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10 results on '"Geological Society of America"'

1. Modeling Zircon growth during open-system crystallization

Author

R. C. Economos, Oscar Laurent, Jörn-Frederik Wotzlaw, Olivier Bachmann, Cyril Chelle-Michou, Lorenzo Tavazzani, Southern Methodist University Dallas, Institute of Geochemistry and Petrology [ETH Zürich], Department of Earth Sciences [Swiss Federal Institute of Technology - ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institute of Geophysics [ETH Zürich], and The Geological Society of America

Subjects
Materials science, law, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Crystallization, Petrology, Open system (systems theory), Zircon, law.invention
Abstract

International audience; Recent advances in zircon geochronology by isotope dilution thermal-ionization mass spectrometry (ID-TIMS) techniques allow for age precision beyond the 0.02 % level for single zircon 206Pb/238U dates [1] and can resolve zircon crystallization heterogeneities in a dispersed age population. As zircon saturation is dependent on melt temperature and composition, quantitative analysis of dispersed zircon age populations can provide insight into the timing and magnitude of intensive parameter variations during the lifetime of magma reservoirs.

Published
2021
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2. OROGENIC SUTURES IN THE ARCHEAN SUPERIOR PROVINCE, CANADA – A COUNTEREXAMPLE FROM NORTHERN QUEBEC

Author

Gilles Ruffet, Alain Tremblay, François Leclerc, Yannick Daoudene, Département des Sciences de la Terre et de l'Atmosphère, Université du Québec à Montréal = University of Québec in Montréal (UQAM), Ministère de l’Énergie et des Ressources naturelles, Géosciences Rennes (GR), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Geological Society of America, Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Paleontology, Archean, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, Counterexample
Abstract

International audience; Orogenic sutures mark the consumption of oceanic lithosphere by subduction. They are underlined by major faults within collisional orogens, between terranes of contrasting geological evolution. Archean cratons consist of greenstone belts juxtaposed to deeper crustal rocks dominated by TTG’s. The greenstone belts show steep folds and localised shear zones, whereas plutonic belts display dome structures. These rocks usually preserve MT/HT-LP/MP metamorphism that varies from greenschist- to granulite-facies, from upper to lower crustal domains. The nature of Archean tectonism remains debated: were Archean processes similar to those of present-day plate tectonics? Archean greenstone belts thus recording plate convergence and subduction/collision, or was Archean tectonics different? in which case, burying and exhumation of crustal rocks can be mainly attributed to vertical tectonics.We present a structural and metamorphic study of the Abitibi Greenstone Belt (AGB) and Opatica Plutonic Belt (OPB) of the Archean Superior Province in Quebec. The AGB-OPB contact is currently interpreted as an archetype example of Archean subduction, based on a LITHOPROBE seismic profile showing a North-dipping lithospheric-scale reflector interpreted as the vestige of subduction of an AGB plate. However, our mapping indicates that the AGB overlies the OPB. Moreover, that contact does not show evidences of significant shear deformation, as expected if it is a major upper plate-lower plate boundary. Furthermore, it does not show any metamorphic break but a progressive increase of metamorphism toward the OPB, from greenschist- to amphibolite-facies. Thus, we think that the OPB exposes the deepest part of a composite AGB-OPB crustal sequence. 40Ar/39Ar ages from the study area suggest that from ~2685 Ma to ~2632 Ma, the deepest level of the AGB and underlying OPB reached amphibolite-facies conditions, and that progressive cooling was accompanied by strain localisation along strike-slip shear zones, when lateral flow of the lower crust became predominant over vertical tectonics after ~2600 Ma. Comparison with adjacent areas suggests that regional metamorphism has been coeval over a large region, which is consistent with pervasive deformation and slow cooling as expected in Archean vertical tectonic models.

