FIRE HISTORY IN PEARL RIVER BASIN SINCE 50 KABP: SEDIMENT RECORDS FROM THE SOUTH CHINA SEA

Black carbon(BC), a special kind of charted materials, is the product of incomplete combustion, which can be found in soils, sediments, atmosphere and ice cores. Due to its physical and chemical inertness, BC is often used as a proxy for wildfires reconstruction. Here we present a combined analysis of clay minerals, major and trace elements, black carbon content and isotopes of sediments from core K6-2 on the inner continental shelf of the northwestern South China Sea in order to constrain the sediment source and further reconstruct the fire history of South China. Clay mineral assemblages and trace elements composition suggest that the fine-grained silicate fractions of the sediment are mainly derived from Pearl River by the Guangdong offshore current. Therefore, BC of core K6-2 can be used to reconstruct fire history around the Pearl River Basin. From this study, we draw the following conclusions: (1) 47~27 kaBP: fire activities were relatively high, but showed a decrease trend since 35 kaBP. (2)13~6 kaBP: fire activities were almost the highest except for some particular phases. (3) 6~4 kaBP: fire activities weakened than before. In general, there were more fires when climate was warmer and wetter, and less fires when climate became colder and drier, suggesting the dominant control of climate on fire dynamics since 50 kaBP. Further study indicates that an increase in temperature can always promote fires while an increase in precipitation may reduce fires. So fire activities around the region may be more frequent with global warming. However, intensified human activities such as deforestation for farmland, slash-and-burn cultivation, metal smelting and wars may play important roles in increasing fire activities since 4 kaBP.