Research:
I am a structural geologist who is primarily interested in the evolution of mountain belts. Much of my research focuses on performing field-based tests of the predictions of models for the processes, dynamics, and feedbacks that operate in orogenic systems. Most of my projects start with geologic mapping, which I integrate with a diverse suite of techniques, including construction and restoration of balanced cross-sections, regional-scale tectonic reconstructions, geochronology, low-temperature thermochronometry, microstructural analyses, and metamorphic temperatures and pressures.
Projects:
1. The evolution of Himalayan deformation in Bhutan
The Himalayan range and Tibetan Plateau are the world’s tallest mountain range and largest area of elevated land, and represent the type-example of a mountain belt that formed as a result of the collision of two continental plates. Therefore, study of the Himalayan orogenic system provides a unique opportunity to understand how the crust evolves during this type of plate collision.
A. Geometry and kinematics of the Bhutan thrust belt (funding: NSF Tectonics to N. McQuarrie, 2006-2010)
My PhD research at Princeton University (2006-2010) focused on the geometry, kinematics, and timing of deformation in the eastern Himalayan kingdom of Bhutan. Collaboration with the Bhutan Department of Geology and Mines allowed us to access the majority of the country, and was an important factor in this project's success. This project was funded by a grant from the National Science Foundation awarded to Nadine McQuarrie.
Publications from this project:
1. Defining the pre-deformational stratigraphy of the foreland part of the fold-thrust belt, through geologic mapping, carbon isotope data, and U-Pb dating of detrital zircons (Long et al., 2011A).
2. Illustrating the geometry and kinematics, and quantifying the crustal shortening accommodated by the Himalayan fold-thrust belt using geologic mapping, and drafting and retro-deformation of balanced cross-sections (Long et al., 2011B).
3. Defining the tectonostratigraphy of the Paro Formation, an enigmatic metasedimentary rock unit in western Bhutan, using mapping, stratigraphic columns, U-Pb dating of detrital zircons, and epsilon neodymium signatures (Tobgay et al., 2010).
4. Constraining the amount of slip along a portion of the South Tibetan Detachment system, and the magnitude of strain distributed through metamorphic rocks in central Bhutan. This study was a test of the controversial 'channel-flow' model (Long and McQuarrie, 2010).
5. Quantifying internal strain and deformation temperature patterns within Himalayan thrust sheets, in order to understand the 3-D evolution of internal deformation, and to assess the relative contribution of internal strain to large-scale deformation (Long et al., 2011C).
6. A new 1:500,000-scale geologic map of Bhutan (Long et al., 2011D). click here for map click here for accompanying text
7. Quantifying the age and rate of displacement on one of the most important Himalayan structures, the Main Central Thrust, in western Bhutan, using Th-Pb geochronology of metamorphic monazite (Tobgay et al., 2012).
8. Documenting ~50% post-metamorphic flattening strain in Greater Himalayan rocks in central Bhutan, utilizing thermobarometry on chemically-zoned garnets to calculate pressure-temperature paths (Corrie et al., 2012).
9. Calculating a 4-part record of shortening rates accommodated by the Bhutan thrust belt between ~23-0 Ma, by integrating multiple geo- and thermochronologic data sets with sequential reconstructions of two balanced cross-sections (Long et al., 2012).
10. Documenting the stratigraphic framework, across-strike basin geometry, and provenance of Neoproterozoic to Ordovician rocks of the northern Indian margin, using mapping, U-Pb ages of detrital zircons, and neodymium and carbon isotopes (McQuarrie et al., 2013).
11. Calculating a multi-part record of shortening rates in western Bhutan from ~20 Ma to present, by integrating Ar/Ar, (U-Th)/He, and fission-track thermochronology, ages of monazite growth, and sequential restoration of a balanced cross-section (McQuarrie et al., 2014).
12. Integrating a balanced cross section through easternmost Bhutan with cooling ages in order to evaluate the influence of foreland structures on driving hinterland exhumation (McQuarrie et al., 2019).
B. A field-based test of the channel flow model in Bhutan (funding: NSF Tectonics, 2013-2016)
This was a collaborative NSF project with University of Nevada, Reno (UNR) geologist Stacia Gordon. Across the Himalaya, rocks that have been buried as deep as 30-40 km and taken to temperatures hot enough to partially melt are observed at the surface today, and there is a vigorous debate over how they were exhumed. The channel flow model predicts that these rocks lost much of their strength after partial melting, and were then translated southward and towards the surface, in concert with rapid erosion at the Himalayan topographic front. Other models argue that faults and shear zones were responsible for their exhumation, and are less focused on the driving force being the weakness of the rocks. In this project, we tested the applicability of these differing models to metamorphic rocks in northern Bhutan, by determining the pressure, temperature, timing, and evolution of deformation that they experienced.
Field work for this project was completed in 2013, 2014, and 2016. UNR M.S. students Melissa Penfold, Kenjo Agustsson, and Kate Zeiger, who all completed their degrees in 2014, all worked on different aspects of this project. UNR M.S. student Carol Zamora, who completed her M.S. at UNR in 2016, also worked on this project. WSU graduate student Jesslyn Starnes, who completed her Ph.D. in 2021, addressed similar problems in the western and eastern parts of Bhutan. WSU graduate students Laura Pianowski and Keita Hasegawa, who completed their M.S. degrees in 2018 and 2022, respectively, both worked on additional aspects of this project.
Publications from this project:
1. Zeiger, K., Gordon, S.M., Long, S.P., Kylander-Clark, A.R.C., Agustsson, K., and Penfold, M., 2015, Timing and conditions of metamorphism and melt crystallization in Greater Himalayan rocks, eastern and central Bhutan: insight from U-Pb zircon and monazite geochronology and trace-element analyses: Contributions to Mineralogy and Petrology, v. 169, article 47, 19 p., doi: 10.1007/s00410-015-1143-6. click here for pdf
2. Agustsson, K.M., Gordon, S.M.,, Long, S.P., Seward, G.G.E., Zeiger, K., and Penfold, M.*, 2016, Pressure–temperature–structural distance relationships within Greater Himalayan rocks in eastern Bhutan: implications for emplacement models: Journal of Metamorphic Geology, v. 34, p. 641-662, doi: 10.1111/jmg.12197. click here for pdf
3. Long, S.P., Gordon, S.M., Young, J.P., and Soignard, E, 2016, Temperature and strain gradients through Lesser Himalayan rocks and across the Main Central thrust, south-central Bhutan: implications for transport-parallel stretching and inverted metamorphism: Tectonics, v. 35, p. 1863-1891, doi: 10.1002/2016TC004242. click here for pdf
4. Long, S.P., Gordon, S.M., and Soignard, E., 2017, Distributed north-vergent shear and flattening through Greater and Tethyan Himalayan rocks: insights from metamorphic and strain data from the Dang Chu region, central Bhutan: Lithosphere, v. 9, p. 774-795, doi: 10.1130/L655.1. click here for pdf
5. Long, S.P., Mullady, C.L.**, Starnes, J.K.*, Gordon, S.M., Larson, K.P., Miller, R.B., Pianowski, L.S.*, and Soignard, E., 2019, A structural model for the South Tibetan detachment system in northwestern Bhutan from integration of temperature, fabric, strain, and kinematic data: Lithosphere, v. 11, p. 465-487, doi: 10.1130/L1049.1 click here for pdf
6. Starnes, J.K.*, Long, S.P., Gordon, S.M., Zhang, J., and Soignard, E., 2020, Using quartz fabric intensity parameters to delineate strain patterns across the Himalayan Main Central thrust: Journal of Structural Geology: v. 131, 103941, 18 p., doi: 10.1016/j.jsg.2019.103941. click here for pdf
7. Long, S.P., and Robinson, D.M., 2021, Construction of the Lesser Himalayan-Subhimalayan thrust belt: the primary driver of thickening, exhumation, and high elevations in the Himalayan orogen since the middle Miocene: Geology, v. 49, no. 11, p. 1283-1288, doi: 10.1130/G48967.1. click here for pdf
The Himalayan range and Tibetan Plateau are the world’s tallest mountain range and largest area of elevated land, and represent the type-example of a mountain belt that formed as a result of the collision of two continental plates. Therefore, study of the Himalayan orogenic system provides a unique opportunity to understand how the crust evolves during this type of plate collision.
