C1-C8 hydrocarbons at DSDP Site 93-603

Small amounts of C1-C8 hydrocarbons were detected in continental rise sediments from DSDP Site 603. Organiccarbon- lean sections contained only C1-C3 compounds believed to have migrated from organic-carbon-rich sections. Heavier (C4-C8) hydrocarbons were found only in organic-carbon-rich sections. Restricted and sporadic distribution of C4-C6 compounds in 0-1100 m sub-bottom sediments suggest low-temperature (<20°C) biological/chemical generation processes. Increased C4-C8 concentrations and complexity, including unusually high levels of xylene, were detected in two deeper Cretaceous sections (603-34-2, 134 cm and 603-81-3, 120 cm). This behavior, which was not observed in 17 other samples from sub-bottom depths greater than 1100 m, is similar to that observed in immature surface sediments from the geothermally active Guaymas Basin (Gulf of California) area.

深海钻探计划（Deep Sea Drilling Project, DSDP）603站位的大陆隆沉积物中检测到少量C1-C8烃类化合物。贫有机碳地层仅含有C1-C3类化合物，这类化合物被认为是从富有机碳地层运移而来的。重质（C4-C8）烃类仅在富有机碳地层中被检出。0~1100米海底以下沉积物中C4-C6化合物分布局限且零散，这表明其生成过程为低温（<20℃）生物/化学成因。在两个更深的白垩纪地层（603-34-2，134厘米；603-81-3，120厘米）中，检测到C4-C8烃类浓度升高、组分更复杂，其中二甲苯含量异常偏高。这种现象在17份海底以下深度大于1100米的其他沉积物样品中均未出现，但其特征与加利福尼亚湾地热活跃的瓜伊马斯盆地地区的未成熟表层沉积物中观测到的现象一致。