Vegetation and Climate Changes in Patagonia (46°S) during the Last 20 kyr cal. BP from South East Pacific MD 07 3088 Core

The Chilean Patagonia (41°S to 56°S) crossed by the Andes from north to south represents a critical topographic constraint on atmospheric and oceanic systems, and the only continental landmass intercepting the entire Southern Westerlies Wind (SHW) belt in southern hemisphere. Therefore, the southern Chile is a key-area to study the paleoclimate changes and, to understand the synoptic scale ocean-atmospheric circulation systems of the mid to high southern latitudes. However, several questions remain partly unsolved: Is there abrupt reversal event during the Last Glacial-Interglacial transition (LGIT)? Is there a shift or an intensification of the SHW? When begin the Holocene onset? What are the inter or intra hemispheric climatic links? In this aim, we present here a detailed pollen record from the deep-sea core MD 07 3088 (46°04’S; 76°05’W, 1536 m) near Taitao peninsula, taken during the “Pachiderme” cruise (MD 159) within the IMAGES (International MArine Global changES) program (Kissel et al., 2007). The age model (Siani et al., in press) is based upon stable oxygen isotopes of planktonic foraminifera G. bulloïdes coupled to ten AMS 14C measurements performed on planktonic foraminifera and four tephrochronological markers attributed to the Hudson volcano (Haberle and Lumley, 1998). The pollen record expresses vegetation changes and thus climate variations during the last 20 kyr cal. BP. Several vegetation phases are observed during the LGIT and the Holocene onset: Before 18 kyr, the low diversity and pollen influx show the reduced vegetation due to the Patagonian Ice Cap extension and cold temperature. From 17.5 to 14.5 kyr, the diversity and pollen influx increase mark the vegetation development linked to the ice cap melting and temperature increase. From 14.5 to 12 kyr, the Astelia development illustrates the Magellanic Moorland extension and humid conditions linked to the SHW. Later 11.5 kyr, the forest diversification expresses the Holocene onset. Finally, comparison between the pollen and the oxygen isotope record from Antarctic core (EDML, Lemieux-Dudon et al., 2010) shows direct relationships between the vegetation changes and the major climatic events of the LGIT.