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根据冲绳海槽中部的两个沉积岩芯(155和180)浮游有孔虫的氧同位素变化特征,结合沉积序列、千年尺度气候波动事件对比、碳酸盐旋回及AMS~(14)C测年等资料对岩芯进行地层划分和对比,对两岩芯沉积物中记录的古环境信息进行释读,探讨研究区末次间冰期以来古气候的变化规律和冰消期内部的短时间尺度的气候突变事件.结果表明末次冰期最盛时(氧同位素2期)冲绳海槽中部可能有古长江和古黄河的淡水影响,冰期-间冰期氧同位素值及变化幅度证明了边缘海对气候变化的“放大”效应.底栖有孔虫Uvigerina的δ~(13)C值在冰期时明显变轻,表明冰期时黑潮主轴东移,影响范围萎缩.对180岩芯中存在的“新仙女木”(YD)期气候突变事件进行了对比分析,表明冲绳海槽地区的气候变化虽然受全球气候变化的控制,但一些地域性的因素(如东亚季风)对研究区也有一定影响.还对“YD”事件的成因机制进行了探讨,在一定程度上支持了Fairbanks将YD期解释为两大融冰事件引起两次海平面快速上升之间一个短暂的海平面回升-滞缓期的观点.底层水团与西北太平洋深层水团的交换程度减弱,含氧量降低,对CaCO_3物质的溶解作用增强,并使得冲绳海槽地区的CaCO_3旋回与“大西洋型”CaCO_3旋回一致.
Based on the variation of oxygen isotopes of planktonic foraminifera between two sedimentary cores (155 and 180) in the central part of the Okinawa Trough, combined with sedimentary sequences, millennium-scale climatic fluctuations, carbonate cycles and AMS ~ (14) C dating Data are used to divide and contrast the strata of cores. The interpretation of paleoenvironmental information recorded in the sediments of the two cores explores the variation of paleoclimate since the last interglacial and the short-term climate abrupt change The results show that the mid - Okinawa Trough may have the influence of paleo - water on the paleo - Yangtze River and the Paleozoic during the last ice age (oxygen isotope 2), and the “magnification” effect of the marginal sea on climate change is evidenced by the oxygen isotopic values and their ranges The δ ~ (13) C values of the benthic foraminifera Uvigerina obviously decreased during the glacial period, indicating that the main axis of the Kuroshio moved eastward during the glacial period and the influence range atrophied. The results show that the climate change in the Okinawa Trough is controlled by the global climate change, but some regional factors (such as the East Asian monsoon) also have certain impact on the study area. “The mechanism underlying this event is discussed in part to support Fairbanks interpreting YD as a brief sea-level rise-lag period between the two ice melting events that caused two rapid sea-level rises to occur. The exchange with the deep water mass in the Northwest Pacific is weakened, the oxygen content is reduced, the dissolution of CaCO_3 is enhanced, and the CaCO_3 cycle in the Okinawa Trough is consistent with the ”Atlantic" CaCO_3 cycle.