Central Mineral and Environmental Resources Science Center
Argon Geochronology
Project Objectives
This project maintains the 40Ar/39Ar laboratory serving the needs of USGS geologists and other Federal agency projects. The 40Ar/39Ar geochronology laboratory in Denver is a state-of-the-art research facility for determining 40Ar/39Ar ages of minerals and rocks. This facility houses necessary equipment for sample preparation and analysis, including a high-sensitivity noble gas mass spectrometer and UV and IR lasers. The versatility of the 40Ar/39Ar method permits determining the timing of processes and events such as igneous intrusions and extrusions, ore mineralization and hydrothermal fluid circulation, metamorphic cooling and exhumation, mineral formation and recrystallization, and shallow crustal faulting. The geologist is dependent on the geochronologist for data and interpretation to determine these parameters. This laboratory develops methodology for small and difficult sample analysis often at the limits of existing mass spectrometer technology. View more information on the laboratory.
Relevance & Impact
The 40Ar/39Ar geochronology laboratory has a large impact on the centrally located USGS science centers, which have a high demand for 40Ar/39Ar geochronology in a variety of projects. Application of 40Ar/39Ar geochronology is invaluable in determining the absolute age of field relationships and timing of events.
Contact Information
Products
- Albion, J., Ovtcharova, M., Bussy, F., Cosca, M., Schaltegger, U., Bussien, D., and Lewin, E., 2011, Lifetime of an ocean island volcano feeder zone: constraints from U-Pb dating on coexisting zircon and baddeleyite, and 40Ar/39Ar age determinations, Fuerteventura, Canary Islands: Canadian Journal of Earth Sciences, 48 (2), pp. 567-592. doi: 10.1139/E10-032
- Bröcker, M., Klemd, R., Cosca, M., Brock, W., Larionov, A.N., Rodionov, N., 2009, The timing of eclogite facies metamorphism and migmatization in the Orlica-Śnieżnik complex, Bohemian Massif: Constraints from a multimethod geochronological study: Journal of Metamorphic Geology, 27 (5), pp. 385-403. doi: 10.1111/j.1525-1314.2009.00823.x
- Cole, J.C., Trexler, J.H., Cashman, P.H., Miller, I., Shroba, R.R, Cosca M.A., and Workman, J.B., 2010, Beyond Colorado's Front Range: A new look at Laramide basin subsidence, sedimentation, and deformation in north-central Colorado: In: Morgan, L.A., and Quane, S.l., eds., Through the Generations: Geologic and Anthropogenic Field Excursions in the Rocky Mountains fro Modern to Ancient: Geological Society of America Field Guide 18, pp. 55-76.
- Cosca, M.A., Stunitz, H., Bourgeix, A-L., and Lee, J.P., 2011, 40Ar* loss in experimentally deformed muscovite and biotite with implications for 40Ar/39Ar geochronology of naturally deformed rocks: Geochimica et Cosmochimica Acta, 75 (24), pp. 7759-7778. doi: 10.1016/j.gca.2011.10.012
- Larson, P.B., Phillips, A., John, D., Cosca, M.,
Pritchard, C., Andersen, A., and Manion, J., 2009, A preliminary study of older hot spring alteration in Sevenmile Hole,
Grand Canyon of the Yellowstone River, Yellowstone Caldera, Wyoming: Journal of
Volcanology and Geothermal Research, 188 (1-3), pp. 225-236. doi: 10.1016/j.jvolgeores.2009.07.017
- Ramalho, R.S., Helffrich, G., Cosca, M., Vance, D., Hoffmann, D., and Schmidt, D.N., 2010, Vertical movements of ocean island volcanoes: Insights from a stationary plate environment: Marine Geology, 275 (1-4), pp. 84-95. doi: 10.1016/j.margeo.2010.04.009
- Ramalho, R.S., Helffrich, G., Cosca, M., Vance, D., Hoffmann, D., and Schmidt, D.N., 2010, Episodic swell growth inferred from variable uplift of the Cape Verde hotspot islands: Nature Geoscience, 3 (11), pp. 774-777. doi:10.1038/ngeo982
- Schlup, M., Steck, A., Carter, A., Cosca, M., Epard, J-L., and Hunziker, J., 2010, Exhumation history of the NW Indian Himalaya revealed by fission track and 40Ar/39Ar ages: Journal of Asian Earth Sciences, 40 (1), pp. 334-350. doi: 10.1016/j.jseaes.2010.06.008
- van der Lelij, R., Spikings, R.A., Kerr, A., Kounov, A., Cosca, M., Chew, D., and Villagomez, D., 2010, Thermochronology and tectonics of the Leeward Antilles: Evolution of the southern Caribbean Plate boundary zone: Tectonics, 29, TC6003. doi:10.1029/2009TC002654
U.S. Department of the Interior |
U.S. Geological Survey