The geology of the Rouchel Brook - Davis Creek District, N.S.W.

An area of approximately fifty square miles of the Carboniferous System has been mapped, north-east of Muswellbrook, N.S.W.. The earliest deposition outcropping in the area is a sequence of shallow-water, marine deposits (Waverley Formation) consisting mainly of fossiliferous lutites, arenites and minor limestones. The Waverley Formation contains fauna characteristic of the Schellwienella cf. burlingtonensis and Pustula gracilis assemblage zones. This sequence is followed by the non-marine Isismurra Formation, a sequence of coarse, lithic, zeolithic arenites with thin interbedded volcanics (mainly ignimbrites). Only the lowermost ignimbrite member (Curra Keith Ignimbrite Member) can as yet be correlated outside the area, namely with the Greenland Ignimbrite Member (Hansen, 1968). The Isismurra Formation intertoungues extensively with the Woolooma Formation, a sequence of marine lutites and arenites which lenses out to the west in the Stoney Creek area and which thickens in the east until it directly overlies the Waverley Formation. The Woolooma Formation contains fauna characteristic of Thomasaria voiseyi, Werriea australis and Delepinea aspinosa assemblage zones. An attempt was made to correlate the sequence in the area mapped, to the north (Manser, 1968), as well as to the south (Blayden, 1964; Rudd, 1967) and to use nomenclature originating in both areas. In late Palaeozoic times, the are was subjected to the compressive and shearing forces of the Hunter-Bowen Crogeny which produced extensive folding and faulting.