Paleozoic tectonic amalgamation of the Chinese Tian Shan: Evidence from a transect along the Dushanzi-Kuqa Highway

Abstract

The Du-Ku Highway traverses the Tian Shan from the cities of Dushanzi to Kuqa in western China and provides a section across the full width of this Paleozoic orogen.The north Tian Shan consists of an accretionary complex of deformed ophiolite, arc volcanic assemblages, and siliciclastic sedimentary rocks derived mainly from volcanic arcs. The central Tian Shan is underlain by Precambrian basement covered mainly by Carboniferous andesitic tuff, Paleozoic marine carbonate and siliciclastic strata, and abundant Carboniferous-Early Permian granitoids. The south Tian Shan features continuous sequences of Silurian to Lower Carboniferous carbonate, chert, and siliciclastic strata of the deformed Paleozoic passive continental margin of the Tarim block.A high pressure-temperature (P-T) blueschist belt, parallel to and south of the Nikolaev line, which bounds the central and south Tian Shan, is exposed to the west of the Du-Ku Highway. Previously published radiometric ages bracket the blueschist metamorphism of the blueschist belt as 415-315 Ma. A paired coeval magmatic belt to the north was active from at least 400 Ma to ca. 330 Ma. Radiolarian fossils from chert associated with the north Tian Shan ophiolite, and Lower to Middle Carboniferous lithic turbidites structurally imbricated with ophiolite and tuff in the north Tian Shan, indicate that subduction-accretion along the north Tian Shan lasted at least through the end of the Early Carboniferous. Plutonism in the Borohoro arc along the northern margin of the central Tian Shan block culminated during Late Carboniferous-Early Permian time based on radiometric dating.We infer that amalgamation of the Tian Shan proceeded in two steps: (1) accretion of the central Tian Shan block to the northwest margin of the Tarim block by the Middle Carboniferous, with attendant cessation of arc magmatism and high P-T subduction metamorphism; (2) accretion of the Junggar arc complex and the

Palaeozoic tectonics of the south-western Chinese Tianshan: new insights from a structural study of the high-pressure/low-temperature metamorphic belt

“…1). This area was considered as a microcontinent with Proterozoic basement and was correlated with the Central Tianshan (Allen et al 1992;Gao et al 1998;Zhou et al 2001). Neoproterozoic and early Palaeozoic sedimentary rocks are exposed along its northern and southern boundaries (XBGMR 1993), and Carboniferous calc-alkaline volcanic and sedimentary rocks were unconformably deposited on these earlier sedimentary rocks.…”

Late Paleozoic paleogeographic reconstruction of Western Central Asia based upon paleomagnetic data and its geodynamic implications

“…Dextral criteria can be observed along these faults (Laurent-Charvet et al, 2002;2003;Wang et al, 2006Wang et al, , 2007 and Ar-Ar dating yield ages ranging from 290 Ma to 240 Ma for the deformation (Yin and Nie, 1996;Zhou et al, 2001;Laurent-Charvet et al, 2002, 2003. The center of the best fitting small circle intercepting this curved shear zone is around 50°N, 92°E, with a radius of about 880km.…”

“…The boundary between Yili and South Junggar is characterized by a dextral long-lived shear zone called the Chingiz-Alakol-North Tian Shan Shear zone, merging in the Main Tian Shan Shear zone to the east (Zhou et al, 2001;Zhao et al, 2003;Wang et al, 2006Wang et al, , 2007. Dextral criteria can be observed along these faults (Laurent-Charvet et al, 2002;2003;Wang et al, 2006Wang et al, , 2007 and Ar-Ar dating yield ages ranging from 290 Ma to 240 Ma for the deformation (Yin and Nie, 1996;Zhou et al, 2001;Laurent-Charvet et al, 2002, 2003.…”

Structural framework of a major intracontinental orogenic termination zone: the easternmost Tien Shan, China

“…It is likely that reactivation of the Tien Shan was facilitated by the range' s position directly north of the Precambrian Tarim Basin craton, which behaves as a rigid block. In contrast, the Tien Shan is largely underlain by mechanically weaker Palaeozoic arc rocks, accretionary complexes and ophiolitic assemblages that deform more easily in response to the north-northeasterly-derived compressive stress from the Indo-Eurasian collision (Westaway 1995;Neil & Houseman 1997;Zhou et al 2001).…”

“…1), suggesting an easterly decrease in the amount of shortening. For much of its length, the 3D fault architecture within the orogenic core is documented only along a few highways that cross the range (Burtman 1975;Allen et al 1993a, b;Zhou et al 2001). The external zones are much better studied, and active, outward-propagating thrust faults are documented on both north and south sides of the range deforming foreland basin sediments along the length of the chain (e.g.…”