Horizon 1 1 17 ACLN : Articles dans des revues avec comité de lecture non répertoriées par l'AERES Earth and Planetary Science Letters 647-660 EROSION ALTERATION PRECIPITATION MOUSSON D'ETE MOUSSON D'HIVER SEDIMENTATION EN MER PROFONDE PALEOCLIMAT PALEOENVIRONNEMENT TECTONIQUE ARGILE GEOCHIMIE ELEMENT CHIMIQUE MAJEUR CHANGEMENT CLIMATIQUE NIVEAU MARIN ISOTOPE RADIOACTIF SPECTROMETRIE HOLOCENE INDE XIZANG HYMALAYA ANDAMAN MER BENGALE GOLFE 1999 fdi:010019132 ENG Earth and Planetary Science Letters 0012-821X 10.1016/S0012-821X(99)00184-3 https://www.documentation.ird.fr/hor/fdi:010019132 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/pleins_textes_7/b_fdi_51-52/010019132.pdf 171 Horizon (IRD) The results of a clay mineralogy study combined with major element geochemistry, strontium, neodymium and oxygen isotopes, and 14C AMS stratigraphy are reported for deep-sea gravity cores located in the Bay of Bengal (MD77-180) and the Andaman Sea (MD77-169). EpsilonNd(0) and 87Sr/86Sr from Holocene and last glacial maximum (LGM) sediments of fifteen other cores have also been investigated to identify sediment sources and to estimate oceanic sedimentary transport. The data show the contribution of three sources : (1) Ganges/Brahmaputra rivers ; (2) Irrawaddy River ; and (3) sediment derived from the Western part of the Indo-Burman ranges. The dispersion of the detrital material issuing from these sources has been constrained by the geographic distribution of Nd and Sr isotopic ratios. The LGM sediments are characterized by a significant increase of 87Sr/86Sr, small changes in EpsilonNd(0), and a general decrease of smectite/(illite+chlorite), which together imply a decrease in weathering intensity. The increased 87Sr/86Sr are attributed to a decrease in chemical weathering, which should release preferentially 87Sr during weathering processes. In the Andaman Sea sediments, smectite/(illite+chlorite) and kaolinite/quartz ratios combined with a chemical index of alteration (CIA*) indicate that the weathering intesity of the Irraddy River basin is mainly controlled by the summer monsoon rainfall intensity. The wet summer monsoons increase vegetation cover in the plains and favor soil development by the production of pedogenic clays (smectite and kaolinite). (Résumé d'auteur) 064GEOQUA