Organic geochemical characteristics at DSDP Holes 76-534A and 44-391C

Pyrolysis assay, bitumen analysis, and elemental analysis of kerogen were used to characterize the organic matter of selected core samples from Hole 534A (Leg 76) and Hole 391C (Leg 44) on the Blake-Bahama Plateau. The organic matter throughout the stratigraphic section appears to be principally of a terrestrial origin. The data from several isolated horizons in the Hatteras and Blake-Bahama Formations imply the presence of significant quantities of autochthonous marine organic matter. However, these horizons appear so limited that they cannot be considered potential liquid hydrocarbon source rocks. All the analyzed samples are immature and have not evolved sufficiently to enter into the main stage of hydrocarbon generation.
The temporal and spatial restrictions of strata rich in marine organic matter suggest that they do not represent major expansions and contractions of anoxic bottom-water masses, but represent limited occurrences of anoxic conditions.

本研究采用热解分析（Pyrolysis assay）、沥青分析（bitumen analysis）与干酪根元素分析（elemental analysis of kerogen），对布莱克-巴哈马高原（Blake-Bahama Plateau）上534A钻孔（第76航次）及391C钻孔（第44航次）的选定岩心样品中的有机质开展表征工作。整个地层剖面中的有机质整体以陆源成因为主。哈特拉斯组与布莱克-巴哈马组内数个孤立层位的分析数据表明，其中存在大量原地海相有机质（autochthonous marine organic matter）。但这些层位分布范围极为局限，无法被认定为潜在的液态烃源岩（liquid hydrocarbon source rocks）。所有分析样品均处于未成熟阶段，尚未演化至生烃作用（hydrocarbon generation）的主阶段。
富海相有机质地层的时空分布局限提示，其并非缺氧底水团（anoxic bottom-water masses）大规模扩张与收缩的产物，而是局部缺氧环境有限发育的结果。