Published
2018
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3. STRUCTURAL AND METAMORPHIC EVOLUTION OF THE CONNECTICUT VALLEY-GASPÉ TROUGH – INSIGHTS FROM SOUTHERN QUEBEC AND NORTHERN VERMONT

Author

Alain Tremblay, Gilles Ruffet, Morgann Perrot, Félix Gervais, Loïc Labrousse, Département des sciences de la terre et de l'atmosphère [Montréal] (SCTA), Université du Québec à Montréal (UQAM), Géosciences Rennes (GR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Geological Society of America, Université du Québec à Montréal = University of Québec in Montréal (UQAM), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
Paleontology, Metamorphic rock, Trough (geology), [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology
Abstract

International audience; In Québec and New England, the Connecticut Valley-Gaspé (CVG) trough is an orogen-scale Silurian-Devonian basin of the Northern Appalachians. From Gaspé peninsula to southern New England, the CVG trough has experienced contrasting metamorphic and structural evolution during the Acadian orogeny. From north to south, it is characterized by increasing (1) deformation and polyphased structures, (2) intensity of regional metamorphism, i.e. from very low-grade to upper amphibolite facies, and (3) abundance of crosscutting ~ 390 to 370 Ma granitic intrusions. In southern Quebec and northern Vermont, a series of NW-SE transects in the CVG trough have been studied to better understand the along-strike structural and metamorphic variations. Detailed structural analyses, combined with isochemical phase diagram sections (IPDS), Raman spectrometry and muscovite 40Ar/39Ar dating have been performed.In southern Québec, regional deformation is characterized by D1-related NW-verging folds. Towards the Québec-Vermont border, D2 fabrics progressively appears as evidenced by SE-verging F2 folds associated with a S2 crenulation cleavage that wraps around granitic intrusions. D2 structures are locally overprinted by a late-stage crenulation cleavage (S3). Temperature of regional metamorphism (M1) has been determined from Raman spectrometry. It gradually increases toward the south, from ~ 370°C to 420°C, whereas IPDS suggest that M1 pressure reached ~ 4 Kb. At the Quebec-Vermont border, the M1 temperature gradient was partially obliterated by the heat released from granitic intrusions. In Vermont, D2 and D3 structures are more pervasive and IPDS suggest that P-T conditions reached at least ~ 5 Kbar and 500°C. In Southern Québec, 40Ar/39Ar ages of metamorphic muscovites indicate that the D1 -M1 greenschist-facies event, peaked at ~ 380–375 Ma. However, in Québec-Vermont border and northern Vermont, ~ 360-365 Ma and ~ 335-340 Ma metamorphic muscovite from upper greenschist/amphibolite facies rocks reflects cooling, and thus minimum ages for the D2 and D3 events, respectively. Alleghanian metamorphic ages (~ 300 Ma) are found in easternmost part of the Vermont, in the footwall of the Monroe Fault. These results can be attributed to spatial and temporal partitioning of compressive deformation during the Acadian orogeny.

Published
2018
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4. CENOZOIC SOURCE TO SINK RELATION BETWEEN THE QAIDAM BASIN AND THE EASTERN KUNLUN SHAN

Author

Zhaojie Guo, Feng Cheng, Carmala N. Garzione, Marc Jolivet, University of Rochester [USA], Peking University [Beijing], Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Geological Society of America, Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010506 paleontology, Provenance, geography, Plateau, geography.geographical_feature_category, Proterozoic, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Structural basin, Neogene, 01 natural sciences, Mountain formation, Isopach map, Cenozoic, Geology, 0105 earth and related environmental sciences
Abstract

