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The Paleocene of Antarctica: Dinoflagellate cyst biostratigraphy, chronostratigraphy and implications for the palaeo-Pacific margin of Gondwana
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DOI：10.1016/j.gr.2015.10.018.png)
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Abstract
En 中文
The Paleocene (66-56 Ma) was a critical time interval for understanding recovery from mass extinction in high palaeolatitudeswhen global climate waswarmer than today. A unique sedimentary succession fromSeymour Island (Antarctic Peninsula) provides key referencematerial from this important phase of the early Cenozoic. Dinoflagellate cyst data froma 376mthick stratigraphical section, including the Cretaceous-Paleogene boundary, is correlatedwith biozones from New Zealand, the East Tasman Plateau and southeastern Australia. A detailed age model is suggested for the Lopez de Bertodano (LDBF) and Sobral (SF) formations based on dinoflagellate cyst biostratigraphy and U-Pb dating of zircons, supported by correlatedmagnetostratigraphy and strontium isotope values frommacrofossils. The top of the LDBF is confirmed as latest Maastrichtian to earliest Danian (similar to 66.2-65.65 Ma) in age. The overlying SF is mostly Danian in age, with an inferred hiatus near the top overlain by sediments dated as ? late Thanetian. Rare Apectodinium homomorphum first appear in the uppermost SF; the earliest in situ record from Antarctica. The distribution of marine and terrestrial fossils from uppermost Cretaceous to Eocene sediments in Patagonia, Antarctica, New Zealand and Australia required both sea and land connections between these fragments of Gondwana. Fossil evidence and reconstructions of Antarctic palaeogeography and palaeotopography reveal evidence for persistent embayments in the proto-Weddell and Ross Sea regions at this time. We conclude that a coastal dispersal route along the palaeo-Pacificmargin of Gondwana could explain the fossil distribution without requiring a transAntarctic strait or closely spaced archipelago. A region in the West to East Antarctic boundary zone, elevated until the early Paleogene, perhaps acted as a site for high elevation ice caps. This supports fossil, geochemical and sedimentological evidence for cold climate intervals and significant sea level falls during the Maastrichtian and Paleocene. (C) 2015 The Authors. Published by Elsevier B.V. on behalf of International Association for Gondwana Research.
Keywords:
Cretaceous-Paleocene
Antarctic Peninsula
Gondwana
Biostratigraphy
Palaeogeography
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