cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.3453668
title: Heavy mineral record of Andean uplift and changing sediment sources across the NE margin of South America: a case study from Trinidad and Barbados

description: The heavy mineral compositions of sandstones in Trinidad and Barbados record the onset of Andean-related erosion and a reduction of craton-derived sediments into NE South America. The changing provenance was deduced by comparing heavy mineral assemblages interpreted from ancient sandstones with associations recognized in modern sands that can be reasonably correlated to existing tectonic domains. The impact of the Andean orogeny across the margin was to introduce a suite of minerals characteristic of low-temperature metamorphism that today is prevalent adjacent to the Caribbean Mountain belt and differs from the zircon-rich assemblage produced within cratonic plains. Twenty-one Paleocene–Late Pliocene sandstone samples from Trinidad revealed systematic changes in mineral diversity and maturity that recorded this provenance transition, and suggests Andean erosion during deposition of the Late Oligocene Nariva Formation. Similar to Palaeogene sandstones of Trinidad, four Eocene Scotland Formation samples from Barbados support craton derivation, but with additional evidence of minor Andean input probably due to the proximity of the Scotland Formation delivery systems to an earlier uplift episode. By the Late Miocene, most of the sediments delivered into Trinidad basins were supplied from the Andean orogeny as suggested by the relative abundance of minerals of this affinity. The heavy mineral records of Trinidad and Barbados are similar to that described across northern South America from both modern and ancient environments that collectively mark the uplift of the Andean mountain belt, with its strong influence on drainage patterns and reservoir provenance along this sector of the continental margin.
DOI: 10.6084/m9.figshare.3453668.v1
title: Heavy mineral record of Andean uplift and changing sediment sources across the NE margin of South America: a case study from Trinidad and Barbados

description: The heavy mineral compositions of sandstones in Trinidad and Barbados record the onset of Andean-related erosion and a reduction of craton-derived sediments into NE South America. The changing provenance was deduced by comparing heavy mineral assemblages interpreted from ancient sandstones with associations recognized in modern sands that can be reasonably correlated to existing tectonic domains. The impact of the Andean orogeny across the margin was to introduce a suite of minerals characteristic of low-temperature metamorphism that today is prevalent adjacent to the Caribbean Mountain belt and differs from the zircon-rich assemblage produced within cratonic plains. Twenty-one Paleocene–Late Pliocene sandstone samples from Trinidad revealed systematic changes in mineral diversity and maturity that recorded this provenance transition, and suggests Andean erosion during deposition of the Late Oligocene Nariva Formation. Similar to Palaeogene sandstones of Trinidad, four Eocene Scotland Formation samples from Barbados support craton derivation, but with additional evidence of minor Andean input probably due to the proximity of the Scotland Formation delivery systems to an earlier uplift episode. By the Late Miocene, most of the sediments delivered into Trinidad basins were supplied from the Andean orogeny as suggested by the relative abundance of minerals of this affinity. The heavy mineral records of Trinidad and Barbados are similar to that described across northern South America from both modern and ancient environments that collectively mark the uplift of the Andean mountain belt, with its strong influence on drainage patterns and reservoir provenance along this sector of the continental margin.
DOI: 10.6084/m9.figshare.3453665
title: Erosion rates in the source region of an ancient sediment routing system: comparison of depositional volumes with thermochronometric estimates

description: Calculation of the total depositional volume of an ancient source-to-sink system, combined with estimates of the area of catchments acting as source regions using provenance methods, is used to evaluate average catchment erosion rates on a million year time scale. These rates are compared with values derived from thermochronological methods. Using the mid- to late Eocene (33.9–41.6 Ma) Escanilla palaeo-sediment routing system from the south–central Pyrenean orogenic wedge-top zone as an example, <em>c</em>. 3500 ± 300 km<sup>3</sup> of solid particulate sediment was derived from two catchments in the south–central Pyrenees over a 7.7 myr period, equivalent to a mean erosion rate of <em>c</em>. 0.15–0.18 mm a<sup>−1</sup>. Average exhumation rates in contributing catchments over the same time interval are estimated at 0.2–0.3 mm a<sup>−1</sup> based on apatite fission-track analysis of pebbles in proximal conglomerates, and 0.23–0.34 mm a<sup>−1</sup> from fission-track analysis of detrital apatites sampling a wider range of grain size. Sediment supply progressively increased during the mid- to late Eocene time period, at least in part driven by catchment expansion deep into the Pyrenean Axial Zone at <em>c</em>. 39 Ma. The consistency of the rates of catchment-averaged erosion calculated from different methods builds confidence that source areas have been connected to depositional sinks correctly.
DOI: 10.6084/m9.figshare.3453665.v1
title: Erosion rates in the source region of an ancient sediment routing system: comparison of depositional volumes with thermochronometric estimates

