Geophysical and geological interpretation of the Junee ?Narromine Volcanic Belt

Abstract

The Junee-Narromine Volcanic Belt is the westernmost and most poorly outcropping belt of Ordovician rocks that represent the dispersed remnants of the Ordovician Macquarie Arc. The northern part is under deep cover of Surat Basin. In areas of poor or nonexistent outcrop such as these, most of the knowledge of the geometry and components of the geology comes from the interpretation and modelling of gravity and aeromagnetic data - interpolation between outcrops and extrapolation into areas of deep cover. Most of the shape of the Junee-Narromine Volcanic Belt is a reflection of meridional bounding faults of the Tullamore Trend. Individual complexes are elongated N-S or NNW and deformation is generally low, except in the high strain zones. From north to south, Ordovician complexes with approximately meridional Tullamore trends become rotated into the Gilmore Trend and then become aligned along splay faults as thrust sheets (Gidginbung Volcanics) before being truncated by the Gilmore Fault.