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New Late Jurassic to Early Cretaceous Paleomagnetic Results From North China and Southern Mongolia and Their Implications for the Evolution of the Mongol‐Okhotsk Suture
Author(s) -
Ren Qiang,
Zhang Shihong,
Wu Yuqi,
Yang Tianshui,
Gao Yangjun,
Turbold Sukhbaatar,
Zhao Hanqing,
Wu Huaichun,
Li Haiyan,
Fu Hairuo,
Xu Bei,
Zhang Jinjiang,
Tomurtogoo Ogoo
Publication year - 2018
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2018jb016703
Subject(s) - paleomagnetism , geology , polar wander , fibrous joint , cretaceous , apparent polar wander , clockwise , paleontology , block (permutation group theory) , remanence , geodesy , rotation (mathematics) , geometry , magnetic field , physics , magnetization , medicine , anatomy , mathematics , quantum mechanics
Abstract To better constrain the evolution of the Mongol‐Okhotsk suture, we carried out new paleomagnetic studies on Sharilyn Formation (~155 Ma) and Tsagantsav Formation (~130 Ma) in southern Mongolia, Amuria Block (AMU), and Tuchengzi Formation (~140 Ma) and Dadianzi/Yixian Formation (~130 Ma) in the Yanshan belt, North China Block (NCB). A total of 719 collected samples (from 100 sites) were subjected to stepwise thermal demagnetization. After a low‐temperature component of viscous magnetic remanence acquired in the recent field was removed, the stable high‐temperature components were isolated from most samples. The high‐temperature components from each rock unit passed a fold test and a reversal test, indicating their primary origins. The corresponding paleomagnetic poles were thus calculated. For AMU, the ~155 Ma pole is at 74.7°N/232.5°E (A 95 = 3.7°), the ~130 Ma pole at 74.6°N/194.7°E (A 95 = 2.9°); for the NCB, the ~140 Ma pole is at 82.7°N/208.6°E (A 95 = 4.3°), the ~130 Ma pole at 80.5°N/197.4°E (A 95 = 2.3°). By combining our new results with the published data, we refined the 155–100 Ma segment of the apparent polar wander paths for AMU and NCB, which can demonstrate that these two blocks have been tectonically coherent (AMU‐NCB) during 155–100 Ma. Comparison of the apparent polar wander paths, however, revealed a latitudinal plate convergence of 14.3° ± 6.9° and ~19.0° relative rotation between Siberia and the AMU‐NCB after ~155 Ma. Large‐scale latitudinal convergence likely ceased by ~130 Ma, although some relative rotation between them continued along the Mongol‐Okhotsk suture until ~100 Ma.