Jurassic paleomagnetic constraints on the collision of the North and South China Blocks

Abstract

This paper reports a paleomagnetic study of Jurassic rocks from the Ordos Basin in the North China Block (NCB). A recent remagnetization and a high‐temperature and/or high‐coercivity component with dual polarities have been isolated. The Middle Jurassic pole (74°N, 233°E, A95=5°) is roughly consistent with previous results, and the Lower Jurassic pole (82°N, 286°E, A95=7°) is located between the late Triassic and Middle Jurassic poles. These results, combined with paleomagnetic results from adjacent blocks, suggest that 1) the pole for the NCB suffered an angular displacement of 47°+/− 8° between the late Triassic and Middle Jurassic, 2) the SCB underwent final accretion to the NCB in the Middle Jurassic, and 3) accretion of the NCB to Siberia was not complete until the late Jurassic and possibly even until the early Cretaceous.

The tectonic evolution of the Songpan-Garzê (North Tibet) and adjacent areas from Proterozoic to Present: A synthesis

“…Hsü et al (1987) argued that collision was Middle to Late Triassic based on radiometric dating of ophiolites and eclogites in the suture zone, and evidence for the continuation of marine sedimentation well into the Triassic. Paleogeographic reconstructions based on paleomagnetic data show that the collision occurred diachronously from east to west, with major rotation occurring near the Triassic-Jurassic boundary Coe, 1987, 1989;Enkin et al, 1992;Yang et al, 1992;Gilder et al, 1993Gilder et al, , 1999. Moreover, geochronological studies of ultra-high-pressure (UHP) metamorphic rocks in the Qinling orogen indicate that collision was active in the Late Triassic (Ames et al, 1993(Ames et al, , 1996Eide et al, 1994;Rowley et al, 1997;Hacker et al, 1998).…”

Provenance and tectonic-paleogeographic evolution: Constraints from detrital zircon U–Pb ages of Late Triassic-Early Jurassic deposits in the northern Sichuan basin, central China

“…For example, the accretion of the SCB to NCB was suggested to occur along the Shangdan suture zone in Silurian-Devonian following the fact that the South Qinling belt (SQB) began to receive sediments from the North Qinling in middle Paleozoic (Gao et al, 1995;Kröener et al, 1993;Zhang et al, 1997). In contrast, paleomagnetic data (Enkin et al, 1992;Yang et al, 1992), together with ultrahigh-pressure metamorphism at 230 Ma in the easternmost Qinling-Dabie belt (Ames et al, 1996;Hacker et al, 1998;Okay et al, 1993) blocks. The discovery of the Mianlue suture zone between the South Qinling and SCB was invoked to reconcile the above inconsistence and draw a conclusion that it is the Late Triassic collision between the SCB and South Qinling that finally resulted in the accretion of the SCB to NCB Zhang, 1999, 2000;Ratschbacher et al, 2003).…”

Late Paleozoic subduction–accretion along the southern margin of the North Qinling terrane, central China: Evidence from zircon U-Pb dating and geochemistry of the Wuguan Complex

“…The predominant interpretation is that the Paleo-Qinling Ocean closed prior to the Devonian and the Devonian sediments (including the Liuling Group) in the South Qinling terrane are considered to have been deposited in a foreland basin or a passive margin (e.g., Mattauer et al, 1985;Şengör, 1985;Hsü et al, 1987;Xu et al, 1988;Zhang et al, 1988;Ren et al, 1991;Gao et al, 1995;Zhang et al, 2001;Dong et al, 2011bDong et al, , 2013. This hypothesis seems to be supported by a lack of large-scale arc-related volcanism and magmatism, but it conflicts with evidence suggesting that the final collision between the North China and the Yangtze plates took place in the late Permian-Triassic, as inferred from the paleomagnetic data (Lin et al, 1985;Enkin et al, 1992;Yang et al, 1992) and Triassic (ca. 250-220 Ma) HP/UHP rocks in the TongbaiDabie-Sulu areas (Ames et al, 1993;Li et al, 1993;Okay and Sengör, 1993;Ames et al, 1996;Ye et al, 2000;Liu et al, 2009).…”

“…Li et al, 2015). However, this models is at odds with the tectonic constructions based on paleomagnetic data (Lin et al, 1985;Zhao and Coe, 1987;Enkin et al, 1992;Yang et al, 1992), Triassic (ca. 250-220 Ma) HP/UHP rocks in Tongbai-Dabie-Sulu areas (Ames et al, 1993;Li et al, 1993;Okay and Sengör, 1993;Ames et al, 1996;Hacker et al, 1998;Ye et al, 2000;Liu et al, 2009) and the presence of Triassic granitoids in the Qinling orogenic belt (N. .…”