(Table T1) N-alkane, n-alcohol and n-fatty acid concentrations in ODP Site 184-1147 and 184-1148 sediments

Lipid compositions of sediments recovered during Ocean Drilling Program Leg 184 in the South China Sea have been identified and quantified. The identified lipids can be ascribed to terrigenous and marine sources. Terrigenous lipids are mainly C27, C29, C31 n-alkanes, C26, C28, C30 n-fatty acids, and n-alcohols, which were derived from leaf waxes of higher land plants and transported to the sea by airborne dust or fresh water. Marine lipids, mainly C37 and C38 alkenones, C30 diol, and C30 and C32 keto-ols, were from microalgae, notably haptophytes and eustigmatophytes. Elevated concentrations and accumulation rates of both terrigenous and marine lipids in the interval 202-245 meters composite depth (mcd) and 0-166 mcd were postulated to be related to the development of the East Asian monsoon at 6-8 Ma and enhanced variations of the developed East Asian monsoon after 3.2 Ma, respectively. The pronounced late Oligocene input of terrigenous lipids reflects the paleoenvironment of a newly opened, narrow basin, with restricted ocean waters and the proximity of continental runoff.

本数据集针对南海大洋钻探计划（Ocean Drilling Program, ODP）第184航次所获取的沉积物，完成了其内部脂质组成的鉴定与定量分析工作。所鉴定得到的脂质可划分为陆源脂质与海源脂质两类。陆源脂质主要包含C27、C29、C31正构烷烃，C26、C28、C30正构脂肪酸以及正构醇，其来源为高等陆地植物的叶蜡，经大气粉尘或淡水搬运进入海洋环境。海源脂质则以C37、C38烯酮，C30二醇以及C30、C32酮醇为主，源自微藻类，尤以定鞭金藻门（haptophytes）与真眼点藻纲（eustigmatophytes）为主。研究推测，在202~245米综合深度（mcd）与0~166米综合深度（mcd）层位中，陆源与海源脂质的浓度及堆积速率均出现升高；其中前者与6~8 Ma时期东亚季风的形成过程相关，后者则与3.2 Ma之后演化增强的东亚季风波动幅度加剧有关。渐新世晚期陆源脂质输入量的显著升高，反映了当时南海作为新近张开的狭窄盆地，具备受限海水与邻近大陆径流的古环境特征。