Joseph Colgan
I study magmatism and deformation of the earth’s crust, and how these processes influence the formation and distribution of natural resources and geologic hazards. This work involves geologic mapping at different scales, interpretation of subsurface and geophysical data, and laboratory analyses to determine the age and composition of rocks and minerals.
Biography
Education
2005 Ph.D., Geological & Environmental Sciences, Stanford University, Stanford CA
1998 B.A., Geology, Carleton College, Northfield MN
Professional Experience
2014 - present Research Geologist, USGS, Denver CO
2009 - 2014 Research Geologist, USGS, Menlo Park CA
2006 - 2009 Mendenhall Postdoctoral Fellow, USGS, Menlo Park CA
1999 - 2005 Teaching and Research Assistant, Stanford University, Stanford CA
1998 - 1999 Earth Science Intern, USGS, Menlo Park CA
Publications
Watts, K.E., John, D.A., Colgan, J.P., Henry, C.D., Bindeman, I.N., and Valley, J.W., 2019, An oxygen isotopic investigation of silicic magmatism in the Stillwater caldera complex, Nevada: Generation of large-volume low-d18O rhyolitic tuffs and assessment of their regional context in the Great Basin of the western United States: Geological Society of America Bulletin. [link]
Johnstone, S.A., and Colgan, J.P., 2018, Interpretation of low-temperature thermochronometer ages from tilted normal fault blocks: Tectonics, v. 37, 21 p., doi.org/10.1029/2018TC005207. [link]
Colgan, J.P., John, D.A., Henry, C.D., and Watts, K.E., 2018, Insights into the emplacement of upper-crustal plutons and their relationship to large silicic calderas, from field relationships, geochronology, and zircon trace element geochemistry in the Stillwater – Clan Alpine caldera complex, western Nevada, USA: Journal of Volcanology and Geothermal Research, v. 349, p. 163–176, doi:10.1016/j.jvolgeores.2017.10.015. [link]
Colgan, J.P., and Henry, C.D., 2017, Eruptive history, geochronology, and post-eruption structural evolution of the late Eocene Hall Creek Caldera, Toiyabe Range, Nevada: U.S. Geological Survey Professional Paper 1832, 44 p. [link]
Curry, M.A.E., Barnes, J.B., and Colgan, J.P., 2016, Testing fault growth models with low-temperature thermochronology in the northwest Basin and Range, USA: Tectonics, v. 35, doi:10.1002/2016TC004211. [link]
Watts, K.E., John, D.A., Colgan, J.P., Henry, C.D., Bindeman, I.N., and Schmitt, A.K., 2016, Probing the volcanic–plutonic connection and the genesis of crystal-rich rhyolite in a deeply dissected supervolcano in the Nevada Great Basin: Source of the late Eocene Caetano Tuff: Journal of Petrology, v. 57(8), p. 1599–1644, doi: 10.1093/petrology/egw051. [link]
Vikre, P.G., Benson, M.E., Bleiwas, D.I., Colgan, J.P., Cossette, P.M., DeAngelo, J., Dicken, C.L., Drake, R.M., II, du Bray, E.A., Fernette, G.L., Glen, J.M.G., Haacke, J.E., Hall, S.M., Hofstra, A.H., John, D.A., Ludington, S., Mihalasky, M.J., Rytuba, J.J., Shaffer, B.N., Stillings, L.L., Wallis, J.C., Williams, C.F., Yager, D.B., and Zürcher, L., 2016, Geology and mineral resources of the Sheldon-Hart Mountain National Wildlife Refuge Complex (Oregon and Nevada), the Southeastern Oregon and North-Central Nevada, and the Southern Idaho and Northern Nevada (and Utah) Sagebrush Focal Areas: U.S. Geological Survey Scientific Investigations Report 2016–5089–B, 220 p. [link]
Watts, K.E., Coble, M.A., Vazquez, J.A., Henry, C.D., Colgan, J.P., and John, D.A., 2016, Chemical abrasion-SIMS (CA-SIMS) U-Pb dating of zircon from the late Eocene Caetano caldera, Nevada: Chemical Geology, v. 439, p. 139–151, doi:10.1016/j.chemgeo.2016.06.013. [link]
