The impact of African aridity on the isotopic signature of Atlantic deep waters across the Middle Pleistocene Transition
Résumé
A high resolution analysis of benthic foraminifera as well as of aeolian terrigenous proxies extracted from a 37 m-long marine core located off the Mauritanian margin spanning the last ~1.2 Ma, documents the possible link between major continental environmental changes with a shift in the isotopic signature of deep waters around 1.0-0.9 Ma, within the so-called Mid-Pleistocene Transition (MPT) time period. The increase in the oxygen isotopic composition of deep waters, as seen through the benthic foraminifera δ 18 O values, is consistent with the growth of larger ice sheets known to have occurred during this transition. Deep-water mass 2 δ 13 C changes, also estimated from benthic foraminifera, show a strong depletion for the same time interval. This drastic change in δ 13 C values is concomitant with a worldwide 0.3‰ decrease observed in the major deep oceanic waters for the MPT time period. The phase relationship between aeolian terrigeneous signal increase and this δ 13 C decrease in our record, as well as in other paleorecords, supports the hypothesis of a global aridification amongst others processes to explain the deep-water masses isotopic signature changes during the MPT. In any case, the isotopic shifts imply major changes in the end-member δ 18 O and δ 13 C values of deep waters.
Domaines
Sciences de la Terre
Fichier principal
The impact of African aridity on the isotopic signature of Atlantic deep waters across the Middle Pleistocene Transition-V1.pdf (3.56 Mo)
Télécharger le fichier
Origine | Fichiers produits par l'(les) auteur(s) |
---|