Three-dimensional seismic geomorphology and analysis of the Ordovician paleokarst drainage system in the central Tabei Uplift, northern Tarim Basin, western China

• Published in: AAPG bulletin Vol. 95; no. 12; pp. 2061 - 2083
• Main Authors: Zeng, Hongliu, Loucks, Robert, Janson, Xavier, Wang Guizhong, Wang Guizhong, Xia Yiping, Xia Yiping, Yuan Bingheng, Yuan Bingheng, Xu Ligui, Xu Ligui
• Format: Journal Article
• Language: English
• Published: Tulsa, OK American Association of Petroleum Geologists 01-12-2011
• Subjects: applied (geophysical surveys & methods); Asia; caves; China; cores; Earth sciences; Earth, ocean, space; Exact sciences and technology; Far East; Geomorphology; geophysical methods; geophysical profiles; geophysical surveys; Geophysics; Hydrocarbons; Kalpintag Mountains; Ordovician; outcrops; paleokarst; Paleozoic; reflection methods; Sedimentary rocks; seismic methods; seismic profiles; sinkholes; solution features; surveys; Tabei Uplift; Tarim Basin; three-dimensional models; well logs; western China; Xinjiang China; Asia; China; Tarim Basin; Guangxi China; Xinjiang China; Far East; Guilin; damage; paleokarst; sinkholes; dip; drill cores; depressions; modern; unconformities; rivers; outcrops; detection limit; caves; Ordovician; karst; subsurface; Paleozoic; channels; uplifts; hills; drainage; three-dimensional seismics; petroleum exploration; valleys; canyons; collapse
• ISSN: 0149-1423; 1558-9153
• DOI: 10.1306/03111110136

High-quality three-dimensional seismic data acquired in the central Tabei Uplift, Tarim Basin, western China, provide a rare opportunity to characterize in exceptional detail the three-dimensional geomorphology of a deeply buried (5500-6500 m [18,045-21,325 ft]) Ordovician unconformity and the related paleokarst drainage system. An integrated approach was applied that emphasized integration of seismic data with available conventional core, wireline logs, and age-equivalent outcrops. The exceptional quality of the seismic data allowed a seismic detection limit of karstified features of less than 75 x 75 m (246 x 246 ft) horizontally and 6 m (20 ft) vertically. Interpreted geomorphologic and depositional elements include fluvial channels and canyons, fluvial valleys, sinkholes, and tower karsts and hills. The modern tower karst-drainage system in Guilin, China, is very similar to the mapped Ordovician karst-drainage system and is used as a modern analog. The interaction between the surface karst-drainage system and the shallow-subsurface cave-passage system is evidenced by the observation that surface canyons appear to initiate in areas associated with intense sinkhole development. Also, surface river valleys tend to correspond to dip-oriented surface depressions partly related to near-surface cave collapse. During burial into the deeper subsurface, the combination of intrastratal collapse (karstified strata) and suprastratal collapse (postkarst-deposited strata) created large damage zones hundreds of meters thick and kilometers wide. Coalesced-collapsed paleocave systems can be interpreted from the unique circular pattern of faults (observed in map view) that are associated with seismic bright spots.