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Gunnedah Basin

Entity ID: 530016 Compiled by: Stewart, A.J. Year: 2010 Status: Defined

Last Revised: 2013

Rank: province Type: sedimentary Subtype: foreland Location: NSW On-shore

Synonyms: NA Symbol: NA

Minimum age: APT3.3, 238 ± 0 Ma Age method: biozone

Maximum age: Early Permian, 290 ± 2 Ma Age method: isotopic, U/Pb ion probe

Summary: Sequence of non-marine, marine, and volcanolithic sedimentary rocks about 1.2 km thick interfingering (adjoining) Sydney Basin to south and Bowen Basin to north. Abundant coal resources, numerous gas shows (much may be coal seam gas) and two subeconomic gas discoveries, and a few oil shows. Good potential for coal seam gas.

Attributes:
Area (square kilometres): 15000
State: NSW
Country: AUS

Parent: No data

Child Provinces: No data

Relationships:
Interfingers - Bowen Basin [Interfingers], Sydney Basin [Interfingers]
Underlies - Surat Basin

Constituent units: Black Jack Group, Boggabri Volcanics (Lowermost unit), Deriah Formation (Uppermost unit), Digby Formation, Leard Formation, Maules Creek Formation, Napperby Formation, Porcupine Formation, Watermark Formation, Werrie Basalt, Goonbri Formation, Garrawilla Volcanics, Breeza Coal Member, Doona Seam, Goondi Formation, Springfield Seam, Caroona Seam, Clift Seam, Cobbora Formation, Mirrie Formation, Howes Hill Coal Member

Events: Bellata Event, Goondiwindi Event, Denison Event

Mineral Deposits: Vickery, Maules Creek, Canyon, Preston Extended, Gunnedah, Rocglen, Boggabri, Tarrawonga, Werris Creek, Narrabri, Sunnyside, Vickery South, Watermark, Caroona, Gunnedah (EL5183), Gunnedah (CCL701)

Key Reference: Totterdell, J.M., Moloney, J., Korsch, R.J., Krassay, A.A. 2009, Sequence stratigraphy of the Bowen-Gunnedah and Surat Basins in New South Wales, Australian Journal of Earth Sciences, 56(3), p433-459 (Refid:65116)

Comments: Maximum age based on SHRIMP date of 290.5 Ma from Brogans Rhyodacite Member of Woodton Formation, stratigraphically below Werrie Basalt (Korsch et al., 2009).

Overview: Central portion of long and relatively narrow foreland basin, the Sydney-Gunnedah-Bowen Basin, west of New England Fold Belt and east of Thomson Orogen. Mechanical extension led to rapid subsidence in half-grabens along the western margin of the present basin (Boggabri Volcanics to Goonbri Formation). This ceased at about 280 Ma, and passive thermal subsidence followed, leading to widespread uniform sedimentation (Maules Creek Formation to Black Jack Group). At the start of the Late Permian, passive subsidence was interrupted by lithospheric flexure that was driven by convergence in New England Orogen to the east. Viscous corner flow in wedge above the west-dipping subducting slab led to limited tectonic subsidence. This was overwhelmed during the Late Permian by rapid tectonic subsidence (Digby to Deriah Formations) caused by thrust-faulting in New England Orogen. Intruded and overlain by Garrawilla Volcanics and associated teschenitic intrusions (sills).

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This report was generated on Friday, October 31, 2014 4:49:25 PM EST.