干旱区生态环境知识资源中心(Arid): 贵州中西部洞穴水系与碳酸钙沉积物的Mg／Sr比值和地球化学特征

Arid

	贵州中西部洞穴水系与碳酸钙沉积物的Mg／Sr比值和地球化学特征
其他题名	GEOCHEMICAL FEATURES AND Mg/Sr RATIO OF THE SAMPLES FROM CAVE WATER AND SPELEOTHEM IN CENTRAL WESTERN GUIZHOU, CHINA
	李俊云 1; 李红春 2; 刘子琦 1; 袁道先 1; 何潇 1; 王若梅 2
ISSN	1001-4810
出版年	2006
卷号	25 期号:3 页码:177-186
中文摘要	对贵州中西部郑家洞、石将军洞和织金洞三个洞穴中水样和碳酸钙沉积物样品地球化学特征的分析，得出洞穴水Mg／Sr比平均值分别为1278411、1155207、14．02．7。安顺洞穴的水样富Mg贫Sr，与织金洞的相反，一方面可能与围岩组成的差别有关，另一方面可能与洞穴地表的植被和土壤覆盖有关。碳酸钙样品中的微量元素比值反映了洞穴水的比值，而后者受围岩和地表条件的影响。因此，g（Mg／Sr或Mg／Ca比值来反映温度的变化，必须详细了解各种影响因素的影响作用。通过织金洞洞穴水和现代碳酸钙沉积物中St／Ca比值，计算出KSr值为0．04～0．134，平均值为0．0730．035；KMg平均值为0．0210．010。这些结果可为今后利用石笋Mg／Sr比值作为古气候代用指标的研究提供基础数据。
英文摘要	We have collected 23 water and 24 carbonate samples from Zhengjia, Shijiangjun and Zhijin caves in central western Guizhou province. The samples have been analyzed for elements including K^＋, Na^＋, Ca^2＋, Mg^2＋, Sr^2＋, Ba^2＋, Fe^3＋, and Mn^2＋. The average Mg/Sr ratio of the cave waters in Zhengjia, Shijiangjun and Zhiiin caves are 1278411, 1155207 and 14.02.7 respectively. The geochemical feature of cave waters from Zhengjia and Shijiangjun caves is enriched in Mg^2＋ but depleted in Sr^2＋; whereas waters from Zhijin cave depleted in Mg^2＋but enriched in Sr^2＋. The modern speleothems from the studied three caves exhibit the same feature. This feature indicates that not only the bedrock compositions but also vegetations and soils above the caves affect the Mg/Sr ratios of the cave water. We have found that there are three distinguished visible parts of depositional changes in the stalagmites in Shijiangjun cave：（1） a long （20 30cm） and relatively pure CaCO3 depositional period occurred in the oldest age; （2） a relatively short （2- 6cm） and dirty CaCO3 depositional period occurred after; and （3） a thin layer （〈0. 5cm） of pure CaCO3 depositional period occurred recently. The Mg^2＋ concentration increases sharply while the Sr^2＋ concentration decreases strongly from the old part to the new part. Such variations may reflect the changes in the overlying environment, namely karst-desertification caused by climate variability and human activity. The large variations of Mg/Sr ratio in the three parts do not represent the temperature effect on CaCO3 deposition. Therefore, this feature not only indicates that the variation of Mg/Sr in stalagmites may be used for studying evolution of karst rocky desertification in the region, but also reminds us to pin down the controlling factors of Mg/Sr ratio in speleothems before we can use it for paleoclimate reconstruction. Based on the measurements of Mg/Ca and Sr/Ca ratios in both waters and modern carbonates from Zhijin cave, we have calculated the co-precipitation coefficient constants for Mg/Ca and Sr/Ca between calcite and water. The Ks, value ranges from 0. 04 to 0. 134, averaging 0. 0730. 035. The average KMg ratio is 0. 0210. 010. The values provide us the fundamental data for using Mg/Sr ratio as a proxy of paleoclimate reconstruction.
中文关键词	贵州中西部 ; 洞穴水系 ; 洞穴碳酸钙沉积物 ; 微量元素 ; 古气候
英文关键词	Guizhou province Cave water Speleothems Trace element Paleoclimate
语种	中文
国家	中国
收录类别	CSCD
WOS类目	GEOLOGY
WOS研究方向	Geology
CSCD记录号	CSCD:2551081
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/220524
作者单位	1.西南大学地理科学学院, 重庆 400715, 中国; 2.成功大学地球科学系, 台南, 台湾中国
推荐引用方式 GB/T 7714	李俊云,李红春,刘子琦,等. 贵州中西部洞穴水系与碳酸钙沉积物的Mg／Sr比值和地球化学特征[J],2006,25(3):177-186.
APA	李俊云,李红春,刘子琦,袁道先,何潇,&王若梅.(2006).贵州中西部洞穴水系与碳酸钙沉积物的Mg／Sr比值和地球化学特征.,25(3),177-186.
MLA	李俊云,et al."贵州中西部洞穴水系与碳酸钙沉积物的Mg／Sr比值和地球化学特征".25.3(2006):177-186.