|
|||||
|
|
Vein formation and distribution,Ohio and Mt. Baldy districts,Marysvale, Piute County,Utah, USA |
|
| Authors: | L M Nuelle P D Proctor S K Grant |
| Institution: | 1. Missouri Department of Natural Resources, Division of Geology and Land Survey, P.O. Box 250, 65401, Rolla, MO 2. Department of Geology, 258 Eyring Science Center, Brigham Young University, 84602, Provo, UT 3. Department of Geology and Geophysics, University of Missouri — Rolla, 65401, Rolla, MO |
| Abstract: | The Ohio and Mt. Baldy mining districts near Marysvale, Utah, are situated within a calc-alkalic rock assemblage of the Bullion Canyon Volcanics. The assemblage is divisible into three portions: 1) a lower laharic sequence of epiclastic breccias and autobreccias, 2) a middle portion containing mostly lava flows, including a dacite flow with cupola magma characteristics, and tuff and lapilli breccias, and 3) an upper portion containing a local volcanic vent complex and the ash-flow Delano Peak Tuff Member. Fissuring and veining accompanied magmatic doming. Vein types include: 1) early-stage quartz veins, 2) preproductive main-stage quartz veins, 3) productive main-stage quartz veins, and 4) alunite veins. Each vein of the latter two types is surrounded by advanced argillic, sericitic, argillic, and propylitic alteration halos. Environmental changes during vein fluid deposition account for a district wide zonation of vein types: 1) the boiling level accounts for bonanza precious metal deposits at shallower depths than base metal deposits, and 2) a change from an alkaline or neutral state to an acidic, oxygenated environment, near the paleo-water table, accounts for the presence of alunite veins at shallower depths than ore-bearing veins. Vein mineralogy and texture, wallrock alteration, and geologic structure suggest that an unexposed, ore-generating pluton underlies the area and that the districts represent fringe area mineralization and surface expression of a postulated, ore-bearing pluton. |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ | |