Hydromagnesite determination method based on Landsat8 and ZY1-02D data: A case study of the Jiezechaka Salt Lake in Tibet

Abstract

Abstract Hydromagnesite is a natural carbonate mineral that is widely distributed, but large sedimentary hydromagnesite deposits with industrial exploitation value are rare globally. In China, hydromagnesite is mainly distributed in the salt lake area of Qinghai-Tibet Plateau. Because of the harsh environment, it is difficult to use the traditional method to search for ore. Remote sensing technology has been successfully applied to research skarn, pegmatite lithium-beryllium, porphyry-epithermal, salt lake lithium, magmatic nickel-chromium, and orogenic gold deposits; however, research regarding remote sensing determination of hydromagnesite from salt lakes is lacking. We determined the mineral composition and content of hydromagnesite samples in the Jiezechaka area by X-ray diffraction (XRD), and the reflection spectral curve of the hydromagnesite samples was measured using an ASD FieldSpec4 short-wave infrared spectrometer. The analysis indicated three and seven absorption valleys with high and low absorption intensities, respectively, in the reflectance spectral curves of the hydromagnesite samples in the Jiezechaka area. Then, on this basis, we used Landsat8 OLI and ZY1-02D AHSI data, with the mixture tuned matched filtering (MTMF) method to extract hydromagnesite information around Jiezechaka Salt Lake in Tibet. A confusion matrix operation was used to compare the determination results of the two types of data. Among them, the overall accuracy of the extraction results based on Landsat8 data was > 67%, and the kappa coefficient was 0.668. The overall accuracy of the extraction results based on ZY1-02D data was > 72%, and the kappa coefficient was 0.743. Finally, using overlay analysis of the two kinds of data determination results, we concluded that hydromagnesite outcrops in the Jiezechaka area are mainly distributed in the northwestern and southeastern regions of the lake. This study provides a rapid assessment technique for measuring hydromagnesite information from salt lakes.