Apparent polar wander path for East Asia and implications for paleomagnetic low inclination in sedimentary rocks

摘要

The paleogeography of East Asia in the supercontinent (Pangea) during the late Paleozoic to Mesozoic remains incomplete because the temporal and spatial constraints on the rigid attachment of East Asia to Eurasia is still unresolved. One fundamental obstacle to constructing a high-precision apparent polar wander (APW) path for East Asia is the uneven temporal coverage of available paleomagnetic poles with a severe lithologic bias towards sedimentary rocks. In reality, paleomagnetic data from sedimentary rocks are often biased towards a shallower paleomagnetic inclination, resulting in underestimation of paleolatitudes. In the present study, we tested whether the sedimentary paleopoles in the South China Block (SCB) and the North China Block (NCB) can be corrected for their shallow paleomagnetic inclinations. The shallow bias of paleomagnetic inclination in sedimentary rocks from the SCB was corrected using the elongation-inclination (E/I) method. According to paleogeographic comparisons, sedimentary paleopoles for the NCB and volcanic paleopoles for the SCB provide the most realistic paleogeographic distributions from 150 to 120 Ma. Therefore, we propose that the optimum paleogeography between the NCB and the SCB is as follows: (1) apparent polar wander (APW) path was constructed from volcanic data only from 150 Ma to 120 Ma; (2) for time intervals younger than 110 Ma, a new composite APW path was constructed both from volcanic and sedimentary results, with systematic E/I corrections.