Zhou Xinying

Different-(kPa/℃) size method of charcoal analysis in loess and its significance in the study of fire variation

Based on two methods of Sieving and Pollen-slide,the author designed different size method of charcoal analysis to extract and count different fragment charcoal from loess,paleosol and culture layer.Sieving method is used to extract big fragment of charcoal (the size is over 125μm) as the proxy of local fire regime;while Pollen- slide method can be used to get small fragment of charcoal (the size is lower 125μm) as the proxy of regional fire regime.The different size method of charcoal improves the precision of the charcoal analysis and enriches the con- tent on the study of fire history.The method provides a good way to reconstruct the fire variation and an important approach to study the vegetation history and ecological characteristic on the Loess plateau.Furthermore,the method can make great sense to understand the climatic variation and discuss human activity and their impaction to environ- ment.

Records of element geochemistry on the bronze smelting in Hexi Corridor since 4200 aBP

The utilization and smelting of metal is a revolutionary event during developing process of human society.The records of element geochemistry from lacustrine sediment at Lake Tiaohu in Hexi Corridor,during Holocene indicated that the high values of element such as Cu,Pb,Zn,and Ni appeared in the period of 10500-9500 and 8000-7200cal aBP,responding to the episode of glacial meltwater rising in the period of increasing temperature in early Holocene of the and the period of precipitation strength during Holocene optimum,respectively.The highest peak values of Cu,As,Pb,Zn and Ni appeared between 4200 and 3700cal aBP.Additionally,the secondary high values of Cu,Pb,Zn and Ni appeared in the period of 3000-2700cal aBP and 2100- 1900cal aBP.The element abnormality between 4200 and 3700cal aBP record the earliest bronze smelting in Northwest China and the element of arsenic was the major component in bronze alloy in this period.The element high values of Cu,Pb,Zn,Ni in Western Zhou Dynasty(3000-2700cal aBP) and Han Dynasty(2100-1900cal aBP) were probably the result of bronze smelting by ancient people.The record of element geochemistry could identify the starting-end time of bronze smelting,and it also provided the message on the component characteristic of bronze alloy in different periods.