Tectonic thermal evolution of Aksu area in the Tarim Basin, NW China: Indications from apatite fission track thermochronology

Abstract

This manuscript aims to analyze the tectonic evolution of the Aksu area in the Tarim Basin. Fracture orientation, dip angle, and aperture were meticulously measured using geological survey tool. Outfield observations, fluid inclusion testing, and acoustic emission testing were conducted to characterize sets of fracture development. By combining fracture sets with apatite fission track (AFT) thermochronology, we attained a more comprehensive understanding of the multiple stages of tectonic thermal activities. Four primary tectonic movements were identified in the Aksu area. In Stage I, sub-horizontal fractures developed during the Middle-Late Caledonian orogeny, indicating stable sedimentation. Stage II witnessed the formation of medium-angle shear fractures and tensile-shear fractures during the Early-Late Hercynian orogeny. Stage III featured low-angle conjugate shear fractures during the Indo-Yanshanian orogeny. Finally, Stage IV showcased high-angle shear fractures formed during the Himalayan orogeny. Based on AFT thermal evolution simulation and considering the tectonic background, three primary uplifting events and one subduction event were discerned in the Aksu area since the Ordovician period. During the Late Triassic to the early Cretaceous (ca.130-100 Ma), the Aksu area experienced slow uplift. Subsequently, due to the collision between the Indian plate and the Eurasian plate at the end of the Cretaceous, the Aksu area underwent rapid uplift during the Late Cretaceous and early Neogene (ca.90-50 Ma). A rapid subduction event occurred during the Cenozoic period (ca.50 Ma-20 Ma). Consequently, since ca.20 Ma, the Aksu area has undergone rapid uplift, concurrent with the Himalayan orogeny.