Leah E Morgan, Ph.D.
Leah Morgan is a Research Geologist with the Geology, Geophysics, and Geochemistry Science Center.
I joined the 40Ar/39Ar geochronology lab at the USGS in Denver, Colorado as a research geologist in 2015. I was previously a Marie Curie postdoctoral fellow at the Scottish Universities Environmental Research Center and at the Vrije Universiteit Amsterdam. I received a PhD from the University of California at Berkeley in 2009, and a BA from Carleton College in 2004. I was born and raised in Vermont.
I have worked on a range of applications and method development issues in 40Ar/39Ar geochronology. Applications have largely focused on questions in paleoanthropology and the geologic timescale. Method development projects include developing metrologically traceable systems for measuring absolute quantities of 40Ar and 40K, and the design of a mobile neutron source for the future in situ deployment of 40Ar/39Ar capabilities on planetary surfaces
USGS Service
- 2020-present, USGS TRIGA Reactor Operating Committee
- 2017-present, USGS Radiation Safety Committee
- 2016-present, USGS Rocky Mountain Science Seminar Series Convener
- 2018-2020 GGGSC Early Career Advisory Team, GGGSC
Professional Experience
2015-present, Research Geologist, U.S. Geological Survey
2014, Visiting Assistant Professor, Geology Department, Carleton College
2011-2014, Marie Curie Postdoctoral Fellow, Scottish Universities Environmental Research Center, University of Glasgow, Scotland
2009-2011, Marie Curie Postdoctoral Fellow, Vrije Universiteit Amsterdam, The Netherlands
Education and Certifications
Ph.D. Earth & Planetary Science, University of California at Berkeley, 2009
B.S. Geology, Carleton College, 2004
Affiliations and Memberships*
2018-present, Affiliate Faculty, Colorado School of Mines, Golden, CO
2021, co-Chair, Gordon Research Conference on Geochronology
2019, vice-Chair, Gordon Research Conference on Geochronology
2018-2019, Chair and Founder, Geochronology Division of the Geological Society of America
2019-present, Advisory Member, Committee for the Stratigraphy and Chronology Commission, International Union for Quaternary Research
2018-present, Steering Committee Member, EarthRates Research Coordination Network
Honors and Awards
2019, USGS Superior Service Award
Science and Products
Filter Total Items: 32
Gondwanic inheritance on the building of the western Central Andes (Domeyko Range, Chile): Structural and thermochronological approach (U-Pb and 40Ar-39Ar)
Tectonics inheritance controls the evolution of many orogens. To unravel the role of the Gondwanan heritage (late Paleozoic to Triassic) over the building of the Central Andes in northern Chile (Domeyko Range), we performed detrital U‐Pb zircon and 40Ar/39Ar muscovite geochronology along with structural analyses (kinematics and structural balancing). 40Ar/39Ar dating of detrital...
Authors
Mauricio Espinoza, Veronica Oliveros, Paulina Vasquez, Laura Giambiagi, Leah E. Morgan, Rodrigo Gonzalez, Luigi Solari, Florencia Bechis
Constraining central Himalayan (Nepal) fault geometry through integrated thermochronology and thermokinematic modeling
Constraining the subsurface structural geometry of the central Himalaya continues to prove difficult, even after the 2015 Gorkha earthquake and the resulting insights into the trajectory of the Main Himalayan thrust (MHT). To this end, we apply a thermokinematic model to evaluate four possible balanced cross section geometries based on three estimates of the MHT in central Nepal. We...
Authors
Surydoy Ghoshal, Nadine McQuarrie, Delores M. Robinson, D.P. Adhikari, Leah E. Morgan, Todd A. Ehlers
Conditions and timing of high-grade metamorphism and ductile deformation of the southern segment of the Central Anatolian Ophiolite
Ophiolitic fragments scattered over a wide area of Central Anatolia exhibit varying degrees of metamorphism, from unmetamorphosed to upper amphibolite facies, although geochemical similarities suggest they are all part of the Central Anatolian Ophiolite (CAO). Magmatic crystallization of oceanic crust in the CAO at ~ 91 Ma coincided with high-grade metamorphism of rocks that underlie the...
Authors
Molly S. Radwany, Leah E. Morgan, Donna L. Whitney
Interpreting and reporting 40Ar/39Ar geochronologic data
The 40Ar/39Ar dating method is among the most versatile of geochronometers, having the potential to date a broad variety of K-bearing materials spanning from the time of Earth’s formation into the historical realm. Measurements using modern noble-gas mass spectrometers are now producing 40Ar/39Ar dates with analytical uncertainties of ∼0.1%, thereby providing precise time constraints for...
