Testing of the recently developed tectonomagmatic discrimination diagrams from hydrothermally altered igneous rocks of 7 geothermal fields

Abstract

Recently developed multidimensional tectonomagmatic discrimination diagrams based on log-ratio variables of chemical elements, discordant outlier-free databases, and probability-based boundaries have been shown to work better than the earlier diagrams. Hydrothermally altered drilled well rock cuttings obtained from different depths of geothermal fields were used to test these diagrams to compare the inferred tectonic setting with the expected one. In spite of the hydrothermal alteration effects, these diagrams provided the following expected tectonic settings: (1) an arc setting for Ahuachapan and Berlin geothermal fields, El Salvador; (2) a rift setting for Cerro Prieto geothermal field, Mexico, and Tendaho geothermal field, Afar region; (3) a MORB setting for Reykjanes geothermal field, Iceland; (4) a transitional arc and collision setting for Roman volcanic provenance, Italy; and (5) an arc setting for Tongonan geothermal field, Philippines. The present study indicates that the recently developed multielement discriminant function based diagrams may be successfully applied to infer the original tectonic setting of hydrothermally altered rock samples and thus confirms the robustness of these diagrams.