Constraining Dates and Rates of Tectonic Processes with Argon Geochronology
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Welcome to the UVM Noble Gas Lab for argon geochronology and thermochronology.
The 40Ar/39Ar geochronology laboratory at UVM is primarily focused on constraining the timing and rates of tectonic processes, specializing in dating deformation. The laboratory is well-suited to conduct step-heating analyses of small samples (e.g. single grains), as well as total fusion analyses.
Graduate and undergraduate education is an important mission of the laboratory. We welcome new users of all identities and support justice, diversity, equity, and inclusion in the Geosciences. We are a participating laboratory in the Awards for Geochronology Student Research2 (AGeS2) Program; use this link for further information.
Please contact us if you are interested in analyses.
Overview
Overview
Instrumentation:
Nu Instruments Noblesse magnetic sector noble gas mass spectrometer.
Custom ultrahigh-vacuum extraction line (built in house).
Santa Cruz Laser Microfurnace diode laser system.
The establishment of this facility was funded by the National Science Foundation Instrumentation and Facilities Program (NSF EAR 102899) with additional support from UVM.
People
People
Lab Personnel:
Laura Webb, Associate Professor of Geology, lewebb'at'uvm.edu
Dan Jones, Laboratory Research Technician, djones3'at'uvm.edu
The noble gas geochronology lab in Delehanty Hall, Department of Geology, UVM.
Data published in Webb, L.E., and Klepeis, K.A., 2019, 40Ar/39Ar constraints on the Tectonic evolution of the Late Paleozoic and Early Mesozoic accretionary complex of coastal Central Chile. Book chapter in Horton, B., and Folguera, A. eds. Andean Tectonics; Elsevier.
We specialize in teasing out details of polyphase histories from metamorphic tectonites. Our lab regularly conducts step-heating experiments on single grain or small multi-grain aliquots. By targets small rock volumes for mineral separation (e.g., thin-section billet cutoffs), the 40Ar/39Ar data can be interpreted in the context of field, microstructural and petrologic analyes, which is essential in rocks with complex and often polyphase tectonic histories. A new FESEM with EDS and EBSD at UVM funded by a NSF MRI grant (DMR 1828371) provides new opportunities to support these types of research projects on campus.
Data published in Klepeis, K.A., Webb, L.E., Blatchford, H.J., Jongens, R., Turnbull, R., and Schwartz, J.J., 2019, The age and origin of Miocene–Pliocene fault reactivations in the upper plate of an incipient subduction zone, Puysegur Margin, New Zealand. Tectonics, v. 38, doi.org/10.1029/2019TC005674
Publications and conference presentations:
Tam, E., Webb, L.E., Aiken, C., Kim, J., and Klepeis, K., accepted manuscript, Formation of the Green Mountain Anticlinorium in northern Vermont at ca. 420 Ma. Memoir—Geological Society of America: Laurentia: An Evolving Continent.
Brombin, V., Pettitt, E. A., Fahnestock, M. F., Casalini, M., Webb, L. E., Bryce, J. G., and Bianchini, G., 2021. New geochemical and geochronological data on the Cenozoic Veneto Volcanic Province: Geodynamic inferences. Lithos, doi.org/10.1016/j.lithos.2021.106507.
Caswell, B., Gilotti, J.A., Webb, L.E., McClelland, W.C., Kośmińska, K., Piepjohn, K., and von Gosen, W., 2021. 40Ar/39Ar Dating of Paleoproterozoic shear zones in the Ellesmere-Devon Crystalline Terrane, Nunavut, Canadian Arctic, Canadian Journal of Earth Sciences, v. 58, no. 10, p. 1073-1084. DOI 10.1139/cjes-2020-0197.
Boemmels, J.R., Crespi, J.M., Webb, L.E., and Fosdick, J.C., 2021. 40Ar/39Ar and LA-ICP-MS U-Pb geochronology for the New England portion of the Early Cretaceous New England-Quebec igneous province: Implications of the postrift evolution of the eastern North American margin. American Journal of Science, v. 321, p. 365-391. DOI 10.2475/03.2021.03.
