no wonder there is now so much interest in this one..........Mineralisation The Georgina Basin is prospective for a number of mineral commodities. Known Pb-Zn prospects and occurrences are widespread and throughout the succession from Neoproterozoic siliciclastic rocks to Lower Ordovician carbonate and mixed carbonate-siliciclastic rocks. There is a wide range of mineralisation styles. At the Box Hole Mine, galena and barite occur along 6.5 km of strike in the Late Cambrian Arrinthrunga Formation. About 15 t of ore, averaging 65-70% Pb and 60 g/t Ag, has been handpicked. Mineralisation is stratabound epigenetic replacement and vug-fill in a stromatolitic dolostone, possibly localised by proximity to a feeder fault. Similar surface galena and minor pyrite occur at the Trackrider Prospect. Host rocks are vuggy, siliceous and manganiferous dolostone of the Arrinthrunga Formation, just below the contact with the overlying Tomahawk Formation. Mineralisation at both Box Hole and Trackrider is similar to Mississippi Valley-type (MVT) orebodies. Visible Zn-Pb mineralisation (up to 1.2% Zn) occurs in association with hydrocarbons in and just below a shale cap at the contact of the Arthur Creek Formation and Thorntonia Limestone in Baldwin 1 and may have affinities to Century-type, stratiform, shale-hosted base metal mineralisation. A fault breccia at the Boat Hill Prospect contains two intervals with percent levels of Zn. NTGS drilling also intersected percent levels of Zn and visible galena in Thorntonia Limestone in this area, which considerably extends the area of known mineralisation. Previously undocumented visible galena has also been recognised in the Neoproterozoic Elyuah Formation at the Mount Skinner Prospect in ALCOOTA. This core contains 2.44 m assayed at 0.3 m intervals, all of which is >2000 ppm Pb.
Economic phosphate deposits in Middle Cambrian Georgina Basin rocks are being mined at Duchess in Queensland. In the Northern Territory several deposits of collophane mudstone and pelletal phosphorite have been identified in sedimentary intervals on the Alexandria-Wonarah Basement High (see Regional phosphate prospectivity assessment project). These deposits average about 16% P2O5 and could aggregate to similar tonnages to those being exploited at Duchess. Rio Tinto has recently delineated 72 Mt of phosphate ore at the Wonarah deposit on the Alexandria-Wonarah Basement High. Smaller deposits are known at Alexandria, Alroy and Buchanan Creek.
MNM Price at posting:
0.0¢ Sentiment: ST Buy Disclosure: Held
