(Table 1) Organic geochemistry at DSDP Leg 71 Holes

Forty-three core samples from Sites 511 through 514 of DSDP Leg 71 were analyzed geochemically. The black shales at the bottom of Hole 511, in the basin province of the Falkland Plateau, contain an average of 1590 ppm extractable organic matter (EOM) and 120 ppm hydrocarbons. Whereas molecular type-carbon number distributions of mono- and polynuclear aromatic hydrocarbons and their sulphur and oxygen analogues in the black shale "aromatic hydrocarbon" fractions are very similar to those of many crude oils, other data - gas chromatography (GC) fingerprint, pyrolysis GC, visual kerogen analysis, H/C ratio - suggest the black shale section is thermally immature. Together, these observations imply that many of the hydrocarbons were deposited with the original sediments or are diagenetic products of other biological compounds. Pyrograms of the humic acid and kerogen fractions from the black shale interval are typical of geopolymers derived from marine algal material. It appears that these humic acids and kerogens are derived from the same lipid stock.

本研究对深海钻探计划（Deep Sea Drilling Project, DSDP）第71航次511至514站位的43个岩芯样品开展了地球化学分析。位于福克兰高原盆地区域的511号钻孔底部黑色页岩，其可抽提有机质（extractable organic matter, EOM）平均含量达1590 ppm，烃类平均含量为120 ppm。尽管该黑色页岩“芳烃馏分”中单环、多环芳烃及其硫、氧取代类似物的分子类型-碳数分布特征与多数原油高度相似，但气相色谱（gas chromatography, GC）指纹图谱、热解气相色谱、镜下干酪根分析、氢碳比（H/C ratio）等多项数据表明，该黑色页岩层段热演化程度尚未成熟。综合上述观测结果，可推断多数烃类要么与原始沉积物一同沉积，要么为其他生物化合物的成岩产物。该黑色页岩层段的腐殖酸与干酪根馏分的热解色谱图，呈现出海洋藻类来源地质聚合物的典型特征。由此可见，该腐殖酸与干酪根均源自同一类脂类母质。