Molecular biomarker record of paleooceanographic environment in the East China Sea during the last 35000 years

By reference of the δ¹⁸O and δ¹³C isotopic compositions of G.sacculifer and accelerator mass spectrometry (AMS)¹⁴C dates, the U _K ³⁷ , ∑C _– ²¹ /∑C _+- ²² and Pr/Pn in core DGKS9603 have been used to characterize the changes of paleooceanographic environment occurring in the East China Sea (ECS) during the last 35000 years. The stratigraphic records of these proxies have shown that during the last 35 ka the Okinawa Trough has gone through 7 stronger cold-climate events (C₁–C₇) and 9 terrigenous matter-decreasing events (e₂–e₉), of which, the C₁ corresponds to the cold episode occurring in the middle late Holocene, C₂–C₄ and C₇ correspond to the H₁–H₄ events, respectively. e₁ and e₃–e₈ correspond to the decrease of sea surface temperature (SST), respectively. The terrigenous inputs increased when Heinrich events occurred. Climate colding resulted in the decrease of terrigenous matter transported by rivers, and the increase of that transported by winter monsoon. Heinrich events are closely related to East Asia monsoon. During the Last Glacial Maximum (LGM, 15.5–25.8 Cal ka BP), reduction environment fluctuated strongly, bringing forth three stronger reduction events (R₁–R₃) and one weaker reduction event (O), of which, R₁–R₃ correspond to the decrease of SST and increase of terrigenous nutrient and O corresponds to the decrease of terrigenous nutrient. The fluctuation of reduction condition must be related to the change of sea surface productivity.     

东海钓鱼岛北侧Q43柱状样上更新统的沉积

对钓鱼岛北侧东海外陆架Q43孔(26°33 1401′N、124°12 7107′E)岩心的沉积层序、粒度参数和碎屑矿物进行了研究,揭示了东海外陆架末次盛冰期低海面时的滨岸浅水沉积特征。钻孔柱样为一不完整的滨海相沉积层序:上部为粉砂质细砂层(0~230 cm),是末次盛冰期沉积物,代表古海岸前滨高能环境;下部为细砂质粉砂层(230~374 cm),代表滨外浅水低能环境。整个柱样表现出分选程度不高、悬浮组分多、矿物棱角明显、风化程度低和不稳定矿物含量高等特点,表明沉积物分选改造不强烈。这与以往对东海的残留沉积的认识不同,反映出末次盛冰期东海沉积环境的多元性。