土壤和围岩地球化学组成及气候对洞穴滴水水化学的影响——以湖北清江和尚洞为例  

Impact of Soil,Bedrock Geochemical Composition and Climate on Hydrochemistry of Cave Drip Water:A Case Study of Heshang Cave,Qingjiang,Hubei

作　　者：王明达[1] 胡超涌[1] 周炼[2] 朱昌杰[1] 

机构地区：[1]中国地质大学生物地质与环境地质教育部重点实验室,武汉430074 [2]中国地质大学地质过程与矿产资源国家重点实验室,武汉430074

出　　处：《地质科技情报》2010年第3期97-103,共7页Geological Science and Technology Information

基　　金：国家自然科学基金重点项目(40531004)

摘　　要：大气降水渗入土壤,穿过围岩,将气候与地表环境信息导入洞穴滴水,最终被洞穴沉积物所记录,因而研究土壤、围岩与洞穴滴水的地球化学组成及3者之间的联系对了解气候和环境信号的传递以及石笋古环境信息的正确解译十分重要。通过对比清江地区和尚洞上覆土壤、围岩与滴水的元素及锶同位素N(87Sr)/N(86Sr)地球化学组成特征,进而调查土壤和围岩对洞穴滴水水化学的影响。结果表明:滴水的n(Mg)/n(Ca)、n(Ba)/n(Ca)、n(Sr)/n(Ca)及N87Sr)/N(86Sr)介于土壤和围岩之间,说明滴水物质组成来自土壤和围岩的混合;滴水的n(S)/n(Ca)大于土壤和围岩,说明有第三端元的混入,可能是大气硫沉降的结果。通过模型计算可知,土壤和围岩对和尚洞滴水各元素组成的贡献并不相同,贡献的相对大小不仅与元素本身的地球化学性质有关,而且随气候和环境而发生变化。Infiltrating into the soil and passing through the bedrock,the meteoric water carries the climate and environmental information of land surface into the cave drip water,finally recorded in speleothems.This attaches great importance of the geochemical composition of soil,bedrock and the drip water to the better understanding of the transmission of climate and environmental signals,as well as the interpretations of paleoenvironment information by speleothems.In this paper,a comparison is made of the element and 87Sr/86Sr geochemical composition of overlying soil,bedrock and the drip water,investigating the impact of soil and bedrock geochemistry on drip water hydrochemistry.The results show that Mg/Ca,Ba/Ca,Sr/Ca and 87Sr/86Sr of drip water generally fall between values for soil and bedrock which infer the source of drip water originated from two end members.However,S/Ca in drip water has a much larger content than that of soil and bedrock.This indicates that a third end-member component should be mixed in,which might be the result of atmospheric sulfur deposition.It is found with a model that the relative contributions of soil and bedrock to different elements in drip water are not the same,with the contribution ratios varying with the climate and environment change.

关 键 词：微量元素 87Sr/86Sr 滴水 物源 和尚洞 清江 

分 类 号：P641.134[天文地球—地质矿产勘探]