The tectonic history of the Junggar block, one of the largest tectonic units within the Central Asia orogenic belt, is pivotal for understanding the geodynamic processes associated with the India-Eurasia collision. Despite recurrent compressional deformation along numerous faults during the Mesozoic and Cenozoic, the magnitude of Cenozoic tectonic rotations in the Junggar block relative to Eurasia remains poorly constrained. To assess such rotations quantitively, we present paleomagnetic data from the Cenozoic sedimentary rocks in the Zaysan Irtysh zone in the northern part of the Junggar block. Stepwise thermal demagnetization revealed a high laboratory unblocking temperature component, interpreted as primary magnetization based on a positive reversal test. Seven mean directions were calculated for age intervals of 45−40 Ma, 42.5−37.5 Ma, 40−35 Ma, 37.5−32.5 Ma, 35−30 Ma, 25−20 Ma, and 22.5−17.5 Ma. The observed declination variations indicate a local counterclockwise rotation of 18.8° ± 11.4° between 40 ± 2.5 Ma and 35 ± 2.5 Ma. Comparison of these results with 23−3.1 Ma paleomagnetic data from the southern Junggar block obtained in previous studies suggests successive local counterclockwise rotations in the block’s northern and southern regions. At a larger scale, the Central Asia right-slip fault zone experienced two stages of tectonic rotation (ca. 60−30 Ma and 25−5 Ma) driven by the far-field effects of the India-Eurasia collision and strike-slip faulting that propagated through intracontinental settings. These insights have broad implications for the tectonic evolution of intracontinental systems, extending beyond Central Asia to other orogenic belts and collision zones worldwide.
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Research Article|
March 21, 2025
Early Publication
Paleomagnetic evidence for 50 m.y. of tectonic rotations in the Junggar block driven by far-field effects of the India-Eurasia collision
Mengting Zhong;
Mengting Zhong
1
State Key Laboratory of Continental Evolution and Early Life, Department of Geology, Northwest University, Xi’an 710069, China
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Vadim A. Kravchinsky;
Vadim A. Kravchinsky
1
State Key Laboratory of Continental Evolution and Early Life, Department of Geology, Northwest University, Xi’an 710069, China2
Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
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Rui Zhang;
Rui Zhang
3
College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
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Xin Cheng
Xin Cheng
1
State Key Laboratory of Continental Evolution and Early Life, Department of Geology, Northwest University, Xi’an 710069, China
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Mengting Zhong
1
State Key Laboratory of Continental Evolution and Early Life, Department of Geology, Northwest University, Xi’an 710069, China
Vadim A. Kravchinsky
1
State Key Laboratory of Continental Evolution and Early Life, Department of Geology, Northwest University, Xi’an 710069, China2
Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
Rui Zhang
3
College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
Xin Cheng
1
State Key Laboratory of Continental Evolution and Early Life, Department of Geology, Northwest University, Xi’an 710069, China
Publisher: Geological Society of America
Received:
18 Jul 2024
Revision Received:
10 Dec 2024
Accepted:
18 Feb 2025
First Online:
21 Mar 2025
Online ISSN: 1943-2674
Print ISSN: 0016-7606
© 2025 Geological Society of America
GSA Bulletin (2025)
Article history
Received:
18 Jul 2024
Revision Received:
10 Dec 2024
Accepted:
18 Feb 2025
First Online:
21 Mar 2025
Citation
Mengting Zhong, Vadim A. Kravchinsky, Rui Zhang, Xin Cheng; Paleomagnetic evidence for 50 m.y. of tectonic rotations in the Junggar block driven by far-field effects of the India-Eurasia collision. GSA Bulletin 2025; doi: https://doi.org/10.1130/B37904.1
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