北京石花洞全新世石笋微生长层与稳定同位素气候意义初步研究  

PRELIMINARY STUDY ON THE DATA FROM MICROBANDING AND STABLE ISOTOPES OF STALAGMITES OF BEIJING SHIHUA CAVE

作　　者：谭明[1,2,3,4] 刘东生[1,2,3,4] 秦小光 钟华[1,2,3,4] 李铁英 赵树森[1,2,3,4] 李红春 吕金波②鲁向阳[1,2,3,4] 

机构地区：[1]中国科学院地质研究所 [2]北京市地质调查所 [3]美国南加州大学地球科学系 [4]北京大学技术物理系

出　　处：《中国岩溶》1997年第1期1-10,共10页Carsologica Sinica

基　　金：国家自然科学基金;中国科学院PEP-Ⅱ预研究项目;北京石花洞资源开发与环境保护项目

摘　　要：在北京石花洞全新世石笋中发现分辨率很高的微层韵律。通过绝对年代测定和降水记录校订，初步确定石笋微层的年层时标含义和层厚变化响应降水变化的关系。通过对石笋稳定同位素气候意义的分析，提出在季风气候条件下，由于石笋氧同位素主要反映水源氧同位素的变化，因而也反映了季风强弱的变化。碳同位素反映了土壤有机环境的变化。微层层厚与氧同位素主要是自然环境变化信息载体。The stalagmite is a kind of speleothems able to provide climate information with an annual resolutions and much longer time span compared to tree rings. Two kinds of annual banding of stalagmite have been reported:the luminescent microbanding which is only observed under a fluoromicroscope (Y.Shopov 1987, 1994 and A.Baker 1993) and the lamina which is visible to the naked eye (D.Genty 1996).Recently,we have studied a stalagmite from Beijing Shihua Cave within the East Asian monsoon zone and found a new kind of microbanding,the transparent microbanding which is observed under the polarizing microscope. We now report preliminarily about 1100 continuously deposited bands taken from the upper part of 45 mm of the stalagmite.Each band, mostly tens of micron in thickness, consists of two parts: a light part at its bottom which may be deposited from the “old water”existing in the fissure pushed out by the initial rainfall in a year,and a dark part on the top which may be deposited from the “fresh water”coming from covered soil and containing more organic matter. The cave is developed in Ordovician limestone. The stalagmite, which is about 200 mm high and of column shape, was taken in the drip water when it was cut as sample. The AMS 14 C dating suggests that each banding represents one year although the 14 C dating on such material can provide only very approximate time control.It seems reasonable to suppose that the rhyme of the banding reflects the variation of annual precipitation which possesses only one annual peak value in most years in the monsoon zone and changes in a wide range similar to the bands.Assuming that this interpretation is correct,we have developed the time series by comparing the thickness of the bands with the index of drought and flood recovered from the historical documents of last 500 years (from 1470 to 1992) and the instrumental record of precipitation from 1951 to 1980 (according to the data from China National Meteorologic Center).These curves are highly coherent suggesting

关 键 词：石笋微层 稳定同位素 季风 石花洞 古气候 

分 类 号：P532[天文地球—古生物学与地层学] P597[天文地球—地质学]