Yanshanian–Himalayan geodynamic transformation of the northwestern Junggar Basin, southwestern Central Asian Orogenic Belt (CAOB), and its significance for petroleum accumulation

• Published in: Di xue qian yuan. Vol. 14; no. 4; pp. 101565 - 238
• Main Authors: Zhi, Dongming, Zhang, Jingkun, Wu, Tao, Wu, Anbin, Tang, Yong, Liu, Yin, Cao, Jian
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2023; PetroChina Tuha Oilfield Company,Hami 839000,China; PetroChina Xinjiang Oilfield Company,Karamay 843000,China%School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China; State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,Nanjing 210008,China%PetroChina Xinjiang Oilfield Company,Karamay 843000,China%School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China%School of Geosciences,China University of Petroleum(East China),Qingdao 266580,China
• Subjects: Central Asian Orogenic Belt; Geodynamic transformation; Tectonic far-field stress; Total petroleum system; Yanshanian–Himalayan; Geodynamic transformation; Total petroleum system; Central Asian Orogenic Belt; Tectonic far-field stress; Yanshanian–Himalayan; Yanshanian-Himalayan
• ISSN: 1674-9871
• DOI: 10.1016/j.gsf.2023.101565

[Display omitted] •Geodynamic transformation caused by far-field stress related to uplift of the Tibetan Plateau.•A high-angle fault system with shear strains controls the hydrocarbon accumulation.•Tectonic deformation promotes the final formation of the total petroleum systems. The northwestern Junggar Basin in the southwestern Central Asian Orogenic Belt is a typical petroliferous basin. The widely distributed reservoirs in Jurassic–Cretaceous strata indicate that the region records Yanshanian–Himalayan tectonic activity, which affected the accumulation and distribution of petroleum. The mechanism of this effect, however, has not been fully explored. To fill the knowledge gap, we studied the structural geology and geochemistry of the well-exposed Wuerhe bitumen deposit. Our results indicate that deformation and hydrocarbon accumulation in the northwestern Junggar Basin during the Yanshanian–Himalayan geodynamic transformation involved two main stages. During the Yanshanian orogeny, a high-angle extensional fault system formed in Jurassic–Cretaceous strata at intermediate to shallow depths owing to dextral shear deformation in the orogenic belt. This fault system connected at depth with the Permian–Triassic oil–gas system, resulting in oil ascending to form fault-controlled reservoirs (e.g., a veined bitumen deposit). During the Himalayan orogeny, this fault system was deactivated owing to sinistral shear caused by far-field stress related to uplift of the Tibetan Plateau. This and the reservoir densification caused by cementation formed favorable hydrocarbon preservation and accumulation conditions. Therefore, the secondary oil reservoirs that formed during the Yanshanian–Himalayan tectonic transformation and the primary oil reservoirs that formed during Hercynian–Indosinian orogenies form a total and complex petroleum system comprising conventional and unconventional petroleum reservoirs. This might be a common feature of oil–gas accumulation in the Central Asian Orogenic Belt and highlights the potential for petroleum exploration at intermediate–shallow depths.