Turbidite deposition in the southern South China Sea during the last glacial: Evidence from grain-size and major elements records  

作　　者：ZHAO YuLong LIU ZhiFei COLIN Christophe XIE Xin WU Qiong 

机构地区：[1]State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China [2]Laboratoire des Interactions et Dynamique des Environnements de Surface （IDES）, UMR 8148 CNRS-Universite Paris-Sud I 1, Orsay 91405, France

出　　处：《Chinese Science Bulletin》2011年第33期3558-3565,共8页

基　　金：supported by the National Natural Science Foundation of China (40925008, 40876024 and 40776027);the National Basic Research Program of China (2007CB815906);the Program of Shanghai Subject Chief Scientist (10XD1406300)

摘　　要：High-resolution grain size and major element geochemical measurements were performed on the marine sediments of Core MD05-2895 to help understand the formation of turbidite sequences. Grain-size results show that these turbidite sediments contain more coarse sediment grains than normal marls. The coarse sediment grains are mostly derived from relict sediments on the Sunda Shelf. Relict sediments are composed mainly of quartz, feldspar, tephra and a few titaniferous or ferruginous heavy minerals. Corresponding to the concentration of these minerals, increases in Si/Al, K/Al, Ti/Al and Fe/Al ratios are observed in the turbidite layers. As all the observed turbidite sequences were deposited during the last glacial, the occurrence of these turbidity events is implied to be closely related to instabilities in sea-level-induced sediment supply. We suggest that deposition of sediment particles from a single turbidity current is usually controlled by a counterbalance between gravity and buoyancy, with the interaction of individual grains being of minor importance.High-resolution grain size and major element geochemical measurements were performed on the marine sediments of Core MD05-2895 to help understand the formation of turbidite sequences. Grain-size results show that these turbidite sediments con- tain more coarse sediment grains than normal marls. The coarse sediment grains are mostly derived from relict sediments on the Sunda Shelf. Relict sediments are composed mainly of quartz, feldspar, tephra and a few titaniferous or ferruginous heavy miner- als. Corresponding to the concentration of these minerals, increases in Si/A1, K/A1, Ti/A1 and Fe/A1 ratios are observed in the turbidite layers. As all the observed turbidite sequences were deposited during the last glacial, the occurrence of these turbidity events is implied to be closely related to instabilities in sea-level-induced sediment supply. We suggest that deposition of sedi- ment particles from a single turbidity current is usually controlled by a counterbalance between gravity and buoyancy, with the interaction of individual grains being of minor importance.

关 键 词：浊流沉积 末次冰期 南海南部 粒度 海洋沉积物 证据 中国 地球化学测量 

分 类 号：P736.21[天文地球—海洋地质]