Colgan, J.P., and Stanley, R.G., 2016, The Point Sal–Point Piedras Blancas correlation and the problem of slip on the San Gregorio–Hosgri fault, central California Coast Ranges: Geosphere, v. 12(3), p. 971–984, doi:10.1130/GES01289.1. [link]
Ellis (Curry), M.A., Barnes, J.B., and Colgan, J.P., 2015, Geomorphic evidence for enhanced Plio-Quaternary faulting in the northwestern Basin and Range?: Lithosphere, 14 p., doi:10.1130/L401.1. [link]
Colgan, J.P., Henry, C.D., and John, D.A., 2014, Evidence for large-magnitude, post-Eocene extension in the northern Shoshone Range, Nevada, and its implications for the structural setting of Carlin-type gold deposits in the lower plate of the Roberts Mountains allochthon: Economic Geology, v. 109, p. 1843–1862. [link]
Henry, C.D., Bell, J.W., John, D.A., and Colgan, J.P., 2013, Preliminary geologic map of the West Gate quadrangle, Churchill County, Nevada: Nevada Bureau of Mines and Geology Open-File Report 13-9, scale 1:24,000. [link]
Colgan, J.P., 2013, Reappraisal of the relationship between the northern Nevada rift and Miocene extension in the northern Basin and Range Province: Geology, v. 41(2), p. 211-214, doi: 10.1130/G33512.1. [link]
Langenheim, V.E., Jachens, R.C., Graymer, R.W., Colgan, J.P., Wentworth, C.M., and Stanley, R.G., 2013, Fault geometry and cumulative offsets in the central Coast Ranges, California: Evidence for northward increasing slip on the San Gregorio-San Simeon-Hosgri Fault: Lithosphere, v. 5(1), p. 29-48, doi:10.1130/L233.1. [link]
Colgan, J.P., McPhee, D.K., McDougall, K., and Hourigan, J.K., 2012, Superimposed extension and shortening in the southern Salinas Basin and La Panza Range, California: A guide to Neogene deformation of the Salinian block in the central California Coast Ranges: Lithosphere, v. 4(5) p. 411–429, doi:10.1130/L208.1. [link]
Henry, C.D., Hinz, N.H., Faulds, J.E., Colgan, J.P., John, D.A., Brooks, E.R., Cassel, E.J., Garside, L.J., Davis, D.A., and Castor, S.B., 2012, Eocene–Early Miocene paleotopography of the Sierra Nevada–Great Basin–Nevadaplano based on widespread ash-flow tuffs and paleovalleys: Geosphere, v. 8, p. 1–27, doi:10.1130/GES00727.1. [link]
Colgan, J.P. Henry, Christopher D., and John, D.A., 2011, Geologic map of the Caetano caldera, Lander and Eureka Counties, Nevada: Nevada Bureau of Mines and Geology Map 174, Scale 1:75,000. [link]
Colgan, J.P., Egger, A.E., John, D.A., Cousens, B., Fleck, R.J., and Henry, C.D., 2011, Oligocene and Miocene arc volcanism in northeastern California: Evidence for post-Eocene segmentation of the subducting Farallon plate: Geosphere, v. 7, p. 733–755, doi:10.1130/GES00650.1. [link]
Henry, C.D., McGrew, A.J., Colgan, J.P., Snoke, A.W., and Brueseke, M.E., 2011, Timing, distribution, amount, and style of Cenozoic extension in the northern Great Basin, in Lee, J., and Evans, J.P., eds., Geologic Field Trips to the Basin and Range, Rocky Mountains, Snake River Plain, and Terranes of the U.S. Cordillera: Geological Society of America Field Guide 21, p. 27–66, doi:10.1130/2011.0021(02). [link]
John, D.A., Rockwell, B.W., Henry, C.D., and Colgan, J.P., 2011, Hydrothermal alteration of the late Eocene Caetano ash-flow caldera, north-central Nevada: A field and ASTER remote sensing study: Proceedings of the Geological Society of Nevada 2010 Symposium, Reno, Nevada, May 14–22, 2010, p. 1055–1083.
