cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.3454826
title: Effects of Cretaceous plume and convergence, and Early Tertiary tectonomagmatic quiescence on the central and southern Levant continental margin

description: This study synthesizes geological and geophysical evidence concerning the structure and character of the central and southern Jurassic Levant continental margin during Cretaceous–Tertiary time. From the beginning of the Cretaceous and until Cenomanian time, the Levant margin was strongly affected by extensional tectonics, cyclical igneous activity and rifting coupled with thermal and vertical fluctuations. It is suggested here that during the Senonian–Maastrichtian convergence of Afro-Arabia and the Mesotethys, and the Tauride part of Eurasia, the Herodotus basin oceanic crust subducted along the Eratosthenes Arc, below the short-lived abandoned Levant back-arc basin. Such a plate configuration assumes regional shear zones, as follows: (1) between the Eratosthenes Arc from the south and the Kyrenia Arc from the north: the NW–SE Carmel–Azraq–Sirhan fault system; (2) between the Sinai and the African plates: the Suez fault system; (3) between the Mesotethys and the African plates: the northern Egypt–Sinai–Negev west–east transversal fault system. Distinct tectonomagmatic quiescence between Late Maastrichtian and Late Eocene time allowed thermal relaxation and subsidence of the Levant margin until the apparent achievement of local isostatic compensation and the consequent development of the longest transgression over the Afro-Arabian ramp.
DOI: 10.6084/m9.figshare.3454826.v1
title: Effects of Cretaceous plume and convergence, and Early Tertiary tectonomagmatic quiescence on the central and southern Levant continental margin

description: This study synthesizes geological and geophysical evidence concerning the structure and character of the central and southern Jurassic Levant continental margin during Cretaceous–Tertiary time. From the beginning of the Cretaceous and until Cenomanian time, the Levant margin was strongly affected by extensional tectonics, cyclical igneous activity and rifting coupled with thermal and vertical fluctuations. It is suggested here that during the Senonian–Maastrichtian convergence of Afro-Arabia and the Mesotethys, and the Tauride part of Eurasia, the Herodotus basin oceanic crust subducted along the Eratosthenes Arc, below the short-lived abandoned Levant back-arc basin. Such a plate configuration assumes regional shear zones, as follows: (1) between the Eratosthenes Arc from the south and the Kyrenia Arc from the north: the NW–SE Carmel–Azraq–Sirhan fault system; (2) between the Sinai and the African plates: the Suez fault system; (3) between the Mesotethys and the African plates: the northern Egypt–Sinai–Negev west–east transversal fault system. Distinct tectonomagmatic quiescence between Late Maastrichtian and Late Eocene time allowed thermal relaxation and subsidence of the Levant margin until the apparent achievement of local isostatic compensation and the consequent development of the longest transgression over the Afro-Arabian ramp.
DOI: 10.6084/m9.figshare.3454823
title: Early Devonian alkaline intrusive complex from the northern North China craton: a petrological monitor of post-collisional tectonics

description: Laser ablation inductively coupled plasma mass spectrometry zircon U–Pb dating and geochemical data document the Early Devonian Sandaogou alkaline complex (409 Ma) from the northern margin of the North China craton. The rock suite includes pyroxene syenite, quartz syenite and monzonite. These rocks exhibit high contents of K<sub>2</sub>O (5–13 wt%), strong enrichments in large ion lithophile elements and light REE, slightly negative Eu anomalies, and pronounced depletions in high field strength elements. They are characterized by moderate <sup>87</sup>Sr/<sup>86</sup>Sr<sub>i</sub> ratios of 0.7052–0.7071, low ε<sub>Nd</sub>(t) values of −12.7 to −17.9 and zircon ε<sub>Hf</sub>(t) values from −27.8 to −32.3. These geochemical features and quantitative isotopic modelling suggest that they might have been formed through simultaneous fractional crystallization and lower crustal assimilation of a metasomatized mantle-derived alkali basaltic magma. These trachytic rocks, together with the Middle Devonian alkaline rocks and mafic–ultramafic complex from neighbouring regions, constitute a linear post-collisional magmatic belt along the northern North China craton, possibly formed under a tectonic regime of slab breakoff. They serve not only as a magmatic milestone for marking the termination of Early Palaeozoic orogenic cycle around the northern North China craton, but also as a spatial tracer for locating the position of the potential ancient slab breakoff at the surface.
DOI: 10.6084/m9.figshare.3454823.v1
title: Early Devonian alkaline intrusive complex from the northern North China craton: a petrological monitor of post-collisional tectonics

