| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | May 28, 2015 |
| Latest Amendment Date: | May 28, 2015 |
| Award Number: | 1523955 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Stephen Harlan
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | September 1, 2015 |
| End Date: | August 31, 2018 (Estimated) |
| Total Intended Award Amount: | $30,778.00 |
| Total Awarded Amount to Date: | $30,778.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
101 N MERION AVE BRYN MAWR PA US 19010-2899 (610)526-5496 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
101 North Merion Ave. Bryn Mawr PA US 19010-2899 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Tectonics |
| Primary Program Source: |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Folded rock layers are among the most fundamental, instructive and charismatic geologic structures. Folds are studied to investigate mountain building, to understand the engineering properties of rock, to predict the underground movement of water or hydrocarbons, and to give insight into the fundamental processes of folding itself. These applications rely on the accurate interpretation of rock deformation within a fold. Various conceptual and mathematical models predict fold-related deformation. To assess the capabilities of such predictive models, data from natural examples are required. This can be challenging, because most geologic folds at Earth's surface are only partially exposed, with major portions of the fold either buried underground or eroded away. The Whaleback Anticline in Bear Valley, east-central Pennsylvania, is a unique locale where a complete large-scale fold is exposed; strip mining for coal early in the last century revealed it in exquisite detail. This outstanding exposure permits observation of the complete three-dimensional form of the folded surface and provides a highly detailed record of deformation across the fold. This project will use cutting-edge digital imaging techniques and traditional geologic fieldwork to produce a comprehensive data set against which to test hypotheses about folding. In addition to the scientific goals of the project, the research is contributing to achievement of societally relevant outcomes in the areas of science, technology, engineering, and mathematics (STEM) education, including the development of a diverse, globally competitive STEM workforce through graduate and undergraduate student training; the development of research infrastructure of three universities; the broadening of participation of underrepresented groups in science; and increased public scientific literacy and public engagement with science and technology. The Whaleback Anticline is an important educational field trip location for dozens of university geology departments throughout the eastern United States, and it is a well-used recreation site for the local community. As part of this proposed project we will preserve, expand and curate geological observations from the Whaleback, for use by researchers, educators and the community.
Deformation associated with folding is recorded by distributed strain and discrete secondary structures. These features are of fundamental importance to understanding mechanisms and sequence of fold evolution and are of practical importance as records and hosts for fluid migration in and around folds. Incomplete data from natural examples limits the ability to evaluate geometric and physics-based models of folding. Recent advances in digital imaging and analysis now make it possible to produce quantitative three-dimensional descriptions of noncylindrical folds and evaluate the relationships of these forms to the distribution and evolution of fold-related strain. This project has the following objectives: 1) to produce a high-resolution digital surface model of an iconic fold, the Whaleback Anticline in Bear Valley, east-central Pennsylvania; 2) to document the spatial variability of strain around the fold with new observations of grain-scale strain, anisotropy of magnetic susceptibility, and detailed mapping of mesoscale structures in the folded layer; 3) to test the hypothesis that surface curvature controls the spatial variation and style of observed strain around a fold; 4) to evaluate stratigraphic and rheological influences on fold strain, through finite element analysis; 5) to demonstrate the utility of structure-from-motion photogrammetry as a tool for structural geology research and 6) to produce educational resources that will preserve and expand access to a world-class field locality and engage the local community.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Folded and distorted strata have long fascinated artists and observers of the natural world. Since at least as far back as the time of Leonardo da Vinci in the late 1400s, natural scientists have questioned the meaning of warped and slanted rock layers. The general form of folds varies in three dimensions, but most of our conceptual vocabulary for folds is inherently two-dimensional or imposes simplifying geometric assumptions. Historically, studies of folds at the outcrop- to map-scale have relied on two-dimensional outcrop profile views for understanding the kinematics and dynamics in plate tectonic related compressional systems. A growing body of work has sought to evaluate various measures of fold curvature as a proxy for the distribution of deformation in deformed rock layers. A direct connection between fold shape and associated secondary structures remains elusive however, which limits our understanding of the critical link between fold form, fold mechanics and the broader tectonic geodynamics that drive the deformation at active plate margins.
Fold geometry is effectively a record of the deformation history of that area, the key to which links shape and mechanics. Distortion in a folded layer influences the orientation and distribution of minor structures such as fractures and faults, which ultimately control the distribution of some of Earth’s most important natural resources (e.g., water, minerals, gas and petroleum). Improved ability to link spatial variations in fold geometry to deformation will also advance our efforts to characterize and interpret fold evolution and fold- fluid interaction. In particular, the ability to predict fault and fracture distribution in folds has clear implications for work in the energy, natural resource, and environmental sectors, which are commonly concerned with identifying fluid reservoirs, distribution of permeability and fluid migration pathways.
We used a system of three-dimensionally exposed folds in the Bear Valley Strip Mine (BVSM) in east-central Pennsylvania as a case study for understanding the details of folding and deformation. This site was chosen because strip mining for coal in this regional exposed the fold in exquisite detail early in the last century. We used new, modern and inexpensive techniques to collect high-resolution three-dimensional spatial data to produce a detailed digital surface model for the folds, which we then compared to observations of internal deformation within the rock layers in order to link shape to deformation intensity. All aspects of field and lab work for this project involved undergraduate and graduate student form both small elite liberal arts colleges as well as research level graduate universities. Our field work established several generations of mesoscale structures with a well- established and constrained chronology that occurred before, during and after folding in the Central Appalachians. These field observations and data will ultimately be used to better constrain the deformation history in the Valley-and-Ridge province in Pennsylvania, which records the final amalgamation history of the Pangea supercontinent due to the collision of Gondwana (particular present-day Africa and South America) and Laurussia (present-day North America and Europe).
Using our generated datasets, we are testing generalized hypotheses that link fold curvature to the predicted spatial variation and style of deformation around folds. To do this, we have evaluated structure-from-motion photogrammetry as a tool, which shows promise for the broader geology community as a visualization and educational tool. A primary outcome of the work is a high-resolution digital surface model of the folds in the BVSM, which will enable students (those able and those unable to visit the site) from around the world to explore the iconic structure in a digital medium. Furthermore, we are producing a virtual reality field trip for the BVSM location as a free on-line resource for students and instructors. Novel renderings of the produced digital data, as 3D printing of desktop-scale models of the Whaleback, have also been created and will offer further opportunities for those interested to interact with these data in new and exciting ways.
Finally, the BVSM is an important educational resource used by scores of geology programs and local community groups, and is a well-used recreation site for the local community. As part of this project we worked to preserve, expand and curate geological observations from the BVSM, with outreach targeted to these user groups. This includes the future installation of educational kiosks at the mine site, and the publication of virtual reality field trips.
Last Modified: 12/01/2018
Modified by: Arlo B Weil
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