青海察尔汗盐湖达布逊区段和别勒滩区段的成盐年代

８８－０１孔和８９－０４孔是１９８９年后笔者用14Ｃ和230Ｔｈ两种方法较为系统的测定了年龄的钻孔剖面。本文以此两孔为主，结合已有年龄数据的钻孔，重点讨论了达布逊区段的成盐年代，并根据８８－０１孔校正后的年龄，将达布逊区段四个大盐层的底板年龄大致划分为:Ｓ₁约５００００ａ.Ｂ.Ｐ.左右；Ｓ_２约为３６０００ａ.Ｂ.Ｐ.左右；Ｓ₃约３００００ａ.Ｂ.Ｐ.左右；Ｓ₄约１８０００ａ.Ｂ.Ｐ.左右。根据别勒滩区段ＣＫ₂₀₂₂，ＣＫ₆和ＣＫ₁₃₀₈三个钻孔剖面，讨论了此区约２５０００ａ.Ｂ.Ｐ.成盐年代。

Salt-forming Ages of the Dabusun and Bieletan Regions in Qarhan Playa,Qinghai

The14C and 230Th data of the sedimentS from the cores CK₈₂₆ of the Dabusun region and from the cores CK₂₀₂₂ of the Bieletan region have been accumulated in the study of chronology since 1976.From 1989, we made a systematic determination of14C and230Th on the samples of cores 88-01 and 89-04, and obtained more detailed data in the Study of evolution of Qarhan Playa.Cores 88-01 and 89-04 is located in the north shore of Dabusun Lake. The depths of both cores are 47m and 45m, respectively. The sediments are similiar not only in depositional characteristics,but also in salt-forming ages. A ages vs. depth chart is given in this paper, and a linear equation is obtained from the chart.It can be seen from the chart that there is a good correlation between the ages and the depths.From the linear equation, rough salt-forming ages of the four salt layers in the Dabusun region are obtained. The ages of the bottom layer S₁, S₂, S₃, S₄are 50000, 36000, 30000, 18000a. B. P.,respectively. In addition, the surface salt crust of Qarhan Playa was formed in about 8000- 9000a.B. P.. In order to make the explanation more clear, the core section chart and age data of cores 88-01 and 88-04 are made together with those of the four cores described in the reference (3). The result indicates that the salt-forming age in the Dabusun region is about 50000 a. B. P., which is largely different.from those of cores CK₂o₂₂,CK6and CK₁₃₀₈, and they reveal the salt-forming age of the Bieletan region. The salt-forming age of the Dabusun region is about 2000 years older than that of the Bieletan region.