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

0003607 鲍威尔该奖项由极地项目办公室南极地质和地球物理项目提供，为麦凯海山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）期间产生冰盖波动的古环境记录的重要沉积记录的潜力。第四纪地质演替是最近的一个重点，提供高分辨率的记录，过去的环境变化的基础上，未来的预测，并协助破译自然变异的人为引起的变化。这项研究的目的是扩大最近在南极洲建立的高分辨率海洋环境变化地质记录数据库，并探讨第四纪和可能更古老的环境变化，为实现上述目标，目前阶段的工作特别是收集详细的现场调查资料，用于精确确定最佳钻探地点，并且还提供用于钻探和取芯系统的工程评估的数据以满足取样要求。本研究建议的地点是麦凯海谷（MSV），据信这是由麦凯冰川（东南极冰盖的一个主要出口冰川）在新生代早期扩张时产生的侵蚀形成的。MSV穿过花岗岩港延伸到罗斯海西部。自被侵蚀以来，山谷经历了沉积物堆积，至少在第四纪，并可能通过早在晚新生代。在MSV取心地点是很好的目标，因为：（1）水深大，靠近海岸，气候极地，似乎已经导致槽是一个保存的最高分辨率记录第四纪海洋环境变化的网站，罗斯海部分;（2）沉积状况是南极洲研究最深入的沿海环境之一;（3）进行了初步的地球物理现场调查;（4）根据以前的活塞岩心工作，沉积物似乎具有良好的年代控制潜力。最终，取心研究的主要目标是：（1）应用多代用指标技术提取高分辨率（年代际（？）世纪尺度）;（2）建立海洋与陆地的相关性与地质和冰芯记录都在当地和其他地方在南极洲（例如，Dry Valleys和南极半岛第四纪地质记录; Taylor和Siple Dome冰芯记录）;（3）用来自北方半球的记录测试南极的变化，以进行跨半球比较;（4）确定MSV不整合面的年龄，该年龄可能很好地反映了MSV在过去第四纪扩张期间被Mackay冰川切割，并提供了对新近纪侵蚀速率的限制;（5）表征第四纪和新近纪（？）不整合面下的沉积物，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主尺度空间站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.