Direct land/sea correlation of the Eemian, and its comparison with the Holocene: a high-resolution palynological record off the Iberian margin

摘要

High-resolution pollen, dinocyst and isotopic profiles covering the marine isotope stage 5 (MIS 5) are presented from core MD952042 (Tagus abyssal plain, 37deg 47'N, 10deg 09'W). Both marine and terrestrial proxies indicate the occurrence of a Bolling-Allercd-Younger Dryas-like event at the beginning of MI substage Se. The terrestrial Eemian stage coincides withboth the lightest oxygen isotope values of substage Se and the heavier ones approaching the Se/Sd transition. Accordingly, the Eemian is not equivalent to MI substage Se, as the Holocene is not equivalent to MIS 1.Remarkably, both pollen and dinocyst data reflect the same climatic pattern on land and ocean, and they evidence a succession of climatic events that the isotope signal does not identify. The Eemian began with a Mediterranean vegetation that was gradually replaced by Eurosiberian formations indicating a change from Mediterranean to oceanic climates. In the middle of the Eemian, warming conditions were interrupted by an event corresponding to a slight cooling resulting from an increase m precipitation over land and ocean. Finally, a warming trend characterised the last phase of the Eemian. The occurrence of small climatic changes during this interglacial is inconsistent with the dramatic variability suggested by the GRIP ice-core record.