Phosphate and Potash
- Regional Phosphate Prospectivity Assessment Record [ZIP 10mb]
Phosphate Factsheet and Map [PDF 1.1mb]
Phosphate Factsheet and Map [DOCX 576kb]
The Northern Territory contains some of Australia’s largest undeveloped phosphate deposits, with more than 1000 Mt of phosphate ore at a 10% P2O5 cut-off. Known phosphate deposits are present in the Georgina Basin, Arunta Region and Pine Creek Orogen. Deposits in the Georgina Basin account for 98% of identified resources.
Large sedimentary phosphorite deposits (eg Wonarah) in the central Georgina Basin are middle Cambrian (510 Ma) in age. These are within a regional phosphate-rich stratigraphic interval that extends over 500 000 km2 in the NT and into western Queensland where mining of phosphate has been undertaken at the Duchess deposit. The largest undeveloped deposit in the Georgina Basin is Minemakers Ltd’s Wonarah phosphate deposit, which occurs in the Cambrian upper Gum Ridge Formation or basal Wonarah Formation, close to the Barkly Highway. The 2012 resource estimate for the Wonarah project comprises combined Indicated and Inferred resources (at 10% P2O5 cut-off) of 842 Mt at 18% P2O5, comprising 707 Mt in the Main Zone and 135 Mt in the Arruwarra deposit.
An additional phosphate discovery was made in late 2010 by Rum Jungle Resources Ltd at the Barrow Creek-1 prospect, 80 km east from the Alice Springs–Darwin railway. At the end of 2012, the deposit had total Indicated and Inferred resources of 238 Mt at 14.6% P2O5 (at a 10% P2O5 cut-off). The eastern extension of this orebody comprises Central Australian Phosphate Ltd’s Arganara deposit, which has a resource of 310 Mt at 15% P2O5.
Phosphate Australia Ltd’s Highland Plains deposit abuts the Northern Territory/Queensland border on the northern margin of the Georgina Basin. Phosphate occurs in the Cambrian Border Waterhole Formation and has a total Inferred Resource of is 56 Mt at 16% P2O5 (at a 10% P2O5 cut-off).
Sedimentary phosphorite mineralisation is also present in the McArthur Basin (Karns Dolomite), Amadeus Basin (Stairway Sandstone) and Money Shoal Basin (Moonkinu Formation). Phosphate-rich tectonic-related breccias are present in the vicinity of Batchelor (Buckshee Breccia) and South Alligator Valley (Scinto Breccia) within the Pine Creek Orogen. Small deposits (eg Geolsec) have been outlined at the former locality.
Apatite-rich veins and apatite-bearing igneous rocks (eg carbonatite) are present in the Arunta Region. These relatively small deposits often carry high levels of Rare earth elements (REE). The multi-commodity Nolans Bore rare earths orebody has total resources of 47 Mt which includes 11% P2O5.
Significant potential for potash resources occurs within brines associated with salt lakes in central Australia, as well as in evaporitic deposits within the Neoproterozoic to Palaeozoic Amadeus Basin. The Karinga Creek potash project, approximately 200–300 km southwest of Alice Springs, contains hundreds of salt lakes that contain brines enriched in salts containing potassium, magnesium and sulfate. A Rum Jungle Resources Ltd-Reward Minerals Ltd venture is investigating the potassium- and magnesium magnesium-rich brine resources for their potential as a feedstock for the production of potassium sulphsulfate (SOP) and potassium magnesium sulphsulfate (schoenite). The November 2012 resource at Karinga Creek comprises 5.5 Mt of SOP which equates to a maximum schoenite resource of 13 Mt.
