珠江口盆地白云凹陷北坡第四纪层序地层和沉积体系演化及其控制因素

Quaternary sequence stratigraphic evolution of the Pearl River Mouth Basin and controlling factors over depositional systems

  • 摘要: 结合地震、测井及微体古生物等资料,研究了珠江口盆地白云凹陷北斜坡区第四纪的沉积体系、层序地层及控制因素。研究区第四系发育以巨厚的高角度前积层为特征的大陆斜坡沉积体系,可将其划分为4个三级层序。层序的构成包括低位、海进及高位域,沉积体系包括下切谷、北东向单向迁移斜坡水道、陆架边缘三角洲、斜坡扇及高角度陆架边缘前积体系等。随着海平面下降及物源供应,三角洲体系推进至陆架坡折形成巨厚的陆架边缘三角洲和斜坡扇体系。更新世大陆斜坡沉积体系不断从番禺隆起向白云凹陷推进,陆架坡折带向海迁移;陆架区下切谷向上不断发育,在SB3和SB2界面上最密集;而冰后期至今的全新世高位三角洲被局限在内陆架地区。大陆斜坡沉积体系的演化主要受海平面变化、构造作用、气候变化以及沉积供给变化的共同控制。

     

    Abstract: Based on the seismic, well logging and paleontological data, the sequence stratigraphic evolution of the northeastern shelf margin of the Pearl River Mouth Basin and the controlling factors on depositional systems since Quaternary are studied in this paper. Quaternary depositional systems in the study area are characterized by large-scale foresets complexes, which can be further subdivided into four 3rd order sequences, in each of which lowstand, transgressive, highstand systems tracts are observed. Depositional systems recognized in the slope section include slope incised valley, NW-SE oriented unidirectional migration of shelf-margin channels, shelf margin deltas, slope fans, and high-angle progradational complexes. As sea level fell down and/or sediment supply increased, deltaic systems prograded onto shelf-margin, and formed a series of thick shelf-edge deltas and finally deposited as slope fans. Since Pleistocene, these prograding complexes have been formed from the southern Panyu Lower Uplift toward the northern Baiyun Depression. At the same time the shelf slope break migrated to the sea. Incised valley of continental shelf increased upwards and reached a peak at SB3 and SB2. The Holocene highstand delta was limited within the continental shelf after the latest transgression. The evolution of depositional systems of continental slope is mainly controlled by the combination of sea-level changes, tectonic movement, climate changes and sediment supply.

     

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