The Quaternary Glacial History of the Wilkes Land Margin, Antarctica

该奖项由极地方案办公室南极地质和地球物理方案提供，支持对威尔克斯陆地边缘现有沉积岩心(即1968-1971年的USNS-Eltanin、1984年的美国地质调查局和1982-1983年的日本国家石油公司邮轮)的研究，并补充将在2000年2月至3月由意大利的里雅斯特的Osservatorio Geofisico Sperentale(OGS)和澳大利亚霍巴特的南极CRC邮轮到Wilkes陆地的邮轮期间收集的新材料。这项研究的目的是确定南极东部冰盖的演化如何影响威尔克斯陆架、陆坡和海隆上第四纪沉积序列的沉积。威尔克斯陆缘目前的冰川地层学模型表明，陆架、斜坡和隆起的沉积物供应具有很强的周期性。在冰盛期，大部分陆源沉积发生在外陆架、斜坡和隆起。间冰期，大部分陆源沉积发生在内陆架，而外陆架、斜坡和隆起主要接受生物和半深海沉积物。因此，通过结合陆架、斜坡和隆起上的沉积记录，可以获得最完整的冰川/间冰期和较小规模的旋回记录。现有的沉积物岩心(长达11米)将使用硅藻地层学和磁性地层学来确定年代。一旦确定了沉积岩心的年代，将确定每个沉积环境的沉积和堆积速率，以确定边缘沉积中心的移动。将对岩心下部沉积参数的变化(例如，硅质碎屑与生物成因、碎屑丰富与碎屑贫乏、块状与层状)进行研究，以确定：1)控制沉积物分布模式的冰川沉积过程；2)有助于建立与威尔克斯陆地边缘南极冰川事件有关的气候波动的地层旋回。对现有岩心的研究将得到2000年2月10日至3月19日海洋勘探局-南极CRC巡航期间收集的船上和陆上岩心分析的初步结果的补充。船上的分析包括：视觉描述、物性测定、涂片和微化石鉴定。邮轮上的岩芯将储存在澳大利亚霍巴特的南极CRC海洋地球科学研究所。如果可以回收适当的物质，并建立适当的储集层校正，将选择一些样品，在采集后立即冻结的岩心样品上，使用加速器质谱仪技术进行放射性碳测年。该项目的结果将被用来帮助满足在威尔克斯陆地大陆边缘钻探的现有ODP值提案“成熟”的ODP值要求。这项研究预计将提供信息，使现有的沉积模型得以完善，并更好地了解该边缘的冰川/间冰川沉积过程和循环。这项研究是根据最近的国家(NSF-东南极边缘研讨会，俄亥俄州，1997年)和国际(ANTIME和ANTOSTRAT，霍巴特，1997年)讲习班而开发的，在这些讲习班上，威尔克斯陆缘被确定为多学科研究的主要目标之一，包括长期和近期冰川史。

This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports research to study existing sediment cores from the Wilkes Land margin (i.e., USNS-Eltanin 1968-1971, US Geological Survey 1984, and Japanese National Oil Corporation 1982-1983 cruises), supplemented by new material that will be collected during a cruise to Wilkes Land in February-March 2000 by the Osservatorio Geofisico Sperimentale (OGS), Trieste, Italy and Antarctic CRC, Hobart, Australia. The objective of the study is to determine how the evolution of the East Antarctic Ice Sheet has affected the deposition of Quaternary sedimentary sequences on the Wilkes Land continental shelf, slope, and rise. The present model of glacial stratigraphy for the Wilkes Land margin indicates that supply of sediment to the shelf, slope and rise is strongly cyclic. During times of glacial maxima, most terrigenous deposition occurs on the outer shelf, slope and rise. During interglacials, most terrigenous deposition occurs on the inner shelf, while the outer shelf, slope and rise receive mainly biogenic and hemipelagic sediment. The most complete record of glacial/interglacial, and smaller scale cycles can thus be obtained by combining the sedimentary record contained on the shelf, slope and rise. The existing sediment cores (up to 11 meters long) will be dated using diatom stratigraphy and magnetostratigraphy. Once sediment cores are dated, sedimentation and accumulation rates will be determined for each depositional environment to determine shifts in depositional centers across the margin. Studies of downcore variations of sedimentary parameters (e.g., siliciclastic vs. biogenic, clast-rich vs. clast-poor intervals, and massive vs. laminated) will be done in order to determine: 1) glacial sedimentary processes which control patterns of sediment distribution and 2) cyclicities in the strata that can help to establish climatic fluctuations related to Antarctic glacial events in the Wilkes Land margin. Study of existing cores will be complemented by preliminary results from shipboard and onshore analyses of cores collected during the 10 February -19 March 2000 OGS - Antarctic CRC cruise. Shipboard analyses include: visual description, determination of physical properties, smear slides and microfossil identification. Cores from the cruise will be stored in the Antarctic CRC Marine Geoscience institute, Hobart, Australia. If appropriate materials can be recovered, and it appropriate reservoir corrections can be established, some samples will be selected for radiocarbon dating using accelerator mass spectrometry techniques on core samples frozen just after collection. Results from this project will be used to help fulfill ODP requirements for "maturation" of the existing ODP proposal for drilling on the Wilkes Land continental margin.This research is expected to provide information that will allow refinement of the existing depositional models and to understand better the glacial/interglacial sedimentation processes and cycles across this margin. This research was developed in response to recent national (NSF-East Antarctic Margin Workshop, Ohio, 1997) and international (ANTIME and ANTOSTRAT, Hobart, 1997) workshops, where the Wilkes Land margin was identified as one of the main targets for multidisciplinary research, including long-term and recent glacial history.