Crystallization temperature of vein quartz at Peschanka porphyry Cu-Mo-Au deposit, Western Chukchi Peninsula, Russia: Estimation from content of paramagnetic titanium centers in quartz

Abstract

The Al and Ti paramagnetic impurity center concentrations in pre-ore and ore-bearing quartz at the Peschanka porphyry copper-molybdenum-gold deposit in the Western Chukchi Peninsula, Russia were determined using electron paramagnetic resonance (EPR). The [AlO4-/ h+]0 concentration in pre-ore and ore-bearing quartz varies from 29 to 124 and from 13 to- + 0- + 0101 at. ppm, respectively. The contents of [TiO4 /Li ] - and [TiO4 /H ] -centers reach 20 and6,3 at. ppm, respectively. Pre-ore stage quartz associated with the formation of biotite-potassiumfeldspar-quartz alteration and quartz of the ore stage associated with the formation of quartz-sericite rocks followed by the ore deposition are substantially in content of the titanium centers,- + 0- + 0especially [TiO4 /H ] -centers: the [TiO4 /H ]concentration is much higher in the pre-orestage quartz (>2 at. ppm) than that in quartz related to copper mineralization (<2 at. ppm).+ 0The [TiO4-/Li ]concentration also decreases from pre-ore to ore-bearing quartz. Taking intoaccount the data obtained, the formation temperature of pre-ore and ore-bearing quartz estimatedfrom a titanium-in-quartz geothermometer is 590-470 °C (average 520 °C) and 510-310 °C (average 430 °C), respectively. The obtained temperature range of 590 to 310 °C is similar to that determined from homogenization of fluid inclusions in pre-ore and ore-bearing.