Faehnrich, K., McClelland, W.C., Webb, L.E., Rasbury, E.T., Copron, M., and Strauss, J., 2021. Thermochronologic evidence for cretaceous strike-slip displacement on the Porcupine Shear Zone, Alaska and Yukon. Geological Society of America Abstracts with Programs, v. 53, no. 6, doi: 10.1130/abs/2021AM-365077
Spencer, M., Oboh-Ikuenobe, F.E., and Webb, L.E., 2021. The Ordovician meteor event: evidence from impact-damaged acritarchs and the 40Ar/39Ar date of impact spherules from the Crooked Creek structure. Geological Society of America Abstracts with Programs, v. 53, no. 6, doi: 10.1130/abs/2021AM-366001
Henriquez, S., Johnson, C.L., Webb, L.E., Ochir, G., Perkes, R.G., Rea-Downing, G. and Lippert, P.C., 2020, December. Using the volcano-magmatic record to constrain geodynamic evolution during the closure of the Mongol-Okhotsk Ocean in NE Mongolia. In AGU Fall Meeting Abstracts (Vol. 2020, pp. T009-0012).
Nadin, E.S., Yakimova, V., Webb, L.E., 2020. Dating regional events within a brittle fault in the southern Alaskan Chugach accretionary complex. Geological Society of America Abstracts with Programs. Vol 52, No. 6, doi: 10.1130/abs/2020AM-353927.
Cooper-Boemmels, J., Crespi, J., Amidon, W., Fleming, T., and Webb, L.E., 2020. Early Cretaceous postrift magmatism and normal faulting in the northern Appalachians: Implications for the evolution of the eastern North American margin. Geological Society of America Abstracts with Programs. Vol 52, No. 6, doi: 10.1130/abs/2020AM-356541.
Browning-Hanson, J., Viete, D.R., Webb, L.E., Piccoli, P.M., 2020. Resolving the rifting of Rodinia: Detrital geochronologic evidence for spatial and temporal prevalence of sub-orogenic tectonothermal activity in the Appalachian–Caledonian system. Geological Society of America Abstracts with Programs. Vol 52, No. 6, doi: 10.1130/abs/2020AM-353875.
Webb, L.E., Karabinos, P., and Klepeis, K.A., 2020. Evidence for Salinic and Acadian reactivation of Taconic thrusts along the western Green Mountain front. Geological Society of America Abstracts with Programs. doi: 10.1130/abs/2020SE-344590.
Schnalzer, K.M., Webb, L.E., and McCarthy, K., 2020. Evidence for polyphase deformation in the mylonitic zones bounding the Chester and Athens Domes, southeastern Vermont, from 40Ar/39Ar geochronology. Geological Society of America Abstracts with Programs. doi: 10.1130/abs/2020SE-344494.
Cooper-Boemmels, J., Crespi, J., Amidon, W., Fleming, T., and Webb, L.E., 2020. The western New England-Quebec igneous province of Vermont and New York: an example of postrift magmatism and normal faulting from the northern Appalachians. Geological Society of America Abstracts with Programs. doi: 10.1130/abs/2020SE-344836.
Browning-Hanson, J., Webb, L.E., Piccoli, P.M., and Viete, D., 2020. Resolving the rifting of Rodinia: a novel comparative detrital geochronology approach applied along the full length of the Appalachian–Caledonian system. Geological Society of America Abstracts with Programs. doi: 10.1130/abs/2020SE-345286.