A. Geometry and kinematics of the Bhutan thrust belt (funding: NSF Tectonics to N. McQuarrie, 2006-2010)
My PhD research at Princeton University (2006-2010) focused on the geometry, kinematics, and timing of deformation in the eastern Himalayan kingdom of Bhutan. Collaboration with the Bhutan Department of Geology and Mines allowed us to access the majority of the country, and was an important factor in this project's success. This project was funded by a grant from the National Science Foundation awarded to Nadine McQuarrie.
Publications from this project:
1. Defining the pre-deformational stratigraphy of the foreland part of the fold-thrust belt, through geologic mapping, carbon isotope data, and U-Pb dating of detrital zircons (Long et al., 2011A).
2. Illustrating the geometry and kinematics, and quantifying the crustal shortening accommodated by the Himalayan fold-thrust belt using geologic mapping, and drafting and retro-deformation of balanced cross-sections (Long et al., 2011B).
3. Defining the tectonostratigraphy of the Paro Formation, an enigmatic metasedimentary rock unit in western Bhutan, using mapping, stratigraphic columns, U-Pb dating of detrital zircons, and epsilon neodymium signatures (Tobgay et al., 2010).
4. Constraining the amount of slip along a portion of the South Tibetan Detachment system, and the magnitude of strain distributed through metamorphic rocks in central Bhutan. This study was a test of the controversial 'channel-flow' model (Long and McQuarrie, 2010).
5. Quantifying internal strain and deformation temperature patterns within Himalayan thrust sheets, in order to understand the 3-D evolution of internal deformation, and to assess the relative contribution of internal strain to large-scale deformation (Long et al., 2011C).
6. A new 1:500,000-scale geologic map of Bhutan (Long et al., 2011D). click here for map click here for accompanying text
7. Quantifying the age and rate of displacement on one of the most important Himalayan structures, the Main Central Thrust, in western Bhutan, using Th-Pb geochronology of metamorphic monazite (Tobgay et al., 2012).
8. Documenting ~50% post-metamorphic flattening strain in Greater Himalayan rocks in central Bhutan, utilizing thermobarometry on chemically-zoned garnets to calculate pressure-temperature paths (Corrie et al., 2012).
9. Calculating a 4-part record of shortening rates accommodated by the Bhutan thrust belt between ~23-0 Ma, by integrating multiple geo- and thermochronologic data sets with sequential reconstructions of two balanced cross-sections (Long et al., 2012).
10. Documenting the stratigraphic framework, across-strike basin geometry, and provenance of Neoproterozoic to Ordovician rocks of the northern Indian margin, using mapping, U-Pb ages of detrital zircons, and neodymium and carbon isotopes (McQuarrie et al., 2013).
11. Calculating a multi-part record of shortening rates in western Bhutan from ~20 Ma to present, by integrating Ar/Ar, (U-Th)/He, and fission-track thermochronology, ages of monazite growth, and sequential restoration of a balanced cross-section (McQuarrie et al., 2014).
12. Integrating a balanced cross section through easternmost Bhutan with cooling ages in order to evaluate the influence of foreland structures on driving hinterland exhumation (McQuarrie et al., 2019).
B. A field-based test of the channel flow model in Bhutan (funding: NSF Tectonics, 2013-2016)
This was a collaborative NSF project with University of Nevada, Reno (UNR) geologist Stacia Gordon. Across the Himalaya, rocks that have been buried as deep as 30-40 km and taken to temperatures hot enough to partially melt are observed at the surface today, and there is a vigorous debate over how they were exhumed. The channel flow model predicts that these rocks lost much of their strength after partial melting, and were then translated southward and towards the surface, in concert with rapid erosion at the Himalayan topographic front. Other models argue that faults and shear zones were responsible for their exhumation, and are less focused on the driving force being the weakness of the rocks. In this project, we tested the applicability of these differing models to metamorphic rocks in northern Bhutan, by determining the pressure, temperature, timing, and evolution of deformation that they experienced.
Field work for this project was completed in 2013, 2014, and 2016. UNR M.S. students Melissa Penfold, Kenjo Agustsson, and Kate Zeiger, who all completed their degrees in 2014, all worked on different aspects of this project. UNR M.S. student Carol Zamora, who completed her M.S. at UNR in 2016, also worked on this project. WSU graduate student Jesslyn Starnes, who completed her Ph.D. in 2021, addressed similar problems in the western and eastern parts of Bhutan. WSU graduate students Laura Pianowski and Keita Hasegawa, who completed their M.S. degrees in 2018 and 2022, respectively, both worked on additional aspects of this project.