Henry, C.D., and Colgan, J.P., 2011, The regional structural setting of the 2008 Wells earthquake and Town Creek Flat basin—Implications for the Wells earthquake fault and adjacent structures, in dePolo C.M., and LaPointe, D.D., eds., A compendium of earthquake-related investigations prepared by the University of Nevada, Reno: Nevada Bureau of Mines and Geology Special Publication 36, p. 53–64. [link]
Colgan, J.P., Howard, K.A., Fleck R.J., and Wooden J.L., 2010, Rapid middle Miocene extension and unroofing of the southern Ruby Mountains, Nevada: Tectonics, v. 29, doi:10.1029/2009TC002655. [link]
Colgan, J.P., Wyld, S.J., and Wright, J., 2010, Geologic map of the Vicksburg Canyon 7.5’ quadrangle, Humboldt County, Nevada: Nevada Bureau of Mines and Geology Map M169, scale 1:24,000. [link]
Egger, A.E., Colgan, J.P., and York, C., 2009, Provenance and palaeogeographic implications of Eocene–Oligocene sedimentary rocks in the northwestern Basin and Range: International Geology Review, v. 51(9-11), p. 900–911, doi: 10.1080/00206810902949829. [link]
Colgan, J.P., and Henry, C.D., 2009, Rapid middle Miocene collapse of the Mesozoic orogenic plateau in north-central Nevada: International Geology Review, v. 51(9-11), p. 920–961, doi: 10.1080/00206810903056731. [link]
Lerch, D.W., Klemperer, S.L., Egger, A.E., Colgan, J.P., and Miller, E.L., 2009, The northwestern margin of the Basin and Range Province, part 1: Reflection profiling of the moderate-angle (35°) Surprise Valley Fault: Tectonophysics, v. 488(1–4), p. 143–149, doi:10.1016/j.tecto.2009.05.028. [link]
Fosdick, J.C, and Colgan, J.P., 2008, Miocene extension in the East Range, Nevada: A two-stage history of normal faulting in the northern Basin and Range: Geological Society of America Bulletin, v. 120(9-10), p. 1198–1213. doi:10.1130/B26201.1. [link]
Colgan, J.P., Shuster, D.L., and Reiners, P.W., 2008, Two-phase Neogene extension of the northwestern Basin and Range recorded in a single thermochronology sample: Geology, v. 36(8), p. 631–634, doi:10.1130/G24897A.1. [link]
Colgan, J.P., John, D.A., Henry, C.D., and Fleck, R.J., 2008, Large-magnitude Miocene extension of the Eocene Caetano caldera, Shoshone and Toiyabe Ranges, Nevada: Geosphere, v. 4(1), p. 107–130. doi:10.1130/GES00115.1. [link]
John, D.A., Henry, C.D., and Colgan, J.P., 2008, Magmatic and tectonic evolution of the Caetano caldera, north-central Nevada: A tilted mid-Tertiary eruptive center and source of the Caetano Tuff: Geosphere, v. 4(1), p. 75–106. doi:10.1130/GES00116.1. [link]
Lerch, D.W., Miller, E.L., McWilliams, M.O., and Colgan, J.P., 2008, Tectonic and magmatic evolution of the northwestern Basin and Range and its transition to unextended volcanic plateaus: Black Rock Range, Nevada: Geological Society of America Bulletin, v. 120 (3-4), p. 300–311. doi:10.1130/B26151.1. [link]
Mattinson, C.G., Colgan, J.P., Metcalf, J.R., Miller E.L., and Wooden, J.L., 2007, Late Cretaceous to Paleocene metamorphism and magmatism in the Funeral Mountains metamorphic core complex, Death Valley, California, in Cloos, M., Carlson, W.D., Gilbert, M.C., Liou, J.G., and Sorensen, S.S., eds., Convergent Margin Terranes and Associated Regions: A Tribute to W.G. Ernst: Geological Society of America Special Paper 419, p. 205–223, doi:10.1130/2006.2419(11). [link]
Lerch, D.W., Klemperer, S.L., Glen, J.M.G., Ponce, D.A., Miller, E.L., and Colgan, J.P., 2007, Crustal structure of the northwestern Basin and Range Province and its transition to unextended volcanic plateaus: Geochemistry, Geophysics, and Geosystems, v. 8, doi:10.1029/2006GC001429. [link]
Colgan, J.P., Dumitru, T.A., Reiners, P.W., Wooden, J.L., and Miller, E.L., 2006, Cenozoic tectonic evolution of the Basin and Range Province in northwestern Nevada: American Journal of Science, v. 306(8), p. 616–654. [link]
Colgan, J.P., Dumitru, T.A., McWilliams, M.O., and Miller, E.L., 2006, Timing of Cenozoic volcanism and Basin and Range extension in northwestern Nevada: new constraints from the northern Pine Forest Range: Geological Society of America Bulletin, v. 118(1-2), p. 126–139, doi:10.1130/B25681.1. [link]
Colgan, J.P., 2005, Timing and magnitude of Basin and Range extension in northwestern Nevada, Stanford, Calif., Stanford University, Ph.D. Thesis, 172 p.