description: Calculation of the total depositional volume of an ancient source-to-sink system, combined with estimates of the area of catchments acting as source regions using provenance methods, is used to evaluate average catchment erosion rates on a million year time scale. These rates are compared with values derived from thermochronological methods. Using the mid- to late Eocene (33.9–41.6 Ma) Escanilla palaeo-sediment routing system from the south–central Pyrenean orogenic wedge-top zone as an example, <em>c</em>. 3500 ± 300 km<sup>3</sup> of solid particulate sediment was derived from two catchments in the south–central Pyrenees over a 7.7 myr period, equivalent to a mean erosion rate of <em>c</em>. 0.15–0.18 mm a<sup>−1</sup>. Average exhumation rates in contributing catchments over the same time interval are estimated at 0.2–0.3 mm a<sup>−1</sup> based on apatite fission-track analysis of pebbles in proximal conglomerates, and 0.23–0.34 mm a<sup>−1</sup> from fission-track analysis of detrital apatites sampling a wider range of grain size. Sediment supply progressively increased during the mid- to late Eocene time period, at least in part driven by catchment expansion deep into the Pyrenean Axial Zone at <em>c</em>. 39 Ma. The consistency of the rates of catchment-averaged erosion calculated from different methods builds confidence that source areas have been connected to depositional sinks correctly.
DOI: 10.6084/m9.figshare.3453662
title: Seismic stratigraphic subdivision of the Triassic succession in the Central North Sea; integrating seismic reflection and well data

description: The Triassic sedimentary succession in the Central North Sea has been investigated to establish a broader understanding of the Triassic Period, from the combined interpretation of seismic reflection data and well data. The Triassic succession has been subdivided into four seismic units, where unit boundaries are characterized by regional seismic amplitude anomalies, reflecting changes in gross sedimentary facies or rock properties. A successful correlation between sedimentary facies, interpreted within the well sections and distinct seismic reflection patterns, allowed a thorough mapping of the gross palaeoenvironment throughout the Triassic. The method presented of subdividing a continental sedimentary succession into seismic units should be applicable elsewhere in other basins. The main source area during the Triassic was Scandinavia to the north, and sediment transportation was mainly along north–south- and NE–SW-trending lineaments, which are at present located onshore southern Norway, and in the Åsta Graben and the Varnes Graben offshore. An uplifted Skagerrak Graben area acted as source area in the Early and early Middle Triassic, with sediment dispersal to the south and SW. High relief existed for a longer period in western Scandinavia than in eastern Scandinavia, which supports an asymmetric shape of the Scandinavian mountains during the Triassic. Accommodation space in the Early Triassic was mainly controlled by the relief inherited from a Late Carboniferous–Permian rift phase. Although thermally induced regional subsidence continued in the Middle and Late Triassic, creation of local accommodation space was mainly limited to halokinesis, including redistribution and withdrawal of salt from the subsurface. The Upper Triassic succession is eroded across the western and central parts of the study area, although the Upper Triassic unit is preserved in synforms adjacent to salt structures. In the western part of the study area, dry, playa conditions prevailed during the Early Triassic, although fluvial systems supplied long-transported sandy detritus southeastwards in the late Early Triassic. More sandy detritus was transported into the sedimentary basin in the Middle and Late Triassic, concurrently with a gradually wetter climate.
DOI: 10.6084/m9.figshare.3453662.v1
title: Seismic stratigraphic subdivision of the Triassic succession in the Central North Sea; integrating seismic reflection and well data

