Geological Significance for the Lateral Migration of the Late Triassic Black Shales in the Sichuan Basin, the Western Yangtze Block (South China)
Zhaokun Yan, Yuying Huang, Chenyu Yan, Chongjian Shao, Cong Ren, Zhou Nie, Zili Zhang, Shaoze Zhao, Haotian Bai, Daizhu Zhang, Tingting YeABSTRACT
The Upper Triassic black shales in the Sichuan Basin are formed in three stages and are predominantly situated at the forefront of the Longmenshan (LMS) thrust belt. These formations are a result of three rapid subsidence events in the foredeep and the development of an underfilled foreland basin, triggered by three intense thrust nappe movements of the LMS orogenic wedge during the Late Triassic. The lateral migration of black shales in the LMS foreland basin, from the northeast to the southwest, suggests that thrust nappe movements of the LMS orogenic wedge predominantly occurred in the northeastern region during the early Late Triassic and gradually shifted toward the southwestern region in the later Late Triassic. The ongoing convergence between the North China Craton and the Yangtze Block at this time likely influenced this migration process.