Response of Western Pacific marginal seas to glacial cycles: paleoceanographic and sedimentological features

Abstract

This paper reviews the recent progress in late Quaternary studies in five northwestern Pacific marginal seas, especially the South China Sea as an example. A series of marginal seas separate Asia from the Pacific Ocean, and significantly modify the material and energy flux linkage between land and sea. During glacial cycles, the sea-level-induced environmental signal was amplified in the marginal seas, giving rise to drastic changes in areas and configurations of these seas, and to reorganization of sea water circulation in basins. Since most of the Western Pacific marginal seas are influenced by monsoon circulation and some of these are located within the Western Pacific warm pool, the glacial geographic changes have produced a profound impact on regional and global climate. For example, the decrease of sea area and sea surface temperature (SST) in the marginal seas was one of the factors responsible for the enhanced aridity of inland China during the glaciation. Glacial intensification of the winter monsoon and increased seasonality of SST in marginal seas might explain, at least partly, the apparent discrepancy between the tropical paleotemperature estimations based on terrestrial and open-ocean records in this region. As the Western Pacific marginal seas trap terrigenous material supplied by East Asia, the deep-water sedimentation rates there can be one to two orders of magnitude higher than in the open ocean. Down-slope sediment transport is more active when the sea-level changes, particularly during the deglaciation. At least four types of carbonate cycles have been recognized in the Western Pacific marginal seas, and each of those contains environmental signals from the surface and deep sea water, as well as from the drainage basin.