Paleoclimatical History Recorded By Diatom Assemblages From The Huguangyan Maar Lake In Zhanjiang Since The Last 31.5 Ka To 10 Ka

The study of biogenic proxy of tropical and subtropical regions providesimportant evidence about the process and history of climatic and environmentalchanges, and is of global importance for understanding the dynamic mechanism ofplaeoclimatic and paleoenvironmental changes.The sediments from the Huguangyan Maar Lake in Guangdong Province offer acontinuous high-resolution record of the past 78 ka about environmental and climaticchanges. The studies of chronology, and physical, chemical environmental proxieshave provided much important information about the paleoenvironmental andpaleoclimatic histories. Based on diatom, a kind of microfossil sensitive toenvironmental change, this study presents a preliminary result about the variation ofdiatom assemblages, which indicated environmental and climatic changes since thelast 31.5 ka to 10ka. The main results and conclusions include:1. 20 genus and 103 species of diatom from 88 samples have been identified. Thekey species include: Aulacoseira ambigua, A. granulata, Cyclotella bodanica, C.stelligera.2. According to the record of diatom, the sequence of the diatom associations inthe last 31.5 ka to 10 ka have been established for this region. Three assemblagezones and five assemblage subzones in zone â…¢ are defined based on the abundanceof the diatom and characters of the key species, describing the character of everyassemblage zone and subzone in detail.3. Analyzing the variations of the water nutrition, temperature, level andtransparence, the climatic changes experienced three intervals at this area during31.5-10 ka period, showing the variations of hot-humid in late MIS3 to cool-dry inLGM, back to hot-humid in last deglaciation, with short cool-dry fluctuation in thelast one.