Terrestrial Paleoecology and Sedimentary Environment of the Meyer Desert Formation, Beardmore Glacier, Transantarctic Mountains

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，支持对晚新生代迈耶沙漠地层的古生物学研究。从Beogene Meyer沙漠组（Sirius Group）中发现的陆生化石提供了大冰原形成之前南极洲内部的古气候信息。该地点位于北纬85度的上比尔德莫尔冰川上，距离南极约500公里。在粉砂岩、泥灰岩和泥炭石中发现了许多种类的生物化石，这些化石与沉积丘互层。Nothofagus（南山毛榉）的木材和叶子是许多年前发现的，但自1995年以来，这些化石现在包括几种维管植物的种子，包括毛茛（毛茛），几种苔藓的茎和叶，甲虫的身体部位，包括两种象鼻虫，一种高级蝇的蛹，淡水软体动物的壳，包括淋巴纲腹足动物和球形蛤，介形虫的阀门，以及一种鱼的牙齿。该遗址中最大的化石是由维管植物垫成的化石，它们被冰川冲出的沉积物埋在生长位置。这些沉积物沉积在与冰碛岩相关的河道和浅水池中，这些冰碛岩曾被类似苔原的植被占据，那里栖息着昆虫和软体动物。据估计，每年至少有三个月的夏季平均气温在4-5摄氏度左右。这些化石为南极附近的大气能容纳多少热量提供了迄今为止获得的最佳证据。这些化石代表了居住在南极洲的生物，直到气候变化迫使它们灭绝。这些化石是碎片状的，但有希望为系统发育和生物地理学研究提供保存较好的标本。它们与现存的陆生生物和淡水生物的关系比迄今为止在南极洲发现的任何其他化石都要密切。它们很可能是古南极冈瓦纳生物群的直系后代。在发现迈耶沙漠组之前，除了花粉和孢子外，没有陆生生物的化石可以用来回答分布在南美洲南部、澳大利亚、新西兰和亚南极岛屿上的生物之间的进化关系问题。研究小组将重新考察在比尔德莫尔冰川的奥利弗布拉夫斯暴露的迈耶沙漠地层。将进行几项研究，包括定位和采样新的化石层，构建复杂相的精确比例和相关横截面，并为一个试点项目收集样品，使用几种宇宙形成核素系统的组合方法直接确定矿床的年代。古生物学研究的重点是加强古环境的解释，并将化石纳入生物地理研究。星相学和测年研究将集中于解决不同沉积环境解释之间的差异。总的来说，这些研究将提供有助于解决有关新近纪南极东部冰盖的大小和动态的更大问题的信息。公众对南极洲有广泛的兴趣，部分原因是探险的浪漫，但也因为全球变暖的威胁和南极西部冰盖潜在的不稳定。最近有报道称，拉森B冰架（Larsen B Ice Shelf）正在崩塌，像B17这样的巨大冰山被释放到南大洋，这激起了人们的兴趣。由于南极洲对地球的气候、海洋环流和海平面有着巨大的影响，有关新近纪温暖气候的知识引起了广泛的兴趣。媒体、教育工作者和研究人员将能够通过“澳大利亚陆地生物群”（Biota australis Terrestris）的链接，获取有关这些研究的信息，包括化石的照片档案。“澳大利亚陆地生物群”是一个现有的南极洲和亚南极岛屿陆地和淡水生物的可搜索数据库。

This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a study of the paleobiology of the late Cenozoic Meyer Desert Formation. Terrestrial fossils recovered from the Beogene Meyer Desert Formation (Sirius Group) are providing paleoclimatic information about the interior of Antarctica before the growth of the great ice sheets. The site is located on the Upper Beardmore Glacier at latitude 85S, about 500 km from the South Pole. Fossils of numerous types of organisms occur in siltstone, marlstone and lithified peat that are interbedded with lodgment tills. Wood and leaves of Nothofagus (southern beech) were discovered many years ago but since 1995 the fossils now include seeds of several species of vascular plants, including Ranunculus (buttercups), the stems and leaves of several species of mosses, body parts of beetles, including two weevil species, a puparium of a higher fly, shells of freshwater mollusks, including a lymnaeid gastropod and sphaeriid clam, valves of an ostracod, and the tooth of a fish. The largest fossils at the site are cushions of vascular plants buried in their growth positions by sediments of glacial outwash. The sediments were deposited in stream channels and shallow pools associated with moraines that had been colonized by a tundra-like vegetation in that harbored insects and mollusks. Mean summer temperatures are estimated to have been about 4-5C for at least three months per year. The fossils provide the best evidence so far obtained of how much heat the atmosphere near the South Pole can hold.The fossils represent organisms that inhabited Antarctica until climate change forced their extinction. The fossils are fragmentary but hold the promise that better-preserved specimens are available for phylogenetic and biogeographic studies. They are more closely related to living terrestrial and freshwater organisms than any other fossils so far discovered in Antarctica. They are most probably the direct descendants of an ancient Antarctic biota that was part of Gondwana. Until the discovery of the Meyer Desert Formation, no fossils of terrestrial organisms, except for pollen and spores, were available to answer questions about evolutionary relationships between organisms distributed in southern South America, Australia, New Zealand, and the subantarctic islands.The research team will revisit Meyer Desert Formation exposed in the Oliver Bluffs on the Beardmore Glacier. Several studies will be conducted including locating and sampling new fossiliferous horizons, constructing an accurately scaled and correlated cross-section of the complex facies, and collecting samples for a pilot project to directly date the deposits using an approach involving a combination of several cosmogenic nuclide systems. Paleontological studies will focus on enhancing paleoenvironmental interpretations and on integrating the fossils in biogeographic studies. The startigraphic and dating studies will focus on resolving differences between interpretations of sedimentary environments. Collectively, the studies will provide information that should help to address larger questions about the size and the dynamics of the East Antarctic Ice Sheet during the Neogene.There is extensive public interest in Antarctica in part because of the romance of exploration but also because of the threat of global warming and the potential instability of the West Antarctic Ice Sheet. That interest has been fueled recently by reports of the collapse of the Larsen B Ice Shelf and the release of huge icebergs, like B17, to the Southern Ocean. Because Antarctica exerts a huge influence on the Earth's climate, oceanic circulation and sea level, knowledge about warmer climates during the Neogene is of broad interest. Media, educators and researchers will be able to access information about the studies, including a photographic archive for the fossils, through links to "Biota Austarlis Terrestris," an existing searchable database for the terrestrial and freshwater organisms of Antarctica and the subantarctic islands.