Remote sensing technology and its terrestrial components are more useful than classical geological investigation in mineral exploration and mapping the hydrothermal alteration areas and help to investigate larger areas in short time. Intrusive and volcanic rocks, namely Kösedag syenite and Karatas volcanics in Kösedag (Zara) area shows argillic alteration zones. Two different test area were chosen and sampled for mineralogical studies. XRD-CF investigations showed that kaolinite and illite are the dominant clay minerals in test areas of A and B respectively. The spectroradiometer measurements were carried out 5 times on different surfaces of clayey samples with self-illuminated contact-probe lens within the wavelength range of 350-2500 nm. The spectroradiometer measurements used as endmember were resampled to ASTER short wave infrared (SWIR) bandwidths. Band ratio, principal component and decorrelation stretching analysis were performed to visualize the distribution of clay minerals. In spectral classification method, matched filtering (MF) was used for integrating the satellite image and spectroradiometer measurement data. It was concluded that co-interpretations of the band ratio, principal component, decorrelation stretching analysis, MF results and geological map are very useful in determining, classifying and mapping of the argillic alteration zones related to hydrothermal processes on ASTER image and they seem to be very useful to identify the target areas for mineral exploration.

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Abstract:The Çöpler gold deposit occurs within the stockwork of quartz hosted by the Çöpler granitoid (Eosen) and by surrounding metasediments of Keban metamorphic (Late Paleozoic -Early Mesozoic) and the Munzur limestones (Late Carboniferous -Early Cretaceous). Native gold accompanied by small amounts of chalcopyrite, pyrite, magnetite, maghemite, hematite, fahlerz, marcasite, bornite, galena, sphalerite, specular hematite, goethite, lepidochrosite and bravoitic pyrite within the stockwork ore veinlets. In addition, epidote (pistazite -zoisite), garnet, scapolite, chlorite, tremolite/actinolite, muscovite and opaque minerals were determined within the veinlets occurred in skarn zones. The study of fluid inclusions in quartz veinlets showed that the hydrothermal fluids contain CaCl 2 , MgCl 2 and NaCl and the salinities of the two phases (L+V) inclusions range from 1.7 to 20.6% NaCl equivalent. Salinity values up to 44% were determined within the halite bearing three phases inclusions. Their homogenization temperature values have a wide range from 145.0 to 380.0 • C, indicative of catathermal/hypothermal to epithermal conditions. The δ 18 O and δD values of the fluid inclusion waters from the Çöpler granitoid correspond to those assigned to Primary Magmatic Water, those from the metasediments of Keban metamorphics fall outside of the Primary Magmatic and are within the Metamorphic Water field. A sample from a quartz vein within the skarn zone hosted by the Munzur limestones has a particularly low δD value. The results suggest that fluids derived from the granitoids were mixed with those derived from the metasediments of Keban metamorphics and the the Munzur limestones and resulting in quartz veinlets in these lithologies and the formation of stockwork ores. In view of the occurrence, the features described and processes envisaged for this study area may be applicable in similar settings.

Hidrotermal alterasyon alanlarının tespiti, maden arama faaliyetlerinin ilk aşamalarından bir tanesi olup özellikle porfiri tip zenginleşmelerin keşfinde önemli bir adımı oluşturmaktadır. Önceleri arazi çalışmaları ve gözlemlerle tespit edilebilen bu tür alanlar artık günümüzde gelişen teknoloji ile birlikte uydulardan elde edilen görüntüler üzerinde yapılan işlemlerle tespit edilebilmektedir. Bu çalışmada Sivas ilinin Zara ilçesinin kuzeyinde Ağmaşat Yaylası'nda belirlenen hidrotermal alterasyon alanlarının ve çevre jeolojik birimlerinin sınırları ASTER uydusu SWIR görüntüleri ile belirlenmeye çalışılmıştır. Uygulanan dekorelasyon gerilmesi ve ana bileşenler dönüşümü metodları ile elde edilen veriler, arazi çalışmaları sırasında hazırlanan jeoloji haritası ile yüksek oranda örtüştüğü belirlenmiştir. Bu veriler ışığında tespit edilebilecek yeni alterasyon alanları potansiyel maden sahası olarak değerlendirilebilecektir.

In recent years, a large number of studies have been carried out on determining geological characteristics using remote sensing studies and their usefulness. The integrating satellite images and terrestrial spectral data are used distinguishing lithologies in geological units. The use of remote sensing images helps to save time and to reduce the cost of mapping works. In this study, the usability of ASTER SWIR images in distinguishing rock types and in determination of contacts between lithological units in Kösedağ area between Zara and Suşehri towns of Sivas Province. Syenitic, andesitic, basaltic and ophiolitics rocks are cropt out in this area. Spectral signatures of the representative samples from these rock types were measured via ASD spectroradiometer. The signatures were resampled to ASTER SWIR bandwidth as end member. Matched filtering method was performed on the images for spectral classification. The results showed that distinguishing of the mentioned rock types is possible and the boundaries between rock types on the spectral images are mostly coincided with the boundaries on the 1:100.000 scale geological map of the study area.