International audience; Understanding the source to sink relationship through time between the Eastern Kunlun Shan, one of the major mountain belts in the northern Tibetan Plateau, and the actively deforming Qaidam Basin to the north has important implications for unravelling the growth history of the Tibetan Plateau. In this study, we first carried out a flexural loading modeling to estimate the topography load of the Qilian Shan and Eastern Kunlun Shan during the deposition of the Lulehe Fm. and compared this result with the basin shape which was obtained from shortening restoration and decompaction by using the drill core, seismic profile and isopach data. In addition, U-Pb dating of detrital zircons from 22 sandstone samples collected from four sections within the southwestern Qaidam Basin is combined with provenance analysis and new seismic profile interpretation to investigate the mountain building of the Eastern Kunlun Shan and its effects on the development of the Qaidam Basin. Flexural loading estimate suggests that the single Qilian Shan failed to produce a sufficient load to create the observed Qaidam basin during the deposition of Lulehe Fm. The topographic load generated by both the Eastern Kunlun Shan to the south and the Qilian Shan-Altyn Tagh Range to the north was responsible for the flexural subsidence of the Qaidam basin during the deposition of Lulehe Fm. The U-Pb age distributions of detrital grains from Lulehe Fm. strata are characterized by a major component of Paleozoic to late Proterozoic ages. Carbonate debris containing foraminifera have been recognized in the Lulehe Fm. conglomerate sequences. We suggest that the Eastern Kunlun Shan was exhumed during the deposition of Lulehe Fm. The southward onlaps strata (Lulehe Fm. to Shangganchaigou Fm.) observed on seismic profiles and the appearance of a Mesozoic component in the detrital zircon age spectra of Xiaganchaigou Fm. to Shangganchaigou Fm. strata indicate that the Qaidam Basin was widening southward during that early Cenozoic period. Well-developed growth strata and the increasing proportion of Mesozoic and Paleozoic U-Pb ages in detrital zircon grains from late Neogene strata demonstrate that the relief of the Eastern Kunlun Shan and Altyn Tagh Range increased, leading to isolation and narrowing of the Qaidam Basin, from Miocene to the present.

Published
2017
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5. Lithospheric strength: a potential controlling factor over differential subsidence in the Early Triassic Sonoma Foreland Basin (western USA)?

Author

Emmanuel Fara, Gilles Escarguel, Gwénaël Caravaca, Emmanuelle Vennin, Anne-Sabine Grosjean, Nicolas Olivier, Arnaud Brayard, Michel Guiraud, Christophe Thomazo, Biogéosciences [UMR 6282] (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Geological Society of America, ANR-13-JS06-0001,AFTER,Après la fin : la reconstruction des communautés marines durant la rediversification du Trias inférieur.(2013), Biogéosciences [UMR 6282] [Dijon] (BGS), Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement, Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon)

Subjects
[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Permian, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Early Triassic, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Subsidence, 15. Life on land, Structural basin, western USA, lithospheric control, Sonoma Foreland Basin, Allochthon, Paleontology, Basement (geology), integrated study, paleoenvironmental reconstructions, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Sedimentary rock, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, Geomorphology, Foreland basin, Geology
Abstract

International audience; The Sonoma Foreland Basin was formed as a flexural response to the emplacement of the Golconda Allochthon during the Sonoma Orogeny around the Permian/Triassic boundary (~252 Ma), and it includes an excellent fossil and sedimentary record of the Early Triassic. However, sediments deposited from the Permian/Triassic boundary until the end-Smithian (~250.7 Ma) shows marked thickness variations between its southern (up to ~200 m thick) and northern (up to ~550 m thick) parts. Differences in dominant lithologies can also be noticed throughout the basin, with mostly terrigenous sandstones and microbial limestones in the southern part while the northern part is dominantly composed of fine siltstones and carbonates. Based on an integrated study within a high-resolution timeframe and using georeferenced data from sedimentological, paleontological, structural and cartographic approaches, we propose to discuss the controlling factor(s) responsible for spatial variations in sedimentary thickness. Regional palinspastic reconstruction and high time-resolution subsidence analyses are thus conducted to obtain an accurate image of the basin by the time of the deposition. We notably show that sedimentary overload in the basin and heterogeneity of the topographic load exerted by the Golconda Allochthon, when emplaced, are not sufficient to explain the significant discrepancy observed within the Early Triassic sedimentary record. We therefore argue that the age and thus, the rheological properties of the terranes that compose the basin basement are of paramount importance in controlling both the subsidence and thickness spatial distribution across the Sonoma Foreland Basin.

