54～46ka川东北石笋的氧同位素记录及其气候环境意义探讨  

δ^(18)O variation during 54-46 ka recorded by a stalagmite from Northeast Sichuan, Central China and its relationship with summer monsoon evolution

作　　者：迟宝泉[1] 周厚云[1] 赵建新[2] 韦刚健[1] 关华政[1] 俸月星[2] 朱照宇[1] 周国庆[3] 闫峻[4] 

机构地区：[1]中国科学院广州地球化学研究所 [2]澳大利亚昆士兰大学同位素年代学实验室 [3]南京大学地球科学系,江苏南京210093 [4]合肥工业大学资源与环境工程学院,安徽合肥230009

出　　处：《地球化学》2007年第4期337-343,共7页Geochimica

基　　金：国家自然科学基金(40672120);中国科学院知识创新工程重要方向项目(KZCX3-SW-152);国家自然科学基金重点项目(40331009);中国科学院广州地球化学研究所知识创新工程领域前沿项目(GIGCX-04-01)

摘　　要：对采集于川东北诺水河溶洞群狮子洞的石笋SI3进行了TIMS U-Th定年和高精度氧稳定同位素(δ18O)分析,对其气候环境意义及与东亚夏季风演化之间的关系进行了研究。在54～46ka之间,SI3的δ18O记录相对变化趋势与同样位于东亚季风区的葫芦洞和董哥洞石笋δ18O记录、与极地冰芯GISP2和中东以色列Soreq洞次生碳酸盐沉积的δ18O记录具有很好的可比性,显示了其与东亚夏季风气候演化和全球气候变化的密切关系。但与其他石笋数据的对比显示SI3的δ18O记录明显偏重,可能与SI3生长地点接近洞口的环境有关,SI3发生了18O富集。对SI3的δ18O记录与气候环境密切相关的机制进行了探讨。TIMS U-Th dating and high-resolution oxygen isotopic composition measurements were conducted on a stalagmite SI3 collected from Shizi cave, Nuoshuihe, northeastern Sichuan, Central China. The stalagmite SI3 was developed between 54 -46 ka. Its δ^18 O record displays a high similarity with those of stalagmites MSL and MSD from Hulu cave, East China and D4 from Dongge cave, Southwest China, respectively. The trend of the δ^18 O record of SI3 also parallels with those of ice core GISP2 from polar area and of speleothem in Israel. These suggest that the δ^18 O record of SI3 is closely related with summer monsoon variation in East Asia. However, some evidences seem to suggest that carbonates in SI3 are more ^18O enriched than those deposited under oxygen isotopic equilibrium condition. There was probably kinetic fractionation when SI3 was developed. This may be explained by the locus of SI3 that was collected near the entrance of Shizi cave. The possible mechanism between the δ^18 O record of SI3 and the variation in East Asian summer monsoon was speculated. It is suggested that in the East Asian summer monsoon domain, the δ^18 O record of some speleothem deposited even under nonequilibrium condition is still a potential proxy for summer monsoon variation.

关 键 词：石笋 δ^18 O 非平衡分馏 夏季风 四川省 

分 类 号：P597[天文地球—地球化学] X142[天文地球—地质学]