徐万兴,何卫军,陈奎,等. 珠江口盆地西部珠三坳陷古近系物源体系及沉积充填演化特征[J]. 海洋地质与第四纪地质,2023,43(2): 145-159. doi: 10.16562/j.cnki.0256-1492.2022060901
引用本文: 徐万兴,何卫军,陈奎,等. 珠江口盆地西部珠三坳陷古近系物源体系及沉积充填演化特征[J]. 海洋地质与第四纪地质,2023,43(2): 145-159. doi: 10.16562/j.cnki.0256-1492.2022060901
XU Wanxing,HE Weijun,CHEN kui,et al. Provenance system evolutions and sedimentary filling characteristics of the Paleogene in Zhu Ⅲ Depression, the Western Pearl River Mouth Basin[J]. Marine Geology & Quaternary Geology,2023,43(2):145-159. doi: 10.16562/j.cnki.0256-1492.2022060901
Citation: XU Wanxing,HE Weijun,CHEN kui,et al. Provenance system evolutions and sedimentary filling characteristics of the Paleogene in Zhu Ⅲ Depression, the Western Pearl River Mouth Basin[J]. Marine Geology & Quaternary Geology,2023,43(2):145-159. doi: 10.16562/j.cnki.0256-1492.2022060901

珠江口盆地西部珠三坳陷古近系物源体系及沉积充填演化特征

Provenance system evolutions and sedimentary filling characteristics of the Paleogene in Zhu Ⅲ Depression, the Western Pearl River Mouth Basin

  • 摘要: 珠江口盆地西部珠三坳陷近年来一直未获得商业性油气的重大发现,古近系是坳陷内主要的勘探层系,但对其自下而上的物源体系、沉积充填演化规律认识不清。在层序地层划分基础上,以古近系沉积时期三级层序为基本单元,结合区域地质背景、古地貌、周缘水体分布、重矿物组合及岩石薄片等资料,并利用构造地质学、沉积学等分析方法,开展了珠三坳陷古近系沉积时期的物源体系演化及其对大型碎屑岩储集体分布的控制影响研究。认为珠三坳陷古近系存在两大物源区,一是南部神狐隆起,其母岩构成以岩浆岩、浅变质岩及前古近系沉积岩为主;二是北部海南隆起、粤桂隆起及相关河流体系组成的综合物源区,母岩构成以岩浆岩为主。确定了始新统文昌组断陷沉积时期,主要形成了湖泊-(扇)三角洲体系的构造沉积充填格局,且沉积了巨厚的文昌组中深湖相烃源岩,为本区的主力烃源岩;下渐新统恩平组—上渐新统珠海组断拗沉积时期,主要沉积充填了恩平组湖泊-(扇)三角洲体系以及珠海组滨海潮坪-(扇)三角洲体系。以上研究成果为珠江口盆地西部珠三坳陷下一步寻找优质大型储集体并获得油气发现具有一定的指导意义。

     

    Abstract: Commercial-scaled oil and gas has not been discovered in the Zhu Ⅲ Depression of the Western Pearl River Mouth Basin in recent years. The Paleogene is the main exploration strata in the study area. However, its provenance system from the bottom up and sedimentary filling evolution law is unclear, which greatly hampered the new discoveries of large quality reservoirs and oil/gas fields in this area. Based on the sequence stratigraphic division, the third-order sequence of the Paleogene sedimentary period was taken as the basic unit of study, the regional geological background, Paleogene geomorphology, distribution of surrounding water system, heavy mineral assemblages, and rock thin sections were analyzed using structural geology, sedimentology, and other analytical methods. Result shows that there were two major provenance areas in the Zhu Ⅲ Depression during the Paleogene. One was the Shenhu uplift in the south, and its parent rock was magmatic rocks, shallow metamorphic rocks, and pre-Tertiary sedimentary rocks. The second was the provenance area covering the northern Hainan uplift, Guangdong-Guangxi uplift, and related river systems, and the parent rock was mainly magmatic rocks. The Eocene Wenchang Formation reflected a fault-rift scheme, represented by a thick semi-deep to deep water lacustrine delta deposit, being the main hydrocarbon source. The Early Oligocene Enping Formation to Late Oligocene Zhuhai Formation manifested a fault-depression scheme, characterized by evolving from a lake delta system to a coastal tidal flat delta system, respectively. This study provided guidance to the next exploration for large and quality reservoirs in the Zhu Ⅲ depression.

     

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