Publications from this project:
1. Zeiger, K., Gordon, S.M., Long, S.P., Kylander-Clark, A.R.C., Agustsson, K., and Penfold, M., 2015, Timing and conditions of metamorphism and melt crystallization in Greater Himalayan rocks, eastern and central Bhutan: insight from U-Pb zircon and monazite geochronology and trace-element analyses: Contributions to Mineralogy and Petrology, v. 169, article 47, 19 p., doi: 10.1007/s00410-015-1143-6. click here for pdf
2. Agustsson, K.M., Gordon, S.M.,, Long, S.P., Seward, G.G.E., Zeiger, K., and Penfold, M.*, 2016, Pressure–temperature–structural distance relationships within Greater Himalayan rocks in eastern Bhutan: implications for emplacement models: Journal of Metamorphic Geology, v. 34, p. 641-662, doi: 10.1111/jmg.12197. click here for pdf
3. Long, S.P., Gordon, S.M., Young, J.P., and Soignard, E, 2016, Temperature and strain gradients through Lesser Himalayan rocks and across the Main Central thrust, south-central Bhutan: implications for transport-parallel stretching and inverted metamorphism: Tectonics, v. 35, p. 1863-1891, doi: 10.1002/2016TC004242. click here for pdf
4. Long, S.P., Gordon, S.M., and Soignard, E., 2017, Distributed north-vergent shear and flattening through Greater and Tethyan Himalayan rocks: insights from metamorphic and strain data from the Dang Chu region, central Bhutan: Lithosphere, v. 9, p. 774-795, doi: 10.1130/L655.1. click here for pdf
5. Long, S.P., Mullady, C.L.**, Starnes, J.K.*, Gordon, S.M., Larson, K.P., Miller, R.B., Pianowski, L.S.*, and Soignard, E., 2019, A structural model for the South Tibetan detachment system in northwestern Bhutan from integration of temperature, fabric, strain, and kinematic data: Lithosphere, v. 11, p. 465-487, doi: 10.1130/L1049.1 click here for pdf
6. Starnes, J.K.*, Long, S.P., Gordon, S.M., Zhang, J., and Soignard, E., 2020, Using quartz fabric intensity parameters to delineate strain patterns across the Himalayan Main Central thrust: Journal of Structural Geology: v. 131, 103941, 18 p., doi: 10.1016/j.jsg.2019.103941. click here for pdf
7. Long, S.P., and Robinson, D.M., 2021, Construction of the Lesser Himalayan-Subhimalayan thrust belt: the primary driver of thickening, exhumation, and high elevations in the Himalayan orogen since the middle Miocene: Geology, v. 49, no. 11, p. 1283-1288, doi: 10.1130/G48967.1. click here for pdf
2. Geometry, magnitude, and timing of deformation in the Western U.S. Cordillera and Basin and Range Province in Nevada and Utah
The Mesozoic–Paleogene North American Cordillera is the birthplace of models for the genesis and development of magmatic arcs, fold-thrust belts, and foreland basins, which have been exported to explain orogenic systems worldwide. I have multiple research interests in the western U.S. Cordillera, including understanding both its construction and its subsequent extension. I am particularly interested in the hinterland region of the Sevier fold-thrust belt in Nevada and western Utah. Below are details on active projects.
A. Deformation, erosion, and exhumation in the Sevier hinterland plateau, or 'Nevadaplano': (2012-2022)
During the Late Cretaceous, the hinterland of the Sevier thrust belt in Nevada is hypothesized to have been a high-elevation orogenic plateau. However, a complex tectonic overprint of Tertiary extension has obscured the pre-extensional structural geometry of this region. With goals of understanding the style, geometry, magnitude, and timing of contractional deformation in this region, I have published several papers that present tectonic reconstructions in the form of regional sub-unconformity maps and retro-deformable cross sections, which effectively subtract out the effects of overprinting extension, and a paper that reinterprets the exhumation history of the Ruby-East Humboldt core complex in the context of distributed ductile thinning during Cordilleran thrust emplacement.
Publications from this project:
1. Long, S.P., 2012, Magnitudes and spatial patterns of erosional exhumation in the Sevier hinterland, eastern Nevada and western Utah, USA: Insights from a Paleogene paleogeologic map: Geosphere, v. 8, p. 881-901, doi:10.1130/GES00783.1. click here for pdf
2. Long, S.P., 2015, An upper-crustal fold province in the hinterland of the Sevier orogenic belt, eastern Nevada, U.S.A.: a Cordilleran Valley and Ridge in the Basin and Range: Geosphere, v. 11, p. 404-424, doi:10.1130/GES01102.1. click here for pdf
3. Long, S.P., 2019, Geometry and magnitude of extension in the Basin and Range Province (39°N), California, Nevada, and Utah, U.S.A: Constraints from a province-scale cross section: Geological Society of America Bulletin, v. 131, p. 99-119, doi: 10.1130/B31974.1. click here for pdf Click here for a jpg of the cross section (Plate DR1)
4. Long, S.P., and Kohn, M.J., 2020, Distributed ductile thinning during thrust emplacement: a commonly overlooked exhumation mechanism: Geology, v. 48, p. 368-373, doi: 10.1130/G47022.1. click here for pdf
5. Zuza, A.V., Thorman, C.H., Henry, C.D., Levy, D.A., Dee, S., Long, S.P., Sandberg, C., and Soignard, E., 2020, Pulsed Mesozoic deformation in the Cordilleran hinterland and evolution of the Nevadaplano: Insights from the Pequop Mountains, NE Nevada: Lithosphere, v. 2020, 24 p., doi: 10.2113/2020/8850336. click here for pdf
6. Blackford, N.R.*, Long, S.P., Stout, A.J.**, Rodgers, D.W., Cooper, C.M., Kramer, K.**, Di Fiori, R.V.*, and Soignard, E., 2022, Late Cretaceous upper-crustal thermal structure of the Sevier hinterland: implications for the geodynamics of the Nevadaplano: Geosphere, v. 18, no. 1, p. 183-210, doi: 10.1130/GES02386.1. click here for pdf
7. Long, S.P., 2023, Westward underthrusting of thick North American crust: the dominant thickening process that built the Cordilleran orogenic plateau: Geology: published online 9-20-23, doi: 10.1130/G51339.1. click here for pdf
The Mesozoic–Paleogene North American Cordillera is the birthplace of models for the genesis and development of magmatic arcs, fold-thrust belts, and foreland basins, which have been exported to explain orogenic systems worldwide. I have multiple research interests in the western U.S. Cordillera, including understanding both its construction and its subsequent extension. I am particularly interested in the hinterland region of the Sevier fold-thrust belt in Nevada and western Utah. Below are details on active projects.
A. Deformation, erosion, and exhumation in the Sevier hinterland plateau, or 'Nevadaplano': (2012-2022)
During the Late Cretaceous, the hinterland of the Sevier thrust belt in Nevada is hypothesized to have been a high-elevation orogenic plateau. However, a complex tectonic overprint of Tertiary extension has obscured the pre-extensional structural geometry of this region. With goals of understanding the style, geometry, magnitude, and timing of contractional deformation in this region, I have published several papers that present tectonic reconstructions in the form of regional sub-unconformity maps and retro-deformable cross sections, which effectively subtract out the effects of overprinting extension, and a paper that reinterprets the exhumation history of the Ruby-East Humboldt core complex in the context of distributed ductile thinning during Cordilleran thrust emplacement.
