School of Earth Sciences - Theses
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ItemThe geochronology and thermochronology of the Brockman Creek 01, Melita 01 and Melita 02 kimberlites, Western Australia( 2000-10)Due to the difficulties inherent in dating kimberlites, two independent methods are employed to confirm the unusually old ages of approximately 2 Ga for three occurrences in Western Australia. Phlogopite micas from three kimberlites were dated using 40Ar/39Ar and 87Rb/86Sr dating techniques in order to provide an estimate of the intrusion ages. The high reliability of the age estimates is indicated by the similar results produced by the 87Rb/86Sr method. Argon loss is suspected for phlogopite samples, resulting in the apparently reliable 40Ar/39Ar total fusion ages that do not correspond to previously determined emplacement ages. (For complete abstract open document)
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ItemThe thermotectonic evolution of the northern precambrian shield, Western Australia( 2002)Reconnaissance 40Ar/39Ar dating of K-feldspars and muscovites, and fission track and (U-Th)/He thermochronometry on apatites has been applied to ~1 X 106 km2 of the northern Western Australian Shield. The study area includes the Archaean northern Yilgarn Craton and Pilbara Craton, and the intervening Proterozoic basins. The geomorphology of the study area also reveals a subdued relief, which is characteristic for Australian cratonic landscapes. The fact that the shield consists entirely of Precambrian rocks with low topographic relief has led to the widely held view that the West Australian Shield has been tectonically stable for a long period of time. (From Abstract)