Catherine Chauvel
Joseph Fourier University, ISTerre, Faculty Member
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Research Interests: Environmental Science, Combustion, Mediterranean Sea, Aerosol, Case Study, and 12 moreHeavy Metal, Polycyclic Aromatic Hydrocarbon, Source apportionment, Biomass burning, Organic carbon, Emission Inventory, Fugitive Emissions, Biogenic Emissions, Motor vehicles act, Chemical mass balance, Health Outcome, and Organic aerosol
ABSTRACT
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Research Interests: Geology and Subduction
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The Last Climate Cycle (LCC, 130-15kyr) has shown cold, dusty (GS) and warmer, non-dusty (GI) intervals, when the atmosphere was 2-20 times more loaded with dust than today. The alternations between GS and GI occurred on millennial time... more
The Last Climate Cycle (LCC, 130-15kyr) has shown cold, dusty (GS) and warmer, non-dusty (GI) intervals, when the atmosphere was 2-20 times more loaded with dust than today. The alternations between GS and GI occurred on millennial time scales, involving climate forcings other than orbital. The transition between GS and GI lasted on average 50 yrs, resulting from a complete climate reorganization that is not presently understood. A data-model project has acquired and investigated European loess sequences to get high-resolution and well-dated paleodust records of the LCC showing Europe experienced millennial paleodust variations through paleosol-loess unit alternations. These alternations correspond to the millennial climate variability as expressed in the Greenland ice cores, with the paleosol developments occurring during GIs, and loess deposition during GSs. Although evidenced for the last climate cycle along a 50°N transect from Brittany to Ukraine, such system prevailed at least also during the penultimate climate cycle with evidence of similar millennial climate variability during the past 192-130 ka interval, equivalent to marine isotope stage 6. Earth System Models contribute i) to characterize the source regions of the paleodust and ii) to reproduce past variations in dust deposition for key paleoclimate scenarios.A key component of our investigation analyses loess samples dated from the last glacial maximum to detect the origin of the deposited material. A first study on the bulk sediment demonstrates that the paleodust deposited over Europe along a long longitudinal transect (about 2000 km) indicates a short distance transport implying local to regional source. Targeting the <2 microns and 2-20 microns grain size fractions and comparing with the previous results from the bulk samples, preliminary results indicate a local to regional origin for the coarse (2-20 microns and bulk) material and a more distant source for the finer fraction (<2 microns), involving longer transport in relation to general atmospheric circulation, for the finer particles. This is a critical new research question because it implies potentially important order of magnitude regional variations in dust radiative forcing that have never been accounted for in simulations of abrupt events.
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Abstract The Amaga basin between the Western and Central Cordilleras of the Northern Andes of Colombia hosts the Neogene volcanic and volcaniclastic Combia Formation. Deposition of the Combia Formation in relation to Nazca plate... more
Abstract The Amaga basin between the Western and Central Cordilleras of the Northern Andes of Colombia hosts the Neogene volcanic and volcaniclastic Combia Formation. Deposition of the Combia Formation in relation to Nazca plate subduction and arc volcanism is still a matter of debate. Therefore, the timing, petrography and geochemical characteristics of Combia Formation rocks were studied in the western and eastern parts of the Amaga basin, in order to gain more information on the type of magma generation and volcanic activity that led to the deposition of the Combia Formation. Apatite and zircon fission-track dating largely confirm a 12-6 Ma age for the deposition of the Combia Formation. Petrographic and major element analyses show that mainly trachy-andesite ignimbrites with a calc-alkaline composition were deposited in the western Amaga basin, whereas the volcanic rocks of the eastern Amaga basin are lavas flow and fall-out deposits of basaltic andesites of tholeiitic affinity. Trace element and isotopic analyses show that slab dehydration and sediment melting/decarbonation were important in primary magma generation in the mantle wedge, but the primary magma was mixed with lower continental crustal melts (e.g. High-Pb radiogenic), resulting in characteristic isotope signatures in the western and eastern Amaga basin. Then, the hot-zone developed a high Pb-radiogenic, garnet-bearing lower continental crustal (LCC) level as a consequence of the quantity of dehydration of the subducting slab and of changes in the tectonic regime. An extensional pull-apart event (12- 9 Ma), likely facilitated rapid magma ascend to the uppermost crust along a subvertical magma plumbing system throughout the Romeral Fault zone in the eastern Amaga basin, and calc-alkaline magmas with adakite-like signature, which may indicate contractile tectonics that allow the formation of middle-to upper-crustal magma chambers with a garnet fractionation at depth and the evolution of silicate melts into the hot zone mainly related to the amount of water (>4 wt %) present.
