TITANIUM-POTASSIUM RATIO AS AN INDICATOR OF THE TECTONIC ENVIRONMENT OF ERUPTION OF BASALT

Abstract

Basalts are the most common volcanic rocks. The way in which their composition is related to types of geological structure in which they occur is a subject of great interest both for the theory of present-day endogenous processes and for paleoreconstruction purposes. The existing petrochemical classification diagrams are designed to correlate the mineral and chemical compositions of the rocks but are not well suited to provide identification of types of geologic environments in which these rocks exist. We shall present here a new diagram based on the concentrations of titanium and potassium oxides in the basalts. Despite some of these cases of uncertain geological identification on the basis of petrogeochemical analysis, the latter remains an important tool in paleoreconstruction. The new approach based on the titanium-potassium ratio in basalts has several advantages over other geochemical diagrams, namely: 1) a broader body of petrochemical data can be utilized; 2) a larger number of types of tectonic environments can be identified; 3) in addition to determining the type of geological structure evolving a given basalt, its degree of maturity at the time of eruption can also be evaluated.