洞穴次生碳酸盐沉积的Mg/Ca与Sr/Ca比值研究进展--兼论洞穴次生沉积物Mg/Ca与Sr/Ca的影响机制  

Progress of study on Mg/Ca and Sr/Ca ratios of speleothem in caves

作　　者：郑立娜[1,2] 周厚云[1,3] 朱照宇[1] 

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]中国科学院研究生院,北京100039 [3]华南师范大学地理科学学院,广东广州510631

出　　处：《中国岩溶》2010年第2期212-218,共7页Carsologica Sinica

基　　金：国家自然科学基金项目(40973009,40672120);中科院知识创新工程重要方向项目(KZCX3-SW-152);中国科学院广州地球化学研究所知识创新工程前缘领域项目(GIGCX-08-04)

摘　　要：微量元素是岩溶洞穴沉积中非常重要的一类古气候环境替代指标,为近20年来国内外的一个研究热点。总结前人的研究,主要取得了以下一些重要认识:(1)洞穴上覆土壤和围岩是洞穴次生碳酸盐沉积Mg、Sr的主要来源;(2)Mg/Ca与Sr/Ca能够指示气候环境变化,但需结合其它指标综合考虑。(3)洞穴次生碳酸盐沉积Mg/Ca与Sr/Ca受多种气候环境因素(包括土壤和围岩的组成和性质、水-岩相互作用、先期碳酸盐沉积、分配系数等)影响,其古气候环境指示意义具有多解性;(4)矿物结晶作用对Mg/Ca与Sr/Ca有一定的影响,特别是文石在向方解石转变的过程中容易丢失Mg、Sr,此外,杂质的混入也将抑制Mg、Sr进入方解石,从而引起洞穴次生碳酸盐沉积Mg/Ca与Sr/Ca比值的变化。今后应进一步加强对石笋中这些微量元素的影响机制研究,尤其是对一些影响因素与微量元素含量变化之间的定量关系进行探讨。Trace elements in speleothem are important proxies of paleoclimate.In recent years,investigation on speleothem Mg/Ca and Sr/Ca ratios has got some important conclusions as follows：（1） Mg and Sr in speleothems derive mainly from overlying soil layer and wall-rock.（2） Speleothem Mg/Ca and Sr/Ca ratios are able to indicate paleoclimate,but they should be explained in combination with other indices such as oxygen and carbon isotope ratios.（3） Speleothem Mg/Ca and Sr/Ca ratios are influenced by a variety of climatic and environmental parameters including the composition and features of overlying soil layer and wall-rock,interaction between water and rock,advance carbonate deposit,distribution coefficients of Mg and Sr between solution and carbonate etc.Thus their interpretation is multiple depending on the dominant factor.（4） Mineral and crystallization also have certain influences on speleothem Mg/Ca and Sr/Ca ratios.Especially,it is easy to lost Mg and Sr during the transformation from aragonite to calcite,and lead to lower Mg/Ca and Sr/Ca ratios;incorporation of impurity would enhance inhibition of Mg and Sr into calcite lattice.In the future,more efforts should be paid in the mechanisms controlling migration of trace elements in speleothems,particularly in quantifying the connections between speleothem trace elements and forcing factors.

关 键 词：洞穴次生碳酸盐沉积 MG/CA Sr/Ca 古气候环境 影响机制 

分 类 号：P595[天文地球—地球化学] P588.245[天文地球—地质学]