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: 1804395
• 负责人: John Ridge
• 金额: $ 5.42万
• 依托单位: Tufts University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1804395&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.

在上一个冰河时代末期，巨大的冰盖仍然覆盖着北美东北部的大部分地区，充当了其南部边缘积雪融水的水坝。 当冰盖崩塌时，这些新鲜的湖水被释放到大西洋，并被认为扰乱了海洋环流，导致北半球甚至全球范围内突然出现寒流。 在安大略省南部和纽约州北部附近，巨大的易洛魁冰川湖含有大量冷淡水，该湖的现代遗迹包括安大略湖和奥奈达湖。 奥奈达湖位于古易洛魁冰川湖的最东部附近，该地区和莫霍克山谷是融水排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期间沉积的古代沉积物，以确定其精确时间，然后将这些时间与来自格陵兰冰芯以及来自南大洋和大西洋沉积物的过去气候记录进行比较。 研究人员将利用地球物理（声纳）方法对奥奈达湖底部的沉积物进行成像，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沉积物的年代，并将层状沉积物与之前在新英格兰收集的类似记录联系起来。 项目外展工作包括为湖畔社区举办系列公开讲座、参与奥奈达国家高中科学课程，以及在湖东边缘的州立公园安装科学信息亭。该项目正在研究晚第四纪沉积物通过对新的地球物理数据和新的沉积岩芯的分析，获得了纽约州北部奥奈达盆地的记录。异常丰富的地层档案将限制更新世末期劳伦泰德冰原东南边缘的古气候演化。研究人员还将开发古代易洛魁冰川湖的能量平衡水文模型，以更好地限制该盆地的充水和排水事件。扰乱全球气候系统的非线性事件（例如新仙女木期变冷）包括与易洛魁冰川湖及其前身相关的主要融水脉冲和排水路径转换。研究人员将利用奥奈达湖和周围露头丰富的沼泽沉积物记录，以数千年的季节分辨率来评估终止一（最后一次冰川期的结束，约 20,000 年前）。盆地中新发现的湖泊沉积物暴露（varve）的露头观测将与奥奈达湖岩心回收的相关沉积序列相结合。冰川 varve 记录将通过古地磁方法（交叉测年）与北美 Varve 年表进行时间顺序限制，并通过选择性使用有机物的斜坡 PyrOx 放射性碳测年和单独的花粉 14C 测年来进一步确定。初步的高分辨率地震数据揭示了显着的高保真地层学，其中包含爆发洪水事件、冰盖不稳定以及从冰川消融到全新世的连续时间序列的证据。将使用 CHIRP（扫描信号地震）和多道地震反射方法对全湖进行高空间分辨率勘测。校准后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、南极半岛帕尔默深渊和卡里亚科盆地海洋部分。除了直接的科学成果和研究生培训之外，研究人员还将开展外展工作，包括：1）河岸社区讲座系列； 2) 在两个湖滨公园建造两个信息亭，描述易洛魁冰川湖的地质演化以及奥奈达湖的后续演化； 3) 在实地和实验室活动中吸引包括奥奈达族中学生在内的弱势群体参与。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。