Geology of hill end trough Molong high: Stratigraphy and structure of the Sofala Volcanics

Abstract

The Sofala Volcanics are a sequence of chert-laminated lutites, arenites and rudites (Fig. 1),containing graptolites of Gisbornian age (Cas, 19691, and including a possible andesite vent 10 km east of Sofala (Cas, 1969). The clastics are immature sediments of andesitic volcanic detritus, and are thought to have been rapidly emplaced on the flanks of one or more marine volcanoes by subaqueous mass-flow processes, mainly of the grainflow type (Stauffer, 1967; Carter, 1975). Packham (1968) suggested a local source for the uppermost rocks and it is possible that the vent may represent that source. The chert bands, which are radiolarian in part, represent periods of non-supply of volcanoclastic sediment.