Mapping advanced argillic alteration at Cuprite, Nevada, using imaging spectroscopy
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Abstract
Mineral maps based on Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data were used to study late Miocene advanced argillic alteration at Cuprite, Nevada. Distributions of Fe-bearing minerals, clays, micas, sulfates, and carbonates were mapped using the Tetracorder spectral-shape matching system. The Al content of white micas increases toward altered areas and near intrusive rocks. Alunite composition varies from pure K to intimate mixtures of Na-K endmembers with subpixel occurrences of huangite, the Ca analogue of alunite. Intimately mixed Na-K alunite marks areas of relatively lower alteration temperature, whereas co-occurring Na-alunite and dickite may delineate relict hydrothermal conduits. The presence of dickite, halloysite, and well-ordered kaolinite, but absence of disordered kaolinite, is consistent with acidic conditions during hydrothermal alteration. Partial lichen cover on opal spectrally mimics chalcedony, limiting its detection to lichen-free areas. Pods of buddingtonite are remnants of initial quartz-adularia-smectite alteration. Thus, spectral maps provide a synoptic view of the surface mineralogy, and define a previously unrecognized early steam-heated hydrothermal event.
Faulting and episodes of hydrothermal alteration at Cuprite were intimately linked to upper plate movements above the Silver Peak-Lone Mountain detachment and growth, collapse, and resurgence of the nearby Stonewall Mountain volcanic complex between 8 and 5 Ma. Isotopic dating indicates that hydrothermal activity started at least by 7.61 Ma and ended by about 6.2 Ma. Spectral and stable isotope data suggest that Cuprite is a late Miocene low-sulfidation adularia-sericite type hot spring deposit overprinted by late-stage, steam-heated advanced argillic alteration formed along the margin of the Stonewall Mountain caldera.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Mapping advanced argillic alteration at Cuprite, Nevada, using imaging spectroscopy |
| Series title | Economic Geology |
| DOI | 10.2113/econgeo.109.5.1179 |
| Volume | 109 |
| Issue | 5 |
| Year Published | 2014 |
| Language | English |
| Publisher | Society of Economic Geologists |
| Contributing office(s) | Crustal Geophysics and Geochemistry Science Center |
| Description | 43 p. |
| First page | 1179 |
| Last page | 1221 |
| Country | United States |
| State | Nevada |
| Google Analytic Metrics | Metrics page |