Colgan, J.P., Dumitru, T.A., and Miller, E.L., 2004, Diachroneity of Basin and Range faulting and Yellowstone hotpsot volcanism in northwestern Nevada: Geology, v. 32(2), p. 121–124, doi:10.1130/G20037.1. [link]
Brabb, E.E., Colgan, J.P., and Best, T.C., 2000 Map showing inventory and regional susceptibility for Holocene debris flows and related fast-moving landslides in the conterminous United States: U.S. Geological Survey Miscellaneous Field Studies Map MF-2329, scale 1:2,500,000. [link]
Science and Products
Intermountain West Transect
The USGS Intermountain West project was launched with the goal of producing an new digital geologic map database and 3D geologic model of a transect from the Rio Grande rift to the Basin and Range, based on a synthesis of existing geologic maps with new targeted new mapping, subsurface data, and other data sets. This database will integrate disparate map data, resolve inconsistent...
Petrology of volcanic rocks associated with silver-gold (Ag-Au) epithermal deposits in the Tonopah, Divide, and Goldfield Mining Districts, Nevada
Miocene calc-alkaline volcanic rocks, part of the southern segment of the ancestral Cascades magmatic arc, are spatially, temporally, and likely genetically associated with precious metal epithermal deposits in the Tonopah, Divide, and Goldfield Districts of west-central Nevada. In the Tonopah mining district, volcanic rocks include the Mizpah...
du Bray, Edward A.; John, David A.; Colgan, Joseph P.; Vikre, Peter G.; Cosca, Michael A.; Morgan, Leah E.
Petrographic, geochemical, and geochronologic data for cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield Mining Districts, Nevada
The purpose of this report is to summarize geochemical, petrographic, and geochronologic data for samples, principally those of unmineralized Tertiary volcanic rocks, from the Tonopah, Divide, and Goldfield mining districts of west-central Nevada (fig. 1). Much of the data presented here for the Tonopah and Divide districts are for samples...
du Bray, Edward A.; John, David A.; Vikre, Peter G.; Colgan, Joseph P.; Cosca, Michael A.; Morgan, Leah E.; Fleck, Robert J.; Premo, Wayne R.; Holm-Denoma, Christopher S.
Oxygen isotopic investigation of silicic magmatism in the Stillwater caldera complex, Nevada: Generation of large-volume, low-δ18O rhyolitic tuffs and assessment of their regional context in the Great Basin of the western United States
Successive caldera-forming eruptions from ca. 30 to 25 Ma generated a large nested caldera complex in western Nevada that was subsequently dissected by Basin and Range extension, providing extraordinary cross-sectional views through diverse volcanic and plutonic rocks. A high-resolution oxygen isotopic study was conducted on units that represent...
Watts, Kathryn E.; John, David A.; Colgan, Joseph P.; Henry, Christopher D.; Bindeman, Ilya N.; Valley, John W. Interpretation of low‐temperature thermochronometer ages from tilted normal fault blocks
Low‐temperature thermochronometry is widely used to measure the timing and rate of slip on normal faults. Rates are often derived from suites of footwall thermochronometer samples, but regression of age vs. structural depth fails to account for the trajectories of samples during fault slip. We demonstrate that in rotating fault blocks, regression...
Johnstone, Samuel A.; Colgan, Joseph P. Insights into the emplacement of upper-crustal plutons and their relationship to large silicic calderas, from field relationships, geochronology, and zircon trace element geochemistry in the Stillwater – Clan Alpine caldera complex, western Nevada, USA
Geologic mapping, new U-Pb zircon ages, and new and published 40Ar/39Ar sanidine ages document the timing and extent of Oligocene magmatism in the southern Stillwater Range and Clan Alpine Mountains of western Nevada, where Miocene extension has exposed at least six nested silicic calderas and underlying granitic plutons to crustal depths...
