The geology and genesis of a gold-rich, copper porphyry occurrence in the Eastern Pontids, NE Turkey

Röckl, Ludwig Otto (1998) The geology and genesis of a gold-rich, copper porphyry occurrence in the Eastern Pontids, NE Turkey. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The subeconomic, Gümüshane (GMS) porphyry copper-gold system was discovered 1990 by the exploration company Anglo-Tur Madencilik A.S. in the Eastern Pontids of Turkey and represents the first Au-Cu occurrence of this type found in this country. This mineralisation is located within the Eastern Black Sea Metallogenic Province associated with an E-W trending, Jurassic - Eocene volcanic arc complex. The gold-rich, copper porphyry-type system developed in the Early Eocene (52.3Ma) and is related to the emplacement of a composite intrusive stock of calc-alkaline quartz-diorites and tonalites into an Upper Cretaceous to Eocene volcano-sedimentary sequence. Results of drilling have shown that mineralisation is essentially restricted to the GMS stock and contains 20Mt minable ore at an average grade of 0.25% Cu, 0.45g/t Au and 65ppm Mo.

The composite GMS stock and the surrounding area were mapped and sampled for mineralogical and geochemical investigation. K-Ar ages were obtained on one basalt body and four plagioclase-amphibole±quartz - phyric intrusions which have a similar mineralogy and texture to the igneous units of the composite GMS pluton. 7 specimens of the GMS complex and 36 of the country rock were analysed for major and trace elements by the XRF method. Furthermore, the concentration of the rare earth elements in 38 GMS and 23 country rock samples was determined by a solution ICP-MS technique and ⁸⁷Sr/⁸⁶Sr and/or ¹⁴³Nd/¹⁴⁴Nd in 24 representative igneous rocks were measured by TIMS. The source, the nature of the parental magmas and the magmatic evolution of the igneous country rocks and the composite GMS system were investigated and the effects of alteration on the major and REE composition of the hydrothermally altered rocks of the composite GMS pluton were examined. The attempt to date the sedimentary formations in the area by palynological techniques and fitting of the ⁸⁷Sr/⁸⁶Sr measured on four limestone samples to the ⁸⁷Sr/⁸⁶Sr versus age curve of seawater was unsuccessful.