History of coastal dune evolution in the Fujian region of southeastern China over the last millenium

Abstract

Coastal dunes are a product of the evolution of the coastal environment. Previous research shows that dune development in the Fujian coastal region correlates well with the fluctuations of East Asian winter monsoon (EAWM) and sea level. However, comparison of coastal dune evolution along the Fujian coast since 1 ka with various paleoenvironmental indicators shows that, in addition to EAWM and sea level change, increased frequency and intensity of typhoon landfalls and tropical cyclone may have played an important role in dune building. Here we present the results of optically stimulated luminescence (OSL) dating and analyses of lithostratigraphy, grain size, and color of late Holocene aeolian sediments from Shenhu Bay of the Fujian coast, Southeastern China. Together with published chronological data from the region, three phases of coastal aeolian activity are defined: ~1050–1300 CE (the Medieval Climatic Anomaly, MCA), ~1450–1700 CE (early Little Ice Age, LIA), and ~ 1750–1930 CE (late LIA). These phases of sand accumulation had different sand sources: the source for the two phases of ~1050–1300 CE and ~ 1450–1700 CE was the reworking of the adjacent “old red sand”, and that for the phase of ~1750–1930 CE was beach and/or foredune sand. During ~1050–1300 CE, although the sea level was relatively high and the beach sand source was relatively limited, the increased frequency of typhoon landfalls and the widely distributed “old red sand” deposits provided important dynamic and provenance conditions for the formation of coastal dunes. During ~1450–1700 CE, strong EAWM and increased frequency of typhoon landfalls were all conducive to aeolian activities. On the contrary, the strong aeolian activity during ~1750–1930 CE may be related to sea level drop and strong EAWM.