Gravity Flow on Slope and Abyssal Systems in the Qiongdongnan Basin,Northern South China Sea  

作　　者：SU Ming XIE Xinong LI Junliang JIANG Tao ZHANG Cheng HE Yunlong TIAN Shanshan ZHANG Cuimei 

机构地区：[1]Key Laboratory of Tectonics and Petroleum Resources （China University of Geosciences）, Ministry of Education, Wuhan 430074, China [2]CAS Key Laboratory of Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China [3]Department of Technology, Zhanjiang Branch of CNOOC, Zhanjiang 524057, China

出　　处：《Acta Geologica Sinica(English Edition)》2011年第1期243-253,共11页地质学报（英文版）

基　　金：supported by the 973 Project(no. 2007CB411705);the National Natural Science Foundations of China(no.40806019);the Key Laboratory of Marginal Sea Geology,Chinese Academy of Sciences (no.MSGL09-10);the Key Laboratory of Tectonics and Petroleum Resources(China University of Geosciences)project(no.TPR-2009-17)

摘　　要：The study of new seismic data permits the identification of sediment gravity flows in terms of internal architecture and the distribution on shelf and abyssal setting in the Qiongdongnan Basin （QDNB）. Six gravity flow types are recognized： （1） turbidite channels with a truncational basal and concordant overburden relationship along the shelf edge and slope, comprising laterally-shifting and vertically-aggrading channel complexes; （2） slides with a spoon-shaped morphology slip steps on the shelf-break and generated from the deformation of poorly-consolidated and high water content sediments; （3） slumps are limited on the shelf slope, triggered either by an anomalous slope gradient or by fault activity; （4） turbidite sheet complexes （TSC） were ascribed to the basin-floor fan and slope fan origin, occasionally feeding the deep marine deposits by turbidity currents; （5） sediment waves occurring in the lower slope-basin floor, and covering an area of approximately 400 km2, were generated beneath currents flowing across the sea bed; and （6） the central canyon in the deep water area represents an exceptive type of gravity flow composed of an association of debris flow, turbidite channels, and TSC. It presents planar multisegment and vertical multiphase characteristics. Turbidite associated with good petrophysical property in the canyon could be treated as a potential exploration target in the QDNB.The study of new seismic data permits the identification of sediment gravity flows in terms of internal architecture and the distribution on shelf and abyssal setting in the Qiongdongnan Basin （QDNB）. Six gravity flow types are recognized： （1） turbidite channels with a truncational basal and concordant overburden relationship along the shelf edge and slope, comprising laterally-shifting and vertically-aggrading channel complexes; （2） slides with a spoon-shaped morphology slip steps on the shelf-break and generated from the deformation of poorly-consolidated and high water content sediments; （3） slumps are limited on the shelf slope, triggered either by an anomalous slope gradient or by fault activity; （4） turbidite sheet complexes （TSC） were ascribed to the basin-floor fan and slope fan origin, occasionally feeding the deep marine deposits by turbidity currents; （5） sediment waves occurring in the lower slope-basin floor, and covering an area of approximately 400 km2, were generated beneath currents flowing across the sea bed; and （6） the central canyon in the deep water area represents an exceptive type of gravity flow composed of an association of debris flow, turbidite channels, and TSC. It presents planar multisegment and vertical multiphase characteristics. Turbidite associated with good petrophysical property in the canyon could be treated as a potential exploration target in the QDNB.

关 键 词：gravity flow slope and abyssal system Qiongdongnan Basin South China Sea 

分 类 号：P[天文地球]