Precambrian faulting episodes and insights into the tectonothermal history of north Australia: microstructural evidence and K–Ar, 40Ar–39Ar, and Rb–Sr dating of syntectonic illite from the intracratonic Millungera Basin

Australian terranes concealed beneath Mesozoic cover record complex Precambrian tectonic histories involving a successive development of several Proterozoic to Palaeozoic orogenic systems. This study presents an integrated approach combining K–Ar, 40Ar–39Ar, and Rb–Sr geochronologies of Precambrian...

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Bibliographic Details
Published in:Solid earth (Göttingen) 2020-09, Vol.11 (5), p.1653-1679
Main Authors: Uysal, I Tonguç, Claudio Delle Piane, Todd, Andrew James, Zwingmann, Horst
Format: Article
Language:English
Subjects:
Basins
Cores
Deformation
Earth science
Fault lines
Fluids
Geochronology
Geological faults
Geological time
Geology
Illite
Illites
Mesozoic
Metamorphism
Microstructure
Mineral resources
Orogeny
Palaeozoic
Paleozoic
Precambrian
Rubidium-strontium dating
Sandstone
Sedimentary basins
Sediments
Seismic surveys
Surveys
Tectonics
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Summary:Australian terranes concealed beneath Mesozoic cover record complex Precambrian tectonic histories involving a successive development of several Proterozoic to Palaeozoic orogenic systems. This study presents an integrated approach combining K–Ar, 40Ar–39Ar, and Rb–Sr geochronologies of Precambrian authigenic illites from the recently discovered Millungera Basin in north-central Australia. Brittle deformation and repeated fault activity are evident from the sampled cores and their microstructures, probably associated with the large-scale faults inferred from interpretations of seismic surveys. Rb–Sr isochron, 40Ar–39Ar total gas, and K–Ar ages are largely consistent in indicating late Mesoproterozoic and early Proterozoic episodes (∼1115±26, ∼ 1070±25, ∼1040±24, ∼1000±23, and ∼905±21 Ma) of active tectonics in north-central Australia. K–Ar results show that illites from fault gouges and authigenic matrix illites in undeformed adjacent sandstones precipitated contemporaneously, indicating that advection of tectonically mobilized fluids extended into the undeformed wall rocks above or below the fracture and shear (fault gouge) zones. Isotopic age data clearly indicate a Mesoproterozoic minimum age for the Millungera Basin and thus previously unrecorded late Mesoproterozoic–early Neoproterozoic tectonic events in north-central Australia. This study provides insight into the enigmatic time–space distribution of Precambrian tectonic zones in central Australia, which are responsible for the formation of a number of sedimentary basins with significant energy and mineral resources.
ISSN:1869-9510
1869-9529
DOI:10.5194/se-11-1653-2020