Publications from this project:
1. Long, S.P., 2012, Magnitudes and spatial patterns of erosional exhumation in the Sevier hinterland, eastern Nevada and western Utah, USA: Insights from a Paleogene paleogeologic map: Geosphere, v. 8, p. 881-901, doi:10.1130/GES00783.1. click here for pdf
2. Long, S.P., 2015, An upper-crustal fold province in the hinterland of the Sevier orogenic belt, eastern Nevada, U.S.A.: a Cordilleran Valley and Ridge in the Basin and Range: Geosphere, v. 11, p. 404-424, doi:10.1130/GES01102.1. click here for pdf
3. Long, S.P., 2019, Geometry and magnitude of extension in the Basin and Range Province (39°N), California, Nevada, and Utah, U.S.A: Constraints from a province-scale cross section: Geological Society of America Bulletin, v. 131, p. 99-119, doi: 10.1130/B31974.1. click here for pdf Click here for a jpg of the cross section (Plate DR1)
4. Long, S.P., and Kohn, M.J., 2020, Distributed ductile thinning during thrust emplacement: a commonly overlooked exhumation mechanism: Geology, v. 48, p. 368-373, doi: 10.1130/G47022.1. click here for pdf
5. Zuza, A.V., Thorman, C.H., Henry, C.D., Levy, D.A., Dee, S., Long, S.P., Sandberg, C., and Soignard, E., 2020, Pulsed Mesozoic deformation in the Cordilleran hinterland and evolution of the Nevadaplano: Insights from the Pequop Mountains, NE Nevada: Lithosphere, v. 2020, 24 p., doi: 10.2113/2020/8850336. click here for pdf
6. Blackford, N.R.*, Long, S.P., Stout, A.J.**, Rodgers, D.W., Cooper, C.M., Kramer, K.**, Di Fiori, R.V.*, and Soignard, E., 2022, Late Cretaceous upper-crustal thermal structure of the Sevier hinterland: implications for the geodynamics of the Nevadaplano: Geosphere, v. 18, no. 1, p. 183-210, doi: 10.1130/GES02386.1. click here for pdf
7. Long, S.P., 2023, Westward underthrusting of thick North American crust: the dominant thickening process that built the Cordilleran orogenic plateau: Geology: published online 9-20-23, doi: 10.1130/G51339.1. click here for pdf
B. Understanding connections between tectonics, magmatism, and gold mineralization in central Nevada (funding: USGS and Timberline Resources, Inc.; 2011-2015)
This was a collaborative project with Chris Henry and John Muntean at the University of Nevada, Reno (UNR). Despite a 150-year history of gold production, fundamental questions remain regarding the genesis of Carlin-type mineralization in Nevada. The goals of this project were to understand structural and temporal controls on mineralization in the Eureka mining district of central Nevada, by utilizing geologic mapping, retro-deformation of cross-sections, geochronology, and low-temperature thermochronometry. UNR M.S. student Russell DiFiori completed his thesis work on this project in 2014.
Publications from this project:
1. Long, S.P., Henry, C.D., Muntean, J.L., Edmondo, G.P., and Cassel, E.J., 2014, Early Cretaceous construction of a structural culmination, Eureka, Nevada, U.S.A.: implications for out-of-sequence deformation in the Sevier hinterland: Geosphere, v. 10, p. 564-584, doi: 10.1130/GES00997.1. click here for pdf
2. Long, S.P., Henry, C.D., Muntean, J.L., Edmondo, G.P., and Thomas, R.D., 2014, Geologic map of the southern part of the Eureka mining district, and surrounding areas of the Fish Creek Range, Mountain Boy Range, and Diamond Mountains, Eureka and White Pine Counties, Nevada: Nevada Bureau of Mines and Geology Map 183, 1:24,000-scale, 2 plates, 36 p. click here for plate 1 click here for plate 2 click here for accompanying text
3. Di Fiori, R.V., Long, S.P., Edmondo, G.P., and Muntean, J.L., 2014, Preliminary geologic and alteration maps of Lookout Mountain, Ratto Ridge, and Rocky Canyon, southern Eureka mining district, Eureka County, Nevada: Nevada Bureau of Mines and Geology Open-File Report 14-8, 1:10,000-scale, 2 plates. click here for pdf of geologic map click here for pdf of alteration map
4. Long, S.P., Thomson, S.N., Reiners, P.W., and Di Fiori, R.V., 2015, Synorogenic extension localized by upper-crustal thickening: an example from the Late Cretaceous Nevadaplano: Geology, v. 43, p. 351-354, doi:10.1130/G36431.1. click here for pdf
5. Di Fiori, R.V., Long, S.P., Muntean, J.L., and Edmondo, G.P., 2015, Structural analysis of gold mineralization in the southern Eureka mining district, Nevada: a predictive structural setting for Carlin-type gold deposits: in Pennell, W.M., and Garside, L.J., eds., New Concepts and Discoveries: Geological Society of Nevada Symposium Proceedings, May 2015, Sparks, Nevada, v. 1, p. 885-903. click here for pdf
This was a collaborative project with Chris Henry and John Muntean at the University of Nevada, Reno (UNR). Despite a 150-year history of gold production, fundamental questions remain regarding the genesis of Carlin-type mineralization in Nevada. The goals of this project were to understand structural and temporal controls on mineralization in the Eureka mining district of central Nevada, by utilizing geologic mapping, retro-deformation of cross-sections, geochronology, and low-temperature thermochronometry. UNR M.S. student Russell DiFiori completed his thesis work on this project in 2014.
Publications from this project:
1. Long, S.P., Henry, C.D., Muntean, J.L., Edmondo, G.P., and Cassel, E.J., 2014, Early Cretaceous construction of a structural culmination, Eureka, Nevada, U.S.A.: implications for out-of-sequence deformation in the Sevier hinterland: Geosphere, v. 10, p. 564-584, doi: 10.1130/GES00997.1. click here for pdf
2. Long, S.P., Henry, C.D., Muntean, J.L., Edmondo, G.P., and Thomas, R.D., 2014, Geologic map of the southern part of the Eureka mining district, and surrounding areas of the Fish Creek Range, Mountain Boy Range, and Diamond Mountains, Eureka and White Pine Counties, Nevada: Nevada Bureau of Mines and Geology Map 183, 1:24,000-scale, 2 plates, 36 p. click here for plate 1 click here for plate 2 click here for accompanying text
3. Di Fiori, R.V., Long, S.P., Edmondo, G.P., and Muntean, J.L., 2014, Preliminary geologic and alteration maps of Lookout Mountain, Ratto Ridge, and Rocky Canyon, southern Eureka mining district, Eureka County, Nevada: Nevada Bureau of Mines and Geology Open-File Report 14-8, 1:10,000-scale, 2 plates. click here for pdf of geologic map click here for pdf of alteration map
4. Long, S.P., Thomson, S.N., Reiners, P.W., and Di Fiori, R.V., 2015, Synorogenic extension localized by upper-crustal thickening: an example from the Late Cretaceous Nevadaplano: Geology, v. 43, p. 351-354, doi:10.1130/G36431.1. click here for pdf
5. Di Fiori, R.V., Long, S.P., Muntean, J.L., and Edmondo, G.P., 2015, Structural analysis of gold mineralization in the southern Eureka mining district, Nevada: a predictive structural setting for Carlin-type gold deposits: in Pennell, W.M., and Garside, L.J., eds., New Concepts and Discoveries: Geological Society of Nevada Symposium Proceedings, May 2015, Sparks, Nevada, v. 1, p. 885-903. click here for pdf
C. Structural analysis of the Grant Range brittle detachment system, eastern Nevada (funding: USGS and Makoil, Inc.; 2013-2018)
The past 40 years have seen vigorous debates over how the brittle crust accommodates extension, in particular the mechanical feasibility of slip on low-angle normal faults. The Grant Range contains superb exposures of a system of low-angle, brittle normal faults with field relationships indicating slip at angles ≤10˚. The goals of this project were to utilize geologic mapping, retro-deformed cross-sections, and low-temperature thermochronometry to illustrate the geometry and kinematics of this fault system, and quantify the magnitude, timing, and rates of extension.
