Magnetostratigraphy and luminescence dating on a sedimentary sequence from northern East China Sea: Constraints on evolutionary history of eastern marginal seas of China since the Early Pleistocene

Owing to the large and increasing population density in low-lying coastal regions, even small changes in sea level can have substantial societal and economic impacts. Alternations of terrestrial and marine sediments deposited in coastal areas or continental shelves are important and effective indicators of sea-level changes, and thus, have been widely studied in the marginal seas of China over the past 30 years. However, sea-level change results from not only eustatic factors but also tectonic activity. The Zhe-Min (or Zhejiang–Fujian) Uplift (ZMU) was such an important factor in geomorphology, and formed a barrier preventing entry of sea water into the northern marginal seas of China, but its Quaternary history is poorly known.In this study, a new borehole (ECS-DZ1) was drilled in the Zhoushan Islands, northern East China Sea to obtain information on the evolution of the ZMU during the Quaternary. Information from paleomagnetic and luminescence dating was combined with data on sedimentary changes. The main results are: (1) constrained by luminescence ages, the upper sedimentary units were extrapolated to have been deposited since ∼0.2 Ma; (2) paleomagnetic results suggest that the ECS-DZ1 borehole sequence spans from the pre-Olduvai Matuyama reverse chron to the Brunhes normal chron, approximately constraining the age of the basal sedimentary unit to ∼2.0 Ma; (3) a significant hiatus or erosion between two major sedimentary units possibly occurred between the late Early Pleistocene and Middle Pleistocene.As the Zhoushan Islands are within the ZMU and considering previous transgression studies around this region, it is inferred that the ZMU subsided at ∼2.0 Ma, allowing sea water to invade northward in the Yellow Sea basin. The ZMU might have been uplifted again no later than 1.0 Ma, causing a sedimentary hiatus or lacustrine development. After ∼0.2 Ma, the ZMU subsided completely, allowing large transgressions to develop across the northern marginal seas of China in the context of global sea-level changes.