Clarence Moreton Basin

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Clarence Moreton Basin
Walloon Coal Measures 3.jpg
Walloon Coal Measures exposed in quarry at Bexhill
Australia relief map.jpg
Red pog.svg
Location in Australia
Coordinates 30°00′S152°30′E / 30°S 152.5°E / -30; 152.5 Coordinates: 30°00′S152°30′E / 30°S 152.5°E / -30; 152.5
Location Northern Rivers, New South Wales & South East Queensland
Characteristics
Area16,000 km2 (6,200 sq mi)
Range Tweed, Border, Lamington, McPherson
Geology
Basin type Rift basin
Age Late Triassic-Early Cretaceous
Stratigraphy Stratigraphy
Geoscience Australia

The Clarence Moreton Basin is a Mesozoic sedimentary basin on the easternmost part of the Australian continent. It is located in the far north east of the state of New South Wales around Lismore and Grafton and in the south east corner of Queensland. It is the part of the Great Artesian Basin that extends to the east coast in Australia's central eastern lowlands. [1]

Contents

Description

It formed by oblique extension of the underlying Paleozoic New England Orogen basement. It consists of continental deposits, starting with a small amount of Triassic coal beds, and then mostly Jurassic and Cretaceous sedimentary rocks. [2] The basin covers 16,000 square kilometres (6,200 sq mi). [3] The basin was named when the Clarence Basin (named after the Clarence River) and Moreton Basin in Queensland were proved to be one structure. [2]

Oil is likely to be present in the basin. [1]

Stratigraphy

Kangaroo Creek Sandstone Kangaroo Creek Sandstone 4.jpg
Kangaroo Creek Sandstone

The oldest rocks in the Clarence Moreton Basin of New South Wales are the Chillingham Volcanics. These are from some time in the Triassic period, and crop out in a band north and south of Chillingham. They consist of conglomerate at the base, rhyolite, lithic rhyolitic tuff, and shale. [4] The Nymboida Coal Measures extend from Nymboida to Kangaroo Creek. They consist of lithic sandstones (wackes, minor arenites), siltstone, polymictic conglomerate, coal, rhyolitic tuff, and basalt. The total thickness is over 1,000 metres (3,300 ft). The outcrop is 90 square kilometres (35 sq mi), and it forms a north west trending band 29 kilometres (18 mi) long on the southwest tip of the basin. [4] Fossils reveal a date of middle Triassic. A lower part is called Cloughers Creek Formation. [2] [5] The Basin Creek Formation [6] includes the coal mined at Nymboida. The Bardool Conglomerate forming a 180 metres (590 ft) thick layer, [7] is also a unit in the coal measures. The conglomerate includes a 15-metre (49 ft) thick layer of basalt exposed at Copes Creek. [2] The Neranleigh-Fernvale Beds are up to 3,500 metres thick.

The Red Cliff Coal Measures date to the Late Triassic. It forms an outcropping belt 2.5 kilometres (1.6 mi) wide and 19 kilometres (12 mi) long from Buchanans Head through Red Cliff. [8] The Evans Head Coal Measures are correlated with these, but are further up the north coast at Evans Head. [9]

The basin was next uplifted and eroded and then deepened considerably and Bundamba group rocks form a complete V shape on both sides of the basin. In the northern parts the rock is mostly friable sandstone, but in the south it is divided into conglomerate below and siltstone above. The Laytons Range Conglomerate [10] rests on the basin floor and extends from Baryulgil, to Nymboida. The conglomerate often appears as a cliff. The Corindi Conglomerate is a local name for a hailstone sized gravel near Corindi. The Mill Creek Siltstone. [11] are often olive green or yellow-brown with bright red joint planes. [2]

The Marburg Subgroup [12] extends for 225 kilometres (140 mi) along the western side of the basin into Queensland from Corindi. It is mostly clay cemented cross bedded quartz sandstone, but this is interbedded with claystone and shale. At the base is the Blaxland Fossil Wood Conglomerate Member at Blaxlands Creek. The fossil wood is in the form of horizontal tree trunks up to 18 metres (59 ft) long and 600 millimetres (24 in) in diameter. The fossilization process replaced the wood with limonite and hematite. [2] The Towallum Basalt is a 15-metre (49 ft) thick layer near Nymboida, Glenreagh and Moleton trig station overlying the Marburg formation. [2] The Walloon Coal Measures [13] 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. [13]

The next layer of rocks in the basin forming a nested U shape in its exposure is the Kangaroo Creek Sandstone. [14] This sandstone has saccharoidal texture, and glistens white and cream. This is not due to angular sand grains, but results from silica crystallization. It is up to 150 metres (490 ft) thick. [2]

The Grafton Formation [15] is the sedimentary unit in the core of the basin. It is the youngest of the beds being between Late Jurassic and Early Cretaceous. It occurs from Grafton to Casino consisting of soft sandstone, siltstone and claystone. Dolerite has intruded this at Glenugie Peak, and near Banyabba. [2]

Rifting along the east coast of Australia commenced and uplifted the eastern side of the Clarence Moreton Basin. [3] This resulted in the splitting off of the Lord Howe Rise and the opening of the ocean floor. [16]

Related Research Articles

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Geologically the Australian state of New South Wales consists of seven main regions: Lachlan Fold Belt, the Hunter-Bowen Orogeny or New England Orogen (NEO), the Delamerian Orogeny, the Clarence Moreton Basin, the Great Artesian Basin, the Sydney Basin, and the Murray Basin.

