(Table 1) Sample descriptions, carbon contents, and lipid yields across the K/T boundary at DSDP Hole 93-605 and at Stevns Klint, Denmark

This reconnaissance study was undertaken to determine whether the mass extinctions and faunal successions that mark the Cretaceous/Tertiary (K/T) boundary left a discernible molecular fossil record in the sediments of this period. Lipid signatures of sediments taken from above and below the K/T boundary were compared in core and outcrop samples taken from two locations: the U.S. east coast continental margin (western Atlantic Ocean, DSDP Site 605) and Stevns Klint, Denmark. Four calcareous sediments taken from above and below the K/T boundary in DSDP Hole 605, Section 605-66-1, revealed changing lipid signatures between above and below that are characterized by a large component of unresolved naphthenic hydrocarbons and a homologous series of n-alkanes ranging from Ci6 to C33. These lipid signatures are attributed to an influx of a terrestrial higher plant component and to bacterial reworking of the sediments under partially anoxic depositional and/or diagenetic conditions. The outcrop samples from Stevns Klint had extremely low concentrations of indigenous lipids. The fish clay at the K/T boundary contained traces of microbial hydrocarbons and fatty acids, whereas the carbonates above and below had only microbial fatty acids and additional terrestrial resin acids. The data from both sites indicate a perturbation in the deposition of lipid compound classes across the K/T boundary.

本探查性研究旨在探明，标志着白垩纪/第三纪（Cretaceous/Tertiary, K/T）界线的生物大规模灭绝与动物群演替事件，是否在该时期的沉积物中留存了可识别的分子化石（molecular fossil）记录。研究对两处采样点的岩芯与露头样品中该界线上下沉积物的脂质标志物（lipid signature）进行了对比分析，两处采样点分别为美国东海岸大陆边缘（西大西洋，深海钻探计划（Deep Sea Drilling Project, DSDP）605站位）与丹麦斯文斯克林特（Stevns Klint）。在深海钻探计划605号钻孔的605-66-1岩芯段中，取自界线上下的4份钙质沉积物显示，界线上下的脂质标志物存在显著差异：其特征为大量未分辨环烷烃（naphthenic hydrocarbon）组分，以及碳数范围为C16至C33的正构烷烃（n-alkane）同系物系列。上述脂质标志物特征可归因于陆生高等植物输入物的涌入，以及沉积物在部分缺氧沉积及/或成岩环境下受到的细菌改造作用。丹麦斯文斯克林特的露头样品中，内源脂质（indigenous lipid）的浓度极低。该界线处的鱼黏土（fish clay）中检测到微量微生物烃类（microbial hydrocarbon）与脂肪酸（fatty acid），而界线上下的碳酸盐岩仅含有微生物脂肪酸以及额外的陆生树脂酸（terrestrial resin acid）。两处采样点的数据均表明，白垩纪/第三纪界线两侧的脂质化合物类别的沉积过程发生了显著扰动。