Analysis of change in hydrogeological conditions in Tyrnyauz tungsten–molybdenum field

Abstract

Tyrnyauz tungsten–molybdenum deposit is located within the Elbrus volcanic region, on the left bank of the river Baksan. The deposit is associated with a series of granitoids formed during the period of activation of tectonic–magmatic processes at the southern boundary of the Scythian plate in the Meso-Cenozoic, and embedded in carbonate, terrigenous and volcanic rocks of the Devonian, Carboniferous and Jurassic. Groundwater that forms the drainage runoff is mainly fissure or fissure-vein water. In the field, groundwater belongs to an integrated system, within which, subject to the feeding conditions, and to the nature of circulation and chemical composition, two hydrogeological zones are clearly distinguished alongside with a mixing subzone between them. Between 1964 and 1997, the average annual water inflow into the underground openings of Molybdenum Mine varied from 122.4 m3/h in 1965 to 629.0 m3/h in 1986. In recent years of observations, the average annual water inflow ranged from 427.0 m3/h (1993) to 420.0 m3/h (1997). According to the measurements in October–November 2018, the water inflow in Molybdenum Mine was 494.3 m3/h. By the data of VIOGEM, in mid-September 2020, the inflow of groundwater into the mine amounted to 571 m3/h. The temperature of drainage waters in the Central ore field of the deposit, on the upper level of 2767 m during the study period ranged from 4.0 to 5.0 °C. Infrared photography using thermal imager detected hidden glaciers and flows of cold groundwater inside the rock mass.