Integration of PRISMA hyperspectral satellite data with ground based geological investigation for mapping alteration minerals associated with the Neem-ka-Thana Cu belt in Rajasthan, India

Abstract

Hydrothermal deposits are commonly associated with specific alteration minerals that serve as key indicators for mineral exploration. The Neem Ka Thana Cu Belt, situated southeast of the Khetri Cu deposit within the Alwar-Ajabgarh sub-basin of the North Delhi Fold Belt, is notable for its Bornite-rich Cu-S mineralization. Despite its geological significance, detailed spectral mapping to delineate the alteration minerals associated with base metal mineralization remained limited. This study addresses this gap by utilizing the “PRecursore IperSpettrale della Missione Applicativa” (PRISMA) hyperspectral sensor to detect and map alteration minerals associated with Cu-S mineralization.

To achieve this, we applied Relative Band Depth (RBD) indices on targeted spectral subsets of PRISMA data to identify Fe-oxides/hydroxides and Al-OH-bearing minerals. We detected key alteration minerals, including muscovite, illite, chlorite, montmorillonite and Fe-oxide and hydroxides such as goethite, hematite, and limonite, by targeting their diagnostic absorption features. The resulting spectral maps highlighting the spatial distribution of the targeted mineral groups were validated with field investigations and laboratory assessments. The study demonstrates that the integration of hyperspectral analysis with conventional geological techniques can help to understand the mineral distribution and associated alteration processes. The use of PRISMA hyperspectral data provides a powerful, non-invasive means for reconnaissance mapping of exposed lithologies, delivering targeted information that is crucial for optimizing subsequent field investigations and drilling operations. The present work highlights the potential of PRISMA data in advancing the methodologies of mineral exploration and lithological mapping, contributing valuable insights for the geoscientific community.