Tectonostratigraphic units and stratigraphic sequences of the nonmarine Songliao basin, northeast China

Abstract

Through tectonostratigraphic analysis of the nonmarine, intracontinental Songliao basin in northeast China, four episodes of deformation are recognized: mantle upwelling, rift, postrift thermal subsidence and structural inversion.The episodes are related to regional geodynamics and plate motions. Each episode is associated with a speci¢c stratigraphic signature.The ¢rst period of deformation occurred during the Middle and Late Jurassic when asthenospheric upwelling heated, thinned and stretched the lithosphere.These events may have been caused by the narrowing of the Okhotsk Sea through subduction.This deformation is characterized by doming, extension, widespread volcanism and intrusion, and erosion.Volcanics inter¢nger with alluvial fan and alluvial plain facies systems tracts.The second rifting episode began in the latest Jurassic and continued into the Early Cretaceous. It resulted in the formation of a large number of isolated, NNE-trending fault blocks of 'basin-and-range' style. Rifting may have been caused by the formation and subduction of the Izanagi and Paci¢c Plates. Coal-bearing £uvial, £oodplain, lacustrine and fan-delta strata and widespread volcanic rocks ¢lled the fault-block basins.Volcanic strata hundreds to several thousand meters thick in the Huoshiling and Yingcheng Formations record multiple intrusive events during the rifting stage in the basin.These events were concurrent with episodes of intrusion and volcanic eruption in northeast China.The third phase of regional postrift deformation and subsidence, which began with the Lower Cretaceous Denglouku Formation, was caused by lithospheric cooling and extension, modulated by multiple compressional events. Subsidence in the Songliao basin permitted accumulation of thick postrift deposits, in contrast with other Cretaceous basins in Mongolia and northeast Asia.Three compressional episodes, which episodically interrupted the long-term cooling subsidence, originated from development of the Okhotsk suture and subduction of the Paci¢c plate. In the Early Cretaceous, pronounced compression originated from closure of Okhotsk Sea, forming the mountain ranges of Daxinganling, which provided sediment to the northern part of the basin. In the Late Cretaceous, the intensity of compression from the Paci¢c margin increased through time, causing westward migration of depocentres and uplift in the east until the end of Cretaceous. Postrift strata, typically 3000^4000 m thick with a maximum thickness of 6000 m, extend beyond the rift blocks and onlap the basin margins to form a large uniform basin. Early thermal subsidence strata include alluvial fan, £uvial, £oodplain, shallow lacustrine and delta facies tracts, overlain by large deltaic and lacustrine facies. Late postrift environments featured by large lakes in the basin centre rimmed by delta, £uvial and £oodplain environments. Re£ection seismic pro¢les show that strong structural inversion, including folding and uplift, began at the end of the Nenjiang Formation and culminated at the end of the Cretaceous...

Late Mesozoic rift evolution and crustal extension in the central Songliao Basin, northeastern China: constraints from cross-section restoration and implications for lithospheric thinning

“…The Songliao Basin, the largest oil-producing basin in China, was the focus of late Mesozoic crustal extension in northeastern China (Ren et al 2002). Intense rifting occurred in NNE-SSW rift zones in this basin during Late Jurassic to Early Cretaceous time, resulting in tens of isolated halfgrabens and grabens, within which up to 7 km syn-rift volcanic rocks and fluvial-lacustrine strata were accumulated (Feng et al 2010). These half-grabens and grabens were overlaid by significant thermal subsidence sequences during the Late Cretaceous and were selectively inverted by subsequent compressional events (e.g.…”

Multiple-stacked Hybrid Plays of lacustrine source rock intervals: Case studies from lacustrine basins in China

“…The Songliao Basin originated with extensional faulting during the Triassic to the Middle Jurassic, followed by a rifting stage in the Late Jurassic. The post-rift stage with a large-scale thermal subsidence depression extended from Early to Late Cretaceous and uncomfortably overlays the syn-rift strata (Feng et al 2010). The fault-bounded sediment fill in the syn-rift and widespread post-rift sediment fill generally thin toward the basin margins, resulting in steer's-head geometry in cross section (Feng et al 2010).…”

“…The post-rift stage with a large-scale thermal subsidence depression extended from Early to Late Cretaceous and uncomfortably overlays the syn-rift strata (Feng et al 2010). The fault-bounded sediment fill in the syn-rift and widespread post-rift sediment fill generally thin toward the basin margins, resulting in steer's-head geometry in cross section (Feng et al 2010). The sedimentary filling of this basin is dominated by Upper Cretaceous strata, which serve as the main petroleum source and reservoir system.…”

“…was deposited in a semi-deep to deep lake that occupied a large area of the Songliao Basin. The Qingshankou shale source rocks cover an area of 40,000 km 2 and have TOC ranges [2% in the basin center, R o values of 0.7%-1.5% and thicknesses of 50-400 m (Feng et al 2010; Fig. 7a).…”

A Three-Fold Classification of Tight Gas Based Primarily on Dynamic Relationship Between Gas Charging History and Reservoir Tightening Process and its Application

“…The main part is located in the Gulong and Changjiaweizi Rift with a strike of NNE and areal extent of approximately 8190 km 2 . The Denglouku formation is developed during the transition from the rifting stage to depression stage [16]. The range of sedimentary facies of the Denglouku formation in study area include: alluvial fan, fan delta, braided river delta, shallow water delta, fluvial, lacustrine, sub-lacustrine fan, and underwater gravity flow [17,18], which formed diverse types of reservoir rock.…”