Abstract:

Large efficient reservoirshallow marine gravity flow deposits of the Huangliu Formation in Yinggehai Basin, south China, which are located at the central Dongfang area, represent the peculiarity in sedimentary features and deposit mechanism. The paleontology study of these gravity flow deposits indicates that the paleowater depth was 40110 m, which implies a shallow shelf environment. The gravity flow features include convolute deformation bedding and contemporaneous deformation structures. The vertical series are mainly Bouma sequence A and AB, which are lack Bouma CDE. The gravity flow deposits show the features of large scale, multiple phases (superposition of turbidite events and combination of vertical series), and sustainable development. The comprehensive genetic mechanism of the large gravity flow deposits that formed in shallow marine environments includes the following features: (1) continuously sources supply, (2) large-scale regression during the syndepositional period and (3) episodic dynamic and differential subsidence of shelf paleogeomorphology. The gravity flow deposits on the shallow marine shelf are the combined controlling results of source supply, tectonic activity, and relative sea level change, which represent high coordinated relationship between these influence factors. Therefore, this study will focus on the microscopic and macroscopic features, accumulation controlling factors, and particular mechanism of the shallow marine gravity flow deposits based on the research method and technique of tectonicsequence stratigraphy, sedimentology, and geophysics exploration. Intensive study of these shallow marine gravity flow deposits provides important theoretical value and practical significance for the theoretical research of large gravity flow deposits in the shallow marine environment, and also provides reference for the frontier exploration of oil and gas.

Key words: Yinggehai Basin, Huangliu Formation, shallow marine facies, gravity flow deposits (turbidites deposits), accumulation mechanism