Spaceborne mapping of hydrothermal alteration zones associated with the Mundiyawas-Khera copper deposit, Rajasthan, India, using SWIR bands of ASTER: Implications for exploration targeting

Abstract

This paper discusses the effectiveness of spectroscopic techniques for identifying hydrothermal alteration zones associated with the Mundiyawas-Khera copper deposit, Alwar Basin, western India, and assesses implications for mineral exploration targeting in the greater Alwar basin. Mineral specific SWIR bands of ASTER were spectrally enhanced to highlight areas of anomalous Al-OH and Mg-OH responses, representing key mappable expressions of the Mundiyawas-Khera copper deposit. The hydroxyl-bearing mineral zones were identified at 98% and 95% threshold pixels, respectively. Kaolinite ± scapolite, sericite (muscovite), tremolite and dolomite, contained in the felsic volcanic and dolomitic copper host rocks, were identified from spectroscopic data and corroborated with petrographic and XRD data. On this basis, distinct argillic, phyllic and propylitic hydrothermal alteration zones could be identified at Mundiyawas-Khera. The integrated approach presented here (i) identified a well defined phyllic alteration pattern in the felsic volcanic rocks, (ii) resulted in a comprehensive remotely sensed hydrothermal alteration map illustrating the spatial distribution of the copper-related hydrothermal alteration zones (i.e., an eastern argillic, a central phyllic, and a western propylitic zone), (iii) helped to delineate potential copper-rich zones coincident with a known lithostructural trend, and (iv) has implications for copper exploration in the greater Alwar basin.