Geology and Isotope Geochemistry (c-O of the Diyadin Gold Deposit, Eastern Turkey: a Newly-Discovered Carlin-Like Deposit

Abstract

Diyadin mineralization is the first reported gold deposit located in a collisional tectonic environment in Eastern Anatolia. The mineralization is related to N-S and N10-20 degrees W-trending fault systems and hosted within the Paleozoic metamorphic basement rocks of the Anatolide-Toride microcontinent. Calc-schist, dolomitic marble and Miocene and Quaternary volcanic rocks comprise the exposed units in the mineralized area. Geochemical signatures, alteration types and host rock characteristics of the Diyadin gold deposit resemble those of Carlin-type deposits. Mineralization is constrained by alteration of overlying volcanic rocks to younger than similar to 14 Ma (K-Ar). Carbon and oxygen stable isotope measurements of carbonate rocks were made on six drill holes (n = 81) with an additional four samples of fresh carbonate rocks from surface outcrops. Background carbonate rocks have delta C-13(V-PDB) similar to 1.8 parts per thousand. and delta O-18(V-SMOW) similar to 27 parts per thousand. Isotopically-altered host rock samples have decreased delta O-18 (down to similar to+11.4 parts per thousand) and variable delta C-13 (from -3.6 to +4.8 parts per thousand). Postore carbonate veins and cave-fill material have distinctly different isotopic signatures, particularly carbon (from delta C-13 = +8.4 to +9.8 parts per thousand). Whether this post-ore carbonate is simply very late in mineralization associated with the gold system, or is a completely different, younger system utilizing the same pathways, is unclear at present. Within the host rock sample set, there is no correlation between gold and delta C-13, and a weak correlation between gold and delta O-18, indicative of water-rock interaction and isotopic alteration. Both the isotopic data and structural mapping suggest that the main upflow zone for the deposit is near the northern portion of the drill fence. Additional data at multiple scales are required to clarify the relationship(s) between fluid flow and mineralization. (C) 2011 Elsevier B.V. All rights reserved.