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

该奖项由极地计划办公室南极地质和地球物理计划提供，支持晚新生代迈耶沙漠组的古生物学研究。从北近纪迈耶沙漠组(天狼星群)发现的陆地化石提供了大冰盖生长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、泥灰岩和岩化泥炭中发现了多种类型的生物化石，这些泥炭与寄宿层互层。Nothofagus(南方山毛榉)的木材和叶子在许多年前被发现，但自1995年以来，这些化石现在包括几种维管植物的种子，包括毛茅属(毛茅属)、几种苔藓的茎和叶、甲虫的身体部位(包括两种象甲)、高等苍蝇的蛹、淡水软体动物的壳(包括淋巴腹足动物和球藻)、介形虫的瓣膜和鱼的牙齿。该遗址最大的化石是被冰川喷发出的沉积物掩埋在生长位置的维管植物垫子。这些沉积物沉积在与冰雹有关的河道和浅水池中，冰雹曾在昆虫和软体动物栖息的苔原状植被中定居。据估计，每年至少有三个月的夏季平均气温约为4-5摄氏度。这些化石提供了迄今为止最好的证据，证明南极附近的大气可以容纳多少热量。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。这些化石是支离破碎的，但有希望保存得更好的标本可用于系统发育和生物地理研究。与迄今为止在南极洲发现的任何其他化石相比，它们与活的陆地和淡水生物的亲缘关系更密切。它们很可能是古代南极生物群的直系后代，该生物群是冈瓦那的一部分。在发现迈耶沙漠组之前，除了花粉和孢子外，没有任何陆地生物化石可以回答分布在南美洲南部、澳大利亚、新西兰和亚南极岛屿的生物之间的进化关系问题。研究小组将重新考察比尔德莫尔冰川上奥利弗断崖中暴露的迈耶沙漠组。将进行几项研究，包括定位和采样新的化石层位，建立复杂相准确缩放和关联的横断面，并为试点项目收集样品，以便使用一种涉及几个宇宙成因核素系统的组合方法直接测定沉积物的年代。古生物学研究的重点将是加强古环境解释，并将化石整合到生物地理研究中。年代学研究将侧重于解决沉积环境解释之间的差异。总而言之，这些研究提供的信息将有助于解决有关新生期间南极东部冰盖的大小和动态的更大问题。公众对南极的广泛兴趣，部分是因为探索的浪漫，但也是因为全球变暖的威胁和西南极冰盖潜在的不稳定。最近，关于拉森B冰架坍塌，以及像B17这样的巨大冰山向南大洋释放的报道，加剧了人们的兴趣。由于南极洲对地球的气候、海洋环流和海平面产生了巨大的影响，有关新近纪气候变暖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链接到“Biota Austarlis terrestris”获取有关研究的信息，包括化石的照片档案。“Biota Austarlis terrestris”是一个现有的可搜索南极洲和亚南极岛屿陆地和淡水生物的数据库。

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.