海洋地质与第四纪地质2017，Vol.37Issue(3)：157-168,12.DOI:10.16562/j.cnki.0256-1492.2017.03.016
下刚果盆地M区块Madingo组烃源岩的岩相特征与有机质富集机制
LITHOFACIES AND ORGANIC MATTER ENRICHMENT IN MADINGO FORMATION OF BLOCK M, LOWER CONGO BASIN
摘要
Abstract
The source rock of the Madingo Formation in the Block M of the Lower Congo Basin is selected as the research object of this paper.Mineralogy,paleontology and lithofacies of the source rock were analyzed using X-ray diffraction,thin sections,backscatter and energy spectrum.Special attention is paid to major elements and organic matters,and the enrichment mechanism of organic matters discussed.The results show that the source rock is mainly composed of clay and silica minerals,followed by calcite,feldspar,dolomite and pyrite.Micro fossils and nanofossiles,such as foraminifera and radiolarian,are rather popular.Based on mineralogy,paleontology,phosphate content and microstructure,six types of lithofacies are identified,i.e.:foraminifera-bearing fine deposits,radiolarian-bearing fine deposits,phosphatic fine deposits,argillaceous fine deposits,silty fine deposits and calcareous fine deposits.The deposition of the source rock in Madingo Formation was under the joint control of sea level eustacy,upwelling current,paleo-climate and paleogeography.Several cycles of transgression and regression events are identified in the Formation.Sea level eustacy constrained the deposition of lithofacies through changes in water depth,redox conditions and sediments types.Foraminifera-bearing fine deposits,phosphatic fine deposits and radiolarian-bearing fine deposits with high organic content are formed in two cycles of upwelling.Depressions in the inner shelf were filled with evaporate deposits during the period while the Madingo Formation was deposited.The relatively closed environment benefited the preservation of organic matters.The paleoclimate experienced three stages of change from dry to relatively humid and to humid climate during the period of Madingo Formation.The abundance and types of organic matter were dependent upon to some extent the input of terrigenous organic matter.关键词
烃源岩/岩相/海平面升降/上升流/古气候/下刚果盆地Key words
lower Congo Basin/source rock/lithofacies/sea level eustacy/upwelling/ancient climate分类
海洋科学引用本文复制引用
季少聪,杨香华,朱红涛,邓运华,康洪全,王波,魏小松..下刚果盆地M区块Madingo组烃源岩的岩相特征与有机质富集机制[J].海洋地质与第四纪地质,2017,37(3):157-168,12.基金项目
国家重大科技专项“西非和南美海域重点区油气地质评价及关键技术研究”(2017ZX05032-001) （2017ZX05032-001）