Authors
Allen J. Schaen, Brian R. Jicha, Kip V. Hodges, Pieter Vermeesch, Mark E. Stelten, Cameron Mark Mercer, David Phillips, Tiffany Rivera, Fred Jourdan, Erin L. Matchan, Sidney R. Hemming, Leah E. Morgan, Simon P. Kelley, William S. Cassata, Matt T. Heizler, Paulo M. Vasconcelos, Jeff A. Benowitz, Anthony A.P. Koppers, Darren F. Mark, Elizabeth M. Niespolo, Courtney J. Sprain, William E. Hames, Klaudia F. Kuiper, Brent R. Turrin, Paul R. Renne, Jake Ross, Sebastian Nomade, Hervé Guillou, Laura E. Webb, Barbara A. Cohen, Andrew T. Calvert, Nancy Joyce, Morgan Ganderød, Jan Wijbrans, Osamu Ishizuka, Huaiyu He, Adán Ramirez, Jörg Pfänder, Margarita Lopez-Martínez, Huaning Qiu, Brad S. Singer
Detrital record of the late Oligocene – Early Miocene mafic volcanic arc in the southern Patagonian Andes (~51 °S) from single-clast geochronology and trace element geochemistry
Retroarc foreland basins are important archives of continental arc magmatism and upper plate deformational processes that control the evolution of continental lithosphere. However, resolving source areas in foreland basin infill dominated from mixed mafic and recycled sediment using conventional methods such as detrital zircon geochronology poses a challenge to thorough analysis due to...
Authors
Rebecca A. VanderLeest, Julie C. Fosdick, Joel S Leonard, Leah E. Morgan
Multiproxy Cretaceous-Paleogene boundary event stratigraphy: An Umbria-Marche basin-wide perspective
The complete and well-studied pelagic carbonate successions from the Umbria-Marche Basin (Italy) permit the study of the event-rich stratigraphical interval around the Cretaceous-Paleogene (K-Pg) boundary (e.g., Deccan volcanism, boundary impact, Paleocene recovery and climate). To test the robustness of various proxy records (bulk carbonate δ13C, δ18O, 87Sr/86Sr and Ca, Fe, Sr and Mn...
Authors
Matthias Sinnesael, Alessandro Montanari, Fabrizio Frontalini, Rodolfo Coccioni, Jerome Gattacceca, Christophe Snoeck, Wencke Wegner, Christian Koeberl, Leah E. Morgan, Niels de Winter, Donald J. DePaolo, Philippe Claeys
The influence of foreland structures on hinterland cooling: evaluating the drivers of exhumation in the eastern Bhutan Himalaya
Understanding, and ideally quantifying, the relative roles of climatic and tectonic processes during orogenic exhumation is critical to resolving the dynamics of mountain building. However, vastly differing opinions regarding proposed drivers often complicate how thermochronometric ages are interpreted, particularly from the hinterland portions of thrust belts. Here we integrate three...
Authors
Nadine McQuarrie, Paul R. Eizenhofer, Sean P. Long, Tobgay Tobgay, Todd A. Ehlers, Ann Blythe, Leah E. Morgan, Michelle Gilmore, Gregory M. Dering
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 Trachyte, Fraction Tuff, and Oddie Rhyolite...
Authors
Edward A. du Bray, David A. John, Joseph P. Colgan, Peter Vikre, Michael A. Cosca, Leah E. Morgan
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 collected by Bonham and Garside (1979) during...
Authors
Edward A. du Bray, David A. John, Peter Vikre, Joseph P. Colgan, Michael A. Cosca, Leah E. Morgan, Robert J. Fleck, Wayne R. Premo, Christopher S. Holm-Denoma
Revisiting Herto: New evidence of Homo sapiens from Ethiopia
Localities in the radiometrically dated Upper Herto Member of Ethiopia’s Bouri Formation continue to produce new data that complement and extend initial reports of fossils and artifacts published in 2003. Results of these revisits are reported here and include the in situ recovery of artifacts from the same sediments containing hominid fossils. We evaluate the absolute and relative...
Authors
Yonatan Sahle, Yonas Beyene, Alban Defleur, Berhane Asfaw, Giday WoldeGabriel, William K Hart, Leah E. Morgan, Paul R. Renne, Joshua Carlson, Tim White
A supervolcano and its sidekicks: A 100 ka eruptive chronology of the Fish Canyon Tuff and associated units of the La Garita magmatic system
Establishing temporal constrains on major volcanic eruptions is limited by the precision of existing geochronometers. Prior work on the La Garita caldera, created by the eruption of the Fish Canyon Tuff, failed to resolve temporal differences between pre-, syn-, and post-collapse eruptive units. Here, we report 40Ar/39Ar geochronologic data supporting a ca. 100 ka eruptive history of the...
Authors
Leah E. Morgan, Samuel Johnstone, Amy K. Gilmer, Michael A. Cosca, Ren A. Thompson
Reverse weathering in marine sediments and the geochemical cycle of potassium in seawater: Insights from the K isotopic composition (41K/39K) of deep-sea pore-fluids
In situ Al-silicate formation, also known as “reverse weathering,” is an important sink of many of the major and minor cations in seawater (e.g. Mg, K, and Li). However, the importance of this sink in global geochemical cycles and isotopic budgets of these elements remains poorly constrained. Here, we report on the potassium isotopic composition (41K/39K) of deep-sea sediment pore-fluids...
Authors
Danielle P. Santiago Ramos, Leah E. Morgan, Nicholas S. Lloyd, John A. Higgins
Non-USGS Publications**
Mark, D.F., P.R. Renne, R. Dymock, V.C. Smith, J.I. SImon, L.E. Morgan, R.A. Staff, and B.S. Ellis, 2017. High-precision 40Ar/39Ar dating of pleistocene tuffs and temporal anchoring of the Matuyama-Brunhes boundary. Quaternary Geochronology 39, 1-23, https://doi.org/10.1016/j.quageo.2017.01.002.
