Deep permeable fault-controlled helium transport and limited mantle flux in two extensional geothermal systems in the Great Basin, United States

作者：Banerjee Amlan^*; Person Mark; Hofstra Albert; Sweetkind Donald; Cohen Denis; Sabin Andrew; Unruh Jeff; Zyvoloski George; Gable Carl W; Crossey Laura; Karlstrom Karl

来源：Geology, 2011, 39(3): 195-198.

DOI：10.1130/G31557.1

This study assesses the relative importance of deeply circulating meteoric water and direct mantle fluid inputs on near-surface He-3/He-4 anomalies reported at the Coso and Beowawe geothermal fields of the western United States. The depth of meteoric fluid circulation is a critical factor that controls the temperature, extent of fluid-rock isotope exchange, and mixing with deeply sourced fluids containing mantle volatiles. The influence of mantle fluid flux on the reported helium anomalies appears to be negligible in both systems. This study illustrates the importance of deeply penetrating permeable fault zones (10(-12) to 10(-15) m(2)) in focusing groundwater and mantle volatiles with high He-3/He-4 ratios to shallow crustal levels. These continental geothermal systems are driven by free convection.

• 出版日期2011-3