The Nonsulphide zinc mineralization at Hakkari (Turkey)

The Hakkari Nonsulphide Zinc project area (Red Crescent Resources) is situated at the extreme SE margin of Turkey (Reynolds & Large, 2010). From the geological point of view its position is within the northern margin of the Arabian Platform. The geology of the area consists of sedimentary units ranging in age from Precambrian-Cambrian to Paleogene-Middle Miocene. The Hakkari orebodies occur in Middle-Triassic to Early Cretaceous shallow water carbonate rocks (Cudi Group): the carbonates consist of both structurally deformed limestones, and of dolomitic to cherty rocks, which exhibit brittle deformation resulting in extensive breccias with calcite veins. The zinc mineralization is generally hosted in a more porous “reef limestone” or in breccia units, flanked by cryptocrystalline or cherty dolomite. The mineralized horizons occur as multiple layers ranging in thickness from a few cm to a few m. It is apparent that the Hakkari area is situated in a fold and thrust belt region adjacent to two suture zones (the Bitlis and Zagros sutures). Compressive tectonism of the area has produced multiple duplications, and hence probable thickening, of the mineralized levels. A complete petrographic and mineralogical characterization of core samples from the Hakkari project has been carried out between the NHM (London) and Naples University. The samples were examined using a range of techniques: XRD qualitative and quantitative (Rietveld) methods, chemical analysis, SEM-EDS and WDS analysis. The main findings of our study were the attribution of most of the zinc to the minerals smithsonite (occurring up to max 55% in the core samples) and hemimorphite (occurring up to max 70%). Zinc is present in Fe-(hydr)oxides as well, and traces are found in minor clay minerals. No sphalerite has been detected. Lead occurs in cerussite (which ranges up to few weight % in most samples), or as remnant galena. Silver is present in some samples, although relatively scarce. Barite can be locally very abundant (up to 13% by weight), and occurs in two different forms: as fragmented and largely unreplaced remnants of presumably primary mineralization, but also as thin secondary needle-like growths, possibly precipitated in association with smithsonite and/or hemimorphite. The calcite veins in the breccia are locally enriched in lead and minor cadmium. In the whole Nonsulphide mineralized area a diffuse As-Sb-Tl geochemical enrichment also occurs: this points to an interesting association of pathfinder elements, which might be useful in further exploration.