Published
2016
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6. Exhuming the Alps through time: clues from detrital zircon fission-track thermochronology

Author

Ml Balestieri, B Ventura, John I. Garver, Matthias Bernet, Massimiliano Zattin, Mark T. Brandon, Laboratoire de Géodynamique des Chaines Alpines (LGCA), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Geology and Geophysics, Yale University [New Haven], Geology Department, Union College, Dipartimento di Scienze della Terra [Firenze] (DST), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Fachbereich Geowissenschaften [Bremen], Universität Bremen, Dipartimento di Geoscienze [Padova], Universita degli Studi di Padova, Geological Society of America, Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), and Università degli Studi di Firenze [Firenze]

Subjects
geography, detrital thermochronology, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Continental collision, Bedrock, Alps, zircon fission tracks, exhumation, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Window (geology), Geology, 010502 geochemistry & geophysics, Fission track dating, 01 natural sciences, Thermochronology, Tectonics, Paleontology, Magmatism, 0105 earth and related environmental sciences, Zircon
Abstract

International audience; The European Alps are a mountain belt that is characterized by a series of discrete orogenic events, which have long been recognized. Despite the inherent episodic nature of orogenic evolution, the Alps have been continuously exhumed, mainly by erosion, but also by normal faulting. Since continental collision started in the late Eocene/Early Oligocene evidence for ongoing erosional exhumation has been preserved in synorogenic sediments that accumulated in basins adjacent to the pro- and retro-side of this double-vergent mountain belt. This long-term erosion record can be used to determine exhumation rates. Lag-times calculated from fission-track (FT) ages of detrital zircon from synorogenic sediments are fairly constant for the European Alps since the Oligocene–Late Miocene. Although the fast exhuming areas were unroofed at rates of 0.4–0.7 km Myr−1, the overall average exhumation rate is between 0.2 and 0.3 km Myr−1 on a regional scale. The detrital and bedrock zircon FT data of the Alps do not detect the increase in erosion rates since the Pliocene over the past ∼5 Myr, as shown elsewhere. This increase cannot be detected yet with the detrital zircon FT method because not enough rock has been removed to widely expose zircons with Pliocene or younger cooling ages in the Alps. Long term (30 Myr) exhumation rates appear to have been approximately constant when averaged over a sliding time window of about 8 Myr, or depth window of 5 to 10 km (ZFT closure depths); shorter-term fluctuations are not identified using this method.

Published
2009
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7. Global analysis of the role of the GRACE satellites in water resources assessments

Author

Scanlon, Bridget R., Long, Di, Longuevergne, Laurent, Bureau of Economic Geology [Austin] (BEG), Jackson School of Geosciences (JSG), University of Texas at Austin [Austin]-University of Texas at Austin [Austin], Géosciences Rennes (GR), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Geological Society of America, Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), and Dubigeon, Isabelle

Subjects
[SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2014

8. A 16kyr-long record of earthquakes preserved in the deep-sea turbidite record of the northern Hikurangi Margin of New Zealand

Author

Pouderoux, Hugo, Lamarche, Geoffroy, Proust, Jean-Noël, Orpin, Alan, Neil, Helen, Géosciences Rennes (GR), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), National Institute of Water and Atmospheric Research [Wellington] (NIWA), Geological Society of America, Dubigeon, Isabelle, Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), and Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2012

9. Can a legal framework help us to share geoscience knowledge? the experience of inspire in Europe

Author

Robida, François, Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), and Geological Society of America

Subjects
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract

International audience; Delivering geoscience data, information and knowledge to users in the Spatial Data Infrastructure (SDI) paradigm means that the content generated by the providers must be made available through specific technical standards, organisational and legal requirements. These standards and requirements are supposed to facilitate the information sharing and re-use within a community (i.e. between geologists), between different scientific communities (i.e. dealing with climate change), or by the citizen. Building an SDI is not just about exposing scientific data through standardised web services (such as WMS web map services), it is also an occasion to redefine the information products, to specialize them according to the target (experts, professional, citizen), and build new applications that aggregate, analyse, combine contents. According to the interoperability principles of service oriented architectures (SOA), these new applications can be developed by combining sources of information and software components from different providers, through new forms of partnerships. In order to develop this type of geo-information ecosystem, Europe has decided to setup a European SDI through a very ambitious legal framework called INSPIRE. This framework will be applied to most of the digital geo-information that is produced by public authorities in Europe. Therefore, a lot of implementing rules are developed to define the technical standards to be used for the web services, and for describing the data content (metadata, data models...) that will be delivered. The OneGeology-Europe project is a prototype of the implementation of INSPIRE at the scale of the European Geological Surveys

