New paleomagnetic results from the upper part of the Jingeryu Formation in the North China craton and their tectonostratigraphic and paleogeographic implications

Abstract

The paleogeographic positions of the North China craton (NCC) during the late Mesoproterozoic to early Neoproterozoic are important to understand the supercontinent evolution. However, the published paleomagnetic results for this period were mainly obtained from the Liaodong–Xuhuai regions, situated along the eastern margin of the craton. They would further benefit from the data from more regions. In this study, we present the new paleomagnetic results obtained from the carbonate rocks of the upper part of the Jingeryu Formation (Fm) in the eastern Heibei Province, Yanliao basin, located in the interior of the NCC. Stepwise demagnetization revealed two distinct paleomagnetic remanence components. The low-stability component is likely a viscous magnetic remanence acquired in the recent geomagnetic field. Ninety-four samples retained a high-stability component, which is dual-polarity and characterized by notably steep inclinations, positioning the paleomagnetic pole at 45.6 °N, 139.6 °E (dp/dm = 8.7°/8.9°). The primary origin of the remanent magnetization is supported by positive fold and reversal tests, as well as the new pole’s distinctiveness from the younger NCC poles. The Jingeryu pole overlaps (at the 95 % confidence level) with poles from the lower part of the correlative strata, which are named Nanfen, Xinxing and Liulaobei formations in the Liaodong–Xuhuai regions at the eastern margin of NCC, but it differs significantly from other Precambrian NCC poles reported previously. We suggest that the upper part of the Jingeryu Fm correlates with the lower part of the Nanfen Fm and its equivalents. These results demonstrate that the previously identified late-Mesoproterozoic high-latitude (>∼70°) carbonate basin, primarily comprising the lower part of the Nanfen Fm and its equivalents situated along the eastern margin of the NCC, also includes the upper part of the Jingeryu Fm, which was deposited in a large area in the craton’s interior. Together with the updated global paleomagnetic database, our reconstruction indicates that the NCC was in high latitudes at ca. 1110 Ma, close to northwestern Laurentia and western Siberia, and separated by tens of degrees in latitude away from the low-latitude continental blocks including the Amazonian, Congo–São Francisco, Indian and Kalahari cratons.