Spectral characterization of ophiolite lithologies in the Troodos Ophiolite complex of Cyprus and its potential in prospecting for massive sulphide deposits

Abstract

The island of Cyprus hosts one of the best preserved ophiolite sequences of the world: the Troodos massif. Lithologically the complex comprises a mantle series of ultramafic rocks overlain by gabbros and (plagio)granites. The crustal sequence consists of dyke swarms with two series of pillow lavas at the top known as the lower pillow lava and the upper pillow lava. Massive sulphide deposits, that have for long been exploited in Cyprus, occur at the contact between the lower and upper pillow lava series. This contact is difficult to map in the field. In this paper we explore the possibility of using advanced image processing techniques to discriminate the main lithological units to guide in mineral prospecting. A detailed field-spectral stratigraphic study forms the basis for the selection of potential spectral end-members characterizing the TM image used. It is shown that spectral angle mapping of TM data can provide mineralogical maps that compare favourably with known surface geology and provide insight in potential prosperous areas for mineral exploration when combined with standard hydroxyl and iron oxide mapping ratio images. Our work demonstrates how remote sensing can be used for mineral exploration at a reconnaissance stage in ultramafic terrains.