Structural evolution of the Kanggur tectonic belt: implications for the latest carboniferous to Permian orogeny in the Eastern Tianshan, NW China

ABSTRACT

The E-W Kanggur tectonic belt, a major tectonic belt in the Eastern Tianshan (ETS) of the Central Asian Orogenic Belt (CAOB), records the amalgamation history between the ETS and the Tarim Craton. Two generations of structural deformation (D1 and D2) are recognized by field observations in the Jingerquan, Huangshan-Jingxia, Yamansu North Mountain, and Nanbeidagou-Kanggurtag areas. Early deformation is exhibited by vertical ‘A’ type (asymmetrical and symmetrical) S0 folds, lenticular symmetrical boudins, S-C fabric, and nearly vertical S1 foliation, demonstrating an ~N-S compressional setting. Late deformation is characterized by ~E-W-trending dextral shearing and local S1 folding. Transpressional deformation explains the kinematic compatibility of these fold and shear structures. The new U-Pb zircon and Ar/Ar age data in this study provide constraints on the timing of deformation, suggesting that D1 occurred in the late Carboniferous-early Permian (300–286 Ma) and that dextral shearing (D2) likely occurred in the middle-late Permian (262–233 Ma). The ~N-S contraction was driven by orogenic thickening during the convergence of the North Tianshan (NTS) island arc system, the Central Tianshan (CTS), and the Tarim Craton. Dextral transpression is related to the oblique convergence between the Eastern Tianshan (ETS) and Tarim Craton. On a larger scale, dextral kinematics along the Main Tianshan Shear Zone in the Eastern and Western Tianshan, together with sinistral shearing in northeastern Kazakhstan and the Chinese Altai, accommodated the eastward escape of central orogenic materials, which were possibly affected by the convergence of the Siberian, Baltic, and Tarim Cratons.

KEYWORDS:

• Transpressional deformation
• structural analysis
• Kanggur tectonic belt
• Eastern Tianshan
• Central Asian orogenic belt

Highlights

1. Two generations of ductile structural deformation (D1: Contractional deformation and D2: Dextral shearing) are recognized by Kanggur tectonic belt.

2. D1 occurred in the late Carboniferous-early Permian (300–286 Ma) and that dextral shearing (D2) likely occurred in the middle-late Permian (262–233 Ma).

3. The ~N-S contraction was driven by orogenic thickening during the convergence of the North Tianshan (NTS) island arc system, the Central Tianshan (CTS), and the Tarim Craton. Dextral transpression is related to the oblique convergence between the Eastern Tianshan (ETS) and Tarim Craton.

Acknowledgments

The National Nature Sciences Foundation of China (Nos. 41,872,201 and 91,955,205) financially supports this work. The (EBSD) fabric analysis is conducted at the China University of Geosciences (Beijing) and the Chinese Academy of Geological Sciences, the LA–ICPMS U–Pb zircon geochronological analysis is performed at Wuhan SampleSolution Analytical Technology Co., Ltd., Wuhan, China, and the ⁴⁰Ar/³⁹Ar geochronology analysis is performed at the School of Earth Sciences, University of Melbourne. We express our gratitude to W.J. Xiao and anonymous reviewer for their constructive suggestions and extensive annotations throughout the manuscript, which led to major improvements in the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

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Additional information

Funding

This work was supported by the National Nature Sciences Foundation of China [91955205]; National Nature Sciences Foundation of China [41872201].