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Magmatic sulfide saturation and ore formation in the Konya Volcanic Belt, Western Anatolia

Ariadni Georgatou1, Chiaradia Massimo2

  • Affiliations: 1Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, Athens, Greece 2Department of Earth Sciences, University of Geneva, Geneva 1205, Switzerland

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 31

  • Programme No: 4.1.22

  • Theme 4 > Session 1

Abstract

We use trace element systematics of magmatic sulfides and volcanic rocks of the Konya Volcanic Belt, hosting, among others, the Doğanbey porphyry-Cu-Au prospect and the Inlice epithermal-Au deposit, to investigate the effect of magmatic sulfide saturation to the Cu and Au fertility of the ore-forming systems. A general decrease in whole rock Cu, PGE, Cu/Ag, Se and S noted with magmatic evolution and coupled with petrographical observations, confirm that the system underwent extensive sulfide saturation with sulfides found in both andesites and dacites characterised by wide ranges of SiO2=56-69 wt.%, Cu=4.6-62 μg/g, and Cu/Ag=182-1785. Nonetheless sulfide occurrence and composition varies. Sulfides composed of mostly pyrrhotite (± pentlandite, chalcopyrite) yielded low Cu and Au contents (EPMA: Cumed=0.46 wt.% and LA-ICP-MS: Cumed=1.3 wt.%, Aumed=0.089 μg/g), and were hosted by early crystallising phenocrysts found in the majority of the volcanic products. In contrast, late sulfides composed of chalcopyrite (± bornite, digenite) and corresponding to high Cu contents (EPMA: Cumed=32-56 wt.%), were hosted exclusively by magnetite found only in andesitic--dacitic lavas. Meanwhile, bulk PGE contents confirm that all magmas (seemingly barren and mineralised) are extremely depleted (Pd/Ptmed=1.61) relative to other porphyry Cu-Au forming magmas (Pd/Pt=7-60). These results suggest that regardless of the timing and nature of the sulfide phase saturating, as well as of the initial metal-poor source, Konya magmas produced an economic deposit as well as numerous other prospects with varying type and extent of mineralisation. This in turn points out to the importance of additional processes that promote ore-formation in the area.