Morgan, L.E., 2017. 40Ar/39Ar and K-Ar Geochronology, in: A.S. Gilbert (ed.), Encyclopedia of Geoarchaeology. Encyclopedia of Earth Science Series. Springer, Dordrecht, https://doi.org/10.1007/978-1-4020-4409-0.
Morgan, L.E., 2015. Noble Gas Mass Spectrometry, in: W.J. Rink, and J.W. Thompson (eds.), Encyclopedia of Scientific Dating Methods. Encyclopedia of Earth Science Series. Springer, Dordrecht, https://doi.org/10.1007/978-94-007-6304-3_118.
Sahle, Y., L.E. Morgan, D.R. Braun, W.K. Hutchings, 2014. Chronological and behavioral contexts of the earliest Middle Stone Age in the Gademotta Formation, Main Ethiopian Rift, Quaternary International, v. 331, p. 6-19, https://doi.org/10.1016/j.quaint.2013.03.010.
Mark, D.F., M. Petraglia, V.C. Smith, L.E. Morgan, D.N. Barfod, B.S Ellis, N.J. Pearce, J.N. Pal, R. Korisettar, 2014. A high-precision 40Ar/39Ar age for the Young Toba Tuff and dating of ultra- distal tephra: forcing of Quaternary climate and implications for hominin occupation of India, Quaternary Geochronology, v. 21, p. 90-103, https://doi.org/10.1016/j.quageo.2012.12.004.
Sahle, Y., W.K. Hutchings, D.R. Braun, J.C. Sealy, L.E. Morgan, A. Negash, B. Atnafu, 2013. Earliest stone-tipped projectiles from the Ethiopian Rift date to >279,000 years ago. PLOS ONE, v. 8, no. 11, e78092, https://doi.org/10.1371/journal.pone.0078092.
Morgan, L.E., D.F. Mark, J. Imlach, D.N. Barfod, 2013. FCs-EK: A new sampling of the Fish Canyon tuff 40Ar/39Ar neutron flux monitor, in: Jourdan, F., Mark, D., and Verati, C. (eds.), Advances in 40Ar/39Ar Dating: from Archaeology to Planetary Sciences. Geological Society, London, Special Publications, 378, https://doi.org/10.1144/SP378.21.
Renne, P.R., A.L. Deino, F.J. Hilgen, K.F. Kuiper, D.F. Mark, W.S. Mitchell, L.E. Morgan, R. Mundil, J. Smit, 2013. Timescales of critical events around the Cretaceous-Paleogene boundary. Science, v. 339, p. 684-687, https://doi.org/10.1126/science.1230492.
Schoene, B., D.J. Condon, L.E. Morgan, N. McLean, 2013. Precision and accuracy in geochronology. Elements Magazine, v.9, no.1, p. 23-28, http://elementsmagazine.org/past-issue-archive/2013-volume-9/#February2013.
Renne, P.R., S.R. Mulcahy, W.S. Cassata,, L.E. Morgan, S.P. Kelley, L. Hlusko, J. Njau, 2012. Retention of inherited Ar by alkali feldspar xenocrysts in a magma: Kinetic constraints from Ba zoning profiles. Geochimica et Cosmochimica Acta, v. 93, p. 129-142, https://doi.org/10.1016/j.gca.2012.06.029.
Morgan, L.E., P.R. Renne, R. Galotti, G. Kieffer, M. Piperno, J.-P. Raynal, 2012. A chronological framework for a long and persistent archeological record: Melka Kunture, Ethiopia. Journal of Human Evolution, v. 62, no. 1, p. 104-115, https://doi.org/10.1016/j.jhevol.2011.10.007.
Frost, S.R., H.L. Schwartz, L. Giemsch, L.E. Morgan, P.R. Renne, M. Wildgoose, C. Saanane, F. Schrenk, K. Harvati, 2012. Refined age estimates and paleoanthropological investigation of the Manyara Beds, Tanzania. Journal of Anthropological Sciences, v. 90, p. 151-161, https://doi.org/10.4436/jass.90001.
Schwartz, H., P.R. Renne, L.E. Morgan, M.M. Wildgoose, P.C. Lippert, S.R. Frost, K. Harvati, F. Schrenk, C. Saanane, 2012. Geochronology of the Manyara Beds, northern Tanzania: stratigraphy and new magnetostratigraphy and 40Ar/39Ar ages. Quaternary Geochronology, v. 7, no. 1, p. 48-66, https://doi.org/10.1016/j.quageo.2011.09.002.
Morgan, L.E., O. Postma, K.F. Kuiper, D.F. Mark, W. van der Plas, S. Davidson, M. Perkin, I. Villa, J.R. Wijbrans, 2011. A metrological approach to measuring 40Ar* concentrations in K-Ar and 40Ar/39Ar mineral standards, Geochem. Geophys. Geosyst., v. 12, p. A0AA20, https://doi.org/10.1029/2011GC003719.
Renne, P.R., A.L. Deino, W.E. Hames, M.T. Heizler, S.R. Hemming, K.V. Hodges, A.A.P. Koppers, D.F. Mark, L.E. Morgan, D. Phillips, B.S. Singer, B.D. Turrin, I.M. Villa, M. Villeneuve and J.R. Wijbrans, 2009. Data reporting norms for 40Ar/39Ar geochronology. Quaternary Geochronology, v. 4, no. 5, p. 346-352, https://doi.org/10.1016/j.quageo.2009.06.005.
