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1. The low-angle breakaway system for the Northern Snake Range décollement in the Schell Creek and Duck Creek Ranges, eastern Nevada, USA: Implications for displacement magnitude

   https://doi.org/10.1130/GES02482.1  

   Long, Sean P.; Lee, Jeffrey; Blackford, Nolan R. (May 2022, Geosphere)

   Documenting the kinematics of detachment faults can provide fundamental insights into the ways in which the lithosphere evolves during high-magnitude extension. Although it has been investigated for 70 yr, the displacement magnitude on the Northern Snake Range décollement in eastern Nevada remains vigorously debated, with published estimates ranging between <10 and 60 km. To provide constraints on displacement on the Northern Snake Range décollement, we present retrodeformed cross sections across the west-adjacent Schell Creek and Duck Creek Ranges, which expose a system of low-angle faults that have previously been mapped as thrust faults. We reinterpret this fault system as the extensional Schell Creek Range detachment system, which is a stacked series of top-down-to-the-ESE brittle normal faults with 5°–10° stratigraphic cutoff angles that carry 0.1–0.5-km-thick sheets that are up to 8–13 km long. The western portion of the Schell Creek Range detachment system accomplished ~5 km of structural attenuation and is folded across an antiformal culmination that progressively grew during extension. Restoration using an Eocene unconformity as a paleohorizontal marker indicates that faults of the Schell Creek Range detachment system were active at ~5°–10°E dips. The Schell Creek Range detachment system accommodated 36 km of displacement via repeated excision, which is bracketed between ca. 36.5 and 26.1 Ma by published geochronology. Based on their spatial proximity, compatible displacement sense, overlapping deformation timing, and the similar stratigraphic levels to which these faults root, we propose that the Schell Creek Range detachment system represents the western breakaway system for the Northern Snake Range décollement. Debates over the pre-extensional geometry of the Northern Snake Range décollement hinder an accurate cumulative extension estimate, but our reconstruction shows that the Schell Creek Range detachment system fed at least 36 km of displacement eastward into the Northern Snake Range décollement. 

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2. DUCTILE STRAIN IN THE FOOTWALL OF THE SCHELL CREEK RANGE DETACHMENT SYSTEM, EASTERN NEVADA, USA: IMPLICATIONS FOR PRE-EXTENSIONAL GEOMETRY

   https://doi.org/10.1130/abs/2022AM-379100  

   Stevens, Julia; Blackford, Nolan; Long, Sean; Lee, Jeffrey (January 2022, Geological Society of America Abstracts with Programs)
3. Ductile strain in the footwall of the Northern Snake Range metamorphic core complex, eastern Nevada, USA: implications for its structural evolution

   Blackford, NR; Long, SP; Lee, J; Stevens, J (October 2022, Geological Society of America)

   The geometry and magnitude of finite strain in the ductile footwalls of metamorphic core complexes are important parameters for testing the predictions of models of extension, yet are often difficult to quantify due to the rare preservation of deformed markers. The footwall of the Northern Snake Range core complex in eastern Nevada preserves a coherent stratigraphy of ductilely thinned Neoproterozoic-Cambrian metasedimentary rocks that are exposed over a 30 km transport-parallel distance, and thus provides an important opportunity to quantify footwall strain. We measured strain ellipsoids from stretched detrital quartz grains and ribbons in 45 samples that span the full exposed distance of the ductilely sheared footwall of the master detachment fault (the Northern Snake Range décollement), and we combined our data with 11 published strain ellipsoids. On the eastern side of the range, where recrystallization limits the preservation of detrital quartz grains, we estimated finite strain by comparing the attenuated thicknesses of Neoproterozoic-Cambrian rock units to their regional stratigraphic thicknesses. Our data demonstrate a dramatic gradient in ductile strain in the transport direction, from 39% subhorizontal extension and 32% subvertical thinning at the western flank of the Northern Snake Range to 450-1440% extension and 81-94% thinning at the eastern flank. The footwall underwent 18-20 km of cumulative ductile extension, which is equivalent to 38-43% of the 47 km of total extension accommodated on brittle structures. Kinematic vorticity estimates from published quartz petrofabrics define an eastward-increasing component of top-to-the-ESE simple shear. Our data are compatible with a rolling hinge model of extension, where displacement on a low-angle, upper-crustal, brittle detachment fault system was fed downward to a zone of distributed, simple shear-dominant, top-down-to-ESE ductile shearing beneath the quartz crystal-plastic transition. The progressive eastward translation and brittle thinning of the hanging wall resulted in the eastward migration of exhumation of footwall rocks. Migrating exhumation may in part be responsible for the eastward-increasing finite strain gradient, as footwall rocks in the eastern part of the range experienced a longer strain history. 

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4. Late Miocene to Quaternary evolution of the McCallum Creek thrust system, Alaska: Insights for range-boundary thrusts in transpressional orogens

   https://doi.org/10.1130/GES01676.1  

   Waldien, Trevor S.; Roeske, Sarah M.; Benowitz, Jeffrey A.; Allen, Wai K.; Ridgway, Kenneth D.; O’Sullivan, Paul B. (October 2018, Geosphere)
5. Snake-Inspired Kirigami Skin for Lateral Undulation of a Soft Snake Robot

   https://doi.org/10.1109/LRA.2020.2969949  

   Branyan, Callie; Hatton, Ross L.; Menguc, Yigit (April 2020, IEEE Robotics and Automation Letters)