequence from the ground surface down to the local siltstone bedrock consists of four till units interbedded with sand/silt/clay beds. The upper two till beds, Mu-1 and Mu-2, are interpreted as being deposited during the Weichselian Glaciation between 115 000–10 000 years ago, the third till bed Mu-3 during the Saalian and the lowest till bed, Mu-4, during the Saalian or pre-Saalian glaciations, i.e. till beds Mu-3 and Mu-4 prior to <em>c.</em> 130 000 years ago. Petrography of the coarse fraction, geochemistry of the fine fraction and heavy minerals of the sand fraction were studied from all four till units and the Muhos siltstone samples. Coarse and fine fractions were separated by dry-sieving. The fine fraction was analysed by XRF and AAS. The mineralogical composition of the heavy fraction was studied by FESEM+EDS and SEM+EDS. The lowest till bed Mu-4 can be divided into three subunits. On the basis of clast content, geochemistry of till fines the ice movement direction was from the NW or NNW during the deposition of the lowermost brown and red till units. The composition of the upper grey unit of till bed Mu-4 shows that the ice flow direction was from the WNW. Petrographical composition of till beds Mu-3 and Mu-2 indicates that the ice flow again was from the NW whereas the petrographical composition of the uppermost till bed Mu-1 suggests that the ice flow during this deposition phase was from the WNW. Younger till beds studied have in part also some reworked and re-deposited material from the older till beds.
DOI: 10.6084/m9.figshare.3453458.v1
title: Application of till geochemical and indicator mineral data to the interpretation of the thick till sequence at Muhos, northern Finland

description: Recent drilling at Muhos, northern Finland has revealed an exceptionally thick Quaternary sediment cover, overlying the unmetamorphosed Neoproterozoic Muhos Siltstone Formation in the Oulujoki River Valley. Here we report preliminary petrographical, geochemical and heavy mineral results from four till units from the Muhos drill-core. The drilling site is located at 27 m asl, <em>c.</em> 1 km south of Oulujoki River and 30 km SE from the city of Oulu and the present shore of the Bothnian Bay of the Baltic Sea. The drilling at this site was performed with a GM 200 GTT drilling platform using 1 -m long sample tubes (HDPV, diameter 5 cm) inside the stainless steel cover tubes. The coring penetrated down to the siltstone bedrock 54 m below the ground surface and the sediment core recovery was over 75%. The sedimentary sequence from the ground surface down to the local siltstone bedrock consists of four till units interbedded with sand/silt/clay beds. The upper two till beds, Mu-1 and Mu-2, are interpreted as being deposited during the Weichselian Glaciation between 115 000–10 000 years ago, the third till bed Mu-3 during the Saalian and the lowest till bed, Mu-4, during the Saalian or pre-Saalian glaciations, i.e. till beds Mu-3 and Mu-4 prior to <em>c.</em> 130 000 years ago. Petrography of the coarse fraction, geochemistry of the fine fraction and heavy minerals of the sand fraction were studied from all four till units and the Muhos siltstone samples. Coarse and fine fractions were separated by dry-sieving. The fine fraction was analysed by XRF and AAS. The mineralogical composition of the heavy fraction was studied by FESEM+EDS and SEM+EDS. The lowest till bed Mu-4 can be divided into three subunits. On the basis of clast content, geochemistry of till fines the ice movement direction was from the NW or NNW during the deposition of the lowermost brown and red till units. The composition of the upper grey unit of till bed Mu-4 shows that the ice flow direction was from the WNW. Petrographical composition of till beds Mu-3 and Mu-2 indicates that the ice flow again was from the NW whereas the petrographical composition of the uppermost till bed Mu-1 suggests that the ice flow during this deposition phase was from the WNW. Younger till beds studied have in part also some reworked and re-deposited material from the older till beds.
DOI: 10.6084/m9.figshare.3453455
title: Impact of erosion and décollements on large-scale faulting and folding in orogenic wedges: analogue models and case studies