Published
2011

10. The redox state of arc mantle using Zn/Fe systematics

Author

Peter Luffi, Cin-Ty A. Lee, Véronique Le Roux, Francis Albarède, William P. Leeman, Rajdeep Dasgupta, Department of Earth Science [Houston], Rice University [Houston], Department of Earth Sciences [Houston], Laboratoire de Sciences de la Terre (LST), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Div Earth Sciences, National Science Foundation [Arlington] (NSF), Geological Society of America, École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
METASOMATISM, Mantle wedge, MAGMAS, OXIDATION-STATE, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, engineering.material, 010502 geochemistry & geophysics, OXYGEN FUGACITY, 01 natural sciences, Mantle (geology), Mineral redox buffer, 010503 geology, Petrology, SOURCE REGIONS, 0105 earth and related environmental sciences, Peridotite, geography, Multidisciplinary, Olivine, geography.geographical_feature_category, Fractional crystallization (geology), Volcanic arc, Partial melting, EARTHS MANTLE, INSIGHTS, DIFFERENTIATION, 13. Climate action, engineering, BASALTS, PERIDOTITES
Abstract

The redox state of the upper mantle beneath arcs is relevant to understanding mantle melting and melt differentiation. Because we have no access to samples from the convective mantle, this question has to be addressed indirectly using information derived from the chemistry of melts. Cin-Ty Lee et al. show that the ratio of zinc to total iron content constrains the valence state of iron in primary arc basalts and their mantle sources. They find that primitive arc magmas have Zn/Fe ratios identical to those of mid-ocean ridge basalts, hinting at a similar iron oxidation state of primary mantle melts in arcs and ridges. The results suggest that the subduction of oxidized crustal material may not significantly alter the redox state of the mantle wedge. They conclude that the observed higher oxidation states of arc lavas must therefore be, in part, a consequence of shallow-level differentiation processes. Here it is shown that the ratio of zinc to total iron content constrains the valence state of iron in primary arc basalts and their mantle sources. Primitive arc magmas have identical Zn/FeT ratios (FeT = Fe2+ + Fe3+) as mid-ocean-ridge basalts, indicating a similar iron oxidation state of primary mantle melts in arcs and ridges and that the subduction of oxidized crustal material may not significantly alter the redox state of the mantle wedge. It is concluded that the observed higher oxidation states of arc lavas must therefore be, in part, a consequence of shallow-level differentiation processes. Many arc lavas are more oxidized than mid-ocean-ridge basalts and subduction introduces oxidized components into the mantle1,2,3,4. As a consequence, the sub-arc mantle wedge is widely believed to be oxidized3,5. The Fe oxidation state of sub-arc mantle is, however, difficult to determine directly, and debate persists as to whether this oxidation is intrinsic to the mantle source6,7. Here we show that Zn/FeT (where FeT = Fe2+ + Fe3+) is redox-sensitive and retains a memory of the valence state of Fe in primary arc basalts and their mantle sources. During melting of mantle peridotite, Fe2+ and Zn behave similarly, but because Fe3+ is more incompatible than Fe2+, melts generated in oxidized environments have low Zn/FeT. Primitive arc magmas have identical Zn/FeT to mid-ocean-ridge basalts, suggesting that primary mantle melts in arcs and ridges have similar Fe oxidation states. The constancy of Zn/FeT during early differentiation involving olivine requires that Fe3+/FeT remains low in the magma. Only after progressive fractionation does Fe3+/FeT increase and stabilize magnetite as a fractionating phase. These results suggest that subduction of oxidized crustal material may not significantly alter the redox state of the mantle wedge. Thus, the higher oxidation states of arc lavas must be in part a consequence of shallow-level differentiation processes, though such processes remain poorly understood.

Published
2010
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