Collaborative Research: P2C2--Continental Response to Abrupt Climate Change Post 70 ka: An Integrated Isotopic and Trace Element Study of Sierra Nevada Speleothems

合作研究：P2C2——70 ka后大陆对突然气候变化的响应：内华达山脉洞穴的同位素和微量元素综合研究

• 批准号: 0823541
• 负责人: Warren Sharp
• 金额: $ 6.16万
• 依托单位: Berkeley Geochronology Center
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0823541&HistoricalAwards=false
• 关键词: Collaborative; Research; P2C2; Continental; Response

Funding is provided to develop precisely dated, high-resolution speleothem-based records of climate change in the Sierra Nevada. The researchers are testing two hypotheses: (1) Sierra speleothems were precipitated in isotopic and geochemical equilibrium with drip waters, and thus archive short-lived changes in regional precipitation, temperature, and vegetation density; and (2) shifts in the position of the polar jet stream and associated winter storm tracks over mid-latitude western North America, forced by large-scale reorganization of the climate system, are archived in Sierra speleothem isotopic and geochemical compositions. To test these hypotheses, the researchers will: 1) complete in situ measurements of surface, soil and cave conditions; 2) analyze the isotopic and trace element contents in modern drip and source waters and recent calcite precipitates to define the natural intra- and inter-cave variability in drip-waters and speleothem calcites and to evaluate the presence of isotopic and trace element equilibrium precipitation of speleothem calcite; and 3) develop precisely dated (U-series with better than 2% precision) geochemical and isotopic time series (minimally multi-decadal-resolution) for stalagmites from three caves. The broader impacts involve improved understanding of the sensitivity of winter storm tracks and mean annual precipitation levels in the mid-latitudes of western North America to changes in northern high-latitude conditions with warming atmospheric temperatures. The project also helps support two graduate students involved with the research.

提供资金用于开发内华达山脉气候变化的精确日期、高分辨率洞穴记录。研究人员正在测试两个假设：（1）山脉洞穴是在同位素和地球化学平衡的情况下通过滴水沉淀出来的，从而记录了区域降水、温度和植被密度的短暂变化； (2)由于气候系统的大规模重组，北美西部中纬度地区极地急流的位置和相关的冬季风暴路径发生了变化，这些变化记录在Sierra 洞穴化石的同位素和地球化学成分中。为了检验这些假设，研究人员将：1）完成地表、土壤和洞穴条件的原位测量； 2) 分析现代滴水和源水以及最近的方解石沉淀物中的同位素和微量元素含量，以确定滴水和洞穴方解石的自然洞内和洞间变异性，并评估同位素和微量元素平衡沉淀的存在洞穴方解石； 3) 为三个洞穴的石笋开发精确测年（精度高于 2% 的 U 系列）地球化学和同位素时间序列（最小数十年分辨率）。更广泛的影响包括更好地了解冬季风暴路径和北美西部中纬度地区的年平均降水量对北部高纬度条件随大气温度变暖而变化的敏感性。该项目还帮助支持两名参与该研究的研究生。