Mineralization Information Extraction And The Prospecting Perspectives In Nixiong District Of Tibet Based On Remote Sensing

Nixong district in which the northern margin of the Gangdise Mountains Tibet is important part of Gangdise Gu-Fe-polymetallic metallogenic belt. After discovered Nixong superlarge iron deposit and Ria medium copper deposit in regional geological survey of china land resource survey, researchers also have found many large or medium polymetallic deposit, such as Luobule iron deposit, Dibucuo iron deposit, Eacier iron deposit, Dajiaxiama Fe-polymetallic deposit, Zuobuari lead-zinc deposit. Nixiong district dispalys a good prospecting future. This paper has specially arranged and generalized data about regional geology, stratigraphy, tectonics, igneous rocks, and used remote sensing to extract mineralization information, and established remote sensing prospecting model suitable for study area, and analyzed the prospecting perspectives which could provide more comprehensive exploration prospecting for the region. This study has the significance of guiding exploration in Nixiong area and good inspiration to use of remote sensing and GIS technology for ore prediction.On the basis of summarizing regional geological features and deposit distribution of the study area, this article determines remote sensing source and data pre-processing methods form the start of remote sensing spatial resolution and spectral resolution. Analyze the feature of remote sensing date and the spectral character of ground object, the paper used the remote sensing technology to extraction the lithologic information, tectonic information and mineralization alternation information.Establish prospecting model of remote sensing and Stack the geologic information, geophysical information and geochemical information with remote sensing information by Geographic Information System, synthesis analysis the mineral exploration information and advance the prospecting perspective. The main completed content of this paper as follow:(1) The paper chooses the Landsat7 ETM+ as the date source of remote sensing information extraction and researchs the data preparation process. According to the principle of image band combination, the paper choose ETM+ 741 as the bands combination of synthetic image. Through radiometic correction, geometric correction, image mosaic, digital convergence, it could get base map for visual interpretation.(2) Based on the type of mineralization alternation and spectrum character of altered rock ,analysis the geologic basis and spectral precondition of the remote sensing information extraction, summarize remote sensing method about extraction of chalybeate altered rock and hydroxyl altered rock. This paper use"Deinterfered Anomalous Principal Component Thresholding Technigue"to extract hydroxylate anomaly and chalybeate anomaly and classifies anomaly levels by normal distribution theory.(3) Based on the established geologic interpret symbol and five features of remote sensing for mineral-prospecting, the paper extracts remote sensing geological characteristics of mineral, such as linear structure, circular structure, mineralization alteration zone, host strata, irruptive rock body, tectonic block information, and analysis the correlation between remote sensing information and the prospecting information with the mathematic statistics.(4) Based on the synthesis analysis information about geology, remote sensing, geophysical exploration, geochemical exploration, the paper established remote sensing prospecting mode of the study area. Thourgh GIS spatial overlay analysis, it indicated that Tianjianle-Dishabu village-Yalang village area, Balong-Songlale area, Nixiong-Chabuqianda-Gangyiema area, Dengjin-Niuqionglaga area, Daria-Pengria area have a good prospecting indicators.