Publications from this project:
1. Long, S.P., 2014, Preliminary geologic map of Heath Canyon, central Grant Range, Nye County, Nevada: Nevada Bureau of Mines and Geology Open-File Report 14-6, 1:24,000-scale, 1 plate, 4 p. click here for pdf of map click here for pdf of text
2. Long, S.P., and Walker, J.P., 2015, Geometry and kinematics of the Grant Range brittle detachment system, eastern Nevada, U.S.A.: an end-member style of upper-crustal extension: Tectonics, v. 34, TC003918, 26 p., doi: 10.1002/2015TC003918. click here for pdf
3. Long, S.P., and Soignard, E., 2016, Shallow-crustal metamorphism during Late Cretaceous anatexis in the Sevier hinterland plateau: peak temperature conditions from the Grant Range, eastern Nevada, U.S.A.: Lithosphere, v. 8, p. 150-164, doi: 10.1130/L501.1. click here for pdf
4. Long, S.P., Heizler, M.T., Thomson, S.N., Reiners, P.W., and Fryxell, J.E., 2018, Rapid Oligocene to early Miocene extension along the Grant Range detachment system, eastern Nevada, U.S.A.: insights from multi-part cooling histories of footwall rocks: Tectonics, v. 37, p. 4752-4779, doi: 10.1029/2018TC005073. click here for pdf
The past 40 years have seen vigorous debates over how the brittle crust accommodates extension, in particular the mechanical feasibility of slip on low-angle normal faults. The Grant Range contains superb exposures of a system of low-angle, brittle normal faults with field relationships indicating slip at angles ≤10˚. The goals of this project were to utilize geologic mapping, retro-deformed cross-sections, and low-temperature thermochronometry to illustrate the geometry and kinematics of this fault system, and quantify the magnitude, timing, and rates of extension.
Publications from this project:
1. Long, S.P., 2014, Preliminary geologic map of Heath Canyon, central Grant Range, Nye County, Nevada: Nevada Bureau of Mines and Geology Open-File Report 14-6, 1:24,000-scale, 1 plate, 4 p. click here for pdf of map click here for pdf of text
2. Long, S.P., and Walker, J.P., 2015, Geometry and kinematics of the Grant Range brittle detachment system, eastern Nevada, U.S.A.: an end-member style of upper-crustal extension: Tectonics, v. 34, TC003918, 26 p., doi: 10.1002/2015TC003918. click here for pdf
3. Long, S.P., and Soignard, E., 2016, Shallow-crustal metamorphism during Late Cretaceous anatexis in the Sevier hinterland plateau: peak temperature conditions from the Grant Range, eastern Nevada, U.S.A.: Lithosphere, v. 8, p. 150-164, doi: 10.1130/L501.1. click here for pdf
4. Long, S.P., Heizler, M.T., Thomson, S.N., Reiners, P.W., and Fryxell, J.E., 2018, Rapid Oligocene to early Miocene extension along the Grant Range detachment system, eastern Nevada, U.S.A.: insights from multi-part cooling histories of footwall rocks: Tectonics, v. 37, p. 4752-4779, doi: 10.1029/2018TC005073. click here for pdf
D) The record of Early Cretaceous growth of the Nevadaplano from syn-orogenic deposits of the Sevier hinterland (funding: NSF Tectonics, 2016-2019)
This was a collaborative project between myself, Kathryn Snell at (UC-Boulder), and Joshua Bonde (UNLV). The Sevier hinterland plateau in Nevada has undergone a complex Cenozoic history of extensional collapse, which hinders direct evaluation of relict surface elevation. This project investigated the timing of plateau uplift early during the Sevier shortening history, by analyzing the Early Cretaceous Newark Canyon Formation, which is the only preserved synorogenic rock unit deposited atop the Nevadaplano. We integrated carbonate clumped isotope thermometry with a geologic context obtained from mapping, lithostratigraphy, facies analysis, biostratigraphy, and U-Pb geochronology. WSU Ph.D. student Russell Di Fiori completed his PhD in 2020, and has recently published two papers and several geologic maps from this project.
Publications from this project:
1. Di Fiori, R.V., Long, S.P., Snell, K.E., Fetrow, A., Bonde, J., and Vervoort, J.D., 2020, Syn-contractional deposition of the Cretaceous Newark Canyon Formation, Diamond Mountains, Nevada: Implications for strain partitioning within the U.S. Cordillera: Geosphere, v. 16, no. 2, p. 546-566, doi: 10.1130/GES02168.1 click here for pdf
2. Fetrow, A.C., Snell, K.E., Di Fiori, R.V., Long, S.P., and Bonde, J.W., 2020, Early Sevier orogenic deformation exerted primary control on changes in depositional environment recorded by the Cretaceous Newark Canyon Formation: Journal of Sedimentary Research: v. 90, p. 1175-1197, doi: 10.2110/jsr.2020.52. click here for pdf
3. Di Fiori, R.V., Long, S.P., Snell, K.E., Fetrow, A.C., Bonde, J.W., and Vervoort, J.D., 2021, The role of shortening in the Sevier hinterland within the U.S. Cordilleran retroarc thrust system: Insights from the Cretaceous Newark Canyon Formation in central Nevada: Tectonics, v. 40, e2020TC006331, doi: 10.1029/2020TC006331. click here for pdf
4. Di Fiori, R.V., and Long, S.P., 2022, Geologic map of the eastern flank of the northern Cortez Mountains, Eureka County, Nevada: Nevada Bureau of Mines and Geology Open-File Report 2022-06, 1:24,000-scale, 1 sheet, 7 p. click here for map click here for text
5. Di Fiori, R.V., and Long, S.P., 2022, Geologic map of the McClure Spring syncline, central Pancake Range, Nye County, Nevada: Nevada Bureau of Mines and Geology Open-File Report 2022-03, 1:24,000-scale, 1 plate, 9 p. click here for map click here for text
7.Di Fiori, R.V., and Long, S.P., 2022, Geologic map of the southern Diamond Mountains, Eureka and White Pine Counties, Nevada: Nevada Bureau of Mines and Geology Open-File Report 2022-04, 1:24,000-scale, 1 plate, 10 p. click here for map click here for text
8. Di Fiori, R.V., and Long, S.P., 2022, Geologic Map of the southern Fish Creek Range, Eureka and Nye Counties, Nevada: Nevada Bureau of Mines and Geology Open-File Report 2022-05, 1:15,000-scale, 1 plate, 9 p. click here for map click here for text
9. Fetrow, A.C., Snell, K.E., Di Fiori, R.V., Long, S.P., and Bonde, J.W., 2022, How hot is too hot? Disentangling signals of primary deposition from diagenesis in mid-Cretaceous terrestrial carbonate stable isotope records: Paleoceanography and Paleoclimatology, v. 37, e2022PA004517, 25 p., doi: 10.1029/2022PA004517. click here for pdf
This was a collaborative project between myself, Kathryn Snell at (UC-Boulder), and Joshua Bonde (UNLV). The Sevier hinterland plateau in Nevada has undergone a complex Cenozoic history of extensional collapse, which hinders direct evaluation of relict surface elevation. This project investigated the timing of plateau uplift early during the Sevier shortening history, by analyzing the Early Cretaceous Newark Canyon Formation, which is the only preserved synorogenic rock unit deposited atop the Nevadaplano. We integrated carbonate clumped isotope thermometry with a geologic context obtained from mapping, lithostratigraphy, facies analysis, biostratigraphy, and U-Pb geochronology. WSU Ph.D. student Russell Di Fiori completed his PhD in 2020, and has recently published two papers and several geologic maps from this project.
