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23 students have participated in the Structural Geology Research Group's investigations of the Stillwell anticline fold system in west Texas and the Sevier Fault system in southern Utah. This research has been supported by the National Science Foundation (Award #1220235; P.I. B. Surpless) , the NSF-funded Keck Geology Consortium, and the Trinity Department of Geosciences. Below, we briefly describe the participation of undergraduate researchers in this project.
In the summer of 2018, Caroline McKeighan and Curtis Segarra (Trinity University), Charley Hankla (College of Wooster), and Madison Woodley (Mt. Holyoke College) investigated the evolution of fault segments at two localities within the Sevier normal fault zone in southern Utah. Caroline used field data in conjunction with Agisoft Photoscan Professional, 3D photogrammetry software, to analyze the fracture network in three dimentions. Curtis Segarra used Abaqus/SAE, geomechanical modeling software, to test the evolution of fracture development as normal faults propagates upward through layered sedimentary strata. Charley focused on field-based fracture data to develop a model of stress-strain evolution in the context of regional tectonics. Madison used GIS-based analysis of fractures and statistical cluster analysis of fracturing to develop a hypothesis of how stress and strain develop across different fault segments within the system. Caroline, Curtis, and Charley presented their results at the Geological Society of America Cordilleran Section Meeting in Spring 2019.
2016 – 2017
In the summer of 2016, Hannah Mathy and Sam Simoneau focused on documentation of fracture networks within and adjacent to the Sevier normal fault zone in southern Utah. Hannah used Move2016, computer 3D modeling software, to investigate the evolution of propagating normal fault systems, thinking carefully about how fracture networks develop in the perturbed stress field associated with such systems. Sam used field research and analysis of high-resolution photographs to analyze fracture systems within and adjacent to the same normal fault systems. The results from their research may allow us to develop a model of fracture formation and propagation that can be applied to less well-exposed normal fault zones elsewhere. They presented results at both the Trinity Research Symposium and the national meeting of the Geological Society of America, in fall 2016.
2015 – 2016
In the summer of 2015, Ashton Crues and Connor Dunn focused on documentation of fracture networks within the Stillwell anticline system. Ashton used a drone-based camera-system to document major fracture systems in a complex area within the anticline. She then used structure-from-motion photogrammetry to build a 3D model of the fold system. Ashton used this model to document and analyze fractures and faults that were not accessible in the field. Connor investigated the initiation of fractures on the bed scale, using high-resolution optical scanning and 3D model building to develop new views of 3D fracture development in rocks that have experienced different magnitudes of shear strain. They presented results at both the Trinity Research Symposium and the national meeting of the Geological Society of America, in fall 2015.
2013 - 2014
Cara Beasley utilized 2D forward kinematic modeling to elucidate likely subsurface fault geometries beneath the Stillwell anticline system, and Sarah Wigginton focused on macro-scale fracture development associated with evolution of the fold system. Both students presented their work at the Geological Society of America's national meeting in Denver, Colorado, in the fall of 2013.
In the summer and fall of 2014, Mark Mlella, Nicola Hill, and Rebecca Schauer performed research on three inter-related topics related to the accommodation of strain across the Stillwell anticline system. Mark investigated fracture-filling characteristics and mechanisms, evaluating the relative timing of calcite precipitation in fractures of different orientations, the source of carbon and oxygen in large fractures, the mechanisms active during the filling process, and change in permeability as fractures formed and were later filled. Rebecca modeled the fault-propagation-fold system using Move2014, industry-grade software, testing models of anticline formation based on field data and cross-section construction. Nicola evaluated the mechanisms that accommodated strain in the forelimb of the anticline system, investigating the roles of inter-layer slip, meter-scale flat-ramp fault geometries, and fracturing. She also used the macro-scale fold geometries exposed where drainage systems cut through the anticline to determine the relative strain expected at different locations, assuming a fault-propagation fold development that involved both trishear and kink-band kinematics. All three students presented their work at the Geological Society of America’s national meeting in Vancouver, B.C., Canada, in the fall of 2014.
2012 - 2013
Luciana de la Rocha investigated the role of structural position in the evolution of transitional-scale fracture networks, and Lauren Mercado used compressive strength testing and field data to estimate the relative roles of fracturing, faulting, and inter-layer slip in the folding process. Lauren presented her research at the Trinity Summer Research symposium, and Luciana presented her work at both the national Geological Society of America meeting in Charlotte, North Carolina, in the fall of 2012, and the Southcentral section of the Geological Society of America in the spring of 2013.
Erich de Zoeten, Grace Keesling, Lauren Mercado, James Schulz, and Nathan Tinker performed a detailed, bed-scale investigation of lithology, macro-fracture systems, compressive strength, and topographic profile within exposed layers of the Santa Elena limestone. In addition, although not directly related to the Stillwell anticline project, Mary Kate Stewart performed a map-based investigation to assess the relative risk of groundwater contamination by fracking in the Eagle Ford shale. These students presented the results of their research at the Southcentral section of the Geological Society of America in the spring of 2013.
2011 - 2012
Daniel Hoin and Brett Mays performed investigations of the Stillwell anticline system, with Daniel investigating the mechanical stratigraphy of the Santa Elena limestone (the unit which best defines the fold system) and Brett focusing on preliminary 2D inverse kinematic modeling of the anticline system. They presented the results of their research at the Southcentral section of the Geological Society of America in the spring of 2012.