Near Infrared Spectroscopic Study of Trioctahedral Chlorites and Its Remote Sensing Application

作者：Min Yang, Ling Han, XU Youning, KE Hailing, Ningchao Zhou, Hui Dong, San Liu, Gang Qiao · 发表于：Open Geosciences · 年份：2019 · DOI：10.1515/geo-2019-0063 · 被引用次数：16 · 研究领域：Geochemistry and Geologic Mapping、Geological and Geochemical Analysis、Remote-Sensing Image Classification

Abstract The mineral chemistry of thirteen trioctahedral chlorite samples from four regions in northwestern China, having a wide range of Fe and Mg contents and relatively constant Al and Si contents, were studied via raman spectroscopy, near infrared (NIR) spectroscopy, X-ray diffraction (XRD) analysis and electron - probe microanalysis. Five absorption features of the twenty samples near 4525, 4440, 4350, 4270 and 4180 cm −1 were observed, and two diagnostic features at 4440 and 4270 cm −1 were recognized. Assignments of the two diagnostic features were made for two combination bands (( ν + δ ) ( AlAl ) O − OH and ( ν + δ ) ( SiAl ) O − OH ) by regression with Raman fundamental absorptions. Furthermore, the determinant factors of the NIR band position were found by comparing the band positions with relative components. The results showed that Fe 2+ /(Fe 2+ +Mg) values are negatively correlated with the two NIR combination bands. The findings provide an interpretation of the NIR band formation and demonstrate a simple way to use NIR spectroscopy to discriminate between chlorites with different components. More importantly, a simple example of mapping Fe-rich and Mg-rich chlorites were executed using remote sensing data based on this theory. The spectroscopic detection of mineral chemical variations in chlorites provides geologists with a tool with which to collect information on hydrothermal alteration zones from hyperspectral-resolution remote sensing data.