Linkage and growth of the independent and coherent faults: Insight into the effect of relay ramps on sedimentation patterns in the northern Bonan Sag, Bohai Bay Basin. (May 2021)

• Record Type: Journal Article
• Authors: Ma, Pengjie; Lin, Chengyan; Ren, Lihua; Jahren, Jens; Dong, Daotao; Yu, Guoding; Ma, Cunfei; Wang, Di; Liu, Lianqi; Hellevang, Helge
• Is Part Of: Marine and petroleum geology. Volume 127(2021)
• Publication Date: 2021-05
• Subjects: Fault linkage and growth -- Relay ramp -- Sedimentation pattern -- Lacustrine rift basin -- Bonan sag -- Bohai bay basin; Submarine geology -- Periodicals; Petroleum -- Geology -- Periodicals; Géologie sous-marine -- Périodiques; Pétrole -- Géologie -- Périodiques; Petroleum -- Geology; Submarine geology; Periodicals; Electronic journals; 551.468
• DOI: 10.1016/j.marpetgeo.2021.104985
• Languages: English
• ISSNs: 0264-8172

Abstract

Abstract: The influence exerted by the linkage and growth of fault segments on the sedimentation pattern in a lacustrine rift subbasin, the northern Bonan Sag in the Jiyang Depression in the Bohai Bay Basin, is studied by integrating drilling cores, wireline logs and 3D seismic data. The NW-trending Guxi Fault formed through the linkage of three fault segments, which display a roughly en echelon arrangement in map view and are probably related to early-stage regional transtensional and slip-strike stress. Between the vertical displacement troughs of normal faults, two narrow relay ramps, attributed to the coherent fault linkage-and-growth model, formed through the linkage of the three fault segments. A relatively wide relay ramp, attributed to the isolated fault linkage-and-growth model, developed due to the linkage of the NW-trending Guxi Fault and E-W-oriented segmented Chengnan Fault. The sedimentation pattern was strongly controlled by the geometry and evolution of the relay ramps. The sediment routing system was dominated by the relay zone, and fan-delta and sublacustrine fan depositional systems developed in the early stage of relay ramp formation. Lateral breaching of the relay ramps through extensive faulting and rifting probably caused an increase in the vertical throw and resulted in deposition of a coarse-grained nearshore subaqueous fan in front of the normal faults. The relay zone that formed from the linkage of independent faults (the Chengnan and Guxi faults) is associated with a broad drainage area and fan-delta and sublacustrine fan deposits, which contain the most effective hydrocarbon reservoirs in this deeply buried setting. Highlights: Structural analysis reveals three main relay ramps in front of the boundary faults in the northern Bonan Sag. Geometric variation in the relay ramps related to the linkage and growth of isolated and coherent fault segments. Sedimentation types are diverse during the linkage of fault segments and breach of relay ramps. The association of fan-deltas and sublacustrine fans formed by the linkage of isolated faults with broader relay zone.