Genetic Features of Gümüsler (Nigde, Turkey) Polymetallic Antimony-Mercury Mineralization

Yalcin M.G.*, Ilbeyli N.*, Yaman S.^Y, Yalcin F.^§

* Akdeniz University, Faculty of Engineering, Department of Geological Engineering, 07058 Antalya, Turkey

Y Cukurova University, Faculty of Engineering, Department of Geological Engineering, 01330 Adana, Turkey

(deceased)

^§ Akdeniz University, Faculty of Science, Department of Mathematics, 07058 Antalya, Turkey

 

Central Anatolia is made up three crystalline massifs: (i) the relatively larger Kirsehir Massif; (ii) the Akdagmadeni Massif; and (iii) the smaller Nigde Massif. The study area is situated in the Nigde Massif which is located to the south of central Anatolia.

The basement of study area is made up of Paleozoic-aged metamorphic rocks (Gümüsler, Kaleboynu, Asigedigi Formations) containing marble, gneiss, amphibolite, schist and quartzite. These units are cut by Pre-Upper Cretaceous-aged ophiolitic rocks (mainly gabbro) and intrusive rocks (Uckapili pluton). They are overlined by Upper Miocene-Lower Pliocene crystal vitric tuff and Quaternary slope wash and alluviums. The Uckapili pluton is mainly in stocks and showing very weak deformation and foliation characteristics (Yalcin, 1995). The pluton is cut by aplitic, pegmatitic and microgranitic dykes. The Uckapili rocks are light to dark grey and medium- to fine-grained. It is mainly granodiorite in composition containing quartz, alkali feldspar, plagioclase, biotite muscovite and Fe-Ti oxides (Yalcin, 1995).

In study area, mineralization takes place in the marbles of Gümüsler formation which forms the sub-series of Nigde metamorphics. This formation present a thickness between 50-150 m. 70% of the formation consists of gneiss and the rest is schist, marble and quartzite. Marbles are seen alternating with gneisses and their thickness reaches up to 90 m. Very coarse and interlocking rhombohedral cleavage in the section samples consists of calcite crystals including pressure twins (Yalcin and Yaman, 1996). These twins show bending and curling. Cracks and gaps close to the mineralization area are partly filled with secondary minerals such as goethite and psilomelane. This feature is not observed in the distant areas. Nodular, colloform, synthetic and banded textures of minerals indicate epithermal formation. Silification, carbonatization, epidotization, chloritization are seen in the wall of ore. Therefore, ore minerals present an epigenetic-hydrothermal formation model.

References

Yalcin M.G., 1995, “Gumusler (Nigde, Turkey) Mineralogy and Geochemical Study of Polymetallic Antimony-Mercury Deposits”, Cukurova University, Phd Thesis, 165 p. Adana, Turkey (in Turkish with English abstract).

Yalcin M.G. and Yaman S., 1996, “Gumusler (Nigde) Antimony - Mercury Mineralogical examination of Mineralization”, Geosound, 28, 189-201.