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Most of the thermokarst lakes are spread appreciably in Beiluhe Basin,Qinghai-Tibet Plateau,China,where ice-rich permafrost exists.Two typical thermokarst lakes with differing area and depth were examined to ascertain their age.We obtained lake-bottom samples of 50 cm length from lake BLH-A and 25 cm length from lake BLH-B.Environmental 137 Cs and 210 Pb and radiocarbon age dating techniques were applied to the 50 cm and 25 cm samples,respectively.The results indicate that the initiation of BLH-A is about 800–900 a B.P.,and approximately 1,450±30 a B.P.to 2,230±30 a B.P.for BLH-B.These results will provide scientific bases for sedimentological study and thermokarst activity in Beiluhe Basin.
Most of the thermokarst lakes are spread appreciably in Beiluhe Basin, Qinghai-Tibet Plateau, China, where ice-rich permafrost exists. Two typical thermokarst lakes with differing area and depth were examined to ascertain their age. We obtained lake-bottom samples of 50 cm length from lake BLH-A and 25 cm length from lake BLH-B. Environmental 137 Cs and 210 Pb and radiocarbon age dating techniques were applied to the 50 cm and 25 cm samples, respectively. The results indicate that the initiation of BLH- A is about 800-900 a BP, and about 1,450 ± 30 a BPto 2,230 ± 30 a BPfor BLH-B. These results will provide scientific bases for sedimentological study and thermokarst activity in Beiluhe Basin.