Abstract:
The statistical method of linear discriminant analysis has been applied to distinguish Pliocene to Recent basic rocks on the basis of their major-element composition. Studied basic rock suites are from four tectonic settings: island arc, continental rift, ocean island, and mid-ocean ridge. Field boundaries were derived by computing probability functions replacing the past practice of fitting lines by "eye." Highly successful discrimination diagrams have been obtained. A testing set shows that the rate of correct classification ranges from 76% to 96%, and from 80% to 92% when three and four tectonic groups are considered at a time, respectively. The high potential of this approach to identify different tectonic settings for basic rocks is only reduced by the complex tectonic history shown by a few of the compiled samples, by crustal contamination effects in some basic rock samples, and the similarities of mantle sources tapped in different tectonic settings.