Vegetation and climate changes during the last 22,000yr from a marine core near Taitao Peninsula, southern Chile

摘要

High-temporal resolution of pollen analyses from marine core MD07-3088 (46°S) documents regional and coastal vegetation changes in the mid-latitude of southern Chile during the last 22kyr BP. The coastal margin was partly ice-free during the last glacial period with the presence of scattered vegetation. After~17.6kyr BP, the expansion of Nothofagus woodland highlights a warming trend and marks the beginning of the last deglaciation. The deglacial forest expansion is interrupted by the development of Magellanic moorland simultaneously with the Antarctic Cold Reversal. This vegetation change illustrates a pause in the warming trend with an abrupt increase in precipitation which is related to strong intensity of Southern Westerly Winds. After 12.8kyr BP, the retreat of Magellanic moorland illustrates a second-step warming that is strengthened after 11.5kyr at the onset of the Holocene. Expansion of heliophytic taxa illustrates warmest and driest conditions of the Holocene from 11 to 7.4kyr BP. Later, the decrease of heliophytic taxa shows a return to cooler and wetter conditions, illustrated by the presence of the North Patagonian rainforest that reaches modern condition after 5kyr. Climate changes inferred from the marine pollen record are consistent with geochemical data changes from the same samples and illustrate a clear synchronicity with δD variations of EPICA Dome C ice core during the last deglaciation and Holocene. Comparison between vegetation changes from the marine core and regional palaeoclimatic records highlights southward-northward shifts of the Southern Westerly Wind belt and supports a close link between Southern Westerly Wind belt and atmospheric CO_2 variability during the last deglaciation.