Basin Details and Geological Overview
The Townsville Basin is an east-west trending extensional basin located between the Queensland and Marion Plateaus offshore northeast Queensland, under water depths of 200 metres to 2000 metres. The basin is 450km long and 20-120km wide, underlies the bathymetric Townsville Trough and is subdivided into several sub-basins.
The basin fill occurs as two main megasequences that reflect the basin evolution from a rift basin with isolated depocentres to a sag basin with a more widespread distribution. The maximum sediment thickness is about 6.5km. The oldest sediments are contained in a generally thin Late Jurassic to Early Cretaceous early synrift sequence with considerable variation in spatial distribution, and are likely to consist of terrigenous deposits derived from the adjacent plateaus and intra-basin highs. This is overlain by up to 2km of a more widespread synrift megasequence, deposited in a variety of environments and inferred to be no younger than Palaeocene in age. A Cainozoic sag-phase megasequence up to 3.8km thick consists of drape fill clastics overlain by mainly carbonates. The Townsville Basin formed through oblique northwest-southeast extension resulting in a half-graben morphology. This early rifting event was separate to and predated extension related to later Coral and Tasman Sea opening. However, a second rift phase in the Early to Late Cretaceous may be related to these regional extensional events. Multiple reactivation events occurred throughout the Cainozoic.
No wells have been drilled in the Townsville Basin and its petroleum prospectivity is speculative. The western part of the basin lies within the Great Barrier Reef Marine Park, in which petroleum exploration is prohibited.
- ProvExplorer - Townsville Basin Details and Geological Overview
|State(s)||Queensland, Coral Sea Islands Territory|
|Area (km2)||Offshore||13 000|
|Maximum thickness (m)||6500|
|Age Range||Cretaceous to Cainozoic.|
|Basin||Overlies||Palaeozoic metasediments of the Tasman Fold Belt.|
|Subdivisions||North Flinders, South Flinders, Tregrosse, Lihou Sub-basins, plus unnamed sub-basin in the east.|
|Other||The western end of the basin grades into the southern Queensland Basin (= 'Halifax Basin'), the eastern end grades into the northern Cato Basin.|
|Indicators||Knowledge||Regional geophysical, some shallow seabed samples and shallow Ocean Drilling Program (ODP) well data.|
|Basin type||Intra-plate rift, then sag.|
|Water Depth (m)||200 - 2000|
|Wells||0 exploration, some shallow ODP into Neogene.|
|Seismic line-km||> 5000|
|Geology||Source(s)||Early Cretaceous synrift shales and probable coals.|
|Seals||Cretaceous intraformational shales (local seals); Paleogene shales and carbonates (regional seal).|
|Trap types||Structural traps; large stratigraphic pinchout traps (BRS, 1996).|
|Palaeogeographic summary||Cretaceous: rift fill sediments of unknown facies;
Paleogene: inferred shallow marine shales to shelf and slope carbonates; Neogene: shelf, upper and middle slope carbonates.
|Timing||Oil generation||Paleogene to Neogene if generation has occurred.|
|Gas generation||Paleogene to Neogene if generation has occurred.|
|Trap formation||Cretaceous (stratigraphic), Neogene (structural).|
|Other key times||Paleogene sea floor spreading in Coral Sea Basin;
Multiple Neogene reactivation of structures.
|Other important information||The western part of the Townsville Basin lies within the Great Barrier Reef Marine Park, in which petroleum exploration activity is prohibited. The rest of the basin is also in a sensitive area due to its proximity to the Park.|
|Geoscience Australia products available||1) Struckmeyer and others, 1994;
2) BRS, 1996.
|Bureau of Resource Sciences||1996||Oil and Gas Resources of Australia 1995. Canberra, Bureau of Resource Sciences, 185p|
|Cotillon, P., Rousselle, B., Courtinat, B. and Crumiere, J.P.||1994||Evolution of sediment fluxes from the middle Miocene to present at ODP Site 817 (Townsville Basin, northeastern Australia) as a record of regional palaeogeographic events. Marine Geology, 121;3-4, 265-291|
|Falvey, D.A., Symonds, P.A., Colwell, J.B., Willcox, J.B., Marshall, J.F., Williamson, P.E. and Stagg, H.M.J.||1990||Australia's deepwater frontier petroleum basins and play types. The Australian Petroleum Production and Exploration Association (APEA) Journal, 30(1), 238-262|
|Struckmeyer, H.I.M., Symonds, P.A., Fellows, M.E., & Scott, D.L.||1994||Structural and stratigraphic evolution of the Townsville Basin, Townsville Trough, offshore northeastern Australia. Canberra, Australian Geological Survey Organisation, Record 1994/50|
|Struckmeyer, H.I.M., & Symonds, P.A.||1997||Tectonostratigraphic evolution of the Townsville Basin, Townsville Trough, offshore northeastern Australia. Australian Journal of Earth Sciences, 44, 799-817|
|Symonds, P.A., Davies, P.J. and Parisi, A.||1983||Structure and Stratigraphy of the Central Great Barrier Reef. BMR Journal of Australian Geology and Geophysics, 8, 277-291|
|Symonds, P.A., Fritsch, J. and Schulter, H.U.||1984||Continental margin around the western Coral Sea Basin: structural elements, seismic sequences and petroleum geological aspects. Watson, S.T. (Editor): Transactions of the third Circum-Pacific Energy and Mineral resources conference, Hawaii. American Association of Petroleum Geologists, Tulsa, 243-252|
|Symonds, P.A., Capon, D., Davies, P.J., Pigram, C.J. and Feary, D.A.||1987||Structural style of the Townsville Trough and its implications for the development of the northeast Australian margin. Extended Abstracts - Applied Extension tectonics, 16th BMR Research Symposium, Canberra, 24th-26th November, 1987. Bureau of Mineral Resources, Australia, Record 1987/51, 165-172|
|Symonds, P.A., Davies, P.J.||1988||Structure, stratigraphy, evolution and regional framework of the Townsville Trough and Marion Plateau region, research cruise proposal. Bureau of Mineral Resources, Australia, Record 1988/48|
|Symonds, P.A., Colwell, J.B., Struckmeyer, H.I.M., Willcox, J.B. and Hill, P.J.||1996||Mesozoic rift basin development off eastern Australia. Abstracts - Geological Society of Australia, 43, 528-542|
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