Geology of New South Wales
It lies on a basement of Cambrian oceanic floor, however, most of this has been subducted leaving the sediment veneer scraped off in chevron folds.
The Florida, Babinda, Majuba and Mineral Hill Volcanics are found on the East side of the Kopyje Shelf.
Subsequently in the early Devonian the basin content was pushed back up, and the Mulga Downs Group was deposited by rivers up until the Carboniferous Period.
[5] The Sydney Basin consists of Permian and Triassic sedimentary rocks stretching from Newcastle to Batemans Bay.
The Greta Coal Measures then formed in the north side in an alluvial fan from the mountains of the New England Orogen.
In the Late Permian river and delta deposition formed the Tomago and Whittingham Coal Measures in the north.
Early in the Triassic the New England Fold Belt was uplifted and an alluvial flood plain formed the Narrabeen group.
[7] Part of the Great Artesian Basin is along the northern border of New South Wales and also extends north into Queensland.
[10][17] In the Cretaceous sea water entered and deposited shale from the Rolling Downs Group[18] which also contains some calcareous sandstone.
[10] Because the basin is an important site for artesian wells, it has been extensively drilled and much is known about the structure of the basement and geothermal temperature gradients.
The Bulloo Embayment north of White Cliffs is over 300 m deep and is disrupted on its west side by the Warratta Fault.
They consist of lithic sandstones (wackes, minor arenites), siltstone, polymictic conglomerate, coal, rhyolitic tuff, and basalt.
The outcrop is 90 square kilometers, and it forms a north west trending band 29 km long on the southwest tip of the basin.
The Laytons Range Conglomerate[28] rests on the basin floor and extends from Baryulgil, to Nymboida.
[19] The Marburg subgroup[30] extends for 225 km along the western side of the basin into Queensland from Corindi.
[19] The Towallum Basalt is a 15-meter thick layer near Nymboida, Glenreagh and Moleton trig station overlying the Marburg formation.
[19] The Walloon Coal Measures[31] forms a U shape around the east, south and west sides of the basin.
It consists of claystone, shale, siltstone, arenites, and coal seams and the plant fossils in it show a Jurassic age.
[31] The next layer of rocks in the basin forming a nested U shape in its exposure is the Kangaroo Creek Sandstone.
[19] During the Cainozoic, rifting along the east coast of Australia commenced and uplifted the eastern side of the Clarence Moreton Basin.
[35] From Paleocene to Eocene the western side was flooded with sea water and deposited the Warina sand.
[39] The sea level rose again in Late Oligocene to mid Miocene forming the Murray Group of sediments, with marl and limestone in the deeper locations, and the Geera Clay[40] in the shallow waters.
[44][45] When sea level fell again in mid Miocene the deposited Geera clay and Olney Formation moved westward over the limestone.
Locally heavy minerals have been concentrated by wave action including rutile zircon and ilmenite forming economic mining opportunities.
[49] The Murray River became dammed by uplift of over 250 meters in the Grampians in Victoria during the Pleistocene about 2.5 Mya.
The Pooraka Formation[52] formed in the north west due to increased erosion resulting in colluvium depositing.
Petroleum exploration within the basin has been minimal, consisting of a small number of geophysical surveys and two stratigraphic wells.
In 2009 four new lines of high quality 2D seismic have been acquired by DTIRIS (formerly the NSW Department of Industry and Investment).
It dates from 360 Mya in the Devonian and includes Groenlandaspis, Canowindra grossi, Remigolepis walkeri and Bothriolepis yeungae.
[64] The Department of Mines commenced in late 1874, and the Geological Survey of New South Wales was brought into existence on 1 January 1875.
