Isotopic composition and lithic grains concentration of sediment core SI90-09
Cobertura |
LATITUDE: 43.786667 * LONGITUDE: -31.748333 * DATE/TIME START: 1990-01-01T00:00:00 * DATE/TIME END: 1990-01-01T00:00:00 |
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Data(s) |
02/06/2001
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Resumo |
Theories explaining the origin of the abrupt, massive discharges of ice-rafted detritus (IRD) into the glacial North Atlantic (the Heinrich layers (HLs)) generally point to the Laurentide ice sheet as the sole source of these events, until it was found that the IRDs also originated from Icelandic and European ice sheets (Bond and Lotti, 1995, doi:10.1126/science.267.5200.1005; Snoeckx et al., 1999, doi:10.1016/S0025-3227(98)00168-6; Grousset et al., 2000, doi:10.1130/0091-7613(2000)28<123:WTNAHE>2.0.CO;2). This apparent contradiction must be reconciled as it raises fundamental questions about the mechanism(s) of HL origin. We have analyzed two ~12 cm thick HLs in an ultrahigh-resolution mode (1-2 century intervals) in a mid-Atlantic ridge piston core. The d18O record (N. pachyderma left coiling) reveals strong excursions induced by the melting of the icebergs; these excursions are associated with a strong decrease in the amount of planktic foraminafersand with a 3°C cooling of the surface waters. Counts of coarse detrital grains reveal that IRD are deposited according to a typical sequence (1) volcanic glass, (2) quartz and feldspars, (3) detrital carbonate, that implies a chronology in the melting of the differentpan-Atlantic ice sheets. Sr and Nd isotopic composition confirm that in both Heinrich layers H1 and H2, "precursor" IRD came from first Europe/Iceland, followed then by Laurentide-derived IRD. An internal cyclicity can be identified: during H1 and H2, about four to six major, abrupt discharges occurred roughly on a century timescale. The d13C and d15N records reveal that dominant inputs of continent-derived organic matter are associated with IRD within the HLs, hiding the plankton productivity signal. |
Formato |
application/zip, 4 datasets |
Identificador |
https://doi.pangaea.de/10.1594/PANGAEA.846660 doi:10.1594/PANGAEA.846660 |
Idioma(s) |
en |
Publicador |
PANGAEA |
Direitos |
CC-BY: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted |
Fonte |
Supplement to: Grousset, Francis E; Cortijo, Elsa; Huon, Sylvain; Herve, Laurence; Richter, Thomas; Burdloff, Didier; Duprat, Josette; Weber, Oliver (2001): Zooming in on Heinrich layers. Paleoceanography, 16(3), 240-259, doi:10.1029/2000PA000559 |
Palavras-Chave | #143Nd/144Nd; 143Nd/144Nd e; 87Sr/86Sr; 87Sr/86Sr e; Calculated; Carb; Carbon, organic, total; Carbon, organic/Nitrogen, total ratio; Carbonate, number per unit mass; Corg/TN; Counting >150 µm fraction; d13C Corg; d15N bulk; delta 13C, organic carbon; delta 15N, bulk sediment; Depth; DEPTH, sediment/rock; Element analyser isotope ratio mass spectrometer (EA-IRMS); e-Nd(0); epsilon-Neodymium (0); Foraminifera, planktic; Foram plankt; Le Suroît; Lithic; Lithic grains; Mass spectrometer Finnigan MAT 261; N. pachyderma d d18O; Neodymium 143/Neodymium 144; Neodymium 143/Neodymium 144, error; Neogloboquadrina pachyderma dextral, d18O; Nitrogen, total; North Atlantic; PALEOCINAT; PC; Piston corer; Quartz; Qz; Sea surface temperature, August; size fraction <50 µm; size fraction >63 µm; size fraction 150-250 µm; SST (8); Strontium 87/Strontium 86, error; Strontium 87/Strontium 86 ratio; SU90-09; TN; TOC; Volcanic grains; Volc grains |
Tipo |
Dataset |