Permian and Triassic Floras of the Beardmore Glacier Area: Icehouse or Greenhouse?

比尔德莫尔冰川地区的二叠纪和三叠纪植物群：冰库还是温室？

• 批准号: 0126230
• 负责人: Edith Taylor
• 金额: $ 9.38万
• 依托单位: University of Kansas Center for Research Inc
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-06-01 至 2005-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0126230&HistoricalAwards=false
• 关键词: Permian; Triassic; Floras; Beardmore; Glacier

This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, provides funds for research to investigate fossil plants from the central Transantarctic Mountains toward an understanding of plant diversity and evolution as well as an improved understanding of the paleoenvironmental conditions. The terrestrial rocks of the central Transantarctic Mountains have been a source of outstanding plant fossil discoveries over the last 30 years, including Permian and Triassic permineralized peat, fossil forests silicified in growth position, and compression floras with cuticular preservation. The rare juxtaposition of sites that include many different types of plant preservation (permineralization, compression/impression, in situ forests, mummified wood), the exceptional quality of the plant preservation, and the richness of the sites make this area unique in the world. This project centers on the collection of Permian and Triassic plant megafossils from the Beardmore Glacier area. Fieldwork is anticipated in the 2003-2004 field season as part of a mini-camp with other researchers. Collections would include compression floras, especially those from Graphite Peak, and permineralized peats from Skaar Ridge and Fremouw Peak, both in the vicinity of Walcott Neve. These permineralizations represent the rarest form of plant fossil preservation. Since they preserve a three-dimensional record of the flora, they are important in understanding the basic morphology and anatomy of fossil plants, as well as detailing relationships among groups. The additional data provided by the juxtaposition of plant fossils preserved both as permineralizations and compressions have already contributed a great deal to our understanding of late Paleozoic-early Mesozoic plant evolution. This project will address several important phylogenetic hypotheses through further collection of material, coupled with material already processed. The Permian and Triassic represent an important time in plant evolution, and one about which we still know relatively little, especially in the southern hemisphere. The glossopterid seed ferns in the Permian (leaf type, Glossopteris), and the corystosperms in the Triassic (leaf type, Dicroidium) were the dominant plant groups in Gondwana. Since both of these groups bore seeds which were enclosed in some manner, they have been proposed at one time or another as possible ancestors of the flowering plants, and have figured prominently in phylogenetic analyses of seed plants. Only through a combination of permineralizations and compressions is it possible to reveal a complete picture of the form and structure of fossil plants, but more importantly, to understand the position of these plant groups in seed plant evolution. Plants and silicified logs will be collected from the section at Graphite Peak, which is believed to contain the Permian/Triassic boundary. These plant fossils will be used to test several hypotheses concerning the floral and paleoclimate changes that may have occurred across this boundary. These include: How early in the Triassic does the Dicroidium flora appear? Does Glossopteris occur with Dicroidium as it does in several other Gondwana floras? Is there any evidence of a megaflora dominated by lycopods, as some of the palynological evidence suggests? Silicified logs have been noted in the lower Buckley Formation (mid-Permian?) at this site and these will be collected and examined for paleoclimate data from tree rings. These can also be compared with tree rings in Late Permian wood (upper Buckley) from nearby Mt. Achernar. The Late Permian has been assumed to be much warmer than Early-Middle Permian and this should be reflected in differences in the width and structure of the tree rings.This project is expected to lead to significant improvements in understanding of both plant evolution and paleoenvironmental conditions during the critical Permian to Triassic interval.

该奖项由极地方案办公室南极地质学和地球物理学方案提供，为研究提供资金，以调查横贯南极山脉中部的化石植物，了解植物多样性和进化，以及更好地了解古环境条件。在过去的30年里，横贯南极山脉中部的陆地岩石一直是杰出的植物化石发现的来源，包括二叠纪和三叠纪的过矿化泥炭，生长位置硅化的化石森林，以及具有角质层保存的压缩植物群。包括许多不同类型的植物保护（渗透矿化，压缩/印象，原位森林，木乃伊化木材），植物保护的特殊质量以及遗址的丰富性的遗址的罕见并列使该地区在世界上独一无二。该项目的中心是从比尔德摩尔冰川地区收集二叠纪和三叠纪植物化石。预计在2003-2004年实地考察季节将进行实地考察，作为与其他研究人员一起举办的小型营地的一部分。收集将包括压缩植物群，特别是那些从石墨峰，和矿化泥炭从斯卡尔岭和弗雷莫峰，都在附近的沃尔科特内夫。这些渗透作用代表了植物化石保存的最稀有形式。由于它们保存了植物群的三维记录，它们对于理解化石植物的基本形态和解剖以及详细说明群体之间的关系非常重要。通过植物化石的并置，以渗透和挤压的方式保存下来，所提供的额外数据已经为我们理解晚古生代-早中生代植物演化做出了很大贡献。该项目将通过进一步收集材料以及已经处理的材料来解决几个重要的系统发育假设。二叠纪和三叠纪代表了植物进化的一个重要时期，而我们对这一时期的了解相对较少，尤其是在南半球。二叠纪的舌羊齿类种子蕨（叶型，舌羊齿）和三叠纪的囊子蕨（叶型，Dicroidium）是冈瓦纳的优势植物类群。由于这两个类群的种子都以某种方式被包围，它们曾被认为是有花植物的可能祖先，并在种子植物的系统发育分析中占有重要地位。只有通过渗透作用和挤压作用的结合，才有可能揭示化石植物形态和结构的全貌，但更重要的是，了解这些植物群在种子植物进化中的地位。植物和硅化原木将从石墨峰（Graphite Peak）剖面采集，据信该剖面包含二叠纪/三叠纪界线。这些植物化石将被用来测试几个假设，关于植物和古气候变化，可能已经发生了跨越这一边界。这些问题包括：Dicroidium植物群在三叠纪出现的时间有多早？舌羊齿属是否和其他冈瓦纳植物区系一样与双轮藻属一起出现？有没有任何证据表明，一个由石松足类占主导地位的巨型植物，因为一些孢粉学证据表明？硅化测井记录已注意到在较低的巴克利组（中二叠世？）在这个地点，这些将被收集和检查的古气候数据，从树木年轮。这些也可以与来自附近Mt.阿切尔纳晚二叠世一直被认为比早中二叠世要温暖得多，这应该反映在树木年轮的宽度和结构上的差异上。该项目预计将大大提高对二叠纪至三叠纪关键时期植物进化和古环境条件的认识。