description: Laser ablation inductively coupled plasma mass spectrometry zircon U–Pb dating and geochemical data document the Early Devonian Sandaogou alkaline complex (409 Ma) from the northern margin of the North China craton. The rock suite includes pyroxene syenite, quartz syenite and monzonite. These rocks exhibit high contents of K<sub>2</sub>O (5–13 wt%), strong enrichments in large ion lithophile elements and light REE, slightly negative Eu anomalies, and pronounced depletions in high field strength elements. They are characterized by moderate <sup>87</sup>Sr/<sup>86</sup>Sr<sub>i</sub> ratios of 0.7052–0.7071, low ε<sub>Nd</sub>(t) values of −12.7 to −17.9 and zircon ε<sub>Hf</sub>(t) values from −27.8 to −32.3. These geochemical features and quantitative isotopic modelling suggest that they might have been formed through simultaneous fractional crystallization and lower crustal assimilation of a metasomatized mantle-derived alkali basaltic magma. These trachytic rocks, together with the Middle Devonian alkaline rocks and mafic–ultramafic complex from neighbouring regions, constitute a linear post-collisional magmatic belt along the northern North China craton, possibly formed under a tectonic regime of slab breakoff. They serve not only as a magmatic milestone for marking the termination of Early Palaeozoic orogenic cycle around the northern North China craton, but also as a spatial tracer for locating the position of the potential ancient slab breakoff at the surface.
DOI: 10.6084/m9.figshare.3454817
title: Discriminating faunal assemblages and their palaeoecology based on museum collections: the Carboniferous Hurlet and Index limestones of western Scotland

description: <strong>Synopsis</strong> Historical collections of Scottish Carboniferous macrofossils stored at the British Geological Survey (BGS), Edinburgh include the sole remaining sources of palaeontological data from numerous localities. Exploratory numerical analyses of such collections from the Hurlet and Index limestones of Ayrshire compare favourably with published qualitative assessments of faunal assemblages and palaeoenvironments; demonstrating that old collections can still be used in modern palaeoecological investigations. Macrofaunas from these formations comprise mainly brachiopods and molluscs and were collected from 67 localities that yielded 20 and 94 samples from the Hurlet and Index limestones respectively. Limitations of the presence/absence data were partly overcome by consolidation and restriction of aspects of the data set. Seriation indicates the lithological and environmental gradients of taxa. Cluster analysis reveals groups of samples linked to lithofacies. Principal Components Analysis (PCA) of diversity data derived from the data set in terms of numbers of genera in higher taxa highlights differences in gross taxonomic composition in terms of trophic structure, lithology and environment. Supplementary material: lists of localities taxa and sample lithologies used in this study are available at http://www.geolsoc.org.uk/SUP18401 .
DOI: 10.6084/m9.figshare.3454817.v1
title: Discriminating faunal assemblages and their palaeoecology based on museum collections: the Carboniferous Hurlet and Index limestones of western Scotland

description: <strong>Synopsis</strong> Historical collections of Scottish Carboniferous macrofossils stored at the British Geological Survey (BGS), Edinburgh include the sole remaining sources of palaeontological data from numerous localities. Exploratory numerical analyses of such collections from the Hurlet and Index limestones of Ayrshire compare favourably with published qualitative assessments of faunal assemblages and palaeoenvironments; demonstrating that old collections can still be used in modern palaeoecological investigations. Macrofaunas from these formations comprise mainly brachiopods and molluscs and were collected from 67 localities that yielded 20 and 94 samples from the Hurlet and Index limestones respectively. Limitations of the presence/absence data were partly overcome by consolidation and restriction of aspects of the data set. Seriation indicates the lithological and environmental gradients of taxa. Cluster analysis reveals groups of samples linked to lithofacies. Principal Components Analysis (PCA) of diversity data derived from the data set in terms of numbers of genera in higher taxa highlights differences in gross taxonomic composition in terms of trophic structure, lithology and environment. Supplementary material: lists of localities taxa and sample lithologies used in this study are available at http://www.geolsoc.org.uk/SUP18401 .
DOI: 10.6084/m9.figshare.3454814
title: Laurentian origin of the Ordovician Grangegeeth volcanic arc terrane, Ireland

