Active Metal Deposition in a Giant Geothermal System

Metallogenic models are vital to mineral exploration. However, there is debate concerning the origin of hydrothermal-type ore deposits such as vein-type U and W deposits. The formation, migration, heating and controls on the composition of metal-fertile fluids in active geothermal systems provide insights into the formation of ore-forming fluids. Fluid's metal contents are relatively high in the Yadong-Yangbajing-Naqu (YYN) geothermal belt of South Tibet, and a similar association of enrichment has been found in saline lakes of the region. This study analysed major ions and trace metal contents together with stable (O, H) isotopes of water samples from geothermal springs and wells and regional saline lakes and rivers along the Beng and YYN fault systems. Results demonstrate that metal-fertile geothermal brines, were sourced from the Bangor saline lake. This study highlights the role of evaporation of saline lake water in the formation of metal-fertile brines and the contrasting behaviors of U and W in hydrothermal conditions.