The Potentials of Multi-spectral Remote Sensing Techniques for Mineral Prognostication — Taking Mongolian Oyu Tolgoi Cu-Au Deposit as an Example

In this paper, we propose a new parameter—the alteration remote sensing anomalies—for predicting mineral resources. The geological basis and the spectral presupposition for the alteration anomalies are discussed. Based on the deposit geology and spectral characteristics of altered minerals, we have constructed a table for the extraction of remote sensing altered anomaly and its geological interpretation. We have developed an advanced system for the extraction of hydrothermal alteration assemblages using ETM+ (Enhanced Thematic Mapper) and ASTER (Advanced Space-borne Thermal Emission and Reflection radiometer) data, which is called the “De-interfered Anomalous Principal Component Thresholding Technique”. In this paperarticle, a simplified flow chart of this system is provided, in which the five main blocks of the system are illustrated; the five main blocks are the preprocessing, the sub-normalization, the anomaly-extraction, the post-processing, and the thresholding. The ETM+ data were used for studying the lithologic characteristics of Hanbogd igneous complex intermediate-acidic rock body in the northeast of the Oyu Tolgoi Cu-Au deposit. The ASTER VNIR and SWIR data were used for extraction of the hydroxylated anomalies for the Oyu Tolgoi Cu-Au deposit and the area close-by. The mineralization type of the Oyu Tolgoi Cu-Au deposit was determined as the porphyry type by the selective principal component analysis of ASTER data. The hydroxylated anomalies for all known ore bodies are obvious; besides, three new prospective hydroxylated anomalies were discovered in the west of the deposit. This work study once more again shows that the multi-spectral remote sensing techniques have excellent potentials for metallic mineral prognostication.