Abstract

The Leichhardt River Fault Trough (LRFT) near Mount Isa is thought to be an ensialic or continental margin rift structure formed about 1800-1650 m.y. ago. Extension in old (1865-1800 m.y.) acid volcanic and granitic basement was followed by deposition of up to 10 km of epicontinental clastics, minor dolomite and redbeds, and marginal fanglomerates, and up to 6 km of subaerial to shallow subaqueous basalt. The latter provides characteristic gravity and magnetic signatures, which define the subsurface extent of the rift. The rift fill is blanketed by an orthoquartzite-carbonate unit about 1750 m.y. old. Deformation and uplift 1680 m.y. ago were accompanied by basic to acid volcanicity, which was followed by intracontinental sedimentation, and finally by 4-6 km of Pb-Zn-bearing dolomitic shale basin deposits. A zone of central uplift (Mount Gordon Arch) divided the LRFT into two meridional basins. Igneous rocks from the LRFT are bimodal in composition, and typical of non-orogenic terrains. They range from basement rhyolite and dacite to tholeiitic basalt, granite and alkali granite, rhyolite and trachybasalt, and finally to tholeiitic dyke swarms. The fault trough formed by extension and sagging of continental crust. Mantle upwelling and subsequent deep rifting tapped basalt sources; magma withdrawal and basalt loading of the crust led to further sagging and epicontinental sedimentation. Heat from earlier mantle upwelling caused lower crustal fusion and subsequent granite intrusion of the rift pile. Genesis of major Cu and Pb-Zn deposits has been partly controlled by early and reactivated growth faults and by the movement of subsidiary crustal blocks within the fault trough.
Google map showing geographic bounding box with values North bound -18.0 East bound 143.0 West bound 138.0 South bound -24.0
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Product Type/Sub Type

nonGeographicDataset

Constraints

Creative Commons Attribution 4.0 International Licence

IP Owner

Commonwealth of Australia (Geoscience Australia)

Author(s)

Date (publication)

1982-01-01T00:00:00

Product Type

nonGeographicDataset

Topic Category

geoscientificInformation

GA Catalogue Number

81105 Product http://www.ga.gov.au/metadata-gateway/metadata/record/81105/

Keywords

GA Publication
Journal
QLD
Earth Sciences

Resource Language

English

Resource Character Set

utf8

Resource Security Classification

unclassified

Geographic Extent

North bound
-18.0
East bound
143.0
West bound
138.0
South bound
-24.0

Lineage

Unknown

Digital Transfer Options

onLine

Distributor

Role
distributor
Organisation Name
Commonwealth of Australia (Geoscience Australia)
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address

Source Description

Source data not available.

Metadata File Identifier

fae9173a-702e-71e4-e044-00144fdd4fa6

Metadata Standard Name

ANZLIC Metadata Profile: An Australian/New Zealand Profile of AS/NZS ISO 19115:2005, Geographic information - Metadata

Metadata Standard Version

1.1

METADATA SECURITY CLASSIFICATION

unclassified

Metadata Contact

Role
pointOfContact
Organisation Name
Commonwealth of Australia (Geoscience Australia)
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address
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