Coal measures

The coal measures is a lithostratigraphical term for the coal-bearing part of the Upper Carboniferous System. In the United Kingdom, the Coal Measures Group consists of the Upper Coal Measures Formation, the Middle Coal Measures Formation and the Lower Coal Measures Formation. The group records the deposition of fluvio-deltaic sediments which consists mainly of clastic rocks interstratified with the beds of coal. In most places, the coal measures are underlain by coarser clastic sequences known as Millstone Grit, of Namurian age. The top of the coal measures may be marked by an unconformity, the overlying rocks being Permian or later in age. In some parts of Britain, however, the Coal Measures grade up into mainly coal-barren red beds of late Westphalian and possibly Stephanian age. Within the Pennine Basin these barren measures are now referred to as the Warwickshire Group, from the district where they achieve their thickest development.

Sherwood Sandstone Group

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Exmouth Plateau

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Bald Hill Claystone

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Munmorah Conglomerate

Munmorah Conglomerate is a geologic formation in the Sydney Basin in eastern Australia. This stratum is up to 140 metres thick. Formed in the early-Triassic, it is part of the Narrabeen Group of sedimentary rocks. This formation includes medium to coarse-grained sandstone and conglomerate. With minor amounts of siltstone and claystone. Below the Munmorah Conglomerates are Newcastle Coal Measures, originating from the Permian.

Terrigal Formation

The Terrigal Formation is a geologic formation in the Sydney Basin in eastern Australia. Commonly seen in the Central Coast region, this stratum is up to 330 metres thick. Formed in the early to mid Triassic, it is part of the Narrabeen Group of sedimentary rocks. This formation includes interbedded fine to medium-grained sandstone and siltstone, with minor deposits of claystone. Hawkesbury Sandstone occasionally overlies the Terrigal Formation.

Neranleigh-Fernvale Beds

The Neranleigh-Fernvale beds is a geologic formation in the north east of New South Wales and Queensland, Australia. This formation was created in the Late Devonian to the Early Carboniferous, of a thickness up to 3,500 metres (11,500 ft).

Newcastle Coal Measures

Newcastle Coal Measures is a major geologic formation in eastern Australia. Found in the Sydney Basin and Lachlan Orogen, this stratum is up to 1200 metres thick, consisting of dozens of different sub types. Formed between the Changhsingian and Wuchiapingian ages, around 256 to 252 Ma in the Permian. This formation includes coal seams, tuffaceous claystone, siltstone, sandstone, and conglomerate. Medium to coarse-grained sandstone is present, often noticed by bathers at the Bogey Hole. Volcanic constituents of the Newcastle Coal Measures include Nobbys Head, which features Nobbys Tuff.

Nobbys Tuff

Nobbys Tuff is a geologic formation in eastern Australia. Found in Newcastle within the Lachlan Orogen, this stratum is up to 25 metres thick. Formed from volcanic ash in an eruption in the Wuchiapingian age, in the late Permian around 255.02 Ma. This formation includes tuff, tuffaceous sandstone, tuffaceous siltstone, claystone, and chert. Often noticed at Nobbys Head in Newcastle.

References

  1. 1 2 Heads, Michael (2013). Biogeography of Australasia: A Molecular Analysis. Cambridge University Press. p. 169. ISBN   9781107471207 . Retrieved 26 July 2017.
  2. 1 2 3 4 5 6 7 8 9 McElroy, C. T. (November 1969). "The Clarence-Moreton Basin in New South Wales". In Packham, G. H. (ed.). The Geology of New South Wales. Sydney: Geological Society of Australia. pp. 457–479.
  3. 1 2 "Clarence-Moreton Basin - Geological Overview". Trade & Investment: Resources and Energy. Government of New South Wales. Archived from the original on 23 June 2015. Retrieved 14 May 2015.
  4. 1 2 "Chillingham Volcanics". Australian Stratigraphic Names Database. Geoscience Australia. 24 September 2008.
  5. "Cloughers Creek Formation". Australian Stratigraphic Names Database. Geoscience Australia. 13 December 2007.
  6. "Basin Creek Formation". Australian Stratigraphic Names Database. Geoscience Australia. 25 August 2008.
  7. "Bardool Conglomerate". Australian Stratigraphic Names Database. Geoscience Australia. 13 December 2007.
  8. "Red Cliff Coal Measures". Australian Stratigraphic Names Database. Geoscience Australia. 19 February 2008.
  9. "Evans Head Coal Measures". Australian Stratigraphic Names Database. Geoscience Australia. 24 September 2008.
  10. "Laytons Range Conglomerate". Australian Stratigraphic Names Database. Geoscience Australia. 22 May 2008.
  11. "Mill Creek Siltstone". Australian Stratigraphic Names Database. Geoscience Australia. 22 May 2008.
  12. "Marburg Subgroup". Australian Stratigraphic Names Database. Geoscience Australia. 16 April 2009.
  13. 1 2 "Walloon Coal Measures". Australian Stratigraphic Names Database. Geoscience Australia. 27 August 2008.
  14. "Kangaroo Creek Sandstone". Australian Stratigraphic Names Database. Geoscience Australia. 4 December 2008.
  15. "Grafton Formation". Australian Stratigraphic Names Database. Geoscience Australia. 27 August 2008.
  16. Geological Survey of New South Wales. "Offshore Clarence-Moreton Basin - Geological Overview".