关键词: 国际标样, 伊利石, 结晶度, 数据校正

Abstract:

The illite crystallinity index(IC),i.e.,Kübler index（K.I.）,is defined as the width of the(001)XRD peak(10×10^-8 cm) at half of its height(FWHM)for illites. It is an indicator widely used to evaluate the degree of metamorphism in the range from late diagenesis to very low-grade metamorphism then to low-grade metamorphism as illite crystallinity increases with metamorphic grade. The lower and upper boundary limits of the anchizone(very low-grade metamorphic zone) were originally defined by illite crystallinity values IC(K.I.)＝0.25（°Δ2θ）and IC(K.I.）＝0.42（°Δ2θ）,respectively. However,the lack of sufficient interlaboratory standardization causes difficulties in comparison of the data measured by different laboratories,among which the sample preparation,conditions of facilities,and the  measurement methods were widely of variety. It is therefore necessary to use commonly accepted standards to calibrate the data produced by different laboratories for making interlaboratory data comparable. In this paper the XRD measurements in our laboratory of illite crystallinity of five international standards provided by L.N.Warr were reported. These international standards consist of four sets of rock chips from the very lowgrade metamorphic belt of Southwestern England and one sample of single muscovite crystal from India.  A linear regression equation of our data versus Warr & Rice（1994）'s data was obtained,i.e.,IC_CIS=0.977 IC_measured＋0.033，6（°Δ2θ），R²＝0.983，5.This equation was then used to calibrate 213 data of illite crystallinity,which were measured under the same condition as that for the measurement of the international standards in our laboratory. It turns out that the data for illite crystallinity measured by this laboratory are  reliable and internationally comparable.

Key words: international standards, illite, crystallinity, calibration of data