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TITLE. Chemical t’ariahility of Zeolites at a Potential NuclearWaste Flepos ltorv, Yucca Mountain, Nevada
AUTHOR@): D. E. FJrO!(t OII, ESS- 1
SUBMITTED TO Proceeding!] of the International S}-rnposium on Management ofHazardous Chemical Waste Sites; October 7-11, !985:Winstcm-SaLem, NC
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CHEMICAL VARIAf31LITY OF ZEOLITES AT A POTENIIALNUCLEAR HASTE REPOSITORY, YUCCA MOIJNTAIN,NEVADA
D. E. Broxton
ABSTRACT
The compositions of clinoptilollte: and their host tuffs have been
examined by electron microprobe and x-ray fluorescence, respectively,
to determine their variability at a potential nuclear waste reposi-
tory, Yucca Mountain, Nevada. Because of their scrptive properties,
these zeolites could provide important geologic barriers to radionu-
clide migration. Variations in clinoptilolite composition can strong-
ly affect the mineral’s thermal and ion-exchange properties, thus
influencing its behavior in the repository environment.
Clinoptilolites and heulandites closest to the proposed repository
have calcium-rich compositions (60-90 mol.% Cd) and silica-to-aluminum
ratios that concentrate between 4.0 and 4.6. In contrast, clinopti lo-
lites and their host tuffs deeper in the volcanic sequence have highly
variable compositions that vary vertically and laterally. ikeper-
occur’ring clinoptilolltes in the eastern part of Yucca Mountain are
characterized by calcic-potassic compositions and tend to become more
calclum-rich with depth. Clinoptilolltes at equivalent stratigraphic
levels on the western side of Yucca Mountain trave sodic-potassic
compositions and tend to become more sodium-rich With depth, Oespite
their differences i~ exchangeable cation com~ositlorrs these two
deeper-occurring compositional suites have simil~r silica-to-aluminum
ratios, concentrating between 4.4 and S.0.
The chemical variability of cl inoptilolites and their host tuffs
ut Yucca Mountain suggest that their physical and chemical properties
will also vary. Compositional ly-dependant clinoptilolite properties
important for repository performance assessment include expansion/
contraction behavior, hydration/dehydration behavior, and ion-exchange
properties. Used in conjunction with experimental results, the data
presented here can be used to model tne behavior of these clinopti lo-
lite properties in the repository environment.
IN-fR~DUCTI()[{
Yucca Mountain is located along tne southwest border of the Nevada
Test Site, 28 km east of i3eatty, Nevada (F
tuffs at Yucca Mountain are being studied
Energy and its subcontractors to determine
g. 1), Ash-flow and bedded
by the U.S. Department of
their suitability to host a
potential underground high-level nljc~ear waste repository. These
studies are supported by the Nev?da Nuclear daste Storage Investiga-
tions (NNWSI) Project as part of the Civilian Radioactive Waste Man-
agement Program. The NNdSl Project i; managed by the Waste Management
Project Office of the U.S. Department of Energy (DOE), Nevada Opera-
tions Office. NNWSI Project work is sponsored by the Office of
Geologic Repositories of the DOE Office of Civ~iian Radioactive Waste
Management.
A major consideration for chousing Yucca Mountain as a potel’tial
repository site is the presence of abundant zeol!tes in the thicK
Tertiary tuffs, Tne principal zeulites at Yucca Mountain are clinop
tilolite, heulandite, mordenite, and analcime. These zeolites could
provide important geologic barriers to nuclear waste migration because
of their ability to exchange their constituent cat!ons with some im-
portant r~dionucl ides without & major change in structure and because
of their ability to gain and lose water reversibly, Factors affecting
-2-
the ability of these zeo!ites to selectively remove radioactive spe-
cies from solution include: (1) cation species (size, charge, hydra-
tion), (2) temperature, (3) concentration of species In solution, and
(4) zeolite structural characteristics (Breck, 1974). Several coun-
tries including the United States, Canada, Great Britain, Fr~nce,
Bulgaria, Hungary, Japan, West Germany, ~nd the Soviet Union have
capitalized on the ion-exchange properties of clinoptilolite to remove
radionucl ides, such as CS137, SrgO, T1204, AsllO, Ca45 from
waste solutions. Studies presently under way show that Yucca Mountain
zeolitic tuffs are selective for strontium, cesium, barium, neptunium,
uranium, and plutonium (Daniels et al., 1982; U.S. Department of
Energy, 1984).
This paper examines the c}lemical variability of clinoptilolites,
the most abundant zeolite at Yucca Mountain. Experimental studies
have shown that the chemical and physical properties cf clinoptilolite
can vary significantly with composition. Data from this study can be
used in conjunction with experimental studies to predict the Dehavior
of clinoptilolites under repository conditions.
GEOLOGIC 5ETTI14GOF THE NEPOSITURY
Yucca Mountain is an east-tilted Basin and Range uplift located on
the southern flank of tne Miocene-Pliocene Timber Mountain-Qesis Val-
ley caldera complex (Byers et al., 1976; Christianson et al., 1977),
Rhyolite and quartz latite ash-flow tuffs are tne dominant lithology
and range in aggregate thickness from 1,;? to over 1,8 km, Zeolites
are best developed in nonwelded tuffs and in the nonwelcied tops and
bottoms of ash flows th~t have denseiy welded, devitrificd inter~ors.
The zeolites formed by replacement of volcanic glass during diagenesis
-3-
of ~he tuffs. Uhere altered, the zeolitic tuffs form mappable inter-
vals that can be correlated laterally throughout most of Yucca Moun-
tain.
The potential repository is sited in the unsaturated zone in the
lowr half of the Topopah Spring Aember of the paintbrush Tuff
(Fig. 2). The repository host rock is densely welded and devitrifiad
to a thermally stable assemblage of alkali feldspar and silica miner-
als. Zeolitic tuffs occur in several stratigraphic intervals between
the repository and the watertable, providing probable barriers to
radionuclide migration in the unsaturated zone. Additional :aolitic
tuffs below the watertable provida potential barriers to radionuclide
migration through the saturated zone. Individual beds of zeolite-
bearing tuffs con’mnly range in thickness from 10 to 150 m and contain
50-75% clinoptilolite in the