america and the thickest “glacigenic” sediment in Gondwana coincide (Fielding et al. 2008). However, if Late Paleozoic cyclothems in North America and Europe were caused by the waxing and waning of Gondwana glaciers, the associated sea-level fluctuations would have been global in scale. Thus, contemporaneous shallow and marginal marine deposits in Gondwana would also have been affected. An absence of Gondwana cyclothems indicates that Gondwana “ice sheets” can be precluded as the sole cause of cyclothems (Isbell et al. 2003). D. Radial sediment transport from Antarctica During the Permian and Triassic, the Gondwana sequence of India, Australia and southeastern Africa, and an upslope equivalent in coastal East Antarctica was deposited in a 7,500-km-wide alluvial fan that radiated through 180o of arc from an inferred upland in East Antarctica (Veevers et al. 1994) (Fig. 3). The outwash fan extended toward the northern continental edge of Gondwanaland, which lay in northern Greater India and northwestern Australia. Detrital zircon provenance studies of Permo-Carboniferous “glacial” diamictites across Gondwana confirm transport of sediment for thousands of kilometers from Antarctica (Craddock et al. 2019). Permian paleogeographic reconstructions for the western Australian margin have long emphasised dominant northward sediment transport along the axes of the Late Paleozoic rift basins (Fig. 2) (Haig et al. 2014). This is supported by northward-directed movement that radiated from the Gamburtsev upland in Antarctica during the Late Paleozoic “Ice Age” (Veevers 2006) (Fig. 3). Veevers et al. (2008) proposed a Phanerozoic transcontinental transport system from Antarctica to Australia based on a characteristic distinctive detrital zircon age signature dominated by 700–500 My ages which is widespread in Gondwana through the Phanerozoic. Paleocurrent studies (Tewari and Veevers 1991) also indicate the flow direction from Antarctica (Fig. 3). Gondwanan basin-fill successions show consistent three-fold stages of lowermost coarse-grained strata (represented by mass flow diamictites and poorly sorted conglomerates), overlain by shales that in turn are succeeded by shallow marine and commonly coal-bearing deltaic and fluvial sandstones. (Eyles et al. 2002). In the northern Perth Basin, for example, the Nangetty Formation diamictite is overFigure 3. A reconstruction of Early Permian southern Pangea (i.e. Gondwana) with radial drainage from a paleo-upland in East Antarctica northward to areas including southwestern Australia (figure after Tewari and Veevers 1991). The arrows indicate the azimuth of Permian and Triassic sediment transport. This upland area may have been the source of Permian flora that later formed coal measures. The East Antarctic paleo-upland area may also have been the site of a geoid high from which supercontinent breakup and subsequent dispersal was driven by migration of southern continents to geoid lows (Gurnis 1988). DICKENS Flood Waters Lead to Seafloor Spreading 2023 ICC 451
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