Hydrothermal Alteration In Research Drill Hole Y 6 Upper Firehole River Yellowstone National Park Wyoming

Author : Setsuko Honda
Publisher :
ISBN 13 :
Total Pages : 24 pages
Book Rating : 4.:/5 (13 download)

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Download or read book Hydrothermal Alteration in Core from Research Drill Hole Y-1, Upper Geyser Basin, Yellowstone National Park, Wyoming written by Setsuko Honda and published by . This book was released on 1970 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Y-1 penetrated an active hot-spring system to 215 feet (65.5 m), where the temperature was 171 (degrees) C. The core is sinter to 12 feet (3.7 m), sandstone, conglomerate, and siltstone composed of rhyolite detritus to 211 feet (64.3 m), and bedrock rhyolite. Hydrothermal minerals replace obsidian and fill open spaces. Original plagioclase and alkali feldspar are unaltered. Clinoptilolite, mordenite, opal, and relic œ-cristobalite occur in the less altered core. In the more intensely altered core analcime is the sole zeolite, hydrothermal quartz is abundant, and œ-cristobalite has been converted to quartz. Montmorillonite and celadonite occur throughout most of the core: calcite, pyrite, muscovite, kaolinite, erionite, and aegirine are sporadic. Hydrothermal alkali feldspar occurs in only one sample. Associated hot-spring fluids are dilute, slightly alkaline, and contain mainly Na, Cl, HCO(3), and SiO(2). Major factors controlling formation of hydrothermal minerals in Y-1 are 1) nature of starting material, 2) elevated temperature, and 3) fluid composition. Parallel distribution patterns of zeolites and silica species suggest that variation in SiO(2) activity is important. Hydrothermal alteration in Y-1 has produced mineral assemblages similar to those produced during low-temperature diagenesis of sedimentary rocks rich in volcanic detritus.