description: U–Pb ages determined by laser-ablation multi-collector inductively coupled plasma mass spectrometry on 199 zircons from a lithic pumice tuff are the first isotopic ages from the Grangegeeth volcanic terrane of Ireland. The youngest zircon population (<em>n</em> = 24) yields an age of 465.4 +2.4/−3.1 Ma. Inherited zircons yield ages of <em>c</em>. 1120–1520, <em>c</em>. 1650–1914 and <em>c</em>. 2540–2890 Ma. The absence of zircons between <em>c</em>. 550 and 700 Ma argues against involvement of Avalonia as a source of inherited crystals. Overall, the inherited age spectra are characteristic of Laurentian crust or metasedimentary successions of peri-Laurentian provenance. These findings suggest that the Grangegeeth volcanic terrane does not represent a continuation of the intra-Iapetus Exploits arc of Newfoundland.
DOI: 10.6084/m9.figshare.3454811
title: Quantitative characterization of textures in mantle spinel peridotite xenoliths

description: A method for quantitative characterization of grain size in thin sections has been established for mantle spinel peridotite xenoliths, using optical scanning of large areas of thin sections, skeletonization of grain-section outlines and computerized measurement of individual grain-section areas. Measurements range from 218 for the coarsest example to more than 3000 in the finest grained. Variability of the samples has been examined in relation to size and number of grain-section areas measured by using multiple and orthogonal sections from several xenoliths. The results show a linear relationship of arithmetic mean against additive standard deviation, including data from coarse-grained protogranular, through porphyroclastic to the finer-grained equigranular examples. This suggests that peridotite textures form a continuous series rather than discrete groups, as suggested by qualitative (subjective) assessment. The observed distributions of grain-section areas have been explored in relation to their description and possible mechanistic origin. By direct measurement and comparison of cumulative number and area distribution curves, we show that qualitatively assessed ‘typical grain sizes’ are influenced by a small number of larger grain sections. Although the arithmetic mean and standard deviation provide a convenient method for comparison, in practice grain-section area distributions show marked positive skewness more consistent with log-normal or power-law functions. Linear log-probability curves also support the existence of a continuous series of peridotite textures, suggesting that the shallow lithospheric mantle has been subject to processes of comminution and/or grain growth dependent on the Law of Proportionate Effect.
DOI: 10.6084/m9.figshare.3454811.v1
title: Quantitative characterization of textures in mantle spinel peridotite xenoliths

description: A method for quantitative characterization of grain size in thin sections has been established for mantle spinel peridotite xenoliths, using optical scanning of large areas of thin sections, skeletonization of grain-section outlines and computerized measurement of individual grain-section areas. Measurements range from 218 for the coarsest example to more than 3000 in the finest grained. Variability of the samples has been examined in relation to size and number of grain-section areas measured by using multiple and orthogonal sections from several xenoliths. The results show a linear relationship of arithmetic mean against additive standard deviation, including data from coarse-grained protogranular, through porphyroclastic to the finer-grained equigranular examples. This suggests that peridotite textures form a continuous series rather than discrete groups, as suggested by qualitative (subjective) assessment. The observed distributions of grain-section areas have been explored in relation to their description and possible mechanistic origin. By direct measurement and comparison of cumulative number and area distribution curves, we show that qualitatively assessed ‘typical grain sizes’ are influenced by a small number of larger grain sections. Although the arithmetic mean and standard deviation provide a convenient method for comparison, in practice grain-section area distributions show marked positive skewness more consistent with log-normal or power-law functions. Linear log-probability curves also support the existence of a continuous series of peridotite textures, suggesting that the shallow lithospheric mantle has been subject to processes of comminution and/or grain growth dependent on the Law of Proportionate Effect.
DOI: 10.6084/m9.figshare.3454808
title: Detrital zircon SHRIMP U–Pb age study of the Cordillera Darwin Metamorphic Complex of Tierra del Fuego: sedimentary sources and implications for the evolution of the Pacific margin of Gondwana