Research Interests: Geology, Geochemistry, Geophysics, Tool, Petrography, and 5 moreVolcanic Rocks, Deposits, Continental-arc, Zone, and Equilibria
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Oceanic sediments deposited at high rate close to continents are dominated by terrigenous material. Aside from dilution by biogenic components, their chemical compositions reflect those of nearby continental masses. This study focuses on... more
Oceanic sediments deposited at high rate close to continents are dominated by terrigenous material. Aside from dilution by biogenic components, their chemical compositions reflect those of nearby continental masses. This study focuses on oceanic sediments coming from the juvenile Canadian Cordillera and highlights systematic differences between detritus deriving from juvenile crust and detritus from old and mature crust. We report major and trace element concentrations for 68 sediments from the northernmost part of the Cascade forearc, drilled at ODP Sites 888 and 1027. The calculated weighted averages for each site can then be used in the future to quantify the contribution of subducted sediments to Cascades volcanism. The two sites have similar compositions but Site 888, located closer to the continent, has higher sandy turbidite contents and displays higher bulk SiO2/Al2O3 with lower bulk Nb/Zr, attributed to the presence of zircons in the coarse sands.Comparison with published data for other oceanic sedimentary piles demonstrates the existence of systematic differences between modern sediments deriving from juvenile terranes (juvenile sediments) and modern sediments derived from mature continental areas (cratonic sediments). The most striking systematic difference is for Th/Nb, Th/U, Nb/U and Th/Rb ratios: juvenile sediments have much lower ratios than cratonic sediments. The small enrichment of Th over Nb in cratonic sediments may be explained by intracrustal magmatic and metamorphic differentiation processes. In contrast, their elevated Th/U and Nb/U ratios (average values of 6.87 and 7.95, respectively) in comparison to juvenile sediments (Th/U ~ 3.09, Nb/U ~ 5.15) suggest extensive U and Rb losses on old cratons. Uranium and Rb losses are attributed to long-term leaching by rain and river water during exposure of the continental crust at the surface. Over geological times, the weathering effects create a slow but systematic increase of Th/U with exposure time.
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The Cretaceous marine sedimentary record is characterized by time intervals rich in organic matter correlating with positive carbon isotope excursions, often called oceanic anoxic events. The Weissert Event corresponds to the first such... more
The Cretaceous marine sedimentary record is characterized by time intervals rich in organic matter correlating with positive carbon isotope excursions, often called oceanic anoxic events. The Weissert Event corresponds to the first such event in the Cretaceous during the Valanginian stage. The associated palaeoenvironmental perturbations, which include increasing marine surface water primary productivity, are hypothesized to have been triggered by volcanic activity from large igneous provinces, and the source of nutrients is not well constrained (continental runoff v. oceanic upwelling). We present isotope ratios of Pb, Sr and Nd, together with concentrations of major and trace elements, for sediments from the central Moroccan margin to test these hypotheses. We demonstrate that the nutrient input was dominated by continental weathering. The source of sedimentary material remained stable during the Valanginian interval and originated from an old source, probably the African Sahara r...
