桂林水南洞1号石笋的年龄与稳定同位素测定及其古气候意义

AGES AND STABLE ISOTOPIC MEASUREMENTS OF NO.1 STALAGMITE FROM SHUINAN CAVE IN GUILIN AND THEIR PALAEOCLIMATIC IMPLICATIONS

本文通过对桂林水南洞 1号石笋进行α能谱铀系测年及碳氧同位素分析 ,获得了距今 2 0～ 8万年的古气候信息。石笋大于 2 0万年前开始生长 ,8.0 7万年后停止生长 ,属中更新世的产物。其年龄与δ1 8O的变化可与深海岩芯V2 8-2 3 8同位素记录所揭示的第五和第六阶段进行对比。它反映此阶段区内经历了寒冷 (间夹短暂的小温期 )和温暖 (间夹短暂的小冷期 )等气候变化 ,与全球古气候变化波动基本一致 。

Stalagmites in karst caves are a better carrier of karst environmental record, and the sophisticated approaches are available for dating and testing of environmental indexes for pure carbonate rocks. The reconstruction of paleoenvironment by using the information on stalagmites in karst caves is one of the popular projects in recent 20 years.\; Paleoclimatic information from 2000 ka B.P. to 80 ka B.P. has been obtained through α\|counting U\|series dating and carbon and oxygen isotopic analysis of No.1 stalagmite from the Shuinan cave in Guilin. The ages and oxygen isotopic records in the Guilin area can be compared with the oxygen isotopic records of deep\|sea cores (or sediments) at V and VI stages. The results have shown the records of climatic change from 200 ka B.P. to 80 ka B.P. in this period in the Guilin area indicates a change from cold to warm and humid. It coincides with the fluctuation of global paleoclimatic change. Meanwhile, regional climatic change is also recognized.\;