Collaborative Research: A high-resolution middle Pleistocene paleoclimate record from the Valles Caldera, New Mexico

合作研究：来自新墨西哥州火山口火山口的高分辨率中更新世古气候记录

• 批准号: 0903018
• 负责人: Peter Fawcett
• 金额: $ 21.59万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0903018&HistoricalAwards=false
• 关键词: Collaborative; Research; resolution; middle; Pleistocene

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This grant supports a collaborative project between the University of New Mexico, Northern Arizona University and the University of Minnesota, Duluth which will conduct detailed analyses of a unique 82-m long lacustrine sediment core (VC-3) from the Valles Caldera, in northern New Mexico. This core represents a critical time interval in the past that is similar to the modern. As such, an understanding of climatic changes observed in the core will lead to the most detailed assessment of expected future climate variability in the southwest ever recorded.Intellectual Merit: In May 2004, the GLAD5 drilling project recovered an 82-m deep lacustrine sediment core from the Valles Caldera, New Mexico. Ar-Ar age estimates from a tephra near the base of the core (552±3 ka), two distinct glacial terminations (VI and V) in multiple proxies, and the identification of a two geomagnetic polarity "events", correlated to globally recognized events (14a; and 11a) constrain these lake sediments to the middle Pleistocene (MIS 14 to MIS 10). Initial work by this group shows an intriguing relationship between temperature and hydroclimate during the two long interglacials present in the core (MIS 11 and MIS 13). Peak interglacial temperatures (MBT proxy, pollen) correlate well with extended dry periods in the core (mudcrack intervals). This is consistent with recent predictions of extended drought in SW North America in response to global warming by a marked reduction in winter precipitation.To better understand this critical relationship, the team will conduct more detailed sampling of the VC-3 core at intervals of ~10 cm or less to analyze for temperature (MBT proxy, pollen), lake productivity (organic carbon, Si/Ti ratios, biogenic silica), hydroclimate (del-18O of diatom silica, core sedimentologic characteristics, and pollen and charcoal). Specifically, they will test the hypothesis that during long interglacials, warming leads to extended dry climates with reduced winter frontal precipitation. Additional analyses to be conducted include remanence and rock magnetic properties, major and minor element geochemistry, XRD, XRF scanner analyses, carbon and nitrogen stable isotopes and C/N ratios, and plant macrofossils, all of which will aid in refining paleoclimate proxies. In conjunction with this work, LANL collaborators will conduct compound specific del-D analyses and obtain U‐series dates to improve the chronology at no cost to NSF. Results from this work will shed light on two important paleoclimate questions: the relationship between peak interglacial temperatures and extended dry conditions, and the nature of orbital- to millennial-scale climate change during the middle Pleistocene.Broader Impacts: This study will further our understanding about the nature of climate change in southwestern North America and its impact on montane ecosystems. This project involves collaborations between four research institutions, UNM, NAU, UMD, and Los Alamos National Lab. Both graduate students and faculty will benefit from interactions with the other institutions and the different expertise that collaborators at each institution bring to bear on the project. The results of this study will be available to the general public using displays and outreach programs through the newly created Valles Caldera National Preserve. This information will include not only the timing of lakes forming in the Valles Caldera and the paleoclimatic records derived from them, but also information about the materials preserved at depth in the Valles Caldera and the nature of the interactions between volcanic processes in the caldera and surficial processes. The project will involve education and training of several graduate students at UNM, NAU and UMD. UNM graduate students include a female Hispanic pursuing a PhD and another female graduate student. The results of this study will be integrated into several courses offered at the participating institutions.

该奖项由2009年美国复苏和再投资法案(公法111-5)资助。这笔赠款支持新墨西哥大学北亚利桑那大学和明尼苏达大学德卢斯分校之间的一个合作项目，该项目将对新墨西哥州北部Valles Caldera独特的82米长的湖泊沉积物岩芯(VC-3)进行详细分析。这一核心代表了过去类似于现代的关键时间间隔。因此，对岩心观察到的气候变化的了解将导致对西南部预期未来气候变化的最详细评估。智力价值：2004年5月，GLAD5钻探项目从新墨西哥州Valles Caldera发现了一个82米深的湖泊沉积物岩心。Ar-Ar年龄估计来自地核底部附近的Tephra(552±3ka)，多个替代物中两个不同的冰川端部(VI和V)，以及与全球公认的事件(14a和11a)相关的两个地磁“事件”的识别，将这些湖泊沉积物限制在中更新世(MIS14至MIS10)。该小组的初步工作表明，在岩心存在的两个漫长的间冰期(MIS11和MIS13)期间，温度和水文气候之间存在着有趣的关系。间冰期最高温度(MBT替代物、花粉)与岩芯(泥岩裂缝间隔)延长的干旱期有很好的相关性。为了更好地理解这一关键关系，研究小组将以大约10厘米或更小的间隔对VC-3岩心进行更详细的采样，以分析温度(MBT替代物、花粉)、湖泊生产力(有机碳、硅钛比、生物硅)、水文气候(硅藻硅藻的del-18O、岩心沉积学特征以及花粉和木炭)。具体地说，他们将检验这一假设，即在漫长的间冰期，气候变暖会导致冬季锋面降水减少，导致干燥气候延长。将进行的其他分析包括剩磁和岩石磁性、主要和次要元素地球化学、X射线衍射仪、XRF扫描仪分析、碳和氮稳定同位素和C/N比，以及植物大型化石，所有这些都将有助于提炼古气候指标。与这项工作相结合，LANL的合作者将进行化合物特定的del-D分析，并获得U&amp；8208；系列日期，以改进年表，而不会对NSF造成任何损失。这项工作的结果将阐明两个重要的古气候问题：间冰期峰值温度与长期干旱条件之间的关系，以及更新世中期轨道至千年尺度气候变化的性质。更广泛的影响：这项研究将进一步加深我们对北美西南部气候变化的性质及其对山地生态系统的影响的理解。该项目涉及四个研究机构之间的合作，这四个机构是：北卡罗来纳大学、北卡罗来纳大学、密歇根大学和洛斯阿拉莫斯国家实验室。研究生和教职员工都将受益于与其他机构的互动，以及每个机构的合作者为该项目带来的不同专业知识。这项研究的结果将通过新创建的Valles Caldera国家级保护区通过展示和推广计划向公众开放。这些信息将不仅包括火山口谷形成湖泊的时间和由此产生的古气候记录，而且还包括有关火山口深部保存的物质以及火山口内火山过程与地表过程之间相互作用的性质的信息。该项目将涉及对新墨西哥州大学、新奥尔良大学和曼彻斯特大学的几名研究生进行教育和培训。北卡罗来纳大学的研究生包括一名攻读博士学位的西班牙裔女性和另一名女性研究生。这项研究的结果将被纳入参与机构提供的几门课程。