Publications from this project:
1. Di Fiori, R.V., Long, S.P., Snell, K.E., Fetrow, A., Bonde, J., and Vervoort, J.D., 2020, Syn-contractional deposition of the Cretaceous Newark Canyon Formation, Diamond Mountains, Nevada: Implications for strain partitioning within the U.S. Cordillera: Geosphere, v. 16, no. 2, p. 546-566, doi: 10.1130/GES02168.1 click here for pdf
2. Fetrow, A.C., Snell, K.E., Di Fiori, R.V., Long, S.P., and Bonde, J.W., 2020, Early Sevier orogenic deformation exerted primary control on changes in depositional environment recorded by the Cretaceous Newark Canyon Formation: Journal of Sedimentary Research: v. 90, p. 1175-1197, doi: 10.2110/jsr.2020.52. click here for pdf
3. Di Fiori, R.V., Long, S.P., Snell, K.E., Fetrow, A.C., Bonde, J.W., and Vervoort, J.D., 2021, The role of shortening in the Sevier hinterland within the U.S. Cordilleran retroarc thrust system: Insights from the Cretaceous Newark Canyon Formation in central Nevada: Tectonics, v. 40, e2020TC006331, doi: 10.1029/2020TC006331. click here for pdf
4. Di Fiori, R.V., and Long, S.P., 2022, Geologic map of the eastern flank of the northern Cortez Mountains, Eureka County, Nevada: Nevada Bureau of Mines and Geology Open-File Report 2022-06, 1:24,000-scale, 1 sheet, 7 p. click here for map click here for text
5. Di Fiori, R.V., and Long, S.P., 2022, Geologic map of the McClure Spring syncline, central Pancake Range, Nye County, Nevada: Nevada Bureau of Mines and Geology Open-File Report 2022-03, 1:24,000-scale, 1 plate, 9 p. click here for map click here for text
7.Di Fiori, R.V., and Long, S.P., 2022, Geologic map of the southern Diamond Mountains, Eureka and White Pine Counties, Nevada: Nevada Bureau of Mines and Geology Open-File Report 2022-04, 1:24,000-scale, 1 plate, 10 p. click here for map click here for text
8. Di Fiori, R.V., and Long, S.P., 2022, Geologic Map of the southern Fish Creek Range, Eureka and Nye Counties, Nevada: Nevada Bureau of Mines and Geology Open-File Report 2022-05, 1:15,000-scale, 1 plate, 9 p. click here for map click here for text
9. Fetrow, A.C., Snell, K.E., Di Fiori, R.V., Long, S.P., and Bonde, J.W., 2022, How hot is too hot? Disentangling signals of primary deposition from diagenesis in mid-Cretaceous terrestrial carbonate stable isotope records: Paleoceanography and Paleoclimatology, v. 37, e2022PA004517, 25 p., doi: 10.1029/2022PA004517. click here for pdf
E) Calibrating quartz fabric intensity as a function of strain magnitude in the Northern Snake Range metamorphic core complex (funding: NSF Tectonics, 2020-2023)
This is a collaborative NSF project with Jeffrey Lee at the Colorado School of Mines. Several recent studies have proposed that statistical intensity parameters calculated from quartz crystallographic fabrics have the potential to delineate zones of high strain, by interpreting fabric intensity as a proxy for finite strain magnitude. However, as these studies were performed within packages of pervasively recrystallized rocks that lack deformed markers from which finite strain can be measured, they cannot quantitatively relate fabric intensity to absolute strain magnitude. In this project, we propose to generate a calibration equation that expresses fabric intensity as a function of finite strain magnitude by investigating strongly-sheared quartzites within the Northern Snake Range metamorphic core complex in easternmost Nevada. The calibration equation that we propose to obtain will provide an important new tool for investigating the spatial patterns of strain localization within deformed rocks globally.
Initial field work for this project began in Summer, 2020. WSU graduate student Nolan Blackford is performing his Ph.D. research on this project. We're really excited for the results from this project, please stay tuned!
Publications from this project:
1. Long, S.P., Lee, J., and Blackford, N.R., 2022, The low-angle breakaway system for the Northern Snake Range décollement in the Schell Creek and Duck Creek Ranges, eastern Nevada, U.S.A.: implications for displacement magnitude: Geosphere, v. 18, no. 4, p. 1194-1222, doi: 10.1130/GES02482.1. click here for pdf
2. Long, S.P., Lee, J., and Blackford, N.R., 2023, Extreme ductile thinning of Cambrian marbles in the Northern Snake Range metamorphic core complex, Nevada, USA: implications for extension magnitude and structural evolution: Journal of Structural Geology, v. 173, 104912, 25 p., doi: 10.1016/j.jsg.2023. click here for pdf
This is a collaborative NSF project with Jeffrey Lee at the Colorado School of Mines. Several recent studies have proposed that statistical intensity parameters calculated from quartz crystallographic fabrics have the potential to delineate zones of high strain, by interpreting fabric intensity as a proxy for finite strain magnitude. However, as these studies were performed within packages of pervasively recrystallized rocks that lack deformed markers from which finite strain can be measured, they cannot quantitatively relate fabric intensity to absolute strain magnitude. In this project, we propose to generate a calibration equation that expresses fabric intensity as a function of finite strain magnitude by investigating strongly-sheared quartzites within the Northern Snake Range metamorphic core complex in easternmost Nevada. The calibration equation that we propose to obtain will provide an important new tool for investigating the spatial patterns of strain localization within deformed rocks globally.