Renne, P.R., W.S. Cassata, and L.E. Morgan, 2009. The isotopic composition of atmospheric argon and 40Ar/39Ar geochronology: time for a change? Quaternary Geochronology, v. 4, no. 4, p. 288-298, https://doi.org/10.1016/j.quageo.2009.02.015.
Renne, P. R., L.E. Morgan, G. WoldeGabriel, W.K. Hart, Y. Haile-Selassie, and T.D. White, 2009. 40Ar/39Ar Ages of the Middle Awash Late Miocene, in: Haile-Selassie, Y., and WoldeGabriel, G. (eds.), Ardipithecus kadabba: Late Miocene evidence from the Middle Awash, Ethiopia. University of California Press, Berkeley, CA.
Morgan, L.E., P.R. Renne, R.E. Taylor, and G. WoldeGabriel, 2009. Archaeological age constraints from eruption ages of obsidian: Examples from the Middle Awash, Ethiopia. Quaternary Geochronology, v. 4, p. 193-203, https://doi.org/10.1016/j.quageo.2009.01.001.
Morgan, L.E. and P.R. Renne, 2008. Diachronous Dawn of Africa’s Middle Stone Age: New 40Ar/39Ar ages from the Ethiopian Rift. Geology, v. 36, no. 12, p. 967-970, https://doi.org/10.1130/G25213A.1.
Gihring, T.M., L.-H. Lin, M. Davidson, T.C. Onstott, L. Morgan, M. Milleson, T.L. Kieft, E. Trimarco, D.L. Balkwill, and M.E. Dollhopf, 2006. The Distribution of Microbial Taxa in the Subsurface Water of the Kalahari Shield, South Africa. Geomicrobiology Journal, v. 23, p. 415-430, https://doi.org/10.1080/01490450600875696.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Filter Total Items: 28
Argon data for Nepal
This dataset accompanies planned publication 'Determining fault geometry through the transport-parallel distribution of thermochronometer cooling ages'. The Ar/Ar data is for samples that record the thermal history of the area. The geochronology provides time constraints for the thermal histories studied in the manuscript. Samples were collected from Nepal, overseen by Nadine McQuarrie...
Argon data for Amazon Craton
This dataset accompanies planned publication 'Genesis of early Neoproterozoic gold deposits, southwestern Amazon Craton, western Brazil'. The Ar/Ar data is for samples that record the mineralization of the area. The geochronology provides time constraints for the mineralization studied in the manuscript. Samples were collected from the Amazon Craton region, and collection was done by...
Argon data for Central Andes (Domeyko Range, Chile)
This dataset accompanies planned publication 'Gondwanan inheritance on the building of the western Central Andes (Domeyko Range, Chile): Structural and thermochronological approach (U-Pb and 40Ar-39Ar)'. The Ar/Ar data is for samples that record the sedimentation of the area. The geochronology provides time constraints for the sedimentation studied in the manuscript. Samples were...
Argon data for Yellow Pine
This dataset accompanies planned publication 'Timing of Hydrothermal Alteration and Au-Sb-W Mineralization, Stibnite-Yellow Pine District, Idaho'. The Ar/Ar data is for samples that record the mineralization of the area. The geochronology provides time constraints for the mineralization studied in the manuscript. Samples were collected from the Yellow Pine region, and collection was done...
Argon data for Central Anatolian Ophiolite
This dataset accompanies planned publication 'Conditions, mechanisms, and timing of high-grade metamorphism and ductile deformation of the southern segment of the Central Anatolian Ophiolite'. The Ar/Ar data are for samples that record the metamorphic deformation of the ophiolite. The geochronology provides time constraints for the deformation studied in the manuscript. Samples were...
Argon data for Southern Patagonian Andes
This dataset accompanies planned publication 'Detrital record of the Late Oligocene - Early Miocene mafic volcanic arc in the Southern Patagonian Andes (~51S) from single-clast geochronology and trace element geochemistry'. The Ar/Ar data is for samples that record the detrital sedimentary record of the basin. The geochronology provides time constraints for the sedimentation studied in...
Argon geochronology data for eastern Bhutan
This dataset accompanies publication 'The influence of foreland structures on hinterland cooling: evaluating the drivers of exhumation in the eastern Bhutan Himalaya'. The Ar/Ar data provides time constraints for the cooling of rocks in the study area.
Argon geochronology data for Multiproxy Cretaceous-Paleogene boundary event stratigraphy: an Umbria-Marche basin-wide perspective
This dataset accompanies publication 'Multiproxy Cretaceous-Paleogene boundary event stratigraphy: an Umbria-Marche basin-wide perspective'.
Data to accompany U.S. Geological Survey Data Series 1099: Petrographic, geochemical and geochronologic data for Cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield Mining Districts, Nevada
This dataset is the assembled analytical results of 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. Much of the data presented here for the Tonopah and Divide districts are for samples collected by Bonham and Garside (1979) during...