Colgan, Joseph P.; John, David A.; Henry, Christopher D.; Watts, Kathryn E. Geochemical and geochronologic data from the Hall Creek caldera, Toiyabe Range, Nevada
The magmatic, tectonic, and topographic evolution of what is now the northern Great Basin remains controversial, notably the temporal and spatial relation between magmatism and extensional faulting. This controversy is exemplified in the northern Toiyabe Range of central Nevada, where previous geologic mapping suggested the presence of a caldera...
Colgan, Joseph P.; Henry, Christopher D.
Eruptive history, geochronology, and post-eruption structural evolution of the late Eocene Hall Creek Caldera, Toiyabe Range, Nevada
The magmatic, tectonic, and topographic evolution of what is now the northern Great Basin remains controversial, notably the temporal and spatial relation between magmatism and extensional faulting. This controversy is exemplified in the northern Toiyabe Range of central Nevada, where previous geologic mapping suggested the presence of a caldera...
Colgan, Joseph P.; Henry, Christopher D. Probing the volcanic-plutonic connection and the genesis of crystal-rich rhyolite in a deeply dissected supervolcano in the Nevada Great Basin: Source of the late Eocene Caetano Tuff
Late Cenozoic faulting and large-magnitude extension in the Great Basin of the western USA has created locally deep windows into the upper crust, permitting direct study of volcanic and plutonic rocks within individual calderas. The Caetano caldera in north–central Nevada, formed during the mid-Tertiary ignimbrite flare-up, offers one of the best...
Watts, Kathryn E.; John, David A.; Colgan, Joseph P.; Henry, Christopher D.; Bindeman, Ilya N.; Schmitt, Axel K.
Geology and mineral resources of the Sheldon-Hart Mountain National Wildlife Refuge Complex (Oregon and Nevada), the Southeastern Oregon and North-Central Nevada, and the Southern Idaho and Northern Nevada (and Utah) Sagebrush Focal Areas: Chapter B in Mineral resources of the Sagebrush Focal Areas of Idaho, Montana, Nevada, Oregon, Utah, and Wyoming
SummaryThe U.S. Department of the Interior has proposed to withdraw approximately 10 million acres of Federal lands from mineral entry (subject to valid existing rights) from 12 million acres of lands defined as Sagebrush Focal Areas (SFAs) in Idaho, Montana, Nevada, Oregon, Utah, and Wyoming (for further discussion on the lands involved see...
Vikre, Peter G.; Benson, Mary Ellen; Bleiwas, Donald I.; Colgan, Joseph P.; Cossette, Pamela M.; DeAngelo, Jacob; Dicken, Connie L.; Drake, Ronald M.; du Bray, Edward A.; Fernette, Gregory L.; Glen, Jonathan M.G.; Haacke, Jon E.; Hall, Susan M.; Hofstra, Albert H.; John, David A.; Ludington, Stephen; Mihalasky, Mark J.; Rytuba, James J.; Shaffer, Brian N.; Stillings, Lisa L.; Wallis, John C.; Williams, Colin F.; Yager, Douglas B.; Zürcher, Lukas Testing fault growth models with low-temperature thermochronology in the northwest Basin and Range, USA
Common fault growth models diverge in predicting how faults accumulate displacement and lengthen through time. A paucity of field-based data documenting the lateral component of fault growth hinders our ability to test these models and fully understand how natural fault systems evolve. Here we outline a framework for using apatite (U-Th)/He...
Curry, Magdalena A. E.; Barnes, Jason B.; Colgan, Joseph P. Chemical abrasion-SIMS (CA-SIMS) U-Pb dating of zircon from the late Eocene Caetano caldera, Nevada
Zircon geochronology is a critical tool for establishing geologic ages and time scales of processes in the Earth's crust. However, for zircons compromised by open system behavior, achieving robust dates can be difficult. Chemical abrasion (CA) is a routine step prior to thermal ionization mass spectrometry (TIMS) dating of zircon to remove...
Watts, Kathryn E.; Coble, Matthew A.; Vazquez, Jorge A.; Henry, Christopher D.; Colgan, Joseph P.; John, David A. The Point Sal–Point Piedras Blancas correlation and the problem of slip on the San Gregorio–Hosgri fault, central California Coast Ranges
Existing models for large-magnitude, right-lateral slip on the San Gregorio–Hosgri fault system imply much more deformation of the onshore block in the Santa Maria basin than is supported by geologic data. This problem is resolved by a model in which dextral slip on this fault system increases gradually from 0–10 km near Point Arguello...
Colgan, Joseph P.; Stanley, Richard G.