PALAEOCLIMATIC CHANGES OF THE BRANSFIELD STRAIT, ANTARCTIC PENINSULA SINCE 6 kaBP, AND THE TELE-CONNECTION WITH ENSO

The Antarctic Peninsula is one of the most sensitive areas to recent global warming. The Holocene climatic variation in this area is a key to the understanding of the mechanism of climate changes in the high latitude Southern Ocean. In this study, multiple proxies, such as tephra concentration, content of coarse fractions, grain size, sea ice related diatoms, have been studied for the core D1-7 collected at the Bransfield Strait, Antarctic Peninsula region, during the 28^th Chinese National Antarctic Expedition, aiming to learn more about Holocene climatic variation in the Antarctic Peninsula region since the 6 ka. Thirteen tephra-bearing layers are identified, which can be regionally correlated and were possibly coming from the Deception Island. Nine Ice Rafted Debris events (IRD 1-9:0.84、0.97、1.18、1.89、2.05、2.25、2.45、4.46 and 5.09 ka) were identified. Frequent IRD events during the late Holocene, especially since 2.5 ka, are tele-connected to the enhanced ENSO variability during this interval, which brings more moisture to the Antarctic Peninsula region and causes the instability of ice shelf. Since 3.5 ka, the increase in the sea ice species of diatom along with the decrease of mean grain size of sortable silt suggested the expansion of sea ice and the weakening of bottom current. These data further suggest the late Holocene cooling of the study area, incorporated with northward shift of the Westerly.