Sediment Characteristics And Change Of East Asian Winter Monsoon Of Core T93 From Gulf Of Thailand

The paleo-environment was reconstructed during Holocene based on one sediment core collected in the Gulf of Thailand.The core sample was analyzed for grain size,color reflectance,magnetic susceptibility,elemental contents,alkenones and GDGTs.The length of this core is 380 cm and the bottom age is about 12400 cal yr BP at the layer of 340 cm.The results showed that sediment composition and sedimentary facies can be divided into four stages: littoral face sedimentary based on black with red clayey silt and lack of organic shells?12.6¹0.7ka?,clayey silt based littoral face?10.7⁸.2 ka?,silt based continental shelf face?8.2².5ka?and clay based neritic continental shelf deposit with stable sedimentary environment?since 2.5ka?.U₃₇^k-SST lied between 6.1²8.4?.Low temperature occurred at 12.6¹0.7ka,which could be in response to Younger Dryas?YD?.SST tended to stabilize after a trend of rapid increase during the 10.6-8.2 ka.TEX₈₆ H based temperature was between 19²2.6 ?,showing high level during 12.6¹0.7ka,which was opposite to U₃₇^k-SST.It was possible that TEX₈₆ H could indicate subsurface seawater temperature.Changes in sensitive grain size components 6.63⁸.63? indicated that the intensity of the East Asian winter monsoon recorded in Thailand Bay increased significantly during 12.6-10.7 ka,which corresponded to the East Asian summer monsoon weakened event recorded by the stalagmites.The intensity of the East Asian winter monsoon reduced significantly during 10.6⁸.2 ka.The decrease continued until 2.5 ka.Since Holocene,sedimentary records showed that the intensity of the East Asian winter monsoon was not stable.