Abstract:
The history of natural fire and its relationship to climate during the last three glacial-interglacial cycles in the southern coastal areas of China and the northern continental shelf of the South China Sea (SOS) are discussed based on a statistical study of charcoal particles and associated pollen data from ODP Site 1144 (20 degrees 3'N, 117 degrees 25'E, 2037 m in water depth). Based on the results of the charcoal and pollen study, the sediments from the upper 225 m are divided into 8 zones (C1-C8), which might be correlated with Marine Isotope Stages 1-8 (MIS 1-8). Our study indicates that during the last glacial period (MIS 2, 4), the influx of charcoal particles was much higher than that during the interglacial period, suggesting the strong occurrence of natural fire and a dry climate. During MIS 6 and MIS 8 (C6, C8), although the influx of fine charcoal particles was quite high, the influx of coarse and medium-sized charcoal particles was very low, which might be due to the smaller source area of fire that probably resulted from the limited exposure of the continental shelf before MISS. During the interglacial period (MIS 1, 5, 7), the influxes of charcoal particles were much lower, implying a drop in the intensity of natural fires and then a humid climate. Another reason may be that the continental shelf was submerged into the sea during the interglacial periods, and the source areas of fire were reduced. Although the influx of fine charcoal particles was much lower during MIS 3, the influx of coarse and medium-sized charcoal particles was almost equal to those of MIS 4 (C4), which suggests that the intensity of natural fire remained quite high and the climate was considerably drier during that period.