Exploration
Exploration
Overview
Rex believes that the potential to make another copper discovery on the Yorke Peninsula is high. Rex’s regional exploration strategy is designed to follow through with the theory that the underlying Yorke Peninsula rocks could host multiple large-scale copper-gold ore deposits. The Hillside Project was the first test of this theory and the Company considers there could be other similar, or possibly larger, deposits that remain hidden underneath a thin layer of cover rocks.
Rex has maintained a focus on target generation within the Company’s tenure on the Yorke Peninsula and beyond the immediate Hillside area, but is of the view that it has only scratched the surface in terms of prospect testing. The regional targeting rationale adopted by Rex has been to break down the many potential targets on the Yorke Peninsula and prioritise those that Rex feels have the potential for near-term growth opportunities that can leverage off the Hillside Project.
Regional Geology
Rex’s broader tenement package lies within the Olympic Copper Gold Province. The Province hosts all the major Iron Oxide Copper Gold (IOCG) deposits of the eastern Gawler Craton including Olympic Dam, Carrapateena and Prominent Hill.
The associated Palaeoproterozoic Wallaroo Group sediments, in the Moonta-Wallaroo area, contain volcanics with ages ranging between 1772±14 Ma and 1735±10 Ma. Outcrop of crystalline basement in the region is rare with only coastal outcrops present near the Hillside deposit. Knowledge of the Wallaroo Group comes mostly from drill-hole intersections and samples. On Yorke Peninsula the Wallaroo Group is dominated by arenaceous to micaceous rocks, psammite, calc-silicate, felsic and mafic volcanics (including the Moonta Porphyry), graphitic sedimentary rocks and an array of albitite, hematite-magnetite-bearing albitite, calc-albitite and scapolite-bearing siltstone. The Wallaroo Group commonly includes broad zones of mineral alteration zoning, calcsilicates and magnetite (± biotite) alteration with or without concomitant sulfide mineralisation. Granite, syenogranite, syenite and gabbroic rock types intrude the Wallaroo Group and are dated at 1580–1590 Ma. Co-mingled gabbroic and syenitic intrusions are intimately associated with the Hillside mineralisation.
Geology of the Eastern Yorke Peninsula - Rex Interpretation
The abundance of drilling that Rex has collected has allowed a study of the geochemical and mineralogical characteristics of the sediments and volcanics on the Eastern Yorke Peninsula. This work has been the basis of a new geological interpretation to accurately reflect Rex’s views of the stratigraphy as of 2019.
Data collected by Rex since 2008 has included air-core, reverse circulation and diamond drilling at many prospects along and adjacent to the Pine Point Structural Corridor (PPSC) including ~233km of diamond drilling (662 drill-holes) at Hillside and ~18.5km of diamond drilling (45 drill-holes) at thirteen regional prospects within the eastern Yorke Peninsula area.
The starting point that Rex has chosen for the regional geological interpretation is the Hillside stratigraphic sequence which has been worked up and analysed in detail by both Rex geologists and external consultant Graham Teale. The eastern margin of the Yorke Peninsula is controlled by the PPSC, and the Hillside deposit is intimately associated with this structure and is confined within it. Younging direction data gathered from graded bedding at Hillside has provided a means of determining if beds are overturned or “right way up” and it has shown that the Hillside sequence is overturned. The key stratigraphic units Rex has used as the basis for our regional geological interpretation are:
Western Volcanic Unit
Pelite/Psammopelite Unit
Carbonaceous, Finely Laminated Meta-Pelites (Not observed at Hillside)
Parara Formation (Transitional Unit)
Impure Carbonate
Hillside Sequence
Hiltaba Suite Equivalents (including the Eastern Granite at Hillside)
Gabbros (Curramulka Gabbro, and other gabbros)
Moonta Porphyry