Geochemical behavior of rare earth elements in high-temperature hot springs and its indications: A case study in the Daggyai hydrothermal area, Tibet

Abstract

The Daggyai hydrothermal area (Tibet) is located on the southern margin of the Lhasa-Gangdise terrane and adjacent to the middle of the Indus-Tsangposuture. Acid, neutral, and weakly alkaline hot springs are ubiquitous in Daggyai, offering a peerless opportunity to study the distribution of rare earth elements (REE) in various geothermal waters as well as their geochemical origins. In this study, different types of the Daggyai hot springs were systematically collected to determine their REE concentrations, to discern the REE patterns and to calculate the REE speciation, which is helpful for revealing the indications of the geochemical behavior of REEs in high-temperature geothermal environments. The results of the study show that the REEs in the Daggyai hot springs behaved conservatively, with their concentrations being affected by the sorption of Fe-or Al-rich minerals or amorphous phases instead of sulfate minerals, and the REE patterns and speciation were controlled by the redox conditions and fluid-rock interactions in the reservoirs, capable of reflecting the geological genesis and the general hydrochemical characteristics of the hot springs. Although the major constituent hydrochemistry of the Daggyai hot springs demonstrates that the reservoir host rocks are primarily felsic rocks, the negative Ce anomaly of the neutral-to-alkaline hot springs implies that there are possibly carbonate rocks in the Daggyai reservoirs. This work is a typical example of relevant studies on REE geochemistry in high-temperature hot springs.

Keywords

• hot spring
• rare earth element
• water-rock interaction
• redox condition
• daggyai