Early devonian igneous activity and some stratigraphic correlations in the tumut region new south wales australia

Barkas, J. P.

North of Talbingo, the Tumut River in southern New South Wales, Australia, traverses a belt of folded Silurian metasediments and volcanic rocks, the latter being part of an extensive association here named the Wiradjuri Volcanics. Several bodies of sub-volcanic leucogranite (the Gocup and Bogong Granites, and the Killimicat and Lobs Hole Adamellites) postdate the rocks of this belt and exhibit clear petrographic and chemical affinities. Ignimbritic rhyolites of the Buddong and Minjary Volcanics and the Gatelee Ignimbrite are stratigraphically equivalent, spatially associated with these leucogranites and also comprise a petrologically coherent group. New radiometric and paleontological evidence indicates that both groups are of Early Devonian age and enables regional stratigraphy to be refined. The ignimbritic rhyolites may represent the extrusive equivalents of the leucogranites but other volcanic and plutonic rocks of post-Silurian age in the area are clearly unrelated to this magmatic episode. Brachiopoda collected include Howellela? jaqueti, Meristina sp., Molongia? sp., Strophonella manta, Strophodonta? sp., Nadiastrophia? sp., Hipparionyx? sp. chonetid indet., Isorthis alpha, Schizophoria convexa and dalmanellid indet. A coelenterate, cladoporid indet., was found.