Consolidation and Calibration of the New England Varve Chronology (NEVC): An Annual Continental Record of Ice Dynamics and Terrestrial Change, 18-11.5 kyr BP

新英格兰 Varve 年表 (NEVC) 的合并和校准：冰动力和陆地变化的年度大陆记录，18-11.5 kyr BP

• 批准号: 0639830
• 负责人: John Ridge
• 金额: $ 33.88万
• 依托单位: Tufts University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-04-01 至 2010-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0639830&HistoricalAwards=false
• 关键词: Consolidation; Calibration; New; England; Varve

Rapid climate change during deglaciation is linked to interactions between the ice sheet, the ocean, and the atmosphere. Understanding these interactions requires high resolution comparisons of climate and continental ice. Although general patterns of Laurentide Ice Sheet variation have been found, they are not continuously resolved at a sub-century scale. This lack of continuous, high-resolution terrestrial glacial chronologies with accurate radiometric controls continues to be a limiting factor in understanding deglacial climate. Such records, especially from the southeastern sector of the ice sheet can provide critical comparisons to N. Atlantic climate records (marine and ice core) and a rigorous test of hypotheses linking glacial activity to climate change.Consolidation of the New England Varve Chronology, and the development of records of glacier dynamics and terrestrial change, is a rare opportunity to formulate a complete, annual-scale terrestrial chronology from 18,000 -11,500 years before present. Glacial varve deposition, which is linked to glacial meltwater discharge, can be used to monitor ice sheet retreat and has a direct tie to glacier mass balance and climate. Complete records of readvances, ice recession rates, and annual meltwater discharge of the southeastern ice sheet could be compared to climatic events in the N. Atlantic region to determine whether the ice sheet was in lock-step with climate and ice rafting events, whether it was a driver or responder, or whether it behaved independently or with time lags. The varve chronology's use as a precise regional chronology of glacial events, including floods that may have been triggers for rapid climate change, would be critical to evaluating climate models and the thresholds necessary for individual floods to influence ocean circulation and climate.The project will be to join sequences of the New England Varve Chronology, forming a single sequence spanning over 6000 years (18.0-11.5 kyr BP). This will be the longest continuous, high resolution record of terrestrial ice front changes, ice recession rates, and glacial lake history in North America. Cores will be collected in critical areas to join existing sequences of the varve chronology and new Carbon-14 ages will be used to improve its calendar-year calibration.Broader impacts:1) The exceptional accuracy and precision of the New England Varve Chronology will demonstrate the potential usefulness of glacial varve chronology in other regions of North America where glacial varve sequences have not been studied for either their glacial chronologies or climate records. This project will serve as a stepping stone to an expansion of the chronology to cover the entire last deglaciation (~24-11.5 kyr BP) and is likely to stimulate varve studies in many other regions of the United States and Canada. 2) Varve chronology will serve as a calibration or consistency test of other dating techniques. The NEVC represents the most precise and accurate opportunity for comparison of cosmogenic-nuclide ages for deglaciation with an independently-calibrated deglacial chronology. Refinement of the varve chronology will dramatically improve the accuracy and confidence in this geological calibration.3) Dissemination of results, in addition to normal publication in scientific journals, will include internet availability of a library of varve records and images for other researchers; instructional presentations on how to collect, formulate, and match varve records; and an image glossary of varve characteristics and features as a reference for students and instructors.4) This project will expand the research program at Tufts University. Undergraduates (two per summer for three years), will be active research participants in field and laboratory phases of the project. Each student will be supervised through a start-to-finish analysis of a complete varve section leading to a year-long thesis or research project. Over three years the project will effectively double the number of people in the United States trained in the analysis of glacial varve cores.

冰川消退期间的快速气候变化与冰盖、海洋和大气之间的相互作用有关。了解这些相互作用需要高分辨率的气候和大陆冰的比较。虽然已经发现了劳伦泰德冰盖变化的一般模式，但它们并没有在亚世纪尺度上连续地得到解决。这种缺乏连续的，高分辨率的陆地冰川年表与准确的辐射控制仍然是一个限制因素，在了解冰消期气候。这些记录，特别是来自冰盖东南部的记录，可以提供与N。大西洋气候记录（海洋和冰芯）和对冰川活动与气候变化之间联系的假设的严格检验。新英格兰Varve年表的合并，以及冰川动力学和陆地变化记录的发展，是一个难得的机会，可以制定一个完整的，从18，000 - 11，500年前的年尺度陆地年表。与冰川融水排放有关的冰川纹管沉积可用于监测冰盖退缩，并与冰川物质平衡和气候有直接联系。完整的记录，再流动，冰衰退率，和每年融水排放的东南冰盖可以比较气候事件在北。大西洋地区，以确定冰盖是否与气候和冰筏漂流事件同步，它是一个驱动程序或响应器，或者它的行为是否独立或与时间滞后。冰涌年表作为冰川事件的精确区域年表，包括可能引发快速气候变化的洪水，对于评估气候模型和单个洪水影响海洋环流和气候所需的阈值至关重要。该项目将加入新英格兰冰涌年表的序列，形成一个单一的序列跨越6000年（18.0-11.5 kyr BP）。这将是北美陆地冰锋变化，冰衰退率和冰川湖历史的最长连续，高分辨率记录。将在关键地区收集岩心，加入现有的纹藻年代学序列，并使用新的碳-14年龄来改进其年代学校准。更广泛的影响：1）新英格兰纹藻年代学的异常准确性和精确性将证明冰川纹藻年代学在北美其他地区的潜在用途，这些地区的冰川纹藻序列尚未被研究用于冰川年代学或气候记录。该项目将作为一个垫脚石，以扩大年表，以涵盖整个末次冰消期（约24-11.5 kyr BP），并有可能刺激在美国和加拿大的许多其他地区的纹泥研究。2)Varve年表将作为其他测年技术的校准或一致性测试。NEVC代表了最精确和准确的机会，比较宇宙成因核素年龄的冰川消退与独立校准的冰川消退年表。3）除了在科学期刊上正常发表外，研究结果的传播还将包括为其他研究人员提供一个纹层记录和图像库;关于如何收集、制定和匹配纹层记录的教学演示;以及一个关于纹藻特征和特征的图像词汇表，作为学生和种植者的参考。4）本项目将扩大塔夫茨大学的研究计划。本科生（每年夏季两名，为期三年）将积极参与该项目的实地和实验室阶段的研究。每个学生将通过一个完整的varve部分的开始到结束的分析，导致长达一年的论文或研究项目的监督。在三年的时间里，该项目将有效地使美国接受冰川纹芯分析培训的人数翻一番。