Collaborative Research: EAGER--Evaluating Fluid Inclusion Geochemistry of U-Th Dated Speleothems as a Tool for Resolving Paleoclimate Controversies in the American Southwest

合作研究：EAGER——评估 U-Th 定年洞穴的流体包裹体地球化学，作为解决美国西南部古气候争议的工具

• 批准号: 1420079
• 负责人: Isabel Montañez
• 金额: $ 11.42万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-03-01 至 2016-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1420079&HistoricalAwards=false
• 关键词: Collaborative; Research; EAGER; Evaluating; Fluid

Global hydrologic reorganization throughout the Northern Hemisphere occurred synchronously with repeated large, sub-millennial-scale climate changes in the northern North Atlantic region during the last deglaciation. However, how this reorganization affected the continental hydroclimate in the drought-prone American Southwest remains poorly resolved. Continental-based paleoclimate reconstructions for this region are contradictory in large part due to two sources of discrepancy: (1) uncertainty in age constraints, and (2) fundamental ambiguity in speleothem-based proxy records.This project-- a collaborative effort between scientists from the University of California at Davis and Harvard University-- seeks to resolve the apparent contradictions in the inferred glacial-interglacial climate reconstructions for the American Southwest using cave deposits from the Sierra Nevada in California. The researchers will employ novel techniques to generate both a robust chronologic framework (using U-Th dating via laser ablation MC-ICPMS) and a record of precipitation (using temperature-dependent noble gas concentrations in fluid inclusions as a temperature proxy independent of other climate processes and stable isotopic composition of inclusion fluids as a more direct proxy of precipitation composition and source region) over the past ~20,000 years at the study site. Successful proof-of-concept of these innovative approaches would open the door for applications to a wide variety of questions in paleoclimate.The outcomes of this work should lead to better understanding of how climate change impacts the hydroclimate of the American Southwest, an area that is vulnerable to water resource limitation. Additional broader impacts include development of a new facility for routine high-precision U-series dating (of which there are only a handful in the US), development of the noble gas proxy in carbonates, and training of graduate students at two institutions.

整个北半球的全球水文重组与上次冰消期间北大西洋北部地区反复出现的亚千年规模的气候变化同时发生。然而，这种重组如何影响易发生干旱的美国西南部的大陆水文气候仍然没有得到很好的解决。该地区基于大陆的古气候重建在很大程度上是矛盾的，因为存在两个差异来源：（1）年龄限制的不确定性，以及（2）基于洞穴的代理记录的基本模糊性。该项目是科学家之间的合作努力来自加州大学戴维斯分校和哈佛大学的研究，旨在解决利用内华达山脉洞穴沉积物推断的美国西南部冰川-间冰期气候重建中的明显矛盾。加利福尼亚州。研究人员将采用新技术来生成强大的年代框架（通过激光烧蚀 MC-ICPMS 使用 U-Th 测年）和降水记录（使用流体包裹体中与温度相关的稀有气体浓度作为独立于其他气候的温度代理）研究地点过去约 20,000 年的过程和包裹体流体的稳定同位素组成（作为降水组成和来源区域的更直接代表）。这些创新方法的成功概念验证将为解决古气候中的各种问题打开大门。这项工作的成果应该有助于更好地了解气候变化如何影响美国西南部的水文气候，该地区容易受到水资源限制。其他更广泛的影响包括开发用于常规高精度 U 系测年的新设施（美国只有少数）、开发碳酸盐中的稀有气体代理以及培训两个机构的研究生。