Collaborative Research: Permian-Triassic Basin History of Southern Victoria Land and the Darwin Mountains

合作研究：维多利亚州南部土地和达尔文山脉的二叠纪-三叠纪盆地历史

• 批准号: 9909637
• 负责人: John Isbell
• 金额: $ 23.45万
• 依托单位: University of Wisconsin-Milwaukee
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-06-01 至 2004-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9909637&HistoricalAwards=false
• 关键词: Collaborative; Research; Permian; Triassic; Basin

9909637IsbellThis award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a collaborative sedimentological, palynological, and paleomagnetic study of Permian and Lower Triassic strata in southern Victoria Land (SVL) and the Darwin Mountains (DM), Antarctica. Results of the study will help constrain the paleoenvironmental, tectonic, biotic, and paleogeographic histories of southern Pangea and provide a unique polar view of the world during an icehouse to greenhouse transition.The assembly and drift of Pangea resulted in heightened orogenic activity and associated development of numerous depositional basins. One of the largest basins was the 10,000+ km long "Gondwanide foredeep" that extended across southern South America, South Africa, the Falkland Islands, Antarctica, and Australia. Antarctica's centralized location between South Africa and Australia, make SVL and DM key areas for testing paleogeographic and paleoclimatic models.Upper Paleozoic and Lower Mesozoic rocks in SVL and DM were deposited during Gondwanaland's drift across the south pole. Based on present plate reconstructions, SVL and DM were located higher than 75 degrees south latitude from 320 to 210 Ma. Despite the putative high latitude position, SVL and DM sedimentary successions record a change from Lower Permian glacial deposits, to Permian fluvial coal measures, to Lower Triassic non-carbonaceous fluvial deposits, and finally to Middle and Upper Triassic fluvial coal measures, with well-developed vegetation during much of this time. Present climatic simulations suggest seasonal climatic extremes within Pangea's polar interior. Discrepancies between the geological evidence and the climate simulations need to be resolved, and may be magnified by incomplete understanding of the influence of paleotopography, large lakes, and river systems at the time of deposition, as well as by incomplete documentation of paleoenvironmental conditions. Furthermore, Late Permian and Triassic mean pole positions for Gondwanaland are not tightly constrained. Paleomagnetic signatures will be recovered from Permian and Triassic petrified wood, silicified peat, and coal, which were cemented during early diagenesis (preliminary results indicate stable remnant magnetizations). Palynological analyses will provide time control for the succession.Objectives of this study include:1) Determination of a late Paleozoic glacial/deglaciation history for SVL and DM as Gondwana drifted over the south pole,2) Documentation of Permian strata as a means to better understand the environments of high latitude fluvial coal-bearing deposits,3) Documentation of Triassic lithofacies as a means to better understand high latitude conditions during the Early to Middle Triassic "coal gap" interval,4) Providing a well-constrained stratigraphic framework for the Permian to lower Triassic succession,5) Testing the diachronous and inversion tectonic models for the Panthalassan Margin of southwestern Pangea, and6) Constructing better paleogeographic models for Gondwana by obtaining new Gondwana reference poles for the Permian and Triassic.

该奖项由极地项目办公室的南极地质和地球物理项目提供，支持对南极洲维多利亚地南部（SVL）和达尔文山脉（DM）的二叠纪和下三叠纪地层进行沉积学、孢粉学和古地磁研究。研究结果将有助于限制南盘古大陆的古环境、构造、生物和古地理历史，并在冰窖到温室过渡期间提供一个独特的极地视角。盘古大陆的组合和漂移导致造山活动加剧，并形成了大量沉积盆地。其中最大的盆地之一是长达1万多公里的“冈瓦尼德前深”，它横跨南美洲南部、南非、福克兰群岛、南极洲和澳大利亚。南极洲位于南非和澳大利亚之间的中心位置，使SVL和DM成为古地理和古气候模式测试的重点区域。SVL和DM的上古生界和下中生界岩石是在Gondwanaland的南极漂移过程中沉积的。基于现有的板块重建，在320 ~ 210 Ma范围内，SVL和DM位于南纬75度以上。尽管假定处于高纬度位置，但SVL和DM沉积序列记录了从下二叠统冰川沉积到二叠统河流煤系，再到下三叠统非碳质河流沉积，最后到中上三叠统河流煤系的变化，其中大部分时间植被发育良好。目前的气候模拟表明，盘古大陆的极地内部存在季节性极端气候。地质证据和气候模拟之间的差异需要解决，并且由于对沉积时期古地形、大型湖泊和河流系统的影响的不完全理解，以及对古环境条件的不完整记录，可能会扩大这种差异。此外，晚二叠世和三叠纪冈瓦纳大陆的平均极位没有受到严格的限制。对二叠系和三叠系早期成岩作用中胶结的石化木、硅化泥炭和煤进行古地磁特征恢复（初步结果显示残余磁化稳定）。孢粉学分析将为演替提供时间控制。本研究的目的包括：1)确定冈瓦纳漂移南极时SVL和DM的晚古生代冰川/脱冰史；2)记录二叠纪地层，以更好地了解高纬河流含煤矿床的环境；3)记录三叠纪岩相，以更好地了解早至中三叠世“煤间隙”段的高纬条件5)验证盘古大陆西南部泛海山脉边缘的历时和反演构造模型；6)通过获得新的二叠纪和三叠纪冈瓦纳参考极，构建更好的冈瓦纳古地理模型。