Junggar, Turfan and Alakol basins as Late Permian to ?Early Triassic extensional structures in a sinistral shear zone in the Altaid orogenic collage, Central Asia

Abstract

The Junggar, Turfan and Alakol basins in northwestern China and Kazakhstan formed as Late Permian to ?Early Triassic extensional structures in a broad sinistral shear zone between large strike-slip faults that separate two main domains of the Altaid orogenic collage. This extension was in response to an inferred large (> l000 km) sinistral motion of the East European craton with respect to the Angaran craton during this time. Deformation associated with the formation of the basins was taken up in part by counter-clockwise rotations of crustal blocks with respect to the Altaid orogenic collage and to the Angaran craton. This event is the only important phase of extension in a region otherwise dominated by compressional tectonics throughout the Phanerozoic. The basement rocks of these basins formed by Altaid subduction–accretion through the latter half of the Palaeozoic and the region was subsequently thrown into compression again during the Mesozoic Cimmeride and Cenozoic Alpide evolution.

Reconstructing the Late Palaeozoic – Mesozoic topographic evolution of the Chinese Tian Shan: available data and remaining uncertainties

“…Similar structures, like the Dalabute Fault to the west or the Kelameili Fault along the Altay, were also active around the Junggar Basin itself submitted to significant extension (e.g. Allen et al, 1991Allen et al, , 1995Allen and Vincent, 1997;Qiu et al, 2005Qiu et al, , 2008Yang et al, 2012). Those large strike-slip faults have been active from Early Permian to Early Triassic (ca.…”

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

“…The new estimate of the Late Carboniferous to Early Permian displacement along the Irtysch Fault is significantly different from that of 620km ± 320 km predicted by Wang et al, (2007), because Junggar was considered as a rigid block and an averaged pole from West and South Jungar was used to calculate the displacement along this fault in Wang et al (2007). The consistence of the Cretaceous poles of Mongolia, South Junggar and Siberia (Chen et al, 1993;Hankard et al, 2005) suggests that the bulk of relative motion mentioned above was completed before Cretaceous and possibly Middle Triassic time (Lyons et al, 2002), although Jurassic motions are also described (Allen et al, 1995). Further studies on Triassic rocks around the Junggar Basin will probably provide better age constraints on these events.…”

“…The estimate of the post Late Permian displacement along the Chingiz-Alakol-North Tian Shan Shear zone is thus 490km ± 250 km, corresponding to the -32.4° ± 16.4° counterclockwise rotation of South Junggar with respect to Yili ( Table 4). As presented in above sections, the Irtysh-Gornotsaev Shear Zone is a major tectonic zone in the Altaids and it is characterized by a sinistral sense of shear and ages of deformation bracketed between 290 Ma to 240 Ma (Ar-Ar dating; Meltnikov et al, 1997;Vladmirov et al, 1998;Trivin et al 2001;Laurent-Charvet et al, 2003;Buslov et al, 2004), with a probable Mesozoic brittle reactivation (Allen et al, 1995). The bent shape of the shear zone proposes an Euler pole at 56°N, 101°E, with a radius of about 1220 km.…”

Mesozoic–Tertiary exhumation history of the Altai Mountains, northern Xinjiang, China: New constraints from apatite fission track data

“…Final closure of the Junggar oceanic basin with collision between the Kazakhstan and Siberian plates occurred by the Late Carboniferous. In the Permian the tectonic regime was predominantly collisional although Allen et al, (1995) propose a Late Permian transentional phase. With ongoing convergence the Junggar oceanic basin evolved into the Jungar intracontinental foreland basin that during the Mesozoic and Cenozoic accommodated up to 5km of non-marine clastic sediments.…”