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Free keywords:
diatom, Asian winter monsoon, the last glacial Holocene.
DDC:
550 - Earth sciences
Abstract:
We present a continuous record of fossil diatoms from Huguang Maar Lake (HML) in southeastern China, spanning the time interval 17,500 to 6000 calendar years (cal years) B.P. The seasonal change in relative abundance of the dominant diatom taxa, Aulacoseira and Cyclotella species, can be used as a proxy of the strength of winter monsoon winds (WMW), which is supported by the results of a sediment trap experiment in HML and by an extensive review of the literature on the autoecologies of these species. In the sediment, high C. stelligera abundance and high-diatom concentration, which indicate warm conditions and low wind-driven turbulence of the water column, characterize an interval equivalent to the Greenland Interstadial 1. This is followed by an interval with low-diatom concentration and with assemblages dominated by Aulacoseira species, which suggests high wind-driven turbulence and therefore strong WMW. This interval corresponds with the Greenland Stadial 1. During the early and middle Holocene, another two episodes with strong WMW are evident from the data between 10,000 and 8500 and between 7000 and 6000 cal years B.P. The diatom record implies that strong winter monsoon episodes not only occurred during the last glacial-Holocene transition but also during the Holocene “thermal maximum.”
