Features of late cenozoic deepwater sedimentation in southern Qiongdongnan Basin, northwestern South China Sea

Abstract

Based on high resolution 2D and 3D seismic data acquired in recent years, using sequence stratigraphy analysis and geophysical methods, we discuss the features of Late Cenozoic deepwater sedimentation in the southern Qiongdongnan (琼东南) basin. The study area entered a bathyal slope environment in the Miocene. The channel developed in the Sanya (三亚) Formation was controlled by a fault break, and its shingled seismic characteristics represent multiple erosion and fill, which may indicate that turbidite current developed in the slope environment. The polygon faults found in mudstone of the Meishan (梅山) Formation represent the deepwater hungry sedimentary environment. The large-scale channels developed on the top of Huangliu (黄流) Formation could be the result of a big sea level drop and an increase of sediment supply. The fantastic turbidite channel developed in Late Quaternary in the slope environment has "fan-like" body and long frontal tiny avulsion channel. The analysis of these features suggests that the sediment supply of the study area in the post-rifting period was dominant from the Vietnam uplift in the southwest. These deepwater sedimentary features could be potential reservoirs or migration pathways for deepwater petroleum systems. KEY WORDS: Qiongdongnan basin, deepwater sedimentary system, channel, polygon fault, the South China Sea.

Tectonics and sedimentary basins of the South China Sea: Challenges and progresses

“…They found that in the BYS a strong post-rifting acceleration of subsidence occurred at 17.5-15.5 Ma accompanied by a sudden shift of depocenter, which might be caused by an important tectonic event. Yuan et al (2009) presented 2D and 3D seismic data showing features of the deepwater sedimentation in the Qiongdongnan basin, including sinuous turbidity channels and polygonal faults. Sun Q L et al (2009) demonstrated that the development of polygonal faults in Miocene formations of this basin might be triggered by over-pressure pore fluid which is restricted in the fine-grained sediments of bathyal facies.…”

Fine-grained Pleistocene deepwater turbidite channel system on the slope of Qiongdongnan Basin, northern South China Sea

“…The surrounding areas could have acted as source areas for the sediment supply into the study area during Cenozoic time (Yao et al, 2008). The QDNB is located in the western part of the South China Sea, which is basically composed of 2 mega sequences: the first represents the rifting period (53.5-23.3 Ma) and the second represents the post-rifting period (23.3 Ma to Quaternary) Yuan et al, 2009b) (Fig. 2).…”

“…2). The shelf-slope system of NSCS started to develop during the middle Miocene period (Chen et al, 1993;Xie et al, 2006;Yao et al, 2008;Yuan et al, 2009b). The shelf break in the QDNB is located near the 200 m isobath, whereas the continental slope ranges between 200 and 2000 m (Wu et al, 1999).…”

“…Concomitant with the advance in deepwater hydrocarbon exploration, more and more work has emphasized the study of deepwater depositional systems in NSCS (Lin et al, 2001;Lü dmann et al, 2005;Jiang et al, 2007;Shao et al, 2007;Wang et al, 2007;Yuan et al, 2009a,b). The structural evolution, sequence stratigraphy, depositional patterns and hydrocarbon potential of the Qiongdongnan Basin (QDNB) have been discussed by several authors (Chen et al, 1993;Wei et al, 2001;He et al, 2006;Xie et al, 2006;Yao et al, 2008;Yuan et al, 2009b). A few hydrocarbon reservoirs such as Ya 13-1 gas field were found in the northern part of the basin (Chen et al, 1993;He et al, 2006).…”

New insight into oil and gas exploration in Miocene and Late Oligocene strata in Qiongdongnan basin

“…The Miocene and Late Oligocene stratigraphy of the Qiongdongnan basin have been only partially studied and documented (Yuan et al, 2009;Wu and Shi, 2005;Wei et al, 2001;Wang et al, 1998). By means of recent well and seismic data, more systemic and reliable information revealed the general and local stratigraphy characteristics of the basin.…”