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(Table 1) Strontium, Neodymium, Hafnium and Lead isotopic compositions from ODP Hole 146-888B, 168-1027B and 168-1027C, supplement to: Carpentier, Marion; Weis, Dominique A M; Chauvel, Catherine (2014): Fractionation of Sr and Hf isotopes by mineral sorting in Cascadia Basin terrigenous sediments...more
Oceanic sediments deposited on continental margins consist mainly of erosion products of the nearby exposed continental areas. Detrital input usually dominates their geochemical budget, and the composition of these sediments should record... more
Oceanic sediments deposited on continental margins consist mainly of erosion products of the nearby exposed continental areas. Detrital input usually dominates their geochemical budget, and the composition of these sediments should record potential changes in their continental sources. However, along margins, mineral sorting associated with transport and sedimentary processes induces significant chemical and isotopic fractionation over a few tens of kilometers. The study of margin sediments should help to quantify the extent of modification of the continental terrigenous supply when it reaches deep oceans. Reported Sr, Nd, Hf and Pb isotopic compositions of fifty-seven sediments from the northernmost part of the Cascade forearc (Ocean Drilling Program, ODP, Sites 888 and 1027) suggest the involvement of two dominant end-members coming from the nearby Canadian Cordillera. Erosion products of the depleted, western part of the Cordillera dominate the detrital input, while the eastern e...
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Daniel Veres (1), Catherine Chauvel (2), Jack Longman (3), Zachary Atlas (4), Aritina Haliuc (1,5), Vasile Ersek (3,1), Călin Gabriel Tămas, (6), Florin Gogaltan (7,1), Enikő Magyari (8), and Frank Schäbitz (9) (1) Romanian Academy,... more
Daniel Veres (1), Catherine Chauvel (2), Jack Longman (3), Zachary Atlas (4), Aritina Haliuc (1,5), Vasile Ersek (3,1), Călin Gabriel Tămas, (6), Florin Gogaltan (7,1), Enikő Magyari (8), and Frank Schäbitz (9) (1) Romanian Academy, Institute of Speleology, 400006 Cluj-Napoca, Romania (daniel.veres@ubbcluj.ro), (2) Université Grenoble Alpes, ISTerre, 38041 Grenoble, France, (3) Department of Geography, Northumbria University, Ellison Building, NE1 8ST, Newcastle upon Tyne, UK, (4) University of South Florida, School of Geosciences, 4202 East Fowler Ave, Tampa, Florida 33620, USA, (5) University of Suceava, Department of Geography, Suceava, Romania, (6) Faculty of Biology and Geology, University Babes-Bolyai, 1 M. Kogalniceanu, 400084 Cluj-Napoca, Romania, (7) Institutul de Arheologie al Academiei, 12-14 M. Kogalniceanu, 400084 Cluj-Napoca, Romania, (8) MTA-MTM-ELTE Research Group for Paleontology, Eotvos Lorand University, Budapest, Hungary, (9) Seminar of Geography and Education, U...
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The Lesser Antilles arc is a particularly interesting island arc because it is presently very active, it is located perpendicular to the South American continent and its chemical and isotopic compositions display a strong north-south... more
The Lesser Antilles arc is a particularly interesting island arc because it is presently very active, it is located perpendicular to the South American continent and its chemical and isotopic compositions display a strong north-south gradient. While the presence in the south of a thick pile of sedimentary material coming from the old South American continent has long been suspected to explain the geochemical gradient, previous studies failed to demonstrate unambiguously a direct link between the arc lava compositions and the subducted sediment compositions.Here, we present new Nd, Sm, Th, U and Pb concentrations and Nd-Pb isotopic data for over 60 sediments from three sites located in the fore arc region of the Lesser Antilles arc. New data for DSDP Site 543 drill core located east of Dominica Island complement the data published by White et al. (1985, doi:10.1016/0016-7037(85)90082-1) and confirm their relatively uniform isotopic compositions (i.e., 206Pb/204Pb between 19.13 and 19.53). In contrast, data obtained on DSDP Site 144 located further south, on the edge of the South American Rise and on sediments from Barbados Island are much more variable (206Pb/204Pb ranges from 18.81 to 27.69). The very radiogenic Pb isotopic compositions are found in a 60 m thick black shale unit, which has no age equivalent in the Site 543 drill core. We interpret the peculiar composition of the southern sediments as being due to two factors, (a) the proximity of the South American craton, which contributes coarse grain old detrital material that does not travel far from the continental shelf, and (b) the presence of older sediments including the thick black shale unit formed during Oceanic Anoxic events 2 and 3.The north-south isotopic change known along the Lesser Antilles arc can be explained by the observed geographical changes in the composition of the subducted sediments. About 1% contamination of the mantle wedge by Site 543 sediments explains the composition of the northern islands while up to 10% sediments like those of [...]