Targeting Mineral Resources with Remote Sensing and Field Data in the Xiemisitai Area, West Junggar, Xinjiang, China

Lei Liu,Lamin Mansaray,Jun Zhou,Dafang Zhuang,Dong Jiang,Bing Zhang

doi:10.3390/rs5073156

Abstract

The Xiemisitai area, West Junggar, Xinjiang, China, is situated at a potential copper mineralization zone in association with small granitic intrusions. In order to identify the alteration zones and mineralization characteristics of the intrusions, Landsat Enhanced Thematic Mapper (ETM+) and Quickbird data of the study area were evaluated in mapping lithological units, small intrusions, and alteration zones. False color composites of the first principal component analyses (PCA1), PCA2, and PCA4 in red (R), green (G), and blue (B) of the ETM+ image, and relevant hue-saturation-intensity (HSI) color model transformations, were performed. This led to the identification of lithologic units and discrimination of granitic intrusions from wall-rocks. A new geological map was generated by integrating the remote sensing results with two internally published local geologic maps and field inspection data. For the selected region, false color composites from PCA and relevant HSI-transformed images of the Quickbird data delineated the details of small intrusions and identified other unknown similar intrusions nearby. Fifteen separate potash-feldspar granites and three separate hornblende biotite granites were identified using ETM+ and Quickbird data. The principal component analysis-based Crosta technique was employed to discriminate alteration minerals. Some of the mapped alteration zones using the Crosta technique agreed very well with the known copper deposits. Field verification led to the discovery of three copper mineralizations and two gold mineralizations for the first time. The results show that the PCA and HSI transformation techniques proved to be robust in processing remote sensing data with moderate to high spatial resolutions. It is concluded that the utilized methods are useful for mapping lithology and the targeting of small intrusion-type mineral resources within the sparsely vegetated regions of Northwest China.

Highlights

Nation-wide geological mapping and mineral resource investigations in China are typically carried out by field traverses
Remote sensing has been mentioned in these standards, it is regarded as a less important approach and the application has been restricted by the image processing and interpretation skills of the geologists
The potash-feldspar granites were well separated from adjacent rocks by a purple-red color, and the hornblende biotite granites were beige (Figure 3)

Summary

Introduction

Nation-wide geological mapping and mineral resource investigations in China are typically carried out by field traverses. Lithologies are often mapped coarsely at scales ranging from 1:50,000 to 1:250,000 [3], which leads to small felsic-ultramafic intrusions often being omitted during field-based geological mapping [4]. It is believed that Ni-Cu-Mo ores, such as the Jinchuan Ni-Cu sulfide deposit, Jinduicheng Mo deposit, and Dexing Cu-Mo deposit, are preferably hosted by small-sized intrusions [5]. It is important for the mineral resource exploration-orientated investigation to locate unknown small intrusions during the reconnaissance stage

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Discussion

Conclusion