摘要
南海珠江口盆地HZ地区珠江组沉积时期主要表现为一稳定沉积的陆棚环境。在研究区西部发育大型的古珠江水系,为整个珠江组大型三角洲沉积提供了丰富的陆源碎屑。本研究以PSQ6为例进行了详细分析,其沉积坡折带具有一定的规模,斜坡宽度约4 km,高差为20～60 m,横向延伸为80 km左右。沉积坡折带主要发育在下伏层序高水位体系域三角洲沉积结束时期,与在前三角洲亚相以东的碳酸盐岩隆起之间构成了一个局部的"沟谷"体系,为PSQ6层序强制海退时期沉积和保存提供了良好的古地貌背景,并进一步控制了陆棚环境中局部强制海退楔的发育。陆棚背景下的"沟谷"古地貌地形往往易于导致强制海退砂的形成,进积砂体能够直接覆盖在下部层序高水位体系域所形成的浅海相泥岩上,其上覆盖着水进域和高位域暗色泥岩,可形成有利的生、储、盖组合,是本地区寻找地层—岩性油气藏的有利场所。
During the deposition of the Miocene Zhujiang Formation,the HZ Sag in the Pearl River Mouth Basin,South China Sea,was a stably deposited shelf setting.A large-scale paleo-Pearl River water system was developed in the western part of the study area and provided abundant terrestrial clastic deposits for the large-scale Pearl River delta.A case study on sequence PSQ6 has been carried out in this paper.The depositional slope break of sequence PSQ6 is characterized by a certain developing scale of about 4 km slope width,20-60 m height difference and 80 km transverse distribution range.Depositional slope breaks were mainly developed during the ending time of the depositional period of highstand systems tract delta of underlying sequence.A regional ＂ditch-trough＂ system was formed along the area between depositional slope break and carbonate buildup in the east of prodeltaic subfacies,thus provided a favorable paleogeomorphic setting for the deposition and preservation of PSQ6 forced regressive wedge systems tract（FRWST） and furthermore controlled the development of regional forced regressive wedge in shelf environment.The forced regressive sandbodies are easily formed due to the ＂ditch-trough＂ paleogeomorphic setting in shelf environment.The prograded sandbodies directly cover the shallow marine mudstones of the underlying sequence highstand systems tract and are overlaid with the dark-color mudstones of transgressive and highstand systems tracts,thus a favorable source-reservoir-caprock assemblage is formed and stratigraphic-lithologic hydrocarbon accumulations usually occur in these areas.
出处
《沉积学报》
CAS
CSCD
北大核心
2011年第5期906-916,共11页
Acta Sedimentologica Sinica
基金
国家重点基础研究发展计划(973计划)课题(编号:2007CB411705/2007CB411703)
国家自然科学基金项目(批准号:40572067)资助
关键词
珠江口盆地
珠海组
沉积坡折带
强制海退体系域
Pearl River Mouth Basin； Zhujiang Formation； depositional slope break； forced regressive wedge systems tract
