Trace Element Geochemical Zoning in the Roosevelt Hot Springs Thermal Area, Utah

Abstract

Chemical interaction of thermal brines with reservoir rock in the Roosevelt Hot Springs thermal area has resulted in the development of distinctive trace element signatures. Geochemical analysis of soil sample, shallow temperature gradient drill hole cuttings and deep drill hole cutting provides a three dimensional perspective of trace element distributions within the system. Distributions of As, Hg and Li provide the clearest expression of hydrothermal activity. Comparison of these distribution suggest that Li, followed by As and Hg, are progressively deposited by outward flowing, cooling, thermal fluids. Hg, in contrast to As and Li, is distributed only think the outer portions of the thermal system where temperatures are less than 225°C. Heating experiments indicate that extensive Hg remobilization in Roosevelt samples occurs at temperatures as low as 200-250°C. This suggests that the distribution of Hg largely reflects the present system thermal configuration and that this distribution may be a useful solid geothermometer.