Bibliothek // Lexikon der Geothermie // S

Spurenelemente

Die Analyse von Spurenelementen dient meist dazu, Alterationen des 'Gastgesteins' bzw. seiner Fluide zu untersuchen. Die Spurenelemente dienen dabei als tracer.

Magmatische Gesteine haben oft Spurenelemente, die untypisch für oberflächennahe Sedimente sind. Oft sind Spurenelemente das Resultat von Gestein/ Fluid Interaktionen. Sie können Auskunft über Schwerkraft- oder Auftriebbedingte Fluidbewegungen geben.

Anwendung in der Geothermie

Christianson, et al., (1983)¹ beschrieb seine Spurenelementanalyse an den Roosevelt hot springs wie folgt:

“Chemical interaction between thermal fluids and reservoir rocks at Roosevelt Hot Springs has resulted in distinctive trace-element enrichments and depletions within the rocks. The chemistry of the solid materials documents the time-integrated effects of chemical redistribution within the geothermal system. Within the Roosevelt system, five characteristic deposits or suites of trace-element enrichments are recognized, each representative of different combinations of physical and chemical conditions within the thermal system. These are:

concentrations of As, Sb, Be, Mn and Hg associated with siliceous sinter or cemented alluvium;
concentrations of Ba, W, Be, Cu, As, Sb and Hg associated with manganese and iron-oxide deposits;
high concentrations of Hg in argillized deposits at fumaroles and lower concentrations in a diffuse halo surrounding the thermal center;
concentrations of As and Li immediately surrounding fluid-flow-controlling fractures or permeable horizons; and (5) deposits of CaCO3 at depth where flashing of brine to steam has occurred.”