Collaborative Research: P2C2: A High Resolution Paleoclimate Archive of Termination I in Oneida Lake and Glacial Lake Iroquois Sediments

合作研究：P2C2：奥奈达湖和易洛魁冰川湖沉积物中 I 期高分辨率古气候档案

• 批准号: 1803944
• 负责人: Anders Noren
• 金额: $ 2.38万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1803944&HistoricalAwards=false
• 关键词: Collaborative; Research; P2C2; Resolution; Paleoclimate

At the end of the last ice age, the vast ice sheet still covering much of northeastern North America served as a dam for ponded meltwaters along its southern edge. When the ice sheet collapsed, those fresh lake waters were released to the Atlantic Ocean, and are thought to have disrupted ocean circulation, causing abrupt cold spells in the northern hemisphere, and perhaps globally. Near southern Ontario and northern New York State, enormous Glacial Lake Iroquois contained massive amounts of cold fresh water, and modern remnants of that lake include Lake Ontario and Oneida Lake. Oneida Lake is located near the easternmost part of ancient Glacial Lake Iroquois, and this area and the Mohawk Valley were a key valve for the release of meltwaters to the Hudson River and to the Atlantic. The Oneida Lake project will study the ancient sediments laid down during these meltwater releases, to determine their precise timing, and will then compare those timings to past climate records derived from Greenland ice cores and from sediments from the Southern and the Atlantic Oceans. The researchers will use geophysical (sonar) methods to image the sediments below the bottom of Oneida Lake, and then collect sediment cores for detailed analyses. Special Carbon-14 dating techniques will be used to date sediments in the cores and to correlate the layered sediments to similar records previously collected in New England. Project outreach efforts include a public lecture series for lake-side communities, engagements with Oneida Nation high school science classes, and the installation of science information kiosks at a State Park on the lake?s eastern edge.This project is examining the Late Quaternary sediment record from the Oneida Basin in Upstate New York, through analyses of new geophysical data and new sediment cores. The unusually rich stratigraphic archive will constrain the paleoclimate evolution along the SE margin of the Laurentide Ice Sheet in the terminal Pleistocene. The researchers will also develop an energy balance hydrologic model of ancient Glacial Lake Iroquois to better constrain fill and discharge events from this basin. Non-linear episodes that perturb the global climate system (e.g., the Younger Dryas cooling) include major meltwater pulses and drainage pathway switches associated with Glacial Lake Iroquois and its precursors. The researchers will evaluate Termination I (the end of the last glaciation, ~20,000 years ago) at seasonal resolution over several millennia, using the rich varved sediment record in Oneida Lake and surrounding outcrops. Outcrop observations of newly discovered lake sediment exposures (varves) in the basin will be integrated with correlative sedimentary sequences recovered by cores from Oneida Lake. The glacial varve record will be chronologically constrained via paleomagnetic methods (cross-dating) with the North American Varve Chronology and further fixed by selective use of Ramped PyrOx radiocarbon dating of organic matter and separately of pollen 14C dating. Preliminary high-resolution seismic data reveal a remarkable, high-fidelity stratigraphy with evidence for outburst flood events, ice sheet instabilities, and a continuous time series from deglaciation through the Holocene. The full lake will be surveyed at high spatial resolution using CHIRP (sweep signal seismic) and multichannel seismic reflection methods. The calibrated time series of events will be compared to three well-established global archives: the Greenland ice core record, the Antarctic Peninsula Palmer Deep and Cariaco Basin marine sections. Beyond the direct scientific outcomes and graduate student training, the researchers will mount an outreach effort including: 1) a riparian community lecture series; 2) construction of two information kiosks describing the geologic evolution of Glacial Lake Iroquois and subsequent evolution of Oneida Lake at two lakeside parks; and 3) engage under-represented groups including secondary school students from the Oneida Nation during both field and laboratory activities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在最后一个冰河时代结束时，仍然覆盖着北美东北部大部分地区的巨大冰盖充当了沿着其南部边缘积水的大坝。 当冰盖崩溃时，这些新鲜的沃茨被释放到大西洋，并被认为扰乱了海洋环流，导致北方突然寒冷，也许是全球。 在安大略南部和纽约州北方附近，巨大的易洛魁冰川湖含有大量的冷淡水，该湖的现代遗迹包括安大略湖和奥奈达湖。 奥奈达湖位于古老的易洛魁冰川湖的最东部附近，这个地区和莫霍克山谷是将融水释放到哈德逊河和大西洋的关键阀门。 奥奈达湖项目将研究这些融水释放过程中沉积的古代沉积物，以确定其精确的时间，然后将这些时间与格陵兰冰芯和来自南部和大西洋沉积物的过去气候记录进行比较。 研究人员将使用地球物理（声纳）方法对奥奈达湖底的沉积物进行成像，然后收集沉积物岩心进行详细分析。 特殊的碳-14测年技术将用于测定岩心中沉积物的年代，并将分层沉积物与以前在新英格兰收集的类似记录相关联。 项目的推广工作包括为湖边社区举办一系列公开讲座，与奥奈达国家高中科学课合作，以及在湖上的一个州立公园安装科学信息亭？该项目通过分析新的地球物理数据和新的沉积物岩心，研究纽约北部奥奈达盆地的晚第四纪沉积物记录。异常丰富的地层档案将制约沿着劳伦泰德冰盖东南缘晚更新世的古气候演化。研究人员还将开发一个古代冰川湖易洛魁的能量平衡水文模型，以更好地约束该流域的填充和排放事件。扰动全球气候系统的非线性事件（例如，新仙女木冷却）包括主要的融水脉冲和排水通道开关与冰川湖易洛魁及其前身。研究人员将使用奥奈达湖和周围露头中丰富的纹状沉积物记录，以数千年的季节分辨率评估终止I（最后一次冰川作用的结束，约20，000年前）。盆地中新发现的湖泊沉积物暴露（纹状岩）的露头观测结果将与奥奈达湖岩心恢复的相关沉积序列相结合。冰川纹层记录将通过古地磁方法（交叉定年）与北美纹层年代学进行年代学约束，并通过选择性使用有机物的Ramped PyrOx放射性碳定年和单独的花粉14 C定年进一步固定。初步的高分辨率地震数据揭示了显着的高保真地层，其中有爆发洪水事件、冰盖不稳定性以及从冰消期到全新世的连续时间序列的证据。将使用CHIRP（扫描信号地震）和多通道地震反射方法以高空间分辨率对整个湖泊进行调查。经过校准的事件时间序列将与三个完善的全球档案进行比较：格陵兰冰芯记录、南极半岛帕尔默深海和卡里亚科盆地海洋剖面。除了直接的科学成果和研究生培训外，研究人员还将开展外展工作，包括：1）河岸社区系列讲座; 2）在两个湖滨公园建造两个信息亭，描述冰川易洛魁湖的地质演变和奥奈达湖的后续演变;及3）根据─在实地和实验室活动中代表了包括奥奈达国家中学生在内的团体。该奖项反映了NSF的法定使命，并被认为是通过使用基金会的知识价值和更广泛的影响审查标准进行评估，