Ice-rafted debris record in the Prydz Bay@en

Ice-rafted debris mass accumulation rates (IRD MAR) at a drill site on the Antarctic continental margin are investigated to evaluate the linkages between East Antarctic Ice Sheet extent and Southern Ocean temperatures in the early to mid-Pliocene. ODP Site 1165 is within 400 km of the Antarctic coastline and in the direct pathway of icebergs released by the Amery Ice Shelf. The Amery Ice Shelf is the largest ice shelf in East Antarctica and it buttresses the Lambert Glacier drainage system, which accounts for 14% of the outflow from the East Antarctic Ice Sheet. IRD MAR were low during peak Southern Ocean warming in the early Pliocene. After a brief precursor, a tenfold increase in IRD MAR at 3.3 Ma marks the termination of the early Pliocene ice sheet minimum, coincident with the M2 glacial. For the mid-Pliocene, a strong correlation exists between the high-amplitude signal in the LR04 benthic stack and IRD MAR, suggesting linkages between East Antarctic ice extent, global ice volume and deep-water temperatures. The IRD record at Site 1165 provides evidence of greater sensitivity of the Lambert Glacier-Amery Ice Shelf system to Southern Ocean warming than is currently predicted by ice sheet models, which may relate to uncertainties in the understanding of ocean heat uptake, poleward heat transport and ice sheet-ocean interactions.本研究针对南极大陆边缘某钻探站位的冰筏碎屑质量堆积速率（Ice-rafted debris mass accumulation rates，IRD MAR）展开分析，旨在探讨上新世早期至中期东南极冰盖范围与南大洋温度之间的关联。大洋钻探计划（Ocean Drilling Program, ODP）1165站位距南极海岸线不足400公里，且处于埃默里冰架（Amery Ice Shelf）释放冰山的直接输运路径之上。埃默里冰架是东南极规模最大的冰架，其支撑着兰伯特冰川（Lambert Glacier）流域，该流域的冰流输出量占东南极冰盖总流出量的14%。上新世早期南大洋暖盛阶段，IRD MAR处于较低水平。经历一段短暂的前驱变化后，约3.3 Ma时IRD MAR增至初始值的10倍，标志着上新世早期冰盖最小期的终结，该事件与M2冰期的发生时间完全重合。针对上新世中期，LR04底栖有孔虫氧同位素栈（LR04 benthic stack）中的强振幅信号与IRD MAR之间存在显著相关性，这表明东南极冰盖范围、全球冰量与深层海水温度三者之间存在关联。1165站位的IRD记录显示，兰伯特冰川-埃默里冰架系统对南大洋变暖的敏感性高于当前冰盖模型的预测结果，该现象或与海洋热吸收、极向热输送以及冰盖-海洋相互作用等领域的认知不确定性存在关联。