description: Deformation mechanisms, long-term kinematics and evolution of fold and thrust belts subjected to erosion are studied through 2D analogue experiments involving large convergence. First-order parameters tested include (1) décollements and/or plastic layers interbedded at different locations within analogue materials and (2) synconvergence surface erosion. Weak layers, depending on their location in the model, favour deformation partitioning characterized by the simultaneous development of underplating domains in the inner part of the wedge (basal accretion) and frontal accretion where the wedge grows forward. Interaction between tectonics and surface processes influences this behaviour. Development of antiformal thrust stacks controlled by underplating shows small- and large-scale cyclicity. Thin plastic layers induce folding processes, which are studied at wedge scale. Recumbent and overturned folds, with large inverted limbs, develop in a shear-induced asymmetric deformation regime via progressive unrolling of synclinal hinges. Surface erosion and underplating at depth induce further rotation (passive tilting) and horizontalization of fold limbs. Model results give insights to discuss the mechanisms responsible for the large-scale structures (i.e. antiformal nappe stacks, klippen and kilometre-scale recumbent fold–nappes) encountered in several mountain belts such as the Montagne Noire (French Massif Central), the Galicia Variscan belt (Spain) and the northern Apennines (Italy).
DOI: 10.6084/m9.figshare.3453455.v1
title: Impact of erosion and décollements on large-scale faulting and folding in orogenic wedges: analogue models and case studies

description: Deformation mechanisms, long-term kinematics and evolution of fold and thrust belts subjected to erosion are studied through 2D analogue experiments involving large convergence. First-order parameters tested include (1) décollements and/or plastic layers interbedded at different locations within analogue materials and (2) synconvergence surface erosion. Weak layers, depending on their location in the model, favour deformation partitioning characterized by the simultaneous development of underplating domains in the inner part of the wedge (basal accretion) and frontal accretion where the wedge grows forward. Interaction between tectonics and surface processes influences this behaviour. Development of antiformal thrust stacks controlled by underplating shows small- and large-scale cyclicity. Thin plastic layers induce folding processes, which are studied at wedge scale. Recumbent and overturned folds, with large inverted limbs, develop in a shear-induced asymmetric deformation regime via progressive unrolling of synclinal hinges. Surface erosion and underplating at depth induce further rotation (passive tilting) and horizontalization of fold limbs. Model results give insights to discuss the mechanisms responsible for the large-scale structures (i.e. antiformal nappe stacks, klippen and kilometre-scale recumbent fold–nappes) encountered in several mountain belts such as the Montagne Noire (French Massif Central), the Galicia Variscan belt (Spain) and the northern Apennines (Italy).
DOI: 10.6084/m9.figshare.3453452
title: Long-term exhumation of a Palaeoproterozoic orogen and the role of pre-existing heterogeneous thermal crustal properties: a fission-track study of SE Baffin Island

description: New apatite fission-track data from SE Baffin Island exhibit central ages that range from just under 200 Ma to 440 Ma, and mean track lengths that vary between <em>c</em>. 12 and 13.3 µm. First-order analysis of the data (a plot of central age v. mean track length) reveals an approximate ‘boomerang’ trend, typical of samples that have experienced contemporaneous cooling from an array of initial temperatures. One-dimensional inverse thermal modelling of single samples suggests that cooling through the partial annealing zone (<em>c</em>. 120–60 °C) occurred over discrete periods ranging from 100 to 300 Ma. Modelling the 3D exhumation of a heterogeneous crust with flat topography demonstrates that some of the variability in observed fission-track ages could be attributed to heterogeneity in crustal heat production and thermal conductivity. The remaining variability in the observed dataset is attributed here to differential erosion from a variable initial topography. However, age discontinuities over short distances require other explanations such as faulting and/or unidentified compositional effects. Collectively, these results suggest that the observed data are consistent with a simple exhumation scenario where the present-day high topography is a remnant of that created during Palaeoproterozoic orogenies. The new data do not require any recent (Cenozoic) periods of exhumation.
DOI: 10.6084/m9.figshare.3453452.v1
title: Long-term exhumation of a Palaeoproterozoic orogen and the role of pre-existing heterogeneous thermal crustal properties: a fission-track study of SE Baffin Island

