The mineralogy and origin of hydrothermally altered Quaternary volcanic rocks on the south flank of Lassen volcano, California: Interim report for USGS Mineral Resource External Research Program grant of $42,000 in FY 2005
Lee RG, Dilles JH, John DA, Abela TL. 2005. The mineralogy and origin of hydrothermally altered Quaternary volcanic rocks on the south flank of Lassen volcano, California: Interim report for USGS Mineral Resource External Research Program grant of $42,000 in FY 2005. Award Number 04HQGR0164. U.S. Geological Survey
Lassen Volcanic National Park hosts the largest active hydrothermal system in the Cascade Range in association with recent dacitic volcanism centered on Lassen Peak, one of the most active of the Cascade volcanoes. During field mapping more than 200 rock samples were collected in a two km2 area extending from Bumpass Hell to Sulphur Works and analyzed with a field-portable, short-wave inferred spectrometer to identify hydrous silicate alteration minerals. The active hydrothermal system consists of steam-heated alteration produced where ascending H2S-rich steam condenses at the water table near the surface. The older and inactive hydrothermal systems produced a series of alteration zones dominated by intermediate argillic and propylitic alteration in Little Hot Springs Valley and near Sulfur Works.
- Type
- Published Report
- Authors
- Lee, Robert; Dilles, John; John, David; Abela, Tanya
- Date of Issue
- 2005-11
- Publisher
- U.S. Geological Survey
- Units
- LAVO
- Keywords
- alteration, brokeoff volcano, geochemistry, hydrothermal, mineralogy, quaternary, volcanic rocks