An Automated Method to Generate and Evaluate Geochemical Tectonic Discrimination Diagrams Based on Topological Theory

Abstract

Discrimination diagrams can be used to distinguish different tectonic settings of igneous rocks. To improve the quality and efficiency of the design of discrimination diagrams, an automatic design and assessment method for discrimination diagrams is proposed based on topology theory. The method is aimed at programming the traditional process of discrimination diagram design, enabling computers to simulate the visual discrimination process. It thus automatically designs tectonic setting discrimination diagrams by investigating all possible combinations of geochemical elements. In the experiment, analyses of 3803 gabbro samples were collected from three tectonic settings, including island arc, ocean island, and mid-oceanic ridge. Using the proposed method, we found thousands of discrimination diagrams with fields overlapping less than 10%. By analyzing these diagrams, the most critical elements (or element ratio pairs) are identified. Based on the result, the feasibility of using gabbroic rocks to discriminate between tectonic settings is illustrated and four representative discrimination diagrams, including the La/Y–Nb/Ba diagram, Nb/Sc–Sc/Ba diagram, Ba/Nb–Ba/Sc diagram, and La/Na2O–Nb/Ba diagram, are recommended for use. This research supports the view that gabbroic rocks can also be used to discriminate between different tectonic settings. The method could also be applied to other rock types.