description: The Triassic sedimentary succession in the Central North Sea has been investigated to establish a broader understanding of the Triassic Period, from the combined interpretation of seismic reflection data and well data. The Triassic succession has been subdivided into four seismic units, where unit boundaries are characterized by regional seismic amplitude anomalies, reflecting changes in gross sedimentary facies or rock properties. A successful correlation between sedimentary facies, interpreted within the well sections and distinct seismic reflection patterns, allowed a thorough mapping of the gross palaeoenvironment throughout the Triassic. The method presented of subdividing a continental sedimentary succession into seismic units should be applicable elsewhere in other basins. The main source area during the Triassic was Scandinavia to the north, and sediment transportation was mainly along north–south- and NE–SW-trending lineaments, which are at present located onshore southern Norway, and in the Åsta Graben and the Varnes Graben offshore. An uplifted Skagerrak Graben area acted as source area in the Early and early Middle Triassic, with sediment dispersal to the south and SW. High relief existed for a longer period in western Scandinavia than in eastern Scandinavia, which supports an asymmetric shape of the Scandinavian mountains during the Triassic. Accommodation space in the Early Triassic was mainly controlled by the relief inherited from a Late Carboniferous–Permian rift phase. Although thermally induced regional subsidence continued in the Middle and Late Triassic, creation of local accommodation space was mainly limited to halokinesis, including redistribution and withdrawal of salt from the subsurface. The Upper Triassic succession is eroded across the western and central parts of the study area, although the Upper Triassic unit is preserved in synforms adjacent to salt structures. In the western part of the study area, dry, playa conditions prevailed during the Early Triassic, although fluvial systems supplied long-transported sandy detritus southeastwards in the late Early Triassic. More sandy detritus was transported into the sedimentary basin in the Middle and Late Triassic, concurrently with a gradually wetter climate.
DOI: 10.6084/m9.figshare.3453659
title: Quantifying bioturbation of a simulated ash fall event

description: Tephrochronology allows the establishment of ‘isochrons’ between marine, lacustrine, terrestrial and ice cores, typically based on the geochemical fingerprint of the tephra. The development of cryptotephrochronology has revealed a vast inventory of isochrons which hold the potential to improve stratigraphic correlation and identify systemic leads and lags in periods of rapid climate change. Unfortunately, bioturbation acts to blur these isochrons, reducing the temporal resolution in marine and lacustrine records. In order to better resolve these event horizons, we require a better understanding of bioturbative processes, and the depth and time over which they operate. To this end, an ash fall event was simulated on the intertidal zone of the Eden Estuary, Fife, Scotland and sediment cores were collected over 10 days. A novel approach to tephra quantification was developed, using the imaging software ImageJ. Our results showed limited bioturbation (mixed depth=18 mm), most likely owing to the fine grain size, low-energy environment and the resulting faunal composition of the sediments. These results imply a strong ecological control on bioturbation, and suggest that inferences may be made about palaeoenvironments from the observed bioturbation profiles.
DOI: 10.6084/m9.figshare.3453659.v1
title: Quantifying bioturbation of a simulated ash fall event

description: Tephrochronology allows the establishment of ‘isochrons’ between marine, lacustrine, terrestrial and ice cores, typically based on the geochemical fingerprint of the tephra. The development of cryptotephrochronology has revealed a vast inventory of isochrons which hold the potential to improve stratigraphic correlation and identify systemic leads and lags in periods of rapid climate change. Unfortunately, bioturbation acts to blur these isochrons, reducing the temporal resolution in marine and lacustrine records. In order to better resolve these event horizons, we require a better understanding of bioturbative processes, and the depth and time over which they operate. To this end, an ash fall event was simulated on the intertidal zone of the Eden Estuary, Fife, Scotland and sediment cores were collected over 10 days. A novel approach to tephra quantification was developed, using the imaging software ImageJ. Our results showed limited bioturbation (mixed depth=18 mm), most likely owing to the fine grain size, low-energy environment and the resulting faunal composition of the sediments. These results imply a strong ecological control on bioturbation, and suggest that inferences may be made about palaeoenvironments from the observed bioturbation profiles.
DOI: 10.6084/m9.figshare.3453656
title: Pliocene to Pleistocene vertical movements in the forearc of the Lesser Antilles subduction: insights from chronostratigraphy of shallow-water carbonate platforms (Guadeloupe archipelago)