Argon geochronology data for La Garita caldera
This dataset accompanies publication 'A supervolcano and its sidekicks: A 100 ka eruptive chronology of the Fish Canyon Tuff and associated units of the La Garita magmatic system', in review in Geology, which analyzed eruptive products from the La Garita caldera.
Data release of geospatial map database, argon geochronology and geochemistry data for: Geologic map of the San Antonio Mountain area, northern New Mexico and southern Colorado
This dataset accompanies publication "Geologic map of the San Antonio Mountain area, northern New Mexico and southern Colorado". Data presented here include the digital geologic database, 40Ar/39Ar geochronology and major and trace element chemistry from lava flows and an ignimbrite. The geologic database includes spatial feature classes and non-spatial tables that collectively contain...
Argon and geochemical data for: 40Ar/39Ar geochronology and petrogenesis of the Table Mountain Shoshonites, Golden, CO
The Argon geochronology dataset was collected by Leah E. Morgan and Alexie Millikin in the Argon Geochronology Laboratory of the USGS in Denver, Colorado in 2016. The dataset contains full raw argon isotopic data. An additional dataset includes whole rock geochemistry data collected under contract with the Central Mineral and Environmental Resources Science Center, USGS Denver. These...
Science and Products
Filter Total Items: 32
Gondwanic inheritance on the building of the western Central Andes (Domeyko Range, Chile): Structural and thermochronological approach (U-Pb and 40Ar-39Ar)
Tectonics inheritance controls the evolution of many orogens. To unravel the role of the Gondwanan heritage (late Paleozoic to Triassic) over the building of the Central Andes in northern Chile (Domeyko Range), we performed detrital U‐Pb zircon and 40Ar/39Ar muscovite geochronology along with structural analyses (kinematics and structural balancing). 40Ar/39Ar dating of detrital...
Authors
Mauricio Espinoza, Veronica Oliveros, Paulina Vasquez, Laura Giambiagi, Leah E. Morgan, Rodrigo Gonzalez, Luigi Solari, Florencia Bechis
Constraining central Himalayan (Nepal) fault geometry through integrated thermochronology and thermokinematic modeling
Constraining the subsurface structural geometry of the central Himalaya continues to prove difficult, even after the 2015 Gorkha earthquake and the resulting insights into the trajectory of the Main Himalayan thrust (MHT). To this end, we apply a thermokinematic model to evaluate four possible balanced cross section geometries based on three estimates of the MHT in central Nepal. We...
Authors
Surydoy Ghoshal, Nadine McQuarrie, Delores M. Robinson, D.P. Adhikari, Leah E. Morgan, Todd A. Ehlers
Conditions and timing of high-grade metamorphism and ductile deformation of the southern segment of the Central Anatolian Ophiolite
Ophiolitic fragments scattered over a wide area of Central Anatolia exhibit varying degrees of metamorphism, from unmetamorphosed to upper amphibolite facies, although geochemical similarities suggest they are all part of the Central Anatolian Ophiolite (CAO). Magmatic crystallization of oceanic crust in the CAO at ~ 91 Ma coincided with high-grade metamorphism of rocks that underlie the...
Authors
Molly S. Radwany, Leah E. Morgan, Donna L. Whitney
Interpreting and reporting 40Ar/39Ar geochronologic data
The 40Ar/39Ar dating method is among the most versatile of geochronometers, having the potential to date a broad variety of K-bearing materials spanning from the time of Earth’s formation into the historical realm. Measurements using modern noble-gas mass spectrometers are now producing 40Ar/39Ar dates with analytical uncertainties of ∼0.1%, thereby providing precise time constraints for...
Authors
Allen J. Schaen, Brian R. Jicha, Kip V. Hodges, Pieter Vermeesch, Mark E. Stelten, Cameron Mark Mercer, David Phillips, Tiffany Rivera, Fred Jourdan, Erin L. Matchan, Sidney R. Hemming, Leah E. Morgan, Simon P. Kelley, William S. Cassata, Matt T. Heizler, Paulo M. Vasconcelos, Jeff A. Benowitz, Anthony A.P. Koppers, Darren F. Mark, Elizabeth M. Niespolo, Courtney J. Sprain, William E. Hames, Klaudia F. Kuiper, Brent R. Turrin, Paul R. Renne, Jake Ross, Sebastian Nomade, Hervé Guillou, Laura E. Webb, Barbara A. Cohen, Andrew T. Calvert, Nancy Joyce, Morgan Ganderød, Jan Wijbrans, Osamu Ishizuka, Huaiyu He, Adán Ramirez, Jörg Pfänder, Margarita Lopez-Martínez, Huaning Qiu, Brad S. Singer
Detrital record of the late Oligocene – Early Miocene mafic volcanic arc in the southern Patagonian Andes (~51 °S) from single-clast geochronology and trace element geochemistry
Retroarc foreland basins are important archives of continental arc magmatism and upper plate deformational processes that control the evolution of continental lithosphere. However, resolving source areas in foreland basin infill dominated from mixed mafic and recycled sediment using conventional methods such as detrital zircon geochronology poses a challenge to thorough analysis due to...
