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Title: Preliminary stratigraphic and petrologic characterization of core samples from USW-G1, Yucca Mountain, Nevada

Abstract

Tuffs of the Nevada Test Site are currently under investigation to determine their potential for long-term storage of radioactive waste. As part of this program, hole USW-G1 was drilled to a depth of 6000 ft below the surface, in the central part of the Yucca Mountain area, Nevada Test Site, Nevada. Petrographic study of the USW-G1 core is presented in this report and shows the tuffs (which generally were variably welded ash flows) are partly recrystallized to a variety of secondary minerals. The important alteration products are zeolites (heulandite, clinoptilolite, mordenite and analcime), smectite clays with minor interstratified illite, albite, micas, potassium feldspar, and various forms of silica. Iijima`s zeolite zones I through IV of burial metamorphism can be recognized in the core. Zeolites are first observed at about the 1300-ft depth, and the high-temperature boundary of zeolite stability in this core occurs at about 4350 ft. Analcime persists, either metastably or as a retrograde mineral, deeper in the core. The oxidation state of Fe-Ti oxide minerals, through most of the core, increases as the degree of welding decreases, but towards the bottom of the hole, reducing conditions generally prevail. Four stratigraphic units transected by the core may be potentiallymore » favorable sites for a waste repository. These four units, in order of increasing depth in the core, are (1) the lower cooling unit of the Topopah Spring Member, (2) cooling unit II of the Bullfrog Member, (3) the upper part of the Tram tuff, and (4) the Lithic-rich tuff.« less

Authors:
;  [1]
  1. eds.
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
OSTI Identifier:
59127
Report Number(s):
LA-8840-MS
ON: DE82010985; TRN: 82:007804
DOE Contract Number:  
W-7405-ENG-36
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Nov 1981
Country of Publication:
United States
Language:
English
Subject:
05 NUCLEAR FUELS; 58 GEOSCIENCES; NEVADA TEST SITE; VOLCANIC ROCKS; STRATIGRAPHY; PETROLOGY; TUFF; DRILL CORES; ZEOLITES; CLAYS; RADIOACTIVE WASTE DISPOSAL; UNDERGROUND DISPOSAL; FEASIBILITY STUDIES; SITE CHARACTERIZATION; EXPERIMENTAL DATA; Yucca Mountain Project

Citation Formats

Waters, A C, and Carroll, P R. Preliminary stratigraphic and petrologic characterization of core samples from USW-G1, Yucca Mountain, Nevada. United States: N. p., 1981. Web. doi:10.2172/59127.
Waters, A C, & Carroll, P R. Preliminary stratigraphic and petrologic characterization of core samples from USW-G1, Yucca Mountain, Nevada. United States. https://doi.org/10.2172/59127
Waters, A C, and Carroll, P R. 1981. "Preliminary stratigraphic and petrologic characterization of core samples from USW-G1, Yucca Mountain, Nevada". United States. https://doi.org/10.2172/59127. https://www.osti.gov/servlets/purl/59127.
@article{osti_59127,
title = {Preliminary stratigraphic and petrologic characterization of core samples from USW-G1, Yucca Mountain, Nevada},
author = {Waters, A C and Carroll, P R},
abstractNote = {Tuffs of the Nevada Test Site are currently under investigation to determine their potential for long-term storage of radioactive waste. As part of this program, hole USW-G1 was drilled to a depth of 6000 ft below the surface, in the central part of the Yucca Mountain area, Nevada Test Site, Nevada. Petrographic study of the USW-G1 core is presented in this report and shows the tuffs (which generally were variably welded ash flows) are partly recrystallized to a variety of secondary minerals. The important alteration products are zeolites (heulandite, clinoptilolite, mordenite and analcime), smectite clays with minor interstratified illite, albite, micas, potassium feldspar, and various forms of silica. Iijima`s zeolite zones I through IV of burial metamorphism can be recognized in the core. Zeolites are first observed at about the 1300-ft depth, and the high-temperature boundary of zeolite stability in this core occurs at about 4350 ft. Analcime persists, either metastably or as a retrograde mineral, deeper in the core. The oxidation state of Fe-Ti oxide minerals, through most of the core, increases as the degree of welding decreases, but towards the bottom of the hole, reducing conditions generally prevail. Four stratigraphic units transected by the core may be potentially favorable sites for a waste repository. These four units, in order of increasing depth in the core, are (1) the lower cooling unit of the Topopah Spring Member, (2) cooling unit II of the Bullfrog Member, (3) the upper part of the Tram tuff, and (4) the Lithic-rich tuff.},
doi = {10.2172/59127},
url = {https://www.osti.gov/biblio/59127}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Nov 01 00:00:00 EST 1981},
month = {Sun Nov 01 00:00:00 EST 1981}
}