description: New apatite fission-track data from SE Baffin Island exhibit central ages that range from just under 200 Ma to 440 Ma, and mean track lengths that vary between <em>c</em>. 12 and 13.3 µm. First-order analysis of the data (a plot of central age v. mean track length) reveals an approximate ‘boomerang’ trend, typical of samples that have experienced contemporaneous cooling from an array of initial temperatures. One-dimensional inverse thermal modelling of single samples suggests that cooling through the partial annealing zone (<em>c</em>. 120–60 °C) occurred over discrete periods ranging from 100 to 300 Ma. Modelling the 3D exhumation of a heterogeneous crust with flat topography demonstrates that some of the variability in observed fission-track ages could be attributed to heterogeneity in crustal heat production and thermal conductivity. The remaining variability in the observed dataset is attributed here to differential erosion from a variable initial topography. However, age discontinuities over short distances require other explanations such as faulting and/or unidentified compositional effects. Collectively, these results suggest that the observed data are consistent with a simple exhumation scenario where the present-day high topography is a remnant of that created during Palaeoproterozoic orogenies. The new data do not require any recent (Cenozoic) periods of exhumation.
DOI: 10.6084/m9.figshare.3453449
title: Syncollisional tholeiitic magmatism induced by asthenosphere upwelling owing to slab detachment at the southern margin of the Central Asian Orogenic Belt

description: The mafic–ultramafic complexes containing magmatic sulphides at the southern margins of the Central Asian Orogenic Belt have been recently proposed to result from an Early Permian mantle plume. However, in this study we show that the plume model cannot account for the observed geological characteristics of the Huangshan–Jingerquan mafic–ultramafic belt in the Northern Tianshan. Low K<sub>2</sub>O contents and positive correlation between TiO<sub>2</sub> and (Fe<sub>2</sub>O<sub>3</sub>)<sub>T</sub>/MgO of the mafic–ultramafic complexes of this belt demonstrate a tholeiitic affinity. Enrichment of large ion lithophile elements and depletion of high field strength elements (in particular Nb and Ta) relative to mid-ocean ridge basalt indicate a subduction-modified mantle source. Lead isotope values and compositions of chromite indicate a significant contribution from the melting of asthenosphere. The absence of Late Carboniferous strata in the Huangshan–Jingerquan belt and Early Permian exhumation of blueschist and eclogite along the Aqikkuduk suture at the southern boundary of the belt indicate that an arc–continent collision occurred in the Late Carboniferous to Early Permian. We propose that the detachment of oceanic lithosphere from continental lithosphere during the collision induced asthenospheric upwelling, which resulted in melting of both the asthenosphere and the overlying metasomatized mantle wedge, and the formation of the mafic–ultramafic complexes with ages of 270–285 Ma along the Huangshan–Jingerquan belt.
DOI: 10.6084/m9.figshare.3453449.v1
title: Syncollisional tholeiitic magmatism induced by asthenosphere upwelling owing to slab detachment at the southern margin of the Central Asian Orogenic Belt

description: The mafic–ultramafic complexes containing magmatic sulphides at the southern margins of the Central Asian Orogenic Belt have been recently proposed to result from an Early Permian mantle plume. However, in this study we show that the plume model cannot account for the observed geological characteristics of the Huangshan–Jingerquan mafic–ultramafic belt in the Northern Tianshan. Low K<sub>2</sub>O contents and positive correlation between TiO<sub>2</sub> and (Fe<sub>2</sub>O<sub>3</sub>)<sub>T</sub>/MgO of the mafic–ultramafic complexes of this belt demonstrate a tholeiitic affinity. Enrichment of large ion lithophile elements and depletion of high field strength elements (in particular Nb and Ta) relative to mid-ocean ridge basalt indicate a subduction-modified mantle source. Lead isotope values and compositions of chromite indicate a significant contribution from the melting of asthenosphere. The absence of Late Carboniferous strata in the Huangshan–Jingerquan belt and Early Permian exhumation of blueschist and eclogite along the Aqikkuduk suture at the southern boundary of the belt indicate that an arc–continent collision occurred in the Late Carboniferous to Early Permian. We propose that the detachment of oceanic lithosphere from continental lithosphere during the collision induced asthenospheric upwelling, which resulted in melting of both the asthenosphere and the overlying metasomatized mantle wedge, and the formation of the mafic–ultramafic complexes with ages of 270–285 Ma along the Huangshan–Jingerquan belt.