description: The Cordillera Darwin Metamorphic Complex in the southernmost Andes includes a basement of probable Palaeozoic age, a mid-Jurassic and younger volcano-sedimentary cover, and a suite of Jurassic granites, all of which were jointly metamorphosed during the Cretaceous. Detrital zircon ages presented here show that some of the amphibolite-facies metamorphic rocks previously mapped as basement have a Jurassic protolith. Overall the detrital zircon age patterns for samples of the Cordillera Darwin basement differ from those of the Madre de Dios Terrane of the western Patagonian Andes with which they had been correlated; instead, they are more comparable with those from the Eastern Andes Metamorphic Complex, which apparently developed in a passive margin setting. The paucity of Cambrian detrital zircons indicates that the meta-igneous basement of the Magallanes foreland basin of central and northern Tierra del Fuego was not the main source of detritus for the protolith of the Cordillera Darwin Metamorphic Complex. The possibility is envisaged that the Magallanes Fagnano transform fault boundary between the Scotia and South America plates resulted from reactivation of an older, pre-Jurassic suture zone between the basement terranes of north–central Tierra del Fuego and Cordillera Darwin.
DOI: 10.6084/m9.figshare.3454808.v1
title: Detrital zircon SHRIMP U–Pb age study of the Cordillera Darwin Metamorphic Complex of Tierra del Fuego: sedimentary sources and implications for the evolution of the Pacific margin of Gondwana

description: The Cordillera Darwin Metamorphic Complex in the southernmost Andes includes a basement of probable Palaeozoic age, a mid-Jurassic and younger volcano-sedimentary cover, and a suite of Jurassic granites, all of which were jointly metamorphosed during the Cretaceous. Detrital zircon ages presented here show that some of the amphibolite-facies metamorphic rocks previously mapped as basement have a Jurassic protolith. Overall the detrital zircon age patterns for samples of the Cordillera Darwin basement differ from those of the Madre de Dios Terrane of the western Patagonian Andes with which they had been correlated; instead, they are more comparable with those from the Eastern Andes Metamorphic Complex, which apparently developed in a passive margin setting. The paucity of Cambrian detrital zircons indicates that the meta-igneous basement of the Magallanes foreland basin of central and northern Tierra del Fuego was not the main source of detritus for the protolith of the Cordillera Darwin Metamorphic Complex. The possibility is envisaged that the Magallanes Fagnano transform fault boundary between the Scotia and South America plates resulted from reactivation of an older, pre-Jurassic suture zone between the basement terranes of north–central Tierra del Fuego and Cordillera Darwin.
DOI: 10.6084/m9.figshare.3454805
title: On the difficulty of assigning crustal residence, magmatic protolith and metamorphic ages to Lewisian granulites: constraints from combined <em>in situ</em> U–Pb and Lu–Hf isotopes

description: Zircons from two granulite facies gneisses from the central region of the Lewisian Complex have been investigated by high spatial resolution ion-microprobe U–Pb dating and laser ablation combined Pb–Hf isotope methods. The ion-microprobe data reveal a complex pattern of zircon ages distributed along the concordia curve between the time of granulite facies metamorphism at <em>c</em>. 2.5 Ga and the oldest zircon in each sample (respectively 2.89 Ga and 3.04 Ga). This Pb-loss pattern complicates assignment of an unambiguous magmatic protolith age to the zircon although cathodoluminescence (CL) imaging is used to suggest a preferred age of <em>c</em>. 2.85 Ga for both samples, with older grains being inherited. <em>In situ</em> Hf isotopes show a larger spread in the sample containing older grains which is also consistent with inheritance and further suggests that several crust extraction events are represented in the inherited population. Comparison of Hf isotope compositions with plausible model evolution curves suggests that crustal precursors to the Lewisian granulites were derived from their mantle source at <em>c</em>. 3.05–3.2 Ga.
DOI: 10.6084/m9.figshare.3454805.v1
title: On the difficulty of assigning crustal residence, magmatic protolith and metamorphic ages to Lewisian granulites: constraints from combined <em>in situ</em> U–Pb and Lu–Hf isotopes

