International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

Testing of multidimensional tectonomagmatic discrimination diagrams on fresh and altered rocks

Pages: 195 - 208


Abstract: We evaluated 55 multidimensional diagrams proposed during 2004–2013 for the tectonic discrimination ofultrabasic, basic, intermediate, and acid magmas. The Miocene to Recent rock samples for testing the diagrams had notbeen used for constructing them. Eighteen test studies (2 from ocean island; 2 from ocean island/continental rift; 6 fromcontinental rift; 4 from continental arc; 2 from island arc; 1 from mid-ocean ridge, and 1 from collision) of relativelyfresh rocks fully confirmed the satisfactory functioning of these diagrams for all tectonic fields for which they wereproposed. Eight additional case studies on hydrothermally altered or moderately to highly weathered rocks were alsopresented to achieve further understanding of the functioning of these diagrams. For these rocks as well, the diagramsindicated the expected tectonic setting. We also show that for testing or using these diagrams the freely-available geochemistry databases should be used with caution but certainly after ascertaining the correct magma types to selectthe appropriate diagram sets. The results encourage us to recommend these diagrams for deciphering the tectonic settingof older terranes or areas with complex or transitional tectonic settings.

Keywords: tectonic setting, discriminant function diagrams, arc, within-plate, rift, collision

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