East Antarctic glacial history through microfossil analyses of the Pagodroma Group

0089899 Harwood该奖项由极地项目办公室南极地质和地球物理项目提供，支持对Pagodroma组沉积物进行微体古生物学调查，以补充和加强对东南极洲新生代冰川沉积物的地层和古环境研究。初步研究结果表明，存在渐新世（？），中中新世、上中新世和上新世-更新世冰海地层，这些地层有可能对我们理解东南极冰盖（EAIS）过去的范围和特征的波动做出重大贡献。这些地层沉积在一个冰川系统，包括EAIS排水通过兰伯特冰川和反复的海洋入侵和冰缘/接地线撤退跨越800多公里的距离。这些地层中的古生物学和沉积学信息有可能提供与EAIS历史有关的基线气候信息。Pagodroma组层序将提供大陆内部新近纪冰海沉积的记录，这将扩大干谷地区和韦斯特福尔丘陵的钻井岩心和露头的已知信息。这些矿床的生物地层学的日期发生在原地硅藻和有孔虫组合，发生在横向连续床内的杂屑岩序列的海相泥岩。这些化石为南大洋和罗斯海生物地层学方案提供了直接的年代对比。在Pagodroma组的几个沉积物中发现了开阔海洋硅藻生产和原地硅藻沉积，这些沉积物距离目前的海岸线至少300公里。这项新的研究将侧重于通过研究原位和冰川改造的微体化石组合来确定Pagodroma组不同沉积物的年龄。这将有助于重建EAIS-兰伯特冰川-埃默里盆地-普拉茨湾系统的复合历史。该提案的主要目标是：（1）开发新第三纪EAIS变化的时间和空间记录，以及（2）利用地质数据测试预测EAIS响应全球温度升高的未来变化的假设。此外，生物地层学和古生态学分析可以揭示沉积时的海面温度、海平面和海冰状况以及其他环境参数。通过对新生代南极含磷沉积物的持续研究，确定年代和解释这些古环境条件的能力正在稳步提高，但仍有许多工作要做。将对1997/98年野外季节收集的250个Pagodroma组样本进行分析。目前，在距离现代海岸250公里的内陆Amery绿洲的沉积物中有116个样品;在距离内陆500公里的Stinear山有5个样品;在距离内陆600公里的Menzies山有84个样品。该项目的大部分工作将由一名博士后科学家进行，他将继续改进硅藻的生物地层学和古生态学用途，并进一步扩大他在新生代南极硅藻古生物学方面的教育和经验。许多国际南极计划计划为南极大陆架和边缘计划的未来地层钻探计划将需要几位经验丰富的硅藻古生物学家的技能，以提供回收材料的年龄和环境控制。总之，该项目将为博士后研究人员提供进一步的经验和培训，这些重要材料将有助于回答当前有关东南极冰盖新第三纪变化的问题，以及未来对全球气温升高的可能反应。

0089899HarwoodThis award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a micropaleontological investigation of Pagodroma Group sediments to complement and enhance prior stratigraphic and paleoenvironmental studies of these Cenozoic glacial deposits of East Antarctica. Preliminary results indicate the presence of Oligocene (?), middle Miocene, upper Miocene and Pliocene-Pleistocene glaciomarine strata that have the potential to contribute significantly to our understanding of the past fluctuations in the extent and character of the East Antarctic Ice Sheet (EAIS). These strata were deposited in a glacial system involving EAIS drainage through the Lambert Glacier and repeated marine incursion and ice margin/grounding line retreat across a distance of more than 800 km. Paleontological and sedimentological information present within these strata have the potential to provide baseline climate information bearing on the history of the EAIS. The Pagodroma Group sequences will provide a Neogene record of glaciomarine deposition on the continental interior that will expand what is already known from drill cores and outcrops in the Dry Valley region and the Vestfold Hills. These deposits are dated biostratigraphically by the occurrence of in situ diatom and foraminifera assemblages that occur in laterally-continuous beds of diatomaceous marine mudstone within a sequence of diamictite. These fossils provide direct age correlation to Southern Ocean and Ross Sea biostratigraphic schemes. Open marine diatom production and in situ diatom sedimentation is noted in several deposits of the Pagodroma Group that are at least 300 km inland from the current coastline. This new research will focus on establishing the age of different deposits of the Pagodroma Group through the study of in situ and glacially reworked microfossil assemblages. This will aid in the reconstruction of a composite history of the EAIS-Lambert Glacier-Amery Basin-Prydz Bay system. Primary objectives of this proposal are: (1) to develop a temporal and spatial record of Neogene EAIS variability, and (2) to test hypotheses that predict future changes in the EAIS in response to elevated global temperatures with geologic data. In addition, biostratigraphical and paleoecological analyses can reveal sea-surface temperature, sea level and sea-ice conditions, among other environmental parameters at the time of deposition. The ability to date and interpret these paleoenvironmental conditions is improving steadily through continued study of Cenozoic Antarctic diatom-bearing deposits, yet much remains to be done. Analyses will be undertaken on 250 Pagodroma Group samples collected during the 1997/98 field season. Currently 116 samples are available from deposits on the Amery Oasis, which is 250 km inland from the modern coast; 5 samples from Mt Stinear, 500 km inland; and 84 samples from Mt Menzies, which is 600 km inland. The bulk of this project will be conducted by a post-doctoral scientist, who will continue to improve the biostratigraphic and paleoecological use of diatoms and further extend his education and experience in Cenozoic Antarctic diatom paleontology. Future stratigraphic drilling programs that are planned for the Antarctic shelf and margin by numerous international Antarctic programs will require the skills of several experienced diatom paleontologists to provide age and environmental control for recovered materials. In summary, this project will provide further experience and training for a postdoctoral researcher on important materials that will help to answer current questions about Neogene variability of the East Antarctic Ice Sheet and the likely response to elevated global temperatures in the future.