Optimization of Paleogeography of East Asia for the Past 150 Ma

Abstract:

Construction of paleogeography relies on the credibility of paleomagnetic investigation. One big potential obstacle in using paleomagnetic results acquired from sedimentary rocks is a bias towards shallow magnetic inclination. Contrary to sedimentary rocks, volcanic rocks are known to preserve faithful ancient geomagnetic record. We have tested the lithologic dependence of magnetic inclination in East Asia for the 150 Ma. Influence of magnetic inclination shallowing results in significant modification of paleolatitude for South China Craton, but was insignificant for North China Craton. We also estimated relative rotation with time by converting shallowing-corrected magnetic poles to representative geographic locations. Then, the relative longitudinal swing was incorporated in constructing paleogeography in addition to absolute longitudinal motions. We propose that a newly defined apparent polar wander path (APWP) with magnetic inclination shallowing treatment would be of help in rigorous construction of East Laurasia.