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 ero...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: εBeL1=1.5×10^(-3) cm/a for the L1 period (10,000—90,000 a) and εBeL2=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.展开更多
Chlorine-36 has various advantages as a dating tool for old groundwater. In this paper, 36CI of Quaternary groundwater in the Hebei plain of North China has been measured using accelerator mass spectrometry (AMS). Age...Chlorine-36 has various advantages as a dating tool for old groundwater. In this paper, 36CI of Quaternary groundwater in the Hebei plain of North China has been measured using accelerator mass spectrometry (AMS). Ages calculated from the 36CI/CI ratio show that ion filtration, which is responsible for the CI- concentration increasing with depth and along flow paths in Hebei plain groundwater. It is concluded that 36CI age of the groundwater in the 3rd Group of the Quaternary (Q2) in the Cangzhou area is 250ka, and that of the 4th Group(Q1) is 300ka.展开更多
基金This work was financially supported both by the Swiss National Science Foundation and by the National Natural Science Foundation of China
文摘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: εBeL1=1.5×10^(-3) cm/a for the L1 period (10,000—90,000 a) and εBeL2=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.
基金This project was supported by the National Natural Science Foundation of China (GrantNo.4917242) the Open Laboratory of Constitution, Interaction and Dynamics of the Crust-Mantle system. We thank Prof.Zhong Zengqiu for helpful comments.
文摘Chlorine-36 has various advantages as a dating tool for old groundwater. In this paper, 36CI of Quaternary groundwater in the Hebei plain of North China has been measured using accelerator mass spectrometry (AMS). Ages calculated from the 36CI/CI ratio show that ion filtration, which is responsible for the CI- concentration increasing with depth and along flow paths in Hebei plain groundwater. It is concluded that 36CI age of the groundwater in the 3rd Group of the Quaternary (Q2) in the Cangzhou area is 250ka, and that of the 4th Group(Q1) is 300ka.
