A Target for High-Resolution Quaternary and Older Environmental Change Records: Site Survey for Drilling Mackay Sea Valley, Western Ross Sea

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，为麦凯海谷的地球物理现场调查提供资金，该调查需要评估该地区在第四纪（大约地球历史的最后160万年）期间冰盖波动的古环境记录的重要沉积记录的潜力。第四纪地质演替已成为最近的研究重点，以提供过去环境变化的高分辨率记录作为未来预测的基础，并有助于从人类引起的变化中破译自然变率。这项研究的目的是扩大最近在南极洲建立的关于环境变化的高分辨率海洋地质记录数据库，并研究第四纪和可能更早的环境变化。为了实现上述目标，当前阶段的工作特别旨在收集详细的现场调查信息，用于精确定位最佳钻井地点，并提供数据用于钻井和取心系统的工程评估，以满足采样要求。本研究建议的位置是麦凯海谷（MSV），它被认为是由新生代早期麦凯冰川扩张的侵蚀形成的，麦凯冰川是南极东部冰盖的主要出口冰川。MSV通过花岗岩港延伸到罗斯海西部。由于受到侵蚀，至少在第四纪和可能在晚新生代更早的时期，山谷经历了沉积物堆积。MSV的取芯点是极好的目标，因为：(1)它们的大水深和近岸位置，以及极地气候，似乎导致槽成为罗斯海部门已知的第四纪海洋环境变化最高分辨率记录的保存地点；(2)沉积制度是南极洲最深入研究的海岸环境之一；(3)初步的地球物理现场调查；(4)根据先前的活塞岩心工作，沉积物似乎具有良好的年代控制潜力。最终，研究的主要目标是：(1)应用多代理技术提取麦克默多海湾地区第四纪的高分辨率（年代际到世纪尺度）；(2)与当地和南极其他地区的地质和冰芯记录（如干谷和南极半岛第四纪地质记录；Taylor和simple Dome冰芯记录）建立海陆对比；(3)用北半球的记录检验南极变率，以便进行跨半球比较；(4)确定MSV不整合的年龄，这可能很好地反映了Mackay冰川在过去第四纪扩张期间在MSV内的冰川切割，并提供了新近纪侵蚀速率的约束条件；(5)表征不整合面下方较老的第四纪和/或新近纪沉积层，这些沉积层也可能提供该地区上新世历史的信息。然而，在适当制定实现这些总体目标的建议之前，需要高质量的现场调查信息。这项工作将为全面评估获取MSV环境变化高分辨率记录的潜力提供所需的现场数据。

0003607 PowellThis award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, provides funds for a geophysical site survey of the MacKay Sea Valley that is needed to evaluate the potential of this area to yield important sedimentary records of paleoenvironmental records of ice sheet fluctuations during Quaternary time (approximately the last 1.6 million years of Earth's history). Quaternary geological successions have been a recent focus for providing high-resolution records of past environmental changes on which to base future predictions, and to assist in deciphering natural variability from human-induced changes. This study is aimed at extending the data base of high-resolution marine geological records of environmental change that have been established recently in Antarctica, and to address Quaternary and perhaps older environmental changes.The current phase of the work, to achieve the goals outlined above, is specifically aimed at collecting information in a detailed site survey to be used for precisely locating the best drill sites, and also to provide data to use in an engineering evaluation of drilling and coring systems to meet sampling requirements. The location proposed for this study is Mackay Sea Valley (MSV), which is believed to have been formed by erosion associated with early Cenozoic expansion of Mackay Glacier, a major outlet glacier of the East Antarctic Ice Sheet. MSV extends through Granite Harbor and out to the western Ross Sea. Since being eroded, the valley has experienced sediment accumulation, at least in the Quaternary and possibly through earlier times during late Cenozoic.Coring sites in the MSV are excellent targets because: (1) their great water depth and near shore location, as well as the polar climate, appears to have led to the trough being a site of preservation for the highest resolution record of Quaternary marine environmental change known in the Ross Sea sector; (2) the sedimentation regime is one of the most intensely studied coastal settings in Antarctica; (3) there is a preliminary geophysical site survey, and (4) based on previous piston core work, the sediments appear to have the potential for good chronological control. Ultimately, the main goals of the coring study are to: (1) apply multi-proxy techniques to extract a high resolution (decadal(?) to century scale) of the Quaternary in the McMurdo Sound area; (2) establish marine-terrestrial correlations with geological and ice core records both locally and from elsewhere in Antarctica (e.g., Dry Valleys and Antarctic Peninsula Quaternary geological records; Taylor and Siple Dome ice core records); (3) test Antarctic variability with records from the Northern Hemisphere for cross-hemispheric comparisons; (4) determine the age of MSV unconformity that may well reflect glacial cutting within the MSV by Mackay Glacier during past Quaternary expansion(s) and provide constraints on Neogene erosion rates; and (5) characterize older Quaternary and/or Neogene(?) sediment below the unconformity that potentially could also provide information on Pliocene history of the area. However, before a proposal to achieve these overarching goals can be properly developed, high quality site survey information is required. This work will provide the site data needed for a full assessment of the potential for acquiring high-resolution records of environmental change in the MSV.