Trace elements in scheelite and quartz from the muruntau/Myutenbai gold deposit, Uzbekistan: constraints on hte nature of the ore-forming fluids

摘要

Inferences on the chemical characteristics of the ore-forming fluids of the giant Muruntau/Myutenbai gold deposit (total Au>4300 tons) in Uzbekistan may be derived by comparing trace element contents of scheelite and quartz from high-grade, steep ore veins. The two minerals exhibit elevated Sr contents indicating the uptake of this element by the fluids during alteration of plagioclase in the wall rocks. REE distribution patterns are controlled by fractionation effects between the different vein minerals. Scheelite and quartz from the neighbouring Muruntau and Myutenbai ore bodies show some distinct variations in their trace element characteristics. Positive Eu anomalies and elevated U contents in scheelite and quartz from Myutenbai as well as the general enrichment of tungsten in the ores from Myutenbai suggest a "rare metal affinity". A concept of a uniform fluid source with variations in the fluid evolution is favoured to explain differences between the two ore bodies.