西沙群岛琛航岛碳酸盐沉积物X射线定量分析方法研究

QUANTITATIVE X-RAY DIFFRACTION ANALYSIS OF CARBONATE SEDIMENTS FROM CHENHANG ISLAND, XISHA ISLANDS, CHINA——A METHODOLOGICAL STUDY

利用X射线衍射分析技术测定碳酸盐沉积物中的矿物成分及其含量是目前研究碳酸盐最有效的方法。本文根据西沙琛航岛碳酸盐矿物组成的具体情况采用了“自清洗法”,用峰值强度测定方解石、白云石、文石和石英的含量,用方解石特征峰所在位置确定其MgCO_3含量,对西沙琛航岛碳酸盐沉积物进行了比较全面的定量分析测定,取得了较好的效果,从而对西沙群岛第四纪礁相沉积作用、白云岩化作用、地球化学、年代学、地层学等问题的解决提供了有价值的资料。

Quantitative X-ray diffraction analysis is considered as the most effective technique applicable to the determination of the mineral composition of carbonate sediments and the contents of various minerals in them at the present time. Described in this paper is the 'auto-washing' method which has been successfully applied to the determination of the mineral composition of carbonate sediments from Chenhang Island, Xisha Islands, Chlna. In this method the peak intensities are used to determine the contents of calcite, dolomite, aragonite and quartz in carbonate sediments. Meanwhile, the content of MgCO_3 in calcite can be determined on the basis of the position of its characteristic peak. Satisfactory results of the quantitative X-ray diffraction analyses of the mineral composition of carbonate sediments from Chenhang Island, Xisha Islands, China have been obtained, thus providing new clues to the problems concerning the sedimentation, dolomitization, geochemistry, geoehronology, stratigraphy, etc. of the Quaternary reef facies on the Xisha Islands.