Remote Sensing Prospecting of Pegmatite Deposits in the Azubai Region, Xinjiang
详细信息
- 责任者：Peng Guangxiong (Key Laboratory of Metallogenic Prediction of Nonferrous Metals ; Ministry of Education ; School of Geosciences and Info-Physics ; Central South University ; Changsha 410083 ; China) ; Gao Guangming
- 刊名：Geotectonica et Metallogenia
- 出版年：2013
- 卷期：37(1)
- 关键词：伟晶岩矿床 ; pegmatite deposit ; 遥感 ; remote sensing ; 新疆 ; Xinjiang
- 页码：p.109-117
- 图表：illus., 2 tables, 17 refs.
- 分类号：1600
- issnNo：ISSN1001-1552
- isbnNo：CN44-1595/P
摘要
Chinese Altay region is one of the important parts of Altay metallogenic belt of central Asia, and is a well-known mineralization area of non-ferrous metals, rare metals and precious metals. There are more than 100,000 pegmatite veins in Chinese Altay region, 90% of which occur in more than 30 pegmatite ore fields. In this paper, the Azubai pegmatite ore field in the central Altay, which is around 500 km2 with the centre coordinate of 88°48′E and 47°56′N, is studied. Remote sensing images of ASTER, RapidEye, QuickBird and ENVISAT-ASAR are used to extract prospecting information on pegmatite deposits in the Azubai region. Greisenization and albitization are the main alterations closely associated with mineralization. Based on the spectral characteristics, the method of Feature-orientated Principal Component Selection (FPCS) was used to optimize the ASTER band combination of 1-4-6-7 and 1-4-6-9 to extract greisenization and albitization respectively. ASTER thermal infrared data were used to estimate the surface content of SiO2, K2O and Na2O based on empirical formula, which provide effective technical support for the classification of magmatic rocks and effective basis for mapping and locating of the contact zones of different lithologies. It is the high reflectivity of pegmatite in the spectral range from visible to near infrared that provides the important physical basis for automatic identification and remote sensing interpretation of pegmatite. The pegmatite interpreted from QuickBird image with spatial resolution of 0.61 m was used to validate the automatic extraction of pegmatite from RapidEye image with 5m spatial resolution whose accuracy is about 86%. ASAR image is only used to do some preliminary experiment to identify pegmatite. Due to the lower spatial resolution, the extracted pegmatite from ASAR image was not used for metallogenic prediction. The conjunction parts of geological structures, contact zones of lithologies and superposed parts of pegmatite enrichment zones and alteration anomalies are the important basis for metallogenic prediction. According to above factors derived from remote sensing, four target areas were delineated, which will provide guidance for further prospecting.
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