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Title: Porosity and permeability of tuffs from the unsaturated zone at Yucca Mountain, Nevada

Abstract

An investigation of the intrinsic flow properties of the rock matrix in the unsaturated zone at Yucca Mountain, Nevada, was carried out by performing single-phase water or air permeability measurements on about 150 selected samples representing all of the different rock units in the unsaturated zone. Pores were studied by examining thin sections of samples impregnated with fluorescent-dyed epoxy. Yucca Mountain is made up of volcanic tuff, which occurs in three distinct textures: welded, nonwelded, and bedded. Welded tuffs occur in two thick, rhyolitic, pyroclastic flow units. In thin sections, the typical welded-tuff pore structure appears to consist of isolated voids interconnected by microfractures. Porosities average about 10 percent, and matrix permeabilities are generally 1 microdarcy or less. The nonwelded tuffs occur in several thin pyroclastic flows between and below the two main welded units. Porosities average about 20 to 30%, and permeabilities are in the microdarcy to millidarcy range. The nonwelded tuffs appear in thin sections to have an open, well-interconnected pore system with significant intragranular porosity in pumice and lithic grains. These tuffs often contain various amounts of secondary clay and zeolite minerals in the pores, which may account for the wide range in permeabilities. The bedded tuffsmore » consist of friable, low-density volcanic ash with porosities of 50% or more and permeabilities often above 1 darcy. These tuffs are the most porous and permeable rock units in the unsaturated zone, and contain large intergranular pores and significant intragranular porosity in frothy pumice clasts. Results of this investigation will help improve the understanding of groundwater movement through the unsaturated zone.« less

Authors:
;  [1]
  1. Geological Survey, Mercury, NV (United States)
Publication Date:
OSTI Identifier:
5862510
Report Number(s):
CONF-921058-
Journal ID: ISSN 0016-7592; CODEN: GAAPBC
Resource Type:
Conference
Journal Name:
Geological Society of America, Abstracts with Programs; (United States)
Additional Journal Information:
Journal Volume: 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; Journal ID: ISSN 0016-7592
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 54 ENVIRONMENTAL SCIENCES; RADIOACTIVE WASTE FACILITIES; SITE CHARACTERIZATION; TUFF; PERMEABILITY; POROSITY; YUCCA MOUNTAIN; GROUND WATER; HYDROLOGY; NEVADA; PORE STRUCTURE; TEXTURE; DEVELOPED COUNTRIES; HYDROGEN COMPOUNDS; MICROSTRUCTURE; MOUNTAINS; NORTH AMERICA; NUCLEAR FACILITIES; OXYGEN COMPOUNDS; USA; WATER; 052002* - Nuclear Fuels- Waste Disposal & Storage; 540250 - Environment, Terrestrial- Site Resource & Use Studies- (1990-)

Citation Formats

Soeder, D J, and Dishart, J E. Porosity and permeability of tuffs from the unsaturated zone at Yucca Mountain, Nevada. United States: N. p., 1992. Web.
Soeder, D J, & Dishart, J E. Porosity and permeability of tuffs from the unsaturated zone at Yucca Mountain, Nevada. United States.
Soeder, D J, and Dishart, J E. 1992. "Porosity and permeability of tuffs from the unsaturated zone at Yucca Mountain, Nevada". United States.
@article{osti_5862510,
title = {Porosity and permeability of tuffs from the unsaturated zone at Yucca Mountain, Nevada},
author = {Soeder, D J and Dishart, J E},
abstractNote = {An investigation of the intrinsic flow properties of the rock matrix in the unsaturated zone at Yucca Mountain, Nevada, was carried out by performing single-phase water or air permeability measurements on about 150 selected samples representing all of the different rock units in the unsaturated zone. Pores were studied by examining thin sections of samples impregnated with fluorescent-dyed epoxy. Yucca Mountain is made up of volcanic tuff, which occurs in three distinct textures: welded, nonwelded, and bedded. Welded tuffs occur in two thick, rhyolitic, pyroclastic flow units. In thin sections, the typical welded-tuff pore structure appears to consist of isolated voids interconnected by microfractures. Porosities average about 10 percent, and matrix permeabilities are generally 1 microdarcy or less. The nonwelded tuffs occur in several thin pyroclastic flows between and below the two main welded units. Porosities average about 20 to 30%, and permeabilities are in the microdarcy to millidarcy range. The nonwelded tuffs appear in thin sections to have an open, well-interconnected pore system with significant intragranular porosity in pumice and lithic grains. These tuffs often contain various amounts of secondary clay and zeolite minerals in the pores, which may account for the wide range in permeabilities. The bedded tuffs consist of friable, low-density volcanic ash with porosities of 50% or more and permeabilities often above 1 darcy. These tuffs are the most porous and permeable rock units in the unsaturated zone, and contain large intergranular pores and significant intragranular porosity in frothy pumice clasts. Results of this investigation will help improve the understanding of groundwater movement through the unsaturated zone.},
doi = {},
url = {https://www.osti.gov/biblio/5862510}, journal = {Geological Society of America, Abstracts with Programs; (United States)},
issn = {0016-7592},
number = ,
volume = 24:7,
place = {United States},
year = {Wed Jan 01 00:00:00 EST 1992},
month = {Wed Jan 01 00:00:00 EST 1992}
}

Conference:
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