description: Zircons from two granulite facies gneisses from the central region of the Lewisian Complex have been investigated by high spatial resolution ion-microprobe U–Pb dating and laser ablation combined Pb–Hf isotope methods. The ion-microprobe data reveal a complex pattern of zircon ages distributed along the concordia curve between the time of granulite facies metamorphism at <em>c</em>. 2.5 Ga and the oldest zircon in each sample (respectively 2.89 Ga and 3.04 Ga). This Pb-loss pattern complicates assignment of an unambiguous magmatic protolith age to the zircon although cathodoluminescence (CL) imaging is used to suggest a preferred age of <em>c</em>. 2.85 Ga for both samples, with older grains being inherited. <em>In situ</em> Hf isotopes show a larger spread in the sample containing older grains which is also consistent with inheritance and further suggests that several crust extraction events are represented in the inherited population. Comparison of Hf isotope compositions with plausible model evolution curves suggests that crustal precursors to the Lewisian granulites were derived from their mantle source at <em>c</em>. 3.05–3.2 Ga.
DOI: 10.6084/m9.figshare.3454802
title: Electronic database of historical natural stones of the Czech Republic: structuring field and laboratory data

description: The structure of the electronic database of natural stones used in the Czech Republic (named <em>Deka</em>) has been completed. The system is based on MySQL, and is comprised of the following crucial items: general data, data regarding the geographic location and status of the quarry; petrographic description, associated mineralogical data and chemical analyses; technical data covering physical and mechanical properties as well as sculptural workability; parameters about the deposit (quarry); and data describing historical exploitation and utilization. Along with the structure of the database, other practical problems such as access to the database, insertions, corrections, erasing a record or reference, etc. are discussed. The database is designed for geologists, historians and restorers resolving problems of a stone's provenance from monuments, architects involved in the selection of promising stone types for new projects and for educational purposes to geologists, restorers, etc. Appendix 1: A description of the eight types of data used in the dimension store database is provided at http://www.geolsoc.org.uk/sup18394
DOI: 10.6084/m9.figshare.3454802.v1
title: Electronic database of historical natural stones of the Czech Republic: structuring field and laboratory data

description: The structure of the electronic database of natural stones used in the Czech Republic (named <em>Deka</em>) has been completed. The system is based on MySQL, and is comprised of the following crucial items: general data, data regarding the geographic location and status of the quarry; petrographic description, associated mineralogical data and chemical analyses; technical data covering physical and mechanical properties as well as sculptural workability; parameters about the deposit (quarry); and data describing historical exploitation and utilization. Along with the structure of the database, other practical problems such as access to the database, insertions, corrections, erasing a record or reference, etc. are discussed. The database is designed for geologists, historians and restorers resolving problems of a stone's provenance from monuments, architects involved in the selection of promising stone types for new projects and for educational purposes to geologists, restorers, etc. Appendix 1: A description of the eight types of data used in the dimension store database is provided at http://www.geolsoc.org.uk/sup18394
DOI: 10.6084/m9.figshare.3454799
title: Two-scale gravitational collapse in the Amazon Fan: a coupled system of gravity tectonics and mass-transport processes

description: Gravity tectonics affects the entire marine sedimentary sequence of the Foz do Amazonas basin, including the topmost Amazon Fan. During the various stages of the margin's evolution, the sedimentary loading and bathymetric slope induced the formation of a linked extensional–compressional system in which gravitational fold-and-thrust belts form significant structural features on the continental slope. Seismic analysis carried out in this study shows that sea-floor relief created along these thrust belts can trigger recurrent mass-transport deposits in the upper–middle Amazon Fan, suggesting a long-lasting linkage between gravity tectonics and mass-transport processes throughout the sedimentary evolution of the Amazon Fan.