A STUDY ON 10 Be IN QUARTZ FROM LOESS OF CHINA (I)——In situ COSMOGENIC ~(10)Be AND EROSION RATES OF SOURCE REGIONS OF LOESS

In situ cosmogenic ~(10)Be in quartz from loess deposited in the last 2,000,000 a is considered to have been derived mainly from initial ~(10)Be in source regions and it bears abundant information about changes in erosion rates of source regions. As [have been estimated, the concentrations of "in situ cosmogenic ~(10)Be" in quartz from samples GL47(L1) andGL83 (L2) collected from the Luochuan loess section are 5×10~5 atom/g and 2.2×10~6 atom/g, respectively. As calculated on the basis of the above estimates, the erosion rates of the source regions are: eBeL1=1.5×10~(-3) cm/a for the L1 period (10,000—90,000 a) and eBeL2=3.8×10~(-4) cm/a for the L2 period (130,000—190,000 a). Studies of "in situ cosmogeuic ~(10)Be" in quartz from loess at deeper levels are expected to be applied to ~(10)Be dating of loess strata.