Was the Deepest Lake in North America a Subglacial Lake?

北美最深的湖泊是冰下湖吗？

• 批准号: 0612385
• 负责人: Slawek Tulaczyk
• 金额: --
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-15 至 2008-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0612385&HistoricalAwards=false
• 关键词: Was; Deepest; Lake; North; America

ABSTRACTTulaczykOPP-0612385Scientific Merit: This is a one-year research project to test the hypothesis that Christie Bay, NE Great Slave Lake, Canada, was a large subglacial lake during at least part of the last glacial period. Past subglacial lakes represent unique and scientifically valuable archives of paleoenvironmental and paleoclimatic data. They may also serve as terrestrial analogs for exploration of past life habitats on icy planetary bodies in our Solar System. Seismic data collected in Christie Bay in summer 2005, during a pilot project, revealed a ~150-to-200-meter-thick sequence of sediments of interpreted (glacio) lacustrine origin. Given that postglacial linear sedimentation rates in large lakes in North America are typically of the order of 0.1 and 1 mm/yr, such a thick sequence may potentially hold a record of subaerial and subglacial lacustrine conditions covering one or more glacial cycles. Before sampling and analyses of the Christie Bay sequence will be warranted, there is need to collect more data to gain confidence in the past presence of a subglacial lake in Christie Bay and to better plan future exploration of the existing sedimentary record. The Principal Investigator will deploy air gun and Chirp seismic tools, together with multibeam echo sounding, and short sediment cores on a geophysical lake survey covering total of 600-800 km. The new data will elucidate the relative importance of subglacial and (glacio) lacustrine processes in deposition of the thick sedimentary sequence found in Christie Bay. They will also provide constraints on linear sedimentation rates within the upper part of the sequence. Understanding of sedimentation rates plays a key role in interpreting whether this sedimentary sequence may have been deposited: 1) entirely since deglaciation ~9,000-10,000 years BP (i.e., no subglacial lake needed to explain observations), 2) in one glacial cycle (~100,000 years), or 3) in multiple glacial cycles. Acceptance of the first, postglacial model will represent rejection of the guiding hypothesis of this proposal.Broader ImpactsContribution to Different Disciplines: Project results will be relevant to a number of disciplines, including glacial geology, geomorphology, sedimentology, geophysics, and climate dynamics.Human Resource Development: The proposed research will represent an important stage in the evolution of Principal Investigator's research group at UCSC because it will enable continuing involvement in Arctic research and will connect bi-polar studies of modern and past subglacial environments. One graduate student will obtain advanced training in application of state-of-the-art geophysical techniques relevant to exploration of sedimentary basins. One African-American undergraduate student will gain laboratory and field research experience and will complete senior thesis based on this work.Impact on Classroom Teaching: Field experience and research results will be incorporated in several different courses reaching annually ~120 students at UCSC. Community and Media Outreach: The study area is under control of First Nations and a number of activities are planned to interface with the local community (e.g., presentation at a school in Lustelk'e, open afternoon for visits to the research vessel, hiring of First Nation members in position of two skippers and one camp manager). The Principal Investigator will work with UCSC science writers to issue press releases when major findings are published.

摘要TulaczykOPP-0612385 科学价值：这是一个为期一年的研究项目，旨在检验加拿大大奴湖东北部克里斯蒂湾至少在末次冰河期的一部分期间是一个大型冰下湖的假设。过去的冰下湖泊代表了独特且具有科学价值的古环境和古气候数据档案。它们还可以作为地球的类似物，用于探索太阳系冰冷行星体上的过去生命栖息地。 2005 年夏天，在一个试点项目期间，在克里斯蒂湾收集的地震数据揭示了约 150 至 200 米厚的沉积物序列，这些沉积物被解释为（冰川）湖泊起源。鉴于北美大型湖泊的冰后线性沉积率通常约为 0.1 和 1 毫米/年，如此厚的序列可能保存着涵盖一个或多个冰川周期的陆上和冰下湖泊条件的记录。在对克里斯蒂湾序列进行采样和分析之前，需要收集更多数据，以获得对克里斯蒂湾过去存在冰下湖的信心，并更好地规划未来对现有沉积记录的勘探。首席研究员将在总面积为 600-800 公里的地球物理湖泊调查中部署气枪和 Chirp 地震工具，以及多波束回声探测和短沉积岩芯。新数据将阐明冰下和（冰河）湖泊过程在克里斯蒂湾发现的厚沉积层序沉积中的相对重要性。它们还将对序列上部的线性沉降速率提供约束。了解沉积速率对于解释这一沉积序列是否可能已经沉积起着关键作用：1）完全自距今 9,000-10,000 年冰川消退以来（即不需要冰下湖来解释观测结果），2）在一个冰川周期中（~ 100,000 年），或 3）在多个冰川周期中。接受第一个冰后模型将代表拒绝本提案的指导假设。更广泛的影响对不同学科的贡献：项目结果将与许多学科相关，包括冰川地质学、地貌学、沉积学、地球物理学和气候动力学。人类资源开发：拟议的研究将代表 UCSC 首席研究员研究小组发展的一个重要阶段，因为它将能够继续参与北极研究，并将两极研究联系起来现代和过去的冰下环境。一名研究生将获得与沉积盆地勘探相关的最先进地球物理技术应用的高级培训。一名非裔美国本科生将获得实验室和实地研究经验，并将根据这项工作完成高级论文。 对课堂教学的影响：实地经验和研究成果将纳入几门不同的课程中，每年覆盖 UCSC 约 120 名学生。社区和媒体外展：研究区域由原住民控制，计划开展一系列与当地社区互动的活动（例如，在 Lustelk'e 的一所学校进行演讲、下午开放参观研究船、雇用原住民成员担任两名队长和一名营地经理）。首席研究员将与 UCSC 科学作家合作，在重大发现发布时发布新闻稿。