Locmelis, M., Moroni, M., Denyszyn, S., Webb, L., Fiorentini, M., Sessa, G., Caruso, S., Mathur, R., Nanzad, B., 2020. On the formation of magmatic sulfide systems in the lower crust by long-lived mass transfer through the lithosphere: Insights from the Valmaggia pipe, Ivrea Verbano Zone, Italy. Terra Nova. DOI: 10.1111/ter.12499
Schaen, A.J., Jicha, B.R., Hodges, K.V., Vermeesch, P., Stelten, M.E., Mercer, C.M., Phillips, D., Rivera, T.A., Jourdan, F., Matchan, E.L., Hemming, S.R., Morgan, L.E., Kelley, S.P., Cassata, W.S., Heizler, M.T., Vasconcelos, P.M., Benowitz, J.A., Koppers, A.P., Mark, D.F., Niespolo, E.M., Sprain, C.J., Hames, W.E., Kuiper, K.F., Turrin, B.D., Renne, P.R., Ross, J., Nomade, S., Guillou, H., Webb, L.E., Cohen, B.A., Calvert, A.T., Joyce, N., Ganerød, M., Wijbrans, J., Ishizuka, O., He, H., Ramirez, A., Pfänder, J.A., Lopez-Martínez, M., Qiu, H., and Singer, B.S., 2020. Interpreting and reporting 40Ar/39Ar geochronologic data. GSA Bulletin. doi.org/10.1130/B35560.1
Klepeis, K.A., Webb, L.E., Blatchford, H.J., Jongens, R., Turnbull, R., and Schwartz, J.J., 2019, The age and origin of Miocene–Pliocene fault reactivations in the upper plate of an incipient subduction zone, Puysegur Margin, New Zealand. Tectonics, v. 38, doi.org/10.1029/2019TC005674.
Klepeis, K.A., Webb, L.E., Blatchford, H., Schwartz, J., Jongens, R., Turnbull, R., and Stowell, H., 2019, Deep slab collision during Miocene subduction causes uplift along crustal-scale reverse faults in Fiordland, New Zealand. GSA Today, v. 29. doi.org/10.1130/GSATG399A.1.
Webb, L.E., Karabinos, P., and Klepeis, K.A., 2019. Geochronologic evidence for Salinic thrusting and Acadian reactivation of external basement massifs in western New England and overprinting of the Ordovician Taconic thrust belt. Geological Society of America Abstracts with Programs. Vol. 51, No. 5, doi: 10.1130/abs/2019AM-334274.
Cooper Boemmels, J., Crespi, J., and Webb, L.E., 2019. Early Cretaceous postrift evolution of the eastern North American margin: Insights from the New England-Quebec igneous province. Geological Society of America Abstracts with Programs. Vol. 51, No. 5, doi: 10.1130/abs/2019AM-336121.
Brombin, V., Bonadiman, C., Jourdan, F., Roghi, G., Coltori, M., Webb, L.E., Callegaro, S., Bellieni, G., De Vecchi, G., Sedea, R., Marzoli, A., 2019, Intraplate magmatism at a convergent plate boundary: the case of the Cenozoic northern Adria magmatism. Earth-Science Reviews, v. 162, p. 355-378.
Webb, L.E., and Klepeis, K.A., 2019, 40Ar/39Ar constraints on the Tectonic evolution of the Late Paleozoic and Early Mesozoic accretionary complex of coastal Central Chile. Book chapter in Horton, B., and Folguera, A. eds. Andean Tectonics; Elsevier.
Cordova, J.L., Mulcahy, S.R., Schermer, E.R., and Webb, L.E., 2018, Subduction initiation and early evolution of the Easton Metamorphic Suite, Northwest Cascades, Washington. Lithosphere, v. 11, no. 1, p. 44-58, doi.org/10.1130/L1009.1.
Aiken, C.L., and Webb, L.E., 2018. Geochronologic Constraints on the Timing of Metamorphism and Exhumation of the Tillotson Peak Complex in Northern Vermont. Geological Society of America Abstracts with Programs. Vol. 50, No. 2, doi: 10.1130/abs/2018NE-310829.
Brombin, V., Webb, L., Bonadiman, C., Marzoli, A., and Coltorti, M., 2017. A geochronological study of mafic and acidic lavas from Veneto Volcanic province (North-East Italy), EGU General Assembly 2017, Vienna, Austria. Geophysical Research Abstracts, Vol. 19, EGU2017-6410, 2017.
