Geophysical Imaging of a Buried Paleovalley in Support of ICDP Deep Dust Project

支持 ICDP 深层尘埃项目的埋藏古山谷地球物理成像

• 批准号: 2201632
• 负责人: Heather Bedle
• 金额: $ 4.83万
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-15 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2201632&HistoricalAwards=false
• 关键词: Geophysical; Imaging; Buried; Paleovalley; Support

Geologists analyze the Earth’s past in order to better understand what may happen in the future. In this study, the investigators test the idea that glaciers may have existed in the Wichita Mountains of Oklahoma a region that was located near the equator roughly 300 million years ago. By using seismic survey techniques this award aims to ‘see’ deep into the Earth’s crust, to image and analyze the shape of an ancient, buried valley to determine its origin. The shape of the valley will reveal critical clues to its formation – if it was formed by a glacier, or if it was formed by river processes. Understanding the origin of the valley will allow us to update and improve climate models that look backwards in time, allowing a better evaluation of what may happen in the future. The imaging of this buried valley will also be used to guide a future deep continental drilling project called Deep Dust, that will retrieve rock samples from this region, to be analyzed by a large team of scientists to answer many questions regarding past climate, and responses of life to climate changes. This research will help test the “outrageous” hypothesis that equatorial uplands hosted glaciation during the late Paleozoic ice age—and thus illuminate fundamental questions about climate and tectonics. If this work supports the hypothesis that the Wichita Mountains were glaciated during the late Paleozoic, then it implies mountain glaciation at relatively low elevation across many regions of equatorial Pangaea, which would fundamentally shift our view of the late Paleozoic icehouse. Because current climate models cannot replicate such a scenario, this outcome would force new modeling efforts to understand how Earth’s system veered to such conditions, thus aiding refinements in our grasp of climate forcing mechanisms. To test this hypothesis, this project funds site-survey work for the proposed International Continental Drilling Program (ICDP) Deep Dust project. Deep Dust aims to recover core of the continental Permian to elucidate environmental conditions, biogeochemical cycling, and responses of the terrestrial biosphere to climate forcing during a critical period in the evolution of Earth and life. One drilling target is the buried paleo-upland of the Wichita uplift of Oklahoma. This drilling objective is designed to access a unique record of upland climate to complement the team's lowland site, which is well imaged. Proprietary seismic data has revealed an apparent paleo-valley feature in the buried Wichita uplift, and to understand and better image this feature a new seismic data acquisition is essential. Two 2D seismic reflection lines will be acquired, one perpendicular to the valley orientation, and a second along the valley axis, to precisely image and characterize the feature at high resolution. In addition, this project will heavily involve student participants, exposing them to a variety of geologic problems, from sediments, to paleoclimates, to geophysical techniques. In this aspect it will spur multiple educational opportunities for field-site planning, acquisition, and interpretation of seismic data. If the Deep Dust ICDP project is funded, these data will enable precise siting of the drill location and thus recovery of core through this feature to reconstruct a detailed record and date that record. Even if Deep Dust is not funded, the seismic data will still enable fundamental assessment of the origin (fluvial or glacial) of the valley, which has significant paleoclimatic implications.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.

地质学家分析地球的过去，以便更好地了解未来可能发生的情况。在这项研究中，研究人员测试了大约 3 亿年前位于赤道附近的俄克拉荷马州威奇托山脉中可能存在冰川的想法。该奖项旨在通过使用地震勘测技术“观察”地壳深处，对古老的埋藏山谷的形状进行成像和分析，以确定其起源。山谷的形状将揭示其形成的关键线索。 – 如果它是由冰川形成的，或者它是由河流过程形成的，了解山谷的起源将使我们能够更新和改进回顾过去的气候模型，从而更好地评估未来可能发生的情况。这个埋藏山谷的成像还将用于指导未来名为“深尘”的大陆深层钻探项目，该项目将从该地区获取岩石样本，由大型科学家团队进行分析，以回答有关过去气候和应对措施的许多问题这项研究将有助于测试生命对气候变化的影响。赤道高地在晚古生代冰河时期发生了冰川作用，这是“令人震惊的”假说，从而阐明了有关气候和构造的基本问题。如果这项工作支持威奇托山脉在古生代晚期发生了冰川作用的假说，那么它意味着山地冰川作用在相对的时期。赤道盘古大陆许多地区的海拔较低，这将从根本上改变我们对晚古生代冰室的看法，因为当前的气候模型无法复制这种情况，这一结果将迫使我们建立新的模型。努力了解地球系统如何转向这种条件，从而帮助我们完善对气候强迫机制的掌握。为了检验这一假设，该项目资助了拟议的国际大陆钻探计划（ICDP）深层尘埃项目的现场调查工作。旨在恢复大陆二叠纪的核心，以阐明地球和生命演化的关键时期的环境条件、生物地球化学循环以及陆地生物圈对气候强迫的响应。该钻探目标旨在获取独特的高地气候记录，以补充该团队的低地场地，该低地场地的成像良好，揭示了该地区明显的古山谷特征。威奇托隆起，为了理解和更好地成像这一特征，必须采集两条二维地震反射线，一条垂直于山谷方向，另一条沿着山谷方向。此外，该项目将大量涉及学生参与者，让他们接触到各种地质问题，从沉积物到古气候，再到地球物理技术。激发地震数据现场规划、采集和解释的多种教育机会如果 Deep Dust ICDP 项目获得资助，这些数据将能够精确定位钻探位置，从而通过此功能恢复岩心以重建详细记录。并注明该记录的日期。尘埃没有得到资助，地震数据仍然可以对山谷的起源（河流或冰川）进行基本评估，这具有重大的古气候影响。该奖项是 NSF 的法定使命，并通过使用基金会的智力价值进行评估，被认为值得支持以及更广泛的影响审查标准。