Entity ID: 529556 Compiled by: Stewart, A.J. Year: 2010 Status: Defined
Last Revised: 2013
Rank: province Type: sedimentary Subtype: intracratonic Location: NT, QLD On-shore
Synonyms: NA Symbol: NA
Minimum age: Devonian, 392 ± 0 Ma Age method: biozone
Maximum age: Neoproterozoic, 840 ± 0 Ma Age method: biozone
Summary: The Georgina Basin is a poorly explored pericratonic (in the Cambrian-Ordovician) largely marine sequence, thickest (4000 m) in the south. Two main depocentres, the Dulcie and Toko Synclines, occur in the south. Cambrian units form good organic-rich source and reservoir rocks. Most of the sequence is in the oil window, and structural and stratigraphic traps have been outlined. Numerous oil and gas shows (and oily smells in water bores) have been identified over last 100 years, but no production.
Area (square kilometres): 330000 State: QLD State: NT Resources: Phosphate Country: AUS
Parent: No data
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Interfingers - Wiso Basin [Inferred, no exposure]
Overlies - Aileron Province [Regional unconformity], McArthur Basin
Underlies - Eromanga Basin
Constituent units: Cravens Peak beds (In Toko Syncline; continental), Dulcie Sandstone (In Dulcie Syncline; continental), Helen Springs Volcanics, Keepera Group (Glacial outwash and till), Mopunga Group (Siliciclastics), Toko Group (Marine siliciclastics), Vaughan Springs Quartzite, Yackah beds, Amesbury Quartzite, Barkly Group, Plenty Group (Fluviatile quartzite, marine carbonate, lacustrine to deep marine sediments), Aroota Group (Tillite and diamictite), Shadow Group (Siliciclastics and carbonate), Narpa Group (Carbonates and siliciclastics), Cockroach Group (Carbonates), Kiana Group, Kalkarindji Suite, Anthony Lagoon Formation
Events: Alice Springs Orogeny, Delamerian Orogeny, Petermann Orogeny, Cenozoic reactivation, Rinkabeena Movement, Larapinta Event
Mineral Deposits: Paradise North, Wonarah, Phantom Hills, D-Tree, Paradise South, Lily Creek, Mount O'Connor, Ardmore, Sherrin Creek, Babbling Brooke Hill, Quita Creek, Riversleigh, Alroy, Duchess, Alexandria, Mount Jennifer, Highland Plains, Thorntonia, Korella, Ammaroo Phosphate, Arganara, Buchanan Dam, Steamboat-Blazan Creek, East Galah Creek
Key Reference: Dunster, J.N., Kruse, P.D., Duffett, M.L., Ambrose, G.J. 2007, Geology and resource potential of the southern Georgina Basin, Northern Territory Geological Survey, Digital Information Package, 007, 1-232 (Refid:64068)
Comments: The Toomba Fault on the basin's southern margin was reactivated in the Cenozoic. Strat units updated according to Geology and mineral resources of the Northern Territory (in prep., 68235)
Overview: The Georgina Basin was initiated when NW-oriented half-grabens formed during the Neoproterozoic in the southern part (not known in the northern part of basin). These filled with fluviatile siliciclastics, carbonates, and partly emergent lacustrine to deep marine sediments of the Plenty Group. These were overlain by glacigene units and diamictite of the Aroota Group.
The Rinkabeena Movement caused some uplift, followed by deposition of the Keepera Group (glacial outwash and till, followed by dolostone). Siliciclastics of the Mopunga Group were deposited, followed by deformation in the Neoproterozoic to Early Cambrian Petermann Ranges Orogeny and deposition of siliciclastics of the Central Mount Stuart Formation in SE-trending fault troughs.
The basin sagged in the Early Cambrian and siliciclastics (lower Shadow Group) accumulated unconformably on the Mopunga Group. This was followed by shallow-marine Early to Late Cambrian carbonates (upper Shadow Group, Narpa, and Cockroach Groups) with some evaporites and siliciclastics. Some deformation of Cambrian sequence occurred in the Delamerian Orogeny. Extension (Larapinta Event) took place in the early to mid Ordovician, resulting in marine deposition of carbonates and siliciclastics (Toko Group). Uplift and erosion was followed by deposition of non-marine sandstone and conglomerate (Dulcie Sst, Cravens Peak beds).
The Alice Springs Orogeny folded and faulted the basin sequence. No metamorphism nor igneous intrusions are known, but alginite reflectivity and other 'measures of thermal maturity' indicate paleothermal anomalies (90-211 deg C) in the south. Fission track studies indicate these were caused by the Alice Springs Orogeny and overprints in the Triassic-Jurassic, Cretaceous, and Cenozoic preiods.
The Georgina Basin has world-class phosphorite deposits, many small occurrences of Cu, Pb, Zn, Mn, and several turquoise occurrences.
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