Initial field work for this project began in Summer, 2020. WSU graduate student Nolan Blackford is performing his Ph.D. research on this project. We're really excited for the results from this project, please stay tuned!
Publications from this project:
1. Long, S.P., Lee, J., and Blackford, N.R., 2022, The low-angle breakaway system for the Northern Snake Range décollement in the Schell Creek and Duck Creek Ranges, eastern Nevada, U.S.A.: implications for displacement magnitude: Geosphere, v. 18, no. 4, p. 1194-1222, doi: 10.1130/GES02482.1. click here for pdf
2. Long, S.P., Lee, J., and Blackford, N.R., 2023, Extreme ductile thinning of Cambrian marbles in the Northern Snake Range metamorphic core complex, Nevada, USA: implications for extension magnitude and structural evolution: Journal of Structural Geology, v. 173, 104912, 25 p., doi: 10.1016/j.jsg.2023. click here for pdf
3. Dynamics of the Central Andes
(figure modified from DeCelles et al., 2009)
A) A field-based test of the Cordilleran cyclicity model in Bolivia (funding: NSF Tectonics, 2013-2016).
This was a collaborative project with Brian Horton at UT-Austin. The Cordilleran cyclicity model proposes linkages and feedbacks between several processes in the continental plates of Cordilleran orogenic systems. In the Andes in Bolivia, isotopic studies argue for rapid middle Miocene surface uplift of the Altiplano, which has been attributed to removal of dense lithosphere at depth. The Cordilleran cyclicity model predicts that the adjacent Andean fold-thrust belt should have responded to this uplift event through rapid eastward propagation of the deformation front. The goal of this project was to perform a field-based study aimed at documenting this response, through geologic mapping, construction and sequential restoration of a balanced cross-section, and integration of this kinematic history with deformation timing constraints from low-temperature thermochronology and basin analysis. Field work for this project took place in 2013-2014. WSU graduate student Ryan Anderson worked on this project, and completed his PhD in 2019.
Publications from this project:
1. Anderson, R.B., Long, S.P., Horton, B.K., and Calle, A.Z., and Ramirez, V., 2017, Shortening and structural architecture of the Andean fold-thrust belt of southern Bolivia (21°S): Implications for kinematic development and crustal thickening of the central Andes: Geosphere, v. 13, p. 1-21, doi:10.1130/GES01433.1. click here for pdf
2. Anderson, R.B., Long, S.P., Horton, B.K., Thomson, S.N., Calle, A.Z., and Stockli, D.F., 2018, Orogenic wedge evolution of the central Andes, Bolivia (21°S): Implications for Cordilleran cyclicity: Tectonics, v. 37, p. 3577-3609, doi: 10.1029/2018TC005132. click here for pdf
3. Calle, A.Z., Horton, B.K., Limachi, R., Stockli, D.F., Uzeda-Orellana, G.V., Anderson, R.B., and Long, S.P., 2018, Cenozoic provenance and depositional record of the Sub-Andean foreland basin during growth of the central Andean fold-thrust belt, southern Bolivia, in Zamora, G., McClay, K.R., and Ramos, V.A., eds., Petroleum basins and hydrocarbon potential of the Andes of Peru and Bolivia: AAPG Memoir 117, p. 483-530, doi: 10.1306/13622132M1173777. click here for pdf
4. Anderson, R.B., Long, S.P., Horton, B.K., and Soignard, E., 2021, Late Paleozoic Gondwanide deformation in the central Andes: Insights from RSCM thermometry and thermal modeling, southern Bolivia: Gondwana Research, v. 94, p. 222-242, doi: 10.1016/j.gr.2021.03.002. click here for pdf
5. Calle, A.Z., Horton, B.K., Garcia, R., Anderson, R.B., Stockli, D.F., Flaig, P.P., and Long, S.P., 2023, Sediment dispersal and basin evolution during contrasting tectonic regimes along the western Gondwanan margin in the central Andes: Journal of South American Earth Sciences, v. 125, 104286, 19 p., doi: 10.1016/j.jsames.2023.104286. click here for pdf
(figure modified from DeCelles et al., 2009)
A) A field-based test of the Cordilleran cyclicity model in Bolivia (funding: NSF Tectonics, 2013-2016).
This was a collaborative project with Brian Horton at UT-Austin. The Cordilleran cyclicity model proposes linkages and feedbacks between several processes in the continental plates of Cordilleran orogenic systems. In the Andes in Bolivia, isotopic studies argue for rapid middle Miocene surface uplift of the Altiplano, which has been attributed to removal of dense lithosphere at depth. The Cordilleran cyclicity model predicts that the adjacent Andean fold-thrust belt should have responded to this uplift event through rapid eastward propagation of the deformation front. The goal of this project was to perform a field-based study aimed at documenting this response, through geologic mapping, construction and sequential restoration of a balanced cross-section, and integration of this kinematic history with deformation timing constraints from low-temperature thermochronology and basin analysis. Field work for this project took place in 2013-2014. WSU graduate student Ryan Anderson worked on this project, and completed his PhD in 2019.
Publications from this project:
1. Anderson, R.B., Long, S.P., Horton, B.K., and Calle, A.Z., and Ramirez, V., 2017, Shortening and structural architecture of the Andean fold-thrust belt of southern Bolivia (21°S): Implications for kinematic development and crustal thickening of the central Andes: Geosphere, v. 13, p. 1-21, doi:10.1130/GES01433.1. click here for pdf
2. Anderson, R.B., Long, S.P., Horton, B.K., Thomson, S.N., Calle, A.Z., and Stockli, D.F., 2018, Orogenic wedge evolution of the central Andes, Bolivia (21°S): Implications for Cordilleran cyclicity: Tectonics, v. 37, p. 3577-3609, doi: 10.1029/2018TC005132. click here for pdf
3. Calle, A.Z., Horton, B.K., Limachi, R., Stockli, D.F., Uzeda-Orellana, G.V., Anderson, R.B., and Long, S.P., 2018, Cenozoic provenance and depositional record of the Sub-Andean foreland basin during growth of the central Andean fold-thrust belt, southern Bolivia, in Zamora, G., McClay, K.R., and Ramos, V.A., eds., Petroleum basins and hydrocarbon potential of the Andes of Peru and Bolivia: AAPG Memoir 117, p. 483-530, doi: 10.1306/13622132M1173777. click here for pdf
4. Anderson, R.B., Long, S.P., Horton, B.K., and Soignard, E., 2021, Late Paleozoic Gondwanide deformation in the central Andes: Insights from RSCM thermometry and thermal modeling, southern Bolivia: Gondwana Research, v. 94, p. 222-242, doi: 10.1016/j.gr.2021.03.002. click here for pdf
5. Calle, A.Z., Horton, B.K., Garcia, R., Anderson, R.B., Stockli, D.F., Flaig, P.P., and Long, S.P., 2023, Sediment dispersal and basin evolution during contrasting tectonic regimes along the western Gondwanan margin in the central Andes: Journal of South American Earth Sciences, v. 125, 104286, 19 p., doi: 10.1016/j.jsames.2023.104286. click here for pdf
4. Structural evolution of Cordilleran terrane accretion in Idaho
A) Evaluating the drivers of exhumation in the Salmon River Suture Zone (funding: NSF Tectonics, 2020-2023).
