Tectonic Switch From Triassic Contraction to Jurassic-Cretaceous Extension in the Western Tarim Basin, Northwest China: New Insights Into the Evolution of the Paleo-Tethyan Orogenic Belt

Abstract

We use stratigraphic, sedimentological, and borehole data and seismic profiles from the western Tarim Basin to document its Mesozoic tectonic evolution. A nearly 60-km-wide, Triassic fold-and-thrust belt along the southwestern margin of Tarim Basin is unconformably overlain by a Jurassic-Cretaceous sedimentary sequence along a regional angular unconformity. The Lower-Middle Jurassic strata consist mainly of an upward-fining sequence ranging from terrestrial conglomerates to turbidite deposits, which represent the products of an initial rift stage. Palaeocurrent analyses show that sediments for these rift deposits were derived from the paleo-Kunlun and paleo-Tienshan Mountains to the southwest and northern, respectively. The overlying Upper Jurassic-Cretaceous series consist of coarse-grained, alluvial fan to braided river deposits in the lower stratigraphic member, and lagoonal mudstones and marine carbonates in the upper member. These finer-grained rocks were deposited in a subsiding basin, indicating that a significant change and reorientation in the drainage system should have occurred within the basin during the Early Cretaceous. The western Tarim Basin evolved from a syn-rift stage to a post-rift stage during the Jurassic-Cretaceous. A post-orogenic stretch developed due to the evolution of the Paleo-Tethyan orogenic belt in Central Asia is a likely geodynamic mechanism for this major tectonic switch from a contractional episode in the Triassic to an extensional deformation phase in the Jurassic-Cretaceous.

Alternating Extensional and Contractional Tectonics in the West Kunlun Mountains during Jurassic: Responses to the Neo-Tethyan Geodynamics along the Eurasian Margin

“…The mid-Mesozoic tectonic evolution of the West Kunlun Mountains and Pamir is somewhat enigmatic, as the first-order geodynamic mechanisms for widespread observed deformation remain unclear. The interpretation of Jurassic molasse deposits has led to differing understandings on the tectonic setting in the region, such as syn-orogeny or post-collisional rifting (Gaetani et al, 1993;Wu et al, 2021). Several major exhumation events, including the Late Triassic and Early Jurassic, Middle-Late Jurassic, Early Cretaceous, and Late Cretaceous, are documented by low-temperature thermochronology in the mountain ranges and surrounding basins (Sobel, 2013;Cao et al, 2015;Li et al, 2019Li et al, , 2023.…”

“…remains equivocal. Existing interpretations of the Jurassic palaeogeography and evolution vary, ranging from syn-orogenic (Cao et al, 2015), post-orogenic (Wu et al, 2021), to transtensional (Sobel, 1999), because of the scarcity of the relevant geological record from this period. Significant challenges also persist in understanding the Mesozoic evolution of the Pamir terranes (Angiolini et al, 2013), including the timing of suturing and exact kinematics of related deformation (Robinson, 2015).…”

“…The Cenozoic contractional deformation episodes, due the northward subduction of the Neo-Tethyan Ocean and the collision of India with Eurasia, further complicates our understanding in this remote region (Burtman and Molnar, 1993;Cowgill, 2010). The limited knowledge of the Jurassic and Cretaceous evolution of the Pamir interior has been preliminarily deduced from the timing and nature of regional magmatic activities (Chapman et al, 2018) that are challenged by the information derived from the surrounding, fragmented sedimentary basins (Leith, 1985;Wu et al, 2021).…”

Crustal density structure and flexure mechanism of the Tarim Basin, China, constrained by latest in situ gravity observations

“…From Ordovician to Permian, the setting switched to compressional due to the closures of oceanic domains, and subsequently undergone collisions between (a) the Tarim and Kunlun to the southwest, (b) the Tarim and Qaidam to the southeast and (c) the Tarim and Tian Shan to the north (Alexeiev et al, 2015; Li et al, 2018; Zhang et al, 2013). During the Mesozoic, the Palaeo‐Tibetan Plateau began to accrete further south, promoted a complex deformation with minor strike‐slip, compressive or extensive reactions of the inherited Palaeo‐Proterozoic structures within the Tarim Basin (Hendrix et al, 1994; Wu et al, 2021).…”

“…During the Mesozoic, the Palaeo-Tibetan Plateau began to accrete further south, promoted a complex deformation with minor strikeslip, compressive or extensive reactions of the inherited Palaeo-Proterozoic structures within the Tarim Basin (Hendrix et al, 1994;Wu et al, 2021).…”