Authors
Rebecca A. VanderLeest, Julie C. Fosdick, Joel S Leonard, Leah E. Morgan
Multiproxy Cretaceous-Paleogene boundary event stratigraphy: An Umbria-Marche basin-wide perspective
The complete and well-studied pelagic carbonate successions from the Umbria-Marche Basin (Italy) permit the study of the event-rich stratigraphical interval around the Cretaceous-Paleogene (K-Pg) boundary (e.g., Deccan volcanism, boundary impact, Paleocene recovery and climate). To test the robustness of various proxy records (bulk carbonate δ13C, δ18O, 87Sr/86Sr and Ca, Fe, Sr and Mn...
Authors
Matthias Sinnesael, Alessandro Montanari, Fabrizio Frontalini, Rodolfo Coccioni, Jerome Gattacceca, Christophe Snoeck, Wencke Wegner, Christian Koeberl, Leah E. Morgan, Niels de Winter, Donald J. DePaolo, Philippe Claeys
The influence of foreland structures on hinterland cooling: evaluating the drivers of exhumation in the eastern Bhutan Himalaya
Understanding, and ideally quantifying, the relative roles of climatic and tectonic processes during orogenic exhumation is critical to resolving the dynamics of mountain building. However, vastly differing opinions regarding proposed drivers often complicate how thermochronometric ages are interpreted, particularly from the hinterland portions of thrust belts. Here we integrate three...
Authors
Nadine McQuarrie, Paul R. Eizenhofer, Sean P. Long, Tobgay Tobgay, Todd A. Ehlers, Ann Blythe, Leah E. Morgan, Michelle Gilmore, Gregory M. Dering
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 Trachyte, Fraction Tuff, and Oddie Rhyolite...
Authors
Edward A. du Bray, David A. John, Joseph P. Colgan, Peter Vikre, Michael A. Cosca, Leah E. Morgan
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 collected by Bonham and Garside (1979) during...
Authors
Edward A. du Bray, David A. John, Peter Vikre, Joseph P. Colgan, Michael A. Cosca, Leah E. Morgan, Robert J. Fleck, Wayne R. Premo, Christopher S. Holm-Denoma
Revisiting Herto: New evidence of Homo sapiens from Ethiopia
Localities in the radiometrically dated Upper Herto Member of Ethiopia’s Bouri Formation continue to produce new data that complement and extend initial reports of fossils and artifacts published in 2003. Results of these revisits are reported here and include the in situ recovery of artifacts from the same sediments containing hominid fossils. We evaluate the absolute and relative...
Authors
Yonatan Sahle, Yonas Beyene, Alban Defleur, Berhane Asfaw, Giday WoldeGabriel, William K Hart, Leah E. Morgan, Paul R. Renne, Joshua Carlson, Tim White
A supervolcano and its sidekicks: A 100 ka eruptive chronology of the Fish Canyon Tuff and associated units of the La Garita magmatic system
Establishing temporal constrains on major volcanic eruptions is limited by the precision of existing geochronometers. Prior work on the La Garita caldera, created by the eruption of the Fish Canyon Tuff, failed to resolve temporal differences between pre-, syn-, and post-collapse eruptive units. Here, we report 40Ar/39Ar geochronologic data supporting a ca. 100 ka eruptive history of the...
Authors
Leah E. Morgan, Samuel Johnstone, Amy K. Gilmer, Michael A. Cosca, Ren A. Thompson
Reverse weathering in marine sediments and the geochemical cycle of potassium in seawater: Insights from the K isotopic composition (41K/39K) of deep-sea pore-fluids
In situ Al-silicate formation, also known as “reverse weathering,” is an important sink of many of the major and minor cations in seawater (e.g. Mg, K, and Li). However, the importance of this sink in global geochemical cycles and isotopic budgets of these elements remains poorly constrained. Here, we report on the potassium isotopic composition (41K/39K) of deep-sea sediment pore-fluids...
Authors
Danielle P. Santiago Ramos, Leah E. Morgan, Nicholas S. Lloyd, John A. Higgins
Non-USGS Publications**
Mark, D.F., P.R. Renne, R. Dymock, V.C. Smith, J.I. SImon, L.E. Morgan, R.A. Staff, and B.S. Ellis, 2017. High-precision 40Ar/39Ar dating of pleistocene tuffs and temporal anchoring of the Matuyama-Brunhes boundary. Quaternary Geochronology 39, 1-23, https://doi.org/10.1016/j.quageo.2017.01.002.
Morgan, L.E., 2017. 40Ar/39Ar and K-Ar Geochronology, in: A.S. Gilbert (ed.), Encyclopedia of Geoarchaeology. Encyclopedia of Earth Science Series. Springer, Dordrecht, https://doi.org/10.1007/978-1-4020-4409-0.
Morgan, L.E., 2015. Noble Gas Mass Spectrometry, in: W.J. Rink, and J.W. Thompson (eds.), Encyclopedia of Scientific Dating Methods. Encyclopedia of Earth Science Series. Springer, Dordrecht, https://doi.org/10.1007/978-94-007-6304-3_118.
Sahle, Y., L.E. Morgan, D.R. Braun, W.K. Hutchings, 2014. Chronological and behavioral contexts of the earliest Middle Stone Age in the Gademotta Formation, Main Ethiopian Rift, Quaternary International, v. 331, p. 6-19, https://doi.org/10.1016/j.quaint.2013.03.010.
