Pasinex owns 50% of Horzum Maden Arama ve Isletme Anonim Sirketi (“Horzum AS”) which holds the producing Pinargozu high grade zinc mine, through its 100% owned subsidiary Pasinex Arama ve Madencilik Anonim Sirketi. The other 50% owner is Akmetal Madencilik Sanayi ve Ticaret A.S. (“Akmetal”), a private Turkish company.
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Summary:
Pinargozu and Horzum’s passive margin setting with inversion and collisional orogeny is favourable for the formation of MVT and Irish-type zinc deposits. The post-collisional Neogene magmatism on the Anatolian plateau is permissive of skarn/manto (or CRD) type deposits; CRD deposits typically form distal from porphyritic intrusions in magmatic arc or back-arc settings.
Pinargozu and Horzum occur within the Tufanbeyli–Horzum Zinc Belt, where mineralisation has generally been interpreted as MVT deposits, formed within the passive- margin platform carbonate sequences with fluid-flow systems related to the Cimmerian or Alpine orogenic compression and uplift. However, the deposits in the Nigde, Zamanti, Keban district have been described as intrusive-related.
Mining to date at Pinargozu has mainly been of secondary zinc mineralisation, formed through supergene oxidation of massive sulphide mineralisation. Primary massive sulphide mineralisation is becoming more dominant as the mine becomes deeper.
Sulphide Mineralisation
The primary mineralisation is characterised by coarse massive sphalerite-rich sulphide with subordinate pyrite. Massive galena also occurs and typically post-dates sphalerite, cutting and replacing sphalerite and associated with more abundant carbonate gangue. The carbonate weathers brown and is interpreted to be iron-rich and potentially manganoan. The absence of a black weathering patina suggests that manganese is subsidiary.
Contacts of massive sulphide with bleached limestone are sharp, with minor disseminated and clotty sulphide in the limestone. Based on mining, the mineralisation is crudely stratabound within the central part of the Degirmentas Formation. Observations underground suggest that massive sulphide contacts are mainly stratabound.
Secondary Zinc Mineralisation
During weathering of massive sulphide deposits in limestone, sulphide oxidation generates acid which readily transports Zn, and to a lesser extent Pb, until neutralised by carbonate wall rocks. Secondary zinc mineralisation can be direct replacement, where neutralisation is almost immediate and secondary minerals directly replace primary, or wall-rock replacement where zinc is transported out of the primary deposit and are precipitated by reaction with the wall rock, often in acid-enhanced karst cavity systems (Hitzman et al., 2003). Acid generation capacity is strongly related to pyrite content, which is low at Pinargozu.
Secondary zinc mineralisation at Pinargozu consists mainly of smithsonite, ZnCO3, and hemimorphite, Zn4Si2O7(OH)2·H2O, with minor amount of replacive hydrozincite, Zn5(CO3)2(OH)6. Secondary zinc mineralisation is associated with abundant concentrations of Fe-oxides and hydroxides and cerussite, PbCO3, as well as remnant galena, sphalerite, and pyrite. Very high-grade zinc mineralisation (>40% Zn) is associated with banded smithsonite.
Mineralisation is accompanied by a general tenor of >50 g/t silver. Local pockets of high grade silver (>250 g/t) exist, most notably in the southern lodes where sulphide proportions are higher. Elevated lead concentrations (typically galena) are almost entirely restricted to these southern lodes where, as development has extended deeper, sulphide mineralisation has become more prevalent.