description: An integrated stratigraphic study was conducted on the shallow water carbonate platforms of the Guadeloupe archipelago to refine the tectonic evolution of the Lesser Antilles forearc. The carbonate platforms are now dated to the Zanclean–Calabrian interval, and their demise occurred between 1.5 and 1.07 Ma. The precise chronostratigraphy allows dating of the main extensional tectonic events since the late Miocene. An initial episode occurred during the late Miocene, related to the reactivation of inherited N130°E-trending shear zones, and led to the emergence of most parts of the forearc. Subsequently, Zanclean to early Piacenzian carbonate platforms developed in association with a general subsidence of the forearc. During the late Piacenzan, a second extensional episode occurred. At this time La Désirade underwent major uplift and emergence whereas most of the forearc remained submerged. Prior to 1.07 Ma, a third north–south extensional episode occurred and led to the final demise of the carbonate platforms. Thus the forearc was characterized by general subsidence since the early Pliocene interrupted by three main extensional episodes and related differential uplifts. This suggests that the Lesser Antilles subduction is probably erosive north of latitude 15°N since <em>c</em>. 5 Ma, related to aseismic ridge subduction.
DOI: 10.6084/m9.figshare.3453656.v1
title: Pliocene to Pleistocene vertical movements in the forearc of the Lesser Antilles subduction: insights from chronostratigraphy of shallow-water carbonate platforms (Guadeloupe archipelago)

description: An integrated stratigraphic study was conducted on the shallow water carbonate platforms of the Guadeloupe archipelago to refine the tectonic evolution of the Lesser Antilles forearc. The carbonate platforms are now dated to the Zanclean–Calabrian interval, and their demise occurred between 1.5 and 1.07 Ma. The precise chronostratigraphy allows dating of the main extensional tectonic events since the late Miocene. An initial episode occurred during the late Miocene, related to the reactivation of inherited N130°E-trending shear zones, and led to the emergence of most parts of the forearc. Subsequently, Zanclean to early Piacenzian carbonate platforms developed in association with a general subsidence of the forearc. During the late Piacenzan, a second extensional episode occurred. At this time La Désirade underwent major uplift and emergence whereas most of the forearc remained submerged. Prior to 1.07 Ma, a third north–south extensional episode occurred and led to the final demise of the carbonate platforms. Thus the forearc was characterized by general subsidence since the early Pliocene interrupted by three main extensional episodes and related differential uplifts. This suggests that the Lesser Antilles subduction is probably erosive north of latitude 15°N since <em>c</em>. 5 Ma, related to aseismic ridge subduction.
DOI: 10.6084/m9.figshare.3453653
title: The timing of sedimentation and Buchan metamorphism in the Grampian Terrane in Scotland from <sup>40</sup>Ar/<sup>39</sup>Ar apparent age spectra

description: New <sup>40</sup>Ar/<sup>39</sup>Ar geochronological data from the Buchan and Barrovian metamorphic sequences on the NE coast of Scotland have been obtained from <em>in vacuo</em> step-heating experiments conducted on white mica extracted from seven samples. The results confirm the synchronous formation of the Barrovian and Buchan metamorphic sequences, with the <sup>40</sup>Ar/<sup>39</sup>Ar apparent age spectra obtained for samples of andalusite grade and higher recording a range of ages between 470.4 ± 1.8 and 464.6 ± 1.3 Ma. These ages are close to the accepted age for peak metamorphism during the Grampian Orogeny, <em>c.</em> 470 Ma, whereas <sup>40</sup>Ar/<sup>39</sup>Ar apparent age spectra of white mica from the lower grade cordierite zone near Banff preserve pre-Grampian detrital ages. In these spectra an age of <em>c.</em> 560 Ma is recorded. This indicates that a tectonothermal event occurred at <em>c.</em> 560 Ma and may provide further insight into the timing of sedimentation. These samples also preserve evidence of ages older than 750 Ma.
DOI: 10.6084/m9.figshare.3453653.v1
title: The timing of sedimentation and Buchan metamorphism in the Grampian Terrane in Scotland from <sup>40</sup>Ar/<sup>39</sup>Ar apparent age spectra