Mark, D.F., M. Petraglia, V.C. Smith, L.E. Morgan, D.N. Barfod, B.S Ellis, N.J. Pearce, J.N. Pal, R. Korisettar, 2014. A high-precision 40Ar/39Ar age for the Young Toba Tuff and dating of ultra- distal tephra: forcing of Quaternary climate and implications for hominin occupation of India, Quaternary Geochronology, v. 21, p. 90-103, https://doi.org/10.1016/j.quageo.2012.12.004.
Sahle, Y., W.K. Hutchings, D.R. Braun, J.C. Sealy, L.E. Morgan, A. Negash, B. Atnafu, 2013. Earliest stone-tipped projectiles from the Ethiopian Rift date to >279,000 years ago. PLOS ONE, v. 8, no. 11, e78092, https://doi.org/10.1371/journal.pone.0078092.
Morgan, L.E., D.F. Mark, J. Imlach, D.N. Barfod, 2013. FCs-EK: A new sampling of the Fish Canyon tuff 40Ar/39Ar neutron flux monitor, in: Jourdan, F., Mark, D., and Verati, C. (eds.), Advances in 40Ar/39Ar Dating: from Archaeology to Planetary Sciences. Geological Society, London, Special Publications, 378, https://doi.org/10.1144/SP378.21.
Renne, P.R., A.L. Deino, F.J. Hilgen, K.F. Kuiper, D.F. Mark, W.S. Mitchell, L.E. Morgan, R. Mundil, J. Smit, 2013. Timescales of critical events around the Cretaceous-Paleogene boundary. Science, v. 339, p. 684-687, https://doi.org/10.1126/science.1230492.
Schoene, B., D.J. Condon, L.E. Morgan, N. McLean, 2013. Precision and accuracy in geochronology. Elements Magazine, v.9, no.1, p. 23-28, http://elementsmagazine.org/past-issue-archive/2013-volume-9/#February2013.
Renne, P.R., S.R. Mulcahy, W.S. Cassata,, L.E. Morgan, S.P. Kelley, L. Hlusko, J. Njau, 2012. Retention of inherited Ar by alkali feldspar xenocrysts in a magma: Kinetic constraints from Ba zoning profiles. Geochimica et Cosmochimica Acta, v. 93, p. 129-142, https://doi.org/10.1016/j.gca.2012.06.029.
Morgan, L.E., P.R. Renne, R. Galotti, G. Kieffer, M. Piperno, J.-P. Raynal, 2012. A chronological framework for a long and persistent archeological record: Melka Kunture, Ethiopia. Journal of Human Evolution, v. 62, no. 1, p. 104-115, https://doi.org/10.1016/j.jhevol.2011.10.007.
Frost, S.R., H.L. Schwartz, L. Giemsch, L.E. Morgan, P.R. Renne, M. Wildgoose, C. Saanane, F. Schrenk, K. Harvati, 2012. Refined age estimates and paleoanthropological investigation of the Manyara Beds, Tanzania. Journal of Anthropological Sciences, v. 90, p. 151-161, https://doi.org/10.4436/jass.90001.
Schwartz, H., P.R. Renne, L.E. Morgan, M.M. Wildgoose, P.C. Lippert, S.R. Frost, K. Harvati, F. Schrenk, C. Saanane, 2012. Geochronology of the Manyara Beds, northern Tanzania: stratigraphy and new magnetostratigraphy and 40Ar/39Ar ages. Quaternary Geochronology, v. 7, no. 1, p. 48-66, https://doi.org/10.1016/j.quageo.2011.09.002.
Morgan, L.E., O. Postma, K.F. Kuiper, D.F. Mark, W. van der Plas, S. Davidson, M. Perkin, I. Villa, J.R. Wijbrans, 2011. A metrological approach to measuring 40Ar* concentrations in K-Ar and 40Ar/39Ar mineral standards, Geochem. Geophys. Geosyst., v. 12, p. A0AA20, https://doi.org/10.1029/2011GC003719.
Renne, P.R., A.L. Deino, W.E. Hames, M.T. Heizler, S.R. Hemming, K.V. Hodges, A.A.P. Koppers, D.F. Mark, L.E. Morgan, D. Phillips, B.S. Singer, B.D. Turrin, I.M. Villa, M. Villeneuve and J.R. Wijbrans, 2009. Data reporting norms for 40Ar/39Ar geochronology. Quaternary Geochronology, v. 4, no. 5, p. 346-352, https://doi.org/10.1016/j.quageo.2009.06.005.
Renne, P.R., W.S. Cassata, and L.E. Morgan, 2009. The isotopic composition of atmospheric argon and 40Ar/39Ar geochronology: time for a change? Quaternary Geochronology, v. 4, no. 4, p. 288-298, https://doi.org/10.1016/j.quageo.2009.02.015.
Renne, P. R., L.E. Morgan, G. WoldeGabriel, W.K. Hart, Y. Haile-Selassie, and T.D. White, 2009. 40Ar/39Ar Ages of the Middle Awash Late Miocene, in: Haile-Selassie, Y., and WoldeGabriel, G. (eds.), Ardipithecus kadabba: Late Miocene evidence from the Middle Awash, Ethiopia. University of California Press, Berkeley, CA.
