东非裂谷系西支中南段Karoo地层分布特点与勘探前景

东非裂谷系一直是世界油气勘探重点关注区,尤其在西支Albertine盆地获得重大油气发现,而与之具有相似成因演化的西支中南段其它盆地,勘探潜力一直不明朗并急待挖掘。中-古生代Karoo地层及分布在该地区广泛分布,特别是作为烃源和主要的勘探层系在东非海岸陆缘盆地被广泛证实后,Karoo的勘探潜力备受关注。然而,Karoo本身经过漫长的演变,涵盖的地质学内容包罗万象,混淆不清,十分不利于该地区油气勘探潜力的研究和判断。本文通过系统查阅国外文献并结合东非裂谷系的研究工作,初步查明Karoo的成因、演变及分布,并系统评价Karoo地层在西支中南段裂谷盆地及周边的分布,探讨其勘探意义。但以Karoo作为东非地区未来勘探领域仍然面临着一系列不确定性的问题和风险,值得思索和总结。

Stratigraphic distribution features and exploration prospect of Karoo in south-central segment of west branch,East African Rift System

The East African Rift System has been focused on oil and gas exploration area in the world, especially gained major oil and gas discovery in the west branch of Albertine basin. Comparing with similar genetic evolution, the basins from the middle-south section of west branch were uncertain for exploration potential. In the Mesozoic-Paleozoic, Karoo stratum distributed widely in the region, especially as hydrocarbon source and the main prospecting strata series on continental margin basin of East Africa coast were widely conifrmed, exploration potential of Karoo got lots attention. However, after long evolution, the Karoo itself contained more geological contents and was hard to be identiifed, which was not conductive to the research and judgment of oil-gas exploration potential. In this paper, Through systematical review of foreign literature and research work of the East African Rift System, the authors initially identiifed the cause, evolution and distribution of Karoo, systematically evaluated Karoo stratum distribution in the middle-south section of west branch and periphery, and discussed the prospecting signiifcance. But the Karoo as future exploration areas in East Africa still faced a series of uncertainty problems and risks, which were worth thinking and summary.