Geochemistry on sediment core CRP-1 (Table 1)
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The CRP-1 core penetrated 148 m of Quaternary and lower Miocene glacigenic sediments. This material complements the Eocene trhough Miocene strata that was cored previously at CIROS-1, 70 km to the south. The paleoclimatic records of CRP-1 and CIROS-1 have been examined by calculating the Chemical Index of Alteration (CIA) of Nesbitt & Young (1982), using new data for CRP-1 materials and the data of Rose & Pyne (1988) for CIROS-1 mudstones. The CIA is calculated from the relative abundance of Al, K, Ca, and Na, and its magnitude increases as the effects of chemical weathering increase. However, changes in sediment provenance can also effect the CIA, and such changes appear to dominate some parts of the CRP-1 and CIROS-1 record. […]
CRP-1岩芯钻取了148米的第四纪及中新世早期冰川成因沉积物。该套样品补充了此前在南侧70公里处的CIROS-1岩芯所获取的始新世至中新世地层样品。研究人员结合CRP-1的新测试数据，以及CIROS-1泥岩的Rose & Pyne (1988)实测数据，通过计算Nesbitt与Young (1982)提出的化学风化指数（Chemical Index of Alteration, CIA），对CRP-1和CIROS-1的古气候记录进行了分析。该指数基于铝、钾、钙、钠的相对丰度计算得到，其数值随化学风化作用强度的增强而升高。不过，沉积物物源的变化同样会对化学风化指数产生影响，此类变化似乎主导了CRP-1与CIROS-1记录中的部分区段。[...]
