School of Earth Sciences - Theses

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Start date: 1990 × Type: PhD thesis × Subject: Western Australia ×

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    Australian lineament tectonics: with an emphasis on northwestern Australia
    Elliott, Catherine I. ( 1994-08)
    Australia is transected by a network of systematic continental-scale lineaments that are considered to be zones of concentrated, aligned tectonic activity which have apparent continuity over vast distances. The influence of lineaments on the rock record can be identified in many types of data-sets, and existing data reveals previously undescribed basement influences. Several continental-scale lineaments can be traced offshore with apparent continuity for hundreds to thousands of kilometres, two of which are seen to cross the Tasman Sea in offshore eastern Australia. Geological and chronological evidence demonstrates that many of the lineaments have been zones of reactivation since at least the Early Proterozoic (- 1880 Ma) and that they appear to cross major terrane boundaries. Alternative models for their origin are a) a pre-existing lineament network maintained in an ancient basement underlying the entire continent; b) lateral propagation of crustal-scale structures; c) alignment of genetically unrelated lineaments giving the appearance of continuity. Australian deep-seismic profiles show that continental-scale lineaments are zones of crustal-scale structure which in some cases transect the crust-mantle boundary. Lineaments demonstrate many faulting styles, e.g. listric extensional (G3), planar moderate-angle thrusts (G2 l), and sub-vertical thrusts (G 17). In some cases the structural style varies laterally along the length of the lineament. (For complete abstract open document)
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    The thermotectonic evolution of the northern precambrian shield, Western Australia
    Weber, Ursula D. ( 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)