Environmental, palaeogeographic, and tectonic setting of the Mullions Range Volcanics, New South Wales

The Mullions Range Volcanics in the Mullion Creek‐Kerrs Creek area consist of Middle to Late Silurian rhyolite and dacite lavas‐and intraformational clastic rocks, lying on the eastern flank of the Molong Rise. They are the products of a shallow water (maximum depth c.500 m) volcanic pile that separated the broad Narragal Lagoon on the Molong Rise from the Hill End Trough to the E. Facies and thickness changes within the Mullions Range Volcanics suggest a major volcanic centre to the S or SE of the area studied, where the pile may have become emergent. Facies changes in the overlying Bay and Cunningham Formations support the existence of a volcanic pile, which had a topographic influence on subsequent deposition. The Mullions Range Volcanics probably represent the silicic phase of volcanism associated with the initiation of rifting to form the Hill End Trough.