Determination of epithermal alteration associated with gold deposits in Western Turkey, using landsat enhanced thematic mapper and aster imagery

Exploration for metallic minerals in Turkey has been increasing for few years by using the latest technologies. Turkish or foreign jointed firms stil continue to exploration and spend on higher costs on mineral searching. Remote sensing method is used to decrease costs and works that is aimed to highlight potential mine deposits. Remote sensing methods comprise LANDSAT TM, ETM+ and ASTER scenes. Alteration zones including iron oxides and clay anomalies are easily identified by LANDSAT scenes and mineral scattering in the alteration halo is also defined by ASTER scenes. The project aimed to assess the suitability of ASTER and TM/ETM+ data for location of potential of gold deposits, associated with high-grade epithermal alteration in Western Turkey. High-sulphidation type deposits of Ergama, Şapdağ and Kirazlı, low-sulphidation type deposits of Ovacık and Küçükdere and finally high-sulphidation related supergene deposit of Ivrindi fields are used to test remotesensing methodology. Clay and iron-oxide dominated gold-bearing epithermal alteration areas in test areas were highlighted with LANDSAT TM/ETM+ scenes by using colour composites, band rationing, principial component analyses and Crosta technique. Determined alteration zones by LANDSAT scenes were discriminated according to mineral scattering with ASTER scenes by using bant rationing, spectral indices and classification methods. Succesfully applied remote sensing methods of known mine deposits show that undefined potential gold deposits in Turkey could be searched by using same metholody so that metholody will help to decrease higher cost amounts and increase efficient in exploration sector. As zones of alteration have been identified, and the minerals are consistent with high-grade alteration, it posses the question of whether precise characterisation is necessary considering ground data, which will characterise the mineral assemblage will inevitably be acquired. Keywords: LANDSAT, ASTER, gold, hydrothermal alteration, epithermal