Morgan, L.E., P.R. Renne, R.E. Taylor, and G. WoldeGabriel, 2009. Archaeological age constraints from eruption ages of obsidian: Examples from the Middle Awash, Ethiopia. Quaternary Geochronology, v. 4, p. 193-203, https://doi.org/10.1016/j.quageo.2009.01.001.
Morgan, L.E. and P.R. Renne, 2008. Diachronous Dawn of Africa’s Middle Stone Age: New 40Ar/39Ar ages from the Ethiopian Rift. Geology, v. 36, no. 12, p. 967-970, https://doi.org/10.1130/G25213A.1.
Gihring, T.M., L.-H. Lin, M. Davidson, T.C. Onstott, L. Morgan, M. Milleson, T.L. Kieft, E. Trimarco, D.L. Balkwill, and M.E. Dollhopf, 2006. The Distribution of Microbial Taxa in the Subsurface Water of the Kalahari Shield, South Africa. Geomicrobiology Journal, v. 23, p. 415-430, https://doi.org/10.1080/01490450600875696.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Filter Total Items: 28
Argon data for Nepal
This dataset accompanies planned publication 'Determining fault geometry through the transport-parallel distribution of thermochronometer cooling ages'. The Ar/Ar data is for samples that record the thermal history of the area. The geochronology provides time constraints for the thermal histories studied in the manuscript. Samples were collected from Nepal, overseen by Nadine McQuarrie...
Argon data for Amazon Craton
This dataset accompanies planned publication 'Genesis of early Neoproterozoic gold deposits, southwestern Amazon Craton, western Brazil'. The Ar/Ar data is for samples that record the mineralization of the area. The geochronology provides time constraints for the mineralization studied in the manuscript. Samples were collected from the Amazon Craton region, and collection was done by...
Argon data for Central Andes (Domeyko Range, Chile)
This dataset accompanies planned publication 'Gondwanan inheritance on the building of the western Central Andes (Domeyko Range, Chile): Structural and thermochronological approach (U-Pb and 40Ar-39Ar)'. The Ar/Ar data is for samples that record the sedimentation of the area. The geochronology provides time constraints for the sedimentation studied in the manuscript. Samples were...
Argon data for Yellow Pine
This dataset accompanies planned publication 'Timing of Hydrothermal Alteration and Au-Sb-W Mineralization, Stibnite-Yellow Pine District, Idaho'. The Ar/Ar data is for samples that record the mineralization of the area. The geochronology provides time constraints for the mineralization studied in the manuscript. Samples were collected from the Yellow Pine region, and collection was done...
Argon data for Central Anatolian Ophiolite
This dataset accompanies planned publication 'Conditions, mechanisms, and timing of high-grade metamorphism and ductile deformation of the southern segment of the Central Anatolian Ophiolite'. The Ar/Ar data are for samples that record the metamorphic deformation of the ophiolite. The geochronology provides time constraints for the deformation studied in the manuscript. Samples were...
Argon data for Southern Patagonian Andes
This dataset accompanies planned publication 'Detrital record of the Late Oligocene - Early Miocene mafic volcanic arc in the Southern Patagonian Andes (~51S) from single-clast geochronology and trace element geochemistry'. The Ar/Ar data is for samples that record the detrital sedimentary record of the basin. The geochronology provides time constraints for the sedimentation studied in...
Argon geochronology data for eastern Bhutan
This dataset accompanies publication 'The influence of foreland structures on hinterland cooling: evaluating the drivers of exhumation in the eastern Bhutan Himalaya'. The Ar/Ar data provides time constraints for the cooling of rocks in the study area.
Argon geochronology data for Multiproxy Cretaceous-Paleogene boundary event stratigraphy: an Umbria-Marche basin-wide perspective
This dataset accompanies publication 'Multiproxy Cretaceous-Paleogene boundary event stratigraphy: an Umbria-Marche basin-wide perspective'.
Data to accompany U.S. Geological Survey Data Series 1099: Petrographic, geochemical and geochronologic data for Cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield Mining Districts, Nevada
This dataset is the assembled analytical results of 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. Much of the data presented here for the Tonopah and Divide districts are for samples collected by Bonham and Garside (1979) during...
Argon geochronology data for La Garita caldera
This dataset accompanies publication 'A supervolcano and its sidekicks: A 100 ka eruptive chronology of the Fish Canyon Tuff and associated units of the La Garita magmatic system', in review in Geology, which analyzed eruptive products from the La Garita caldera.
Data release of geospatial map database, argon geochronology and geochemistry data for: Geologic map of the San Antonio Mountain area, northern New Mexico and southern Colorado
This dataset accompanies publication "Geologic map of the San Antonio Mountain area, northern New Mexico and southern Colorado". Data presented here include the digital geologic database, 40Ar/39Ar geochronology and major and trace element chemistry from lava flows and an ignimbrite. The geologic database includes spatial feature classes and non-spatial tables that collectively contain...
Argon and geochemical data for: 40Ar/39Ar geochronology and petrogenesis of the Table Mountain Shoshonites, Golden, CO
The Argon geochronology dataset was collected by Leah E. Morgan and Alexie Millikin in the Argon Geochronology Laboratory of the USGS in Denver, Colorado in 2016. The dataset contains full raw argon isotopic data. An additional dataset includes whole rock geochemistry data collected under contract with the Central Mineral and Environmental Resources Science Center, USGS Denver. These...
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government