al. 2011). Evidence for the fragmentation of East Gondwana in the Neoproterozoic is provided by the Darling Fault Zone on the western margin of Australia (Dickens 2018). This evidence includes thermal resetting downwards of radiometric dates towards the regional fault zone, hydrothermal alteration indicated by mineral petrography, tectonism associated with regional mafic dykes, a magnetotelluric (MT) conductivity anomaly indicating the presence of water in this regional fault zone, and high-temperature metamorphism associated with supercontinent fragmentation (Dickens 2018). The 1000-kmlong Darling Fault forms the Perth Basin’s eastern boundary against the Archean Yilgarn Craton. The Perth Basin (Fig. 2) is a relatively narrow, half-graben situated on the western continental margin of today’s southwestern Australia. Laurasia, the northern component of Pangea, consisted of North America, Europe and Asia (except peninsular Asia). It has been inferred that episodic rifting events at the margins of North America in the Late Neoproterozoic record supercontinent fragmentation (Bond et al. 1984; Hoffman 1989). Modern thermochronological data indicates enormous Neoproterozoic erosional exhumation of even hard crystalline rocks, for example kilometers of erosion of granite and schist, and peneplanation (the Great Unconformity) at the Grand Canyon (McDannell et al. 2022). 2. Early Paleozoic global marine transgression The Sauk megasequence global sea level rise followed the initial breakup of the supercontinent (Ford and Golonka 2003). Evidence of sea level rise includes an upward-fining sequence observed in Cambrian strata which has been interpreted as a deepening succession in locations such as the USA, Greenland, UK, Russia, Australia, Bolivia and Ghana (Morton 1984). “Global or worldwide marine transgression” is the descriptor in the secular literature (Cook and Shergold 1984; Matthews and Cowie 1979). Around the world there is a very commonly recognised deepening-water succession going upwards from Cambrian towards Ordovician strata (i.e. a basal conglomerate, then orthoquartzite, then glauconitic sandstones, then marine shales and then limestones (Ager 1973). In North America, the large quantity of Cambrian–Early OrFigure 1. Gondwana at the start of the Jurassic (Torsvik and Cocks 2013). DICKENS Flood Waters Lead to Seafloor Spreading 2023 ICC 448
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