Cenozoic reorganization of fluvial systems in eastern China: Sedimentary provenance of detrital K-feldspar in Taiwan

Cenozoic passive margin sediments in Taiwan provide an important natural archive to reconstruct drainage reorganization in eastern China. In this study, we used Pb isotope compositions of detrital K-feldspar to investigate the sedimentary provenance of Cenozoic strata in Taiwan and to constrain fluvial system evolution in eastern China. Eocene to lower Oligocene sandstones in Taiwan are characterized by radiogenic K-feldspar grains (Pb-206/Pb-2(04)>18.4), indicating that the eastern Cathaysia Block served as the dominant sediment contributor. In contrast, a late Oligocene sample has a Pb isotopic character indistinguishable from that of the Gan River, a major tributary of the Yangtze River. This provenance change is interpreted as the result of headward (westward) migration of the paleo-Min River to the Wuyishan (Wuyi Mountains) during the late Oligocene. Miocene deposits are enriched in relatively unradiogenic K-feldspar (Pb-206/Pb-2(04)<17.0) which can be reliably traced back to the Dabie and Sulu orogenic belts. Since the early Miocene, the paleo-Yangtze River, mainly draining the Yangtze Craton and the Dabie orogenic belt, delivered a large volume of detritus to the East China Sea Shelf Basin and also to the proto-Taiwan region.