摘要
南方四套区域性高、过成熟海相烃源岩的地球化学特征有:(1)干酪根显微组分以Ⅱ型为主;各层系干酪根和沥青"A"的δ13C随时代变新而变重,反映了高等植物输入的增多。(2)上古生界烃源岩沥青"A"和总烃含量比过成熟的下古生界烃源岩高出6～10倍;与相同层系低成熟烃源岩比较,高、过成熟烃源岩已大量排烃。(3)下古生界烃源岩抽提物正烷烃的双峰型分布代表了两类具不同脂肪链结构的藻类输入;上古生界既有双峰型又有单峰型分布,反映了水生生物与高等植物的不同贡献。(4)Pr/Ph比和甾、萜烷常规生物标志物的分布在高、过成熟热演化阶段已经趋同和失效,难以区分不同层系烃源岩和用作油源对比。(5)三芳甾烷、甲基三芳甾烷,特别是三芳甲藻甾烷等生物标志物,可以区分不同地区、不同层系烃源岩,并可用作油源对比。
The geochemical characteristics of the 4 sets of regional high-over mature marine source rocks are as follows： （1） The kerogen maceral is mainly Type Ⅱ, also there are some Types Ⅰ and Ⅲ and the δ^13C of kerogen and the extracted bitumen ＂A＂ get heavier as the geological time gets younger, which reflects the increasing of the higher plant inputting. （2） The content values of extracted bitumen ＂A＂ and total hydrocarbon in Upper Paleozoic source rocks is 6-10 times of those in the over mature Lower Paleozoic source rocks. Compared with the low mature source rocks in the identical strata, a large amount of hydrocarbon has already been expulsed out from the high-over mature source rocks. （3）The bimodal n-alkane distribution of the extract from the Lower paleozoic source rocks represents the input of two different kinds of aliphatic chain algae, and the existence of both bimodal and unimodal distributions of the extract from the Upper Paleozoic source rocks reflects the different contributions of aquatic organism and higher plant. （4） The Pr/Ph ratios and the routine biomarkers of steroid and terpane are so convergent in distribution as to lose effectiveness, which results in difficulty to differentiate from the source rocks in the different formations that are used to oil-source correlation. （5）The special biomarkers, such as triaromatic steroid and methyl triaromatic steroid, and especially triaromatic dinoflagellate sterane, can be used to distinguish the source rocks in different regions and different formations so that they can be used to oil-source correlation. The distribution of these compounds is reduced from Cambrian to Permian and the concentrating areas of these compounds basically accord with the generating centers of the different formations, so they can be used to locate the positions of hydrocarbon source areas.
出处
《海相油气地质》
2009年第1期1-15,共15页
Marine Origin Petroleum Geology
关键词
古生代
海相地层
碳酸盐岩烃源岩
地球化学特征
生烃中心
Paleozoic
Marine facies formation
Carbonate source rocks
Geochemical characteristics
Generating center
