Study On The Hyperspectral Characteristics And Hydrothermal Alteration Of The Drill Core From Chuduoqu Lead-zinc Deposit In Tuotuo River Area,Qinghai Province

Hyperspectral remote sensing technology has a unique advantage in extraction of altered minerals,by observing the spectrum of water or OH-containing minerals,high and low temperature sulfate minerals and carbonate minerals in the spectral region of the shortwave infrared,the type of the altered minerals and the alteration zone can be determined efficiently and accurately,now it is widely used in the digital core logging.Through the visible-shortwave infrared hyperspectral scanning of the borehole core,Combined with the characteristic mineral spectral parameters and full borehole susceptibility,we did the study on the analysis and extraction of the altered minerals and its combination in the ChuDuoqu 3201 borehole.The interpretation for spectrums shows that the main altered minerals in this core are(relative percentage is greater than 5%):mica(mainly muscovite,small amount of paragonite and phengite),kaolinite,calcite,ankerite;secondary minerals(relative percentage is less than 5%)are:dickite,gypsum,dolomite and little montmorillonite.Combined with the analysis for the geological environment of the ore-forming period on this deposit,we draw a conclusion that the sequence of alteration of the ChuDuoqu lead-zinc deposit is silicification-advanced argillization-carbonation-sulfation.Many seams are in the main fractured-altered zone shows that the mineralization is related to structure,and this deposit has many characters like:Shallow depth mineralization,hydrothermal intrusion of times,which mean that the deposit is a typical medium-low-temperature hydrothermal sulfide deposit.We do a research on the data of metal elements scanned by XRF(X-Ray Fluorescence)X-ray Fluorescence Spectrometer and the altered minerals,we regarded the ankerite + kaolinite + calcite as the indicator minerals for this deposit.By further studying on the spectral parameters of the muscovite which are close to the ore body and away from the ore body in the same stratum,the absorption peak position is negatively correlated with the Cu ore body.The absorption peak near the Cu ore body is small.The crystallinity of muscovite is obviously negatively correlated with Zn ore body which is limited to the average crystallinity 1.2 and the phenomenon is the same like the absorption peak position.Finally,total borehole magnetic susceptibility scan analysis shows that for this borehole,the ore-hosting horizon does not contain any ferromagnetic or ferrimagnetic minerals.The peak of the magnetic susceptibility only proves that the paramagnetic minerals are in the zone,such as pyrite.It does not have the significance of indicating mineralization,but for the muscovite,the higher the magnetic susceptibility,the lower the reflectivity.This study provided evidence for further understanding of the genetic types of ore deposits and geological environment,it also provides effective indicators for the next exploration of concealed ore bodies.