The Paleocene of Antarctica: Dinoflagellate cyst biostratigraphy, chronostratigraphy and implications for the palaeo-Pacific margin of Gondwana
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
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发表时间：
2016-10-01
影响因子：
6.1
通讯作者：
Ferraccioli, F.
中科院分区：
文献类型：
--
作者：
Bowman, V.;Ineson, J.;Ferraccioli, F.
古新世（66-56 Ma）是研究古纬度高地区生物大灭绝恢复的关键时期，当时全球气候比现在温暖。一个独特的沉积序列从西摩岛（南极半岛）提供了关键的参考材料，从这一重要阶段的早新生代。根据376 m厚的地层剖面（包括古近系-古近系界线）的甲藻孢囊资料，与新西兰、东塔斯曼高原和澳大利亚东南部的生物带进行了对比。根据甲藻孢囊生物地层学和锆石U-Pb定年，结合相关的磁性地层学和大型化石的锶同位素值，提出了洛佩斯德贝尔托达诺组（LDBF）和索布拉尔组（SF）的详细年龄模式。LDBF顶的年龄为最晚的Maastrichtian至最早的Danian（66.2- 65.65Ma）。上覆的SF主要是达尼亚时代，与推断的裂缝附近的顶部覆盖的沉积物日期为？萨尼西亚晚期罕见的Apectodinium homomorphum首次出现在SF的最上部;南极洲最早的原位记录。巴塔哥尼亚、南极洲、新西兰和澳大利亚从白垩纪到始新世沉积物的海洋和陆地化石的分布要求冈瓦纳大陆的这些碎片之间既有海洋也有陆地。南极古地理和古地形的化石证据和重建揭示了当时在原始威德尔海和罗斯海地区持续存在海湾的证据。我们的结论是，沿海传播路线沿着古太平洋边缘的冈瓦纳可以解释化石的分布，而不需要一个跨南极海峡或密集的群岛。南极洲东西边界地带的一个地区，直到古近纪早期才升高，可能是高海拔冰盖的所在地。这支持化石，地球化学和沉积学证据寒冷的气候间隔和显着的海平面下降福尔斯在马斯特里赫特和古新世。(C)2015年，作者。由Elsevier B. V.代表国际冈瓦纳研究协会出版。
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.