This is a collaborative NSF project with Matthew McKay from Missouri State University. In the North American Cordilleran orogen in central Idaho, the Salmon River suture zone is a ~30 km-wide region that experienced Jurassic-Early Cretaceous contractional deformation associated with collision of a volcanic island arc terrane with the western edge of the North American continent. Rocks in the suture zone record burial to and subsequent exhumation from depths as great as 40 km, and therefore are ideal for investigating the processes that drive high-magnitude exhumation during accretionary orogenesis. This project will test two primary hypotheses: 1) Rocks in the Salmon River suture zone were exhumed via hinged unroofing following lithospheric delamination; or 2) Rocks in the suture zone were exhumed via forward-breaking thrust propagation. To test these hypotheses, we will integrate structural analysis and geochronology of field relationships, the timing and pressure-temperature conditions of metamorphism, and multi-part temperature-time paths. The results of this project will have important implications for our understanding of the geodynamic processes that operate during accretionary orogenesis.
Initial field work began in 2020-2021, and WSU Ph.D. student Andrea Richardson started working on this project in 2022. We're really looking forward to the results of this project, please stay tuned!
Publications from this project:
1. Long, S.P., Barba, W.K., McKay, M.P., and Soignard, E., 2023, Thermal architecture of the Salmon River suture zone, Idaho, USA: Implications for the structural evolution of a ductile accretionary complex during arc-continent collision: Geosphere, v. 19, no. 4, p. 1103-1127, doi: 10.1130/GES02621.1. click here for pdf
A) Evaluating the drivers of exhumation in the Salmon River Suture Zone (funding: NSF Tectonics, 2020-2023).
This is a collaborative NSF project with Matthew McKay from Missouri State University. In the North American Cordilleran orogen in central Idaho, the Salmon River suture zone is a ~30 km-wide region that experienced Jurassic-Early Cretaceous contractional deformation associated with collision of a volcanic island arc terrane with the western edge of the North American continent. Rocks in the suture zone record burial to and subsequent exhumation from depths as great as 40 km, and therefore are ideal for investigating the processes that drive high-magnitude exhumation during accretionary orogenesis. This project will test two primary hypotheses: 1) Rocks in the Salmon River suture zone were exhumed via hinged unroofing following lithospheric delamination; or 2) Rocks in the suture zone were exhumed via forward-breaking thrust propagation. To test these hypotheses, we will integrate structural analysis and geochronology of field relationships, the timing and pressure-temperature conditions of metamorphism, and multi-part temperature-time paths. The results of this project will have important implications for our understanding of the geodynamic processes that operate during accretionary orogenesis.
Initial field work began in 2020-2021, and WSU Ph.D. student Andrea Richardson started working on this project in 2022. We're really looking forward to the results of this project, please stay tuned!
Publications from this project:
1. Long, S.P., Barba, W.K., McKay, M.P., and Soignard, E., 2023, Thermal architecture of the Salmon River suture zone, Idaho, USA: Implications for the structural evolution of a ductile accretionary complex during arc-continent collision: Geosphere, v. 19, no. 4, p. 1103-1127, doi: 10.1130/GES02621.1. click here for pdf
5. Investigating the timing and mechanisms of exhumation of ultrahigh-pressure rocks during the early stages of India-Asia collision
A) How do ultrahigh-pressure metamorphic sheets form and exhume? A case study from the Tso Morari complex, India (funding: NSF Tectonics, 2022-2025).
This is a collaborative project with Boise State University researcher Matthew Kohn. The structural processes that govern the exhumation of ultrahigh-pressure (UHP) rocks are hotly debated. In northwestern India, eclogite-bearing rocks of the Tso Morari nappe were subducted to depths of ~100 km shortly after initial India-Asia collision at ~55 Ma and were subsequently exhumed to the surface. The P-T-t-D details of their exhumation path, as well as the structures that accommodated their exhumation, are at present only broadly constrained. In this project, we will collect pressure, temperature, microstructural, and exhumation timing data from these UHP rocks, as well as the country rocks in which they reside, in order to provide details on their exhumation path. The results of this project will have important implications for our understanding of buoyancy-driven mass-transfer processes during orogenesis.
A pilot field season was performed in 2018, and initial field work for the NSF project will begin in Summer, 2023. WSU Ph.D. student Adelie Ionescu started working on this project in Fall, 2022. We're incredibly excited to return to India! Stay tuned for more results from this project!
Publications from this project:
1. Long, S.P., Kohn, M.J., Kerswell, B.C., Starnes, J.K., Larson, K.P., Blackford, N.R., and Soignard, E., 2020, Thermometry and microstructural analysis imply protracted extensional exhumation of the Tso Morari UHP nappe, northwestern Himalaya: implications for models of UHP exhumation: Tectonics, v. 39, 36 p., e2020TC006482, doi: 10.1029/2020TC006482. click here for pdf
A) How do ultrahigh-pressure metamorphic sheets form and exhume? A case study from the Tso Morari complex, India (funding: NSF Tectonics, 2022-2025).
This is a collaborative project with Boise State University researcher Matthew Kohn. The structural processes that govern the exhumation of ultrahigh-pressure (UHP) rocks are hotly debated. In northwestern India, eclogite-bearing rocks of the Tso Morari nappe were subducted to depths of ~100 km shortly after initial India-Asia collision at ~55 Ma and were subsequently exhumed to the surface. The P-T-t-D details of their exhumation path, as well as the structures that accommodated their exhumation, are at present only broadly constrained. In this project, we will collect pressure, temperature, microstructural, and exhumation timing data from these UHP rocks, as well as the country rocks in which they reside, in order to provide details on their exhumation path. The results of this project will have important implications for our understanding of buoyancy-driven mass-transfer processes during orogenesis.
A pilot field season was performed in 2018, and initial field work for the NSF project will begin in Summer, 2023. WSU Ph.D. student Adelie Ionescu started working on this project in Fall, 2022. We're incredibly excited to return to India! Stay tuned for more results from this project!
Publications from this project:
1. Long, S.P., Kohn, M.J., Kerswell, B.C., Starnes, J.K., Larson, K.P., Blackford, N.R., and Soignard, E., 2020, Thermometry and microstructural analysis imply protracted extensional exhumation of the Tso Morari UHP nappe, northwestern Himalaya: implications for models of UHP exhumation: Tectonics, v. 39, 36 p., e2020TC006482, doi: 10.1029/2020TC006482. click here for pdf