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

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

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.