Permian and Triassic Biogenic Structures in the Shackleton Glacier Area,Transantarctic Mountains: Record of Nonmarine Benthic Communities and their Response to Climate Change

该奖项支持了一个项目，以研究在二叠纪和三叠纪部分的灯塔超群在中部transanaitic山脉的痕迹化石。 横贯大陆山脉中部的沉积序列表明，在二叠纪和三叠纪，冈瓦纳古太平洋边缘的这一部分相继被大陆冰川覆盖（宝塔阵），被内海淹没（Mackellar组），被河流流经桑迪辫状平原沉积的沉积物覆盖（费尔柴尔德组），并覆盖着沉积在辫状河道和洪泛平原（巴克利和Fremouw组）的砂和粉砂。 这一系列事件是由气候的改善和构造体制的变化引起的。 虽然丰富的植物区系的巴克利和Fremouw组和保存完好的脊椎动物动物群的Fremouw组是持续广泛的研究的主题，很少有人知道底栖动物，居住在广泛的内陆沃茨整个二叠纪和三叠纪及其对气候变化的反应。 这些动物本身并没有作为化石保存下来，但生物成因的结构，包括遗迹化石（遗迹动物群;离散的足迹、小径和洞穴）和遗迹组构（生物活动造成的一般破坏），提供了关于产生它们的底栖动物群的信息。 这些信息包括：1）生产者的大小和总体结构，给出了它们身份的关键; 2）动物区系多样性的近似值; 3）生产者的行为; 4）生产者的环境偏好; 5）生产者对营养和空间资源的利用;遗迹组构反映的底栖动物的活动和丰度与物理和沉积过程的关系。 在这项研究中，在不同的水下相内的Mackellar，费尔柴尔德，巴克利和下Fremouw组的遗迹化石和遗迹组构将被描述和解释，以开发一个图片的二叠纪和最早的三叠纪底栖水生动物群及其对气候变化的响应。 将在实地描述遗迹化石及其沉积学背景并拍照，将收集代表性标本进行实验室研究，并将评估动物对沉积物的破坏程度。 样品将在实验室切割和抛光，以阐明痕迹形态和增强遗迹组构。 很少有人知道古代非海洋水生底栖生物群落和遗迹动物群，尽管事实上，这些栖息地已被占领以来的古生代。 最近的研究表明，这些社区的主要变化发生在二叠纪和三叠纪早期，当时穴居人变得更加丰富。 这项研究将提供罕见的记录在不同的水生环境中的遗迹动物群（和间接动物群）分布在水生底栖生物群落的演变过程中的关键时刻，并将独特的解决问题的水生底栖动物群如何应对冰川后的气候改善。 同样重要的是，收集到的数据将用于评估南极洲和冈瓦纳大陆其他大陆，特别是南美洲和非洲之间的相关单位的遗迹动物群的相似性，并测试假设之间的差异在海洋和非海洋环境中的等效沉积制度中发现的遗迹动物群。

This award supports a project to study trace fossils in the Permian and Triassic portions of the Beacon Supergroup in the central Transantarctic Mountains. The sedimentary sequence in the central Transantarctic Mountains indicates that during the Permian and Triassic this portion of the paleo-Pacific margin of Gondwana was successively covered by a continental glacier (Pagoda Formation), flooded by an inland sea (Mackellar Formation), blanketed with sediment deposited by rivers flowing across a sandy braid plain (Fairchild Formation), and covered with sands and silts deposited in braided river channels and floodplains (Buckley and Fremouw Formations). This sequence of events was induced by amelioration of the climate and changes in tectonic regime. Although the rich floras of the Buckley and Fremouw Formations and well preserved vertebrate fauna of the Fremouw Formation are the subject of continuing extensive studies, little is known about the benthic fauna that inhabited the widespread inland waters throughout the Permian and Triassic and its response to climate change. The animals themselves are not preserved as fossils, but biogenic structures, including both trace fossils (ichnofauna; discrete tracks, trails and burrows) and ichnofabric (general disruption caused by biologic activity), give information about the benthic fauna that produced them. This information includes: 1) the size and general body plan of the producers, giving keys to their identity; 2) an approximation of the faunal diversity; 3) the behavior of the producers; 4) the environmental preferences of the producers; 5) the use of trophic and spatial resources by the producers; and 6) the activity and abundance of the benthic fauna relative to physical and depositional processes, as reflected by ichnofabric. In this study, the trace fossils and ichnofabric in diverse subaqueous facies within the Mackellar, Fairchild, Buckley and lower Fremouw Formations will be described and interpreted t o develop a picture of the Permian and earliest Triassic benthic aquatic fauna and its response to climate change. Trace fossils and their sedimentological context will be described and photographed in the field, representative specimens will be collected for laboratory study, and the extent of sediment disruption by animals will be evaluated. Samples will be cut and polished in the laboratory to elucidate trace morphology and enhance ichnofabric. Very little is known about ancient nonmarine aquatic benthic communities and ichnofaunas, in spite of the fact that these habitats have been occupied since the Paleozoic. Recent work suggest that major changes in these communities occurred during the Permian and earliest Triassic when burrowers became more abundant. This study will provide rare documentation of ichnofaunal (and indirectly faunal) distributions in diverse aquatic environments at a crucial time during evolution of aquatic benthic communities, and will uniquely address the question of how aquatic benthic faunas responded to climate amelioration after glaciation. Equally important, data collected will be used to assess the ichnofaunal similarity in correlative units between Antarctica and other Gondwana continents, particularly South America and Africa, and to test hypotheses regarding differences between ichnofaunas found in equivalent depositional regimes in marine and nonmarine environments.