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

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事情。在这项研究中，研究人员验证了冰川可能存在于俄克拉荷马州威奇托山脉的想法，该地区大约在3亿年前位于赤道附近。通过使用地震勘探技术，该奖项旨在‘看到’地壳深处，成像和分析一个古老的埋藏山谷的形状，以确定其起源。山谷的形状将揭示其形成的关键线索--它是由冰川形成的，还是由河流过程形成的。了解硅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事情。这个被掩埋的山谷的图像还将被用来指导未来一个名为深尘的大陆深部钻探项目，该项目将从该地区提取岩石样本，由一个庞大的科学家团队进行分析，以回答许多关于过去气候和生命对气候变化的反应的问题。这项研究将有助于检验赤道高地在晚古生代冰河时代曾有冰川的“离奇”假设，从而阐明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是在晚古生代冰化的假设，那么它意味着赤道联合古陆许多地区海拔相对较低的山脉冰川，这将从根本上改变我们对晚古生代冰库的看法。由于目前的气候模型无法复制这样的情景，这一结果将迫使新的建模工作来理解地球系统是如何转向这种条件的，从而有助于我们对气候强迫机制的精细化理解。为了验证这一假设，该项目为拟议的国际大陆钻探计划(ICDP)深尘项目提供了现场勘测工作资金。深尘的目的是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、生物地球化学循环和陆地生物圈对气候强迫的响应。一个钻探目标是俄克拉荷马州威奇托隆起埋藏的古高地。这一钻探目标旨在获得独特的高地气候记录，以补充团队的低地场地，那里的图像很好。专有的地震数据揭示了埋藏的威奇托隆起中明显的古山谷特征，为了了解和更好地成像这一特征，新的地震数据采集是必不可少的。将获得两条二维地震反射线，一条垂直于山谷方向，另一条沿山谷轴线，以高分辨率精确成像和表征地物。此外，这个项目将大量涉及学生参与者，使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。在这方面，它将促进现场规划、采集和解释地震数据的多种教育机会。如果深尘ICDP项目得到资助，这些数据将能够准确定位钻探位置，从而通过这一功能恢复岩心，以重建详细记录和该记录的日期。即使深尘没有得到资助，地震数据仍将使人们能够从根本上评估山谷的起源(河流或冰川)，这具有重大的古气候影响。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.