A mineralogical study of the Suzdal sediment-hosted gold deposit, Eastern Kazakhstan: Implications for ore genesis

Abstract

The Suzdal gold deposit is located in the Western Kalba gold ore belt, Eastern Kazakhstan. The mineralization is confined to the NE-trending tectonic zone that crosscuts Early Carboniferous carbonaceous carbonate and terrigenous clastic rocks. The Suzdal ore system consists of a primary ore zone overlain by an Au-bearing weathering crust, now mined out. The primary ore zone has a low sulfide content (0.5 to 15 vol.%) and contains both visible and invisible gold. Three main ore types and host rocks are recognized: 1) sulfidized bedded carbonaceous sandstone and turbidite-facies siltstone; 2) partly silicified calcareous breccia and carbonaceous sedimentary rock with disseminated sulfides; and 3) strongly silicified brecciated rock. On the basis of the geological, mineralogical, and geochemical data we suggest that the Suzdal deposit was formed by multistage processes. All these processes were accompanied by redistribution of the earlier deposited sulfides and gold and the development of higher grade gold mineralization. 40Ar/ 39Ar dating of hydrothermal sericite yielded ages of 281.9 ± 3.3 Ma and 248.3 ± 3.4 Ma, bracketing the timing of the mineralization between the Early Carboniferous and Early Triassic. The Suzdal ore system has some similarities with Carlin-type mineralization, but differs from Carlin deposits by the presence of gold-bearing arsenopyrite and native gold, the low As-content in pyrite, absence of realgar and orpiment, and low contents of Hg and Tl.