Caswell, B., Gilotti, J.A., Webb, L.E., Jones, D.A., McClelland, W.C., 2018. 40Ar/39Ar Geochronology of Biotite from Ductile Shear Zones of the Ellesmere-Devon Crystalline Terrane, Nunavut, Canadian Arctic. Geological Society of America Abstracts with Programs. Vol. 50, No. 2, doi: 10.1130/abs/2018NE-310455
Cordova, J.L., Schermer, E., Mulcahy, S.R., and Webb, L.E., 2017. Initiation and early evolution of a subduction zone: T-t-D history of the Easton metamorphic suite, northwest Washington State, Geological Society of America Abstracts with Programs. Vol. 49, No. 6, doi: 10.1130/abs/2017AM-303853.
Klepeis, K., Webb, L.E., Blatchford, H.J., Schwartz, J.J., Turnbull, R., and Jongens, R., 2017. Unraveling a history of repeated fault reactivations and differential uplift above a young subduction zone in SW New Zealand, Geological Society of America Abstracts with Programs. Vol. 49, No. 6, doi: 10.1130/abs/2017AM-306155.
Klepeis, K., Webb, L.E., Merson, M.Q., and Kim, J.J., 2018. Unraveling Fault Reactivations and Their Tectonic Significance Using Integrated Structural Data and 40Ar/39Ar Geochronology, Examples from N. Vermont and S.W. New Zealand. Geological Society of America Abstracts with Programs. Vol. 50, No. 2, doi: 10.1130/abs/2018NE-311301.
Lagor, S. and Webb, L.E., 2015, Evidence for syntectonic intrusion of the Knox Mountain Pluton in the Connecticut Valley-Gaspe Trough, central Vermont, Geological Society of America Abstracts with Programs. Vol. 47, No. 3, p. 101.
Mulhern, J. S., and Johnson, C. L., 2016, Time–space variability of paralic strata deposited in a high accommodation, high sediment supply setting: example from the Cretaceous of Utah. Geological Society, London, Special Publications, 444, SP444-7.
Tam, E., Webb, L.E., and Aiken, C.L., 2017, Role of the Prospect Rock Fault in the Exhumation of High Pressure Rocks in North-Central Vermont. (EOS, Transactions, American Geophysical Union).
Tam, E., Webb, L.E., and Aiken, C., 2018. Geochronologic Constraints on the Timing of Deformation in the Footwall of the Prospect Rock Fault in North-Central Vermont. Geological Society of America Abstracts with Programs. Vol. 50, No. 2, doi: 10.1130/abs/2018NE-310928.
Tsai, C.-H., Liu, C., Webb, L., and Keyser, W., 2016, New P-T and Geochronological Constraints on High-Pressure Garnet-Bearing Paragonite-Epidote Amphibolite in the Yuli Belt, Eastern Taiwan. Goldschmidt Conference, Yokohama, Japan.
Webb, L.E., 2017. Strange results or: How I learned to stop worrying and love complicated 40Ar/39Ar apparent age spectra. Geological Society of America Abstracts with Programs. Vol. 49, No. 6, doi: 10.1130/abs/2017AM-306106.
Webb, L.E. and Klepeis, K.A., 2015. Punctuated melt-enhanced deformation and tectonic reactivation above a long-lived subduction zone, coastal Andes, central Chile. Geological Society of America Abstracts with Programs. Vol. 47, No. 7, p. 495.
Webb, L.E., Klepeis, K.A., Jones, D.A., Webber, J.R., Cembrano, J., Morata, D., Mora-Klepeis, G., and Arancibia, G., 2014, Thermochronologic Constraints on the Late Paleozoic and Early Mesozoic Tectonic Evolution of Coastal Central Chile (33.5 S). Geological Society of America Abstracts with Programs. Vol. 46, No. 6, p.445.
Webb, L.E., Klepeis, K.A., and Kim, J.J., 2018. New Insights on Acadian Deformation and Reactivation in Northern Vermont from Integrated Structural and Geochronological Studies. Geological Society of America Abstracts with Programs. Vol. 50, No. 2, doi: 10.1130/abs/2018NE-311032.
Webb, L.E., Klepeis, K.A., Kim, J., and Sullivan, P., 2017, Reactivation of Taconic Thrust Faults in the Late Acadian Orogenic Front. 2017 EarthScope National Meeting. Anchorage, Alaska.
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