Authors / CoAuthors
Smithies, R.H. | Champion, D.C. | Sun, S.S.
Abstract
The ENE-trending Mallina Basin developed in the central part of the Pilbara Craton, NW Australia, between c. 3010 and 2940 Ma, over the boundary between two distinct terrains characterised by greenstones aged c. 3120 and older. The basin preserves an association of igneous rocks characterised by an unusual combination of high-Mg and high LILE concentrations, that provides valuable insight into the geological evolution of the region. The oldest dated components of the Mallina Basin are c. 3010 Ma volcaniclastic rocks found only in the far northwest. Geochronology and field relationships indicate that the main basin deposition, of clastic rocks, occurred from 2970 to 2955 Ma. Towards the end of this depositional phase, siliceous high-Mg basalts (SHMB) formed the upper part of the stratigraphy in the northwestern part of the basin (Whim Creek Belt), and their subvolcanic equivalents intruded the southern part of the basin. Sedimentation was terminated by ESE?WNW compression at c. 2955-2950 Ma. Rocks with boninitic compositions and spatially associated low-Ti tholeiitic gabbro formed sub-volcanic sills in coarse siliciclastic rocks in the southern part of the basin, probably during the waning stages of compression. Immediately after compression, an extensive alkaline granite complex was emplaced into the central and northern part of the basin, coeval with intrusion of a 2955-2945 Ma high-Mg diorite (or sanukitoid) suite. Renewed extension also resulted in renewed basin sedimentation between 2945 and 2935 Ma. Voluminous high-K monzogranite swamped the region between c. 2935 and 2930 Ma, particularly adjacent to, and south of the basin, and was early- to syn-tectonic with respect to SE-NW compression. Monzogranite magmatism becomes systematically younger and less voluminous away from the Mallina Basin.
Product Type
nonGeographicDataset
eCat Id
36996
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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Keywords
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- GA PublicationConference Paper
- ( Theme )
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- geology
- ( Theme )
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- geochemistry
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- AU-WA
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2001-01-01T00:00:00
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unknown
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geoscientificInformation
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Unknown
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Extents
[-22.0, -18.0, 118.0, 120.0]
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