Facies analysis and facies associations in the recognition of volcanic centres in silicic terranes: An example from the Early Devonian of Australia

Abstract

The Snowy River Volcanics, a belt of rhyolitic to basaltic volcanics, volcanogenic sediments and shallow intrusives, accumulated during the Early Devonian in a predominantly terrestrial continental rift basin. The uppermost part of the Snowy River Volcanics contains a complex stratigraphy of lensoidal silicic volcanics, lesser mafic volcanics and sedimentary units which can be divided into five domains displaying distinctive facies and facies associations. Recent studies of modern silicic volcanoes and their products allow the formulation of a schematic facies model for subaerial silicic centres. This model divides the silicic centre into proximal‐vent and distal facies associations. Stratigraphic complications arise from the interaction of several volcanic centres. The model is applied to facies associations recognized in the upper Snowy River Volcanics. One probable caldera succession is recognized, with indications for the existence of two other silicic centres outside the immediate area of study. The ...