East Antarctic glacial history through microfossil analyses of the Pagodroma Group

0089899 harwood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Pagodroma群沉积物进行微观古生物学调查，以补充和加强之前对东南极洲新生代冰川沉积物的地层学和古环境研究。初步结果表明，渐新世、中中新世、上中新世和上新世-更新世冰川海地层的存在，可能对我们理解南极东部冰盖（EAIS）的范围和特征的过去波动有重要贡献。这些地层沉积在一个冰川系统中，包括通过Lambert冰川的EAIS排水，以及在800多公里的距离上反复的海洋入侵和冰缘/接地线退缩。这些地层中存在的古生物学和沉积学信息有可能为EAIS的历史提供基线气候信息。Pagodroma组序列将提供大陆内部新近纪冰川海洋沉积的记录，这将扩展从干谷地区和Vestfold Hills的钻探岩心和露头中已经知道的东西。这些矿床的生物地层学年代是根据硅藻和有孔虫组合在硅藻海相泥岩的横向连续层内的出现来确定的。这些化石提供了与南大洋和罗斯海生物地层方案的直接年龄相关性。开阔的海洋硅藻生产和原位硅藻沉积在Pagodroma群的几个矿床中被注意到，这些矿床离现在的海岸线至少有300公里。这项新的研究将重点通过原位和冰川改造微化石组合的研究来确定Pagodroma群不同矿床的年龄。这将有助于重建EAIS-Lambert冰川- amery盆地- prydz湾系统的复合历史。本研究的主要目标是：(1)建立新近纪EAIS变化的时空记录；(2)利用地质数据验证预测未来EAIS随全球气温升高而变化的假设。此外，生物地层学和古生态学分析可以揭示沉积时的海表温度、海平面和海冰状况等环境参数。通过对新生代南极硅藻沉积的持续研究，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年实地季节收集的250个Pagodroma组样本进行分析。目前，在距离现代海岸250公里的Amery绿洲，有116个样品来自沉积物；5个样本来自内陆500公里处的Stinear山；还有84个样本来自距离内陆600公里的孟席斯山。该项目的主要工作将由一名博士后科学家进行，他将继续完善硅藻的生物地层和古生态利用，并进一步扩展他在新生代南极硅藻古生物学方面的教育和经验。未来，许多国际南极项目计划对南极大陆架和边缘进行地层钻探，这将需要几位经验丰富的硅藻古生物学家的技能，为回收的材料提供年龄和环境控制。总而言之，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有关南极东部冰盖新近纪变化以及未来对全球气温升高的可能反应的当前问题。

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.