Broken Hill Exploration Initiative - Ameroo Hill GeoPDF

As part of the Broken Hill Exploration Initiative (BHEI), Geoscience Australia and the Department of Primary Industries South Australia (PIRSA) recently embarked on a two-year joint project to better understand the deformational history and tectonic evolution of Palaeoproterozoic rocks in the Outalpa Inlier, South Australia. This project is one of several structural studies undertaken on these rocks although to date no consensus has emerged regarding the number, orientation and geometry of the main deformational events. To address this problem, detailed structural and stratigraphic studies were undertaken around Ameroo Hill and Tommie Wattie Bore region in the central part of the inlier where a well defined stratigraphic succession is exposed. Comparable studies undertaken in other parts of the Olary Domain indicate that the same stratigraphy and structural history are developed across the entire Curnamona Province and that the structures developed around Ameroo Hill are not atypical of the province as a whole. Included in the Olary stratigraphy is the regionally extensive and highly prospective "Bimba Formation", a marble and calc-silicate dominated unit known for its high base-metal content (Pb, Zn, Mn, Cu, Co). Geochronological studies have recently confirmed this unit as a correlative of the Ettlewood Calc-silicate in the Broken Hill Group and there is growing geochronological evidence (Page et al., 2000) that other parts of the Olary sequence can be similarly matched to equivalent units in the Broken Hill Domain. Lithostratigraphic nomenclature follows Conor (2000, 2001) who subdivided the Willyama Supergroup into two major units of contrasting magnetic susceptibility and composition: the Curnamona and Strathearn Groups. REFERENCES: Conor, C.H.H., 2000. Definition of major sedimentary and igneous units of the Olary Domain, Curnamona Province. MESA Journal, V.19: 51-56. Conor, C.H.H., 2001. Geology of the Olary Domain, Curnamona Province, South Australia: Field Guide book. PIRSA, Adelaide. Page, R.W., Stevens, B.P.J., Gibson, G.M. and Conor, C.H.H., 2000. Geochronology of Willyama Supergroup rocks between Olary and Broken Hill, and a comparison to northern Australia. In: Peljo, M. (compiler) Broken Hill Exploration Initiative Abstracts Volume, AGSO Record 2000/10: 72-75.