description: New <sup>40</sup>Ar/<sup>39</sup>Ar geochronological data from the Buchan and Barrovian metamorphic sequences on the NE coast of Scotland have been obtained from <em>in vacuo</em> step-heating experiments conducted on white mica extracted from seven samples. The results confirm the synchronous formation of the Barrovian and Buchan metamorphic sequences, with the <sup>40</sup>Ar/<sup>39</sup>Ar apparent age spectra obtained for samples of andalusite grade and higher recording a range of ages between 470.4 ± 1.8 and 464.6 ± 1.3 Ma. These ages are close to the accepted age for peak metamorphism during the Grampian Orogeny, <em>c.</em> 470 Ma, whereas <sup>40</sup>Ar/<sup>39</sup>Ar apparent age spectra of white mica from the lower grade cordierite zone near Banff preserve pre-Grampian detrital ages. In these spectra an age of <em>c.</em> 560 Ma is recorded. This indicates that a tectonothermal event occurred at <em>c.</em> 560 Ma and may provide further insight into the timing of sedimentation. These samples also preserve evidence of ages older than 750 Ma.
DOI: 10.6084/m9.figshare.3453650
title: The Gondwana connections of northern Patagonia

description: A multidisciplinary study (U–Pb sensitive high-resolution ion microprobe geochronology, Hf and O isotopes in zircon, Sr and Nd isotopes in whole-rocks, as well as major and trace element geochemistry) has been carried out on granitoid samples from the area west of Valcheta, North Patagonian Massif, Argentina. These confirm the Cambrian age of the Tardugno Granodiorite (528 ± 4 Ma) and the Late Permian age of granites in the central part of the Yaminué complex (250 Ma). Together with petrological and structural information for the area, we consider a previously suggested idea that the Cambrian and Ordovician granites of northeastern Patagonia represent continuation of the Pampean and Famatinian orogenic belts of the Sierras Pampeanas, respectively. Our interpretation does not support the hypothesis that Patagonia was accreted in Late Palaeozoic times as a far-travelled terrane, originating in the Central Transantarctic Mountains, and the arguments for and against this idea are reviewed. A parautochthonous origin is preferred with no major ocean closure between the North Patagonian Massif and the Sierra de la Ventana fold belt.
DOI: 10.6084/m9.figshare.3453650.v1
title: The Gondwana connections of northern Patagonia

description: A multidisciplinary study (U–Pb sensitive high-resolution ion microprobe geochronology, Hf and O isotopes in zircon, Sr and Nd isotopes in whole-rocks, as well as major and trace element geochemistry) has been carried out on granitoid samples from the area west of Valcheta, North Patagonian Massif, Argentina. These confirm the Cambrian age of the Tardugno Granodiorite (528 ± 4 Ma) and the Late Permian age of granites in the central part of the Yaminué complex (250 Ma). Together with petrological and structural information for the area, we consider a previously suggested idea that the Cambrian and Ordovician granites of northeastern Patagonia represent continuation of the Pampean and Famatinian orogenic belts of the Sierras Pampeanas, respectively. Our interpretation does not support the hypothesis that Patagonia was accreted in Late Palaeozoic times as a far-travelled terrane, originating in the Central Transantarctic Mountains, and the arguments for and against this idea are reviewed. A parautochthonous origin is preferred with no major ocean closure between the North Patagonian Massif and the Sierra de la Ventana fold belt.
DOI: 10.6084/m9.figshare.3453644
title: Observation of centimetre-scale argon diffusion in alkali feldspars: implications for <sup>40</sup>Ar/<sup>39</sup>Ar thermochronology

description: New data from a gem-quality feldspar from Itrongay, Madagascar, record naturally occurring <sup>40</sup>Ar/<sup>39</sup>Ar age profiles which can be numerically modelled by invoking a single diffusion mechanism and show that microtexturally simple crystals are capable of recording complex thermal histories. We present the longest directly measured, naturally produced <sup>40</sup>Ar*-closure profiles from a single, homogeneous orthoclase feldspar. These data appear to confirm the assumption that laboratory derived diffusion parameters are valid in nature and over geological timescales. Diffusion domains are defined by crystal faces and ancient cracks, thus in gem-quality feldspars the diffusion domain size equates to the physical grain size. The data also illustrate the potential of large, gem-quality feldspars to record detailed thermal histories over tens of millions of years and such samples should be considered for future studies on the slow cooling of continental crust.