Characteristics, Extent and Origin of Hydrothermal Alteration at Mount Rainier Volcano, Cascades Arc, USA: Implications for Debris-flow Hazards and Mineral Deposits
Journal of Volcanology and Geothermal Research 175 (2008) 289–314 Contents lists available at ScienceDirect Journal of Volcanology and Geothermal Research journal homepage: www.elsevier.com/locate/jvolgeores Characteristics, extent and origin of hydrothermal alteration at Mount Rainier Volcano, Cascades Arc, USA: Implications for debris-flow hazards and mineral deposits David A. John a,⁎, Thomas W. Sisson b, George N. Breit c, Robert O. Rye d, James W. Vallance e a U.S. Geological Survey, MS-901, 345 Middlefield Rd., Menlo Park, CA 94025, USA b U.S. Geological Survey, MS-910, 345 Middlefield Rd., Menlo Park, CA 94025, USA c U.S. Geological Survey, MS-964, Federal Center, Denver, CO 80225, USA d U.S. Geological Survey, MS-963, Federal Center, Denver, CO 80225, USA e U.S. Geological Survey, Cascades Volcano Observatory, 1300 SE Cardinal Ct., Suite 100, Vancouver, WA 98683, USA ARTICLE INFO ABSTRACT Article history: Hydrothermal alteration at Mount Rainier waxed and waned over the 500,000-year episodic growth of the Received 1 June 2007 edifice. Hydrothermal minerals and their stable-isotope compositions in samples collected from outcrop and as Accepted 2 April 2008 clasts from Holocene debris-flow deposits identify three distinct hypogene argillic/advanced argillic Available online 2 June 2008 hydrothermal environments: magmatic-hydrothermal, steam-heated, and magmatic steam (fumarolic), with minor superimposed supergene alteration. The 3.8 km3 Osceola Mudflow (5600 y BP) and coeval Keywords: phreatomagmatic F tephra contain the highest temperature and most deeply formed hydrothermal minerals. hydrothermal alteration volcano hazards Relatively deeply formed magmatic-hydrothermal alteration minerals and associations in clasts include quartz debris flows (residual silica), quartz–alunite, quartz–topaz, quartz–pyrophyllite, quartz–dickite/kaolinite, and quartz–illite O, H, S stable isotopes, magmatic-hydrother- (all with pyrite).
[Show full text]