The Lopingian of Australasia: a review of biostratigraphy, correlations, palaeogeography and palaeobiogeography

摘要

This paper presents an overview of the space and time distributions of Lopingian strata and biotas in Australia, New Zealand, Timor and New Caledonia. Based on this review, we propose a new schematic Late Permian (Lopingian) regional palaeogeographical reconstruction and marine palaeobiogeographical synthesis. The latter also incorporates some key features of the ocean circulation patterns around southeastern Gondwana, inferred primarily from the distribution of regional marine Lopingian faunas. Across Australasia, Lopingian successions accumulated in a wide range of tectonic, palaeoenvironmental and palaeolatitudinal settings. In New Zealand, Lopingian strata are found in several tectonostratigraphical terranes, notably the Brook Street, Dun Mountain-Maitai, Caples, Waipapa and Torlesse terranes/supertenanes, each originating as a distinctive basin, island arc or ocean ridge. For the most part, these successions represent displaced segments of volcanic arcs, arc-flanking elastic aprons, intra- and fore-arc basins and accretionary complexes, some of which have been traced via stratigraphical, biostratigraphical and petrological correlations into New Caledonia and eastern Australia. This spectrum of Lopingian tectono-sedimentary environments in New Zealand is interpreted to have been originally located near northeastern Australia on a convergent continental margin (i.e. the Panthalassan margin of southeastern Gondwana). Brachiopod and bivalve faunas occur widely throughout the Lopingian successions of New Zealand and have been closely studied. A total of five successive faunal zones are recognized, ranging in age from mid-late Wuchiapingian to the end of the Changhsingian. In Australia, Lopingian deposits are dominated by non-marine successions in a large number of widely distributed sedimentary basins; onshore exposures of marine deposits are known only from the Gympie Terrane in eastern Australia and the Canning and Bonaparte basins in Western Australia. Lopingian terrestrial sediments are most extensively represented in eastern Australia within a major meridional foreland basin complex (the Tasmania, Sydney, Gunnedah and Bowen basins), for which the evolution through the Lopingian and Early Triassic was governed by the dynamics of the New England Orogen along the Panthalassan margin of southeastern Gondwana. Most of the non-marine successions in eastern Australia are rich in coal measures and plant fossils and locally contain well-preserved non-marine invertebrate and vertebrate fossils. A succession of six palynostratigraphical zones has been recognized in eastern Australia spanning the Lopingian through the Early Triassic. Several of these palynozones have also been recognized in Western Australia, allowing the discrimination and correlation of Lopingian deposits in both onshore and offshore successions. In contrast to eastern Australia and New Zealand, the marine Lopingian successions of Western Australia and Timor are dominated by carbonates that are only locally interbedded with siliciclastic sediments and sparse volcaniclastics; these successions accumulated in a giant sedimentary basin located on a passive and actively rifting continental margin. Marine connections and free and frequent biotic interchanges between this Western Australian superbasin (including Timor) and the Himalayan region of Nepal, southern Tibet and northern India throughout the Lopingian are evident from the shared occurrences of many shallow-marine invertebrate species. Copyright (C) 2010 John Wiley & Sons, Ltd.