Tectonic evolution of Tethyan tectonic field, formation of Northern Margin basin and explorative perspective of natural gas in Tarim Basin

 Analyzing the characteristics of the Tethyantectonic field, the authors think that the Tethyan tectonicfield underwent three evolutional stages: closing of Pa-leo-Tethys and rifting of Neo-Tethys from early Permian tolate Triassic, subduction of Neo-Tethys and collision betweenthe Indian plate and the Eurasia plate from Jurassic to earlyof low Tertiary, and collision between the Arab plate and theEurasia plate and the A-type subduction of Indian plate fromlate of low Tertiary to the present. Combining the evolutionof the Tethyan orogenic belt with the characteristics of theNorthern Margin basin, it is suggested that the sedimentaryand tectonic characteristics and types of the Northern Mar-gin basin are controlled by the formation and evolution ofthe Tethyan orogenic belt and the ingression of Tethys. Theevolution of Northern Margin basin can be divided into threedevelopment stages: back-arc foreland basin from late Per-mian to Triassic, the back-arc fault subsidence and depres-sion from Jurassic to the early of low Tertiary, and the reac-tive foreland basin from the late of low Tertiary to the pre-sent. The Northern Margin basin in the Tethyan tectonicfield is an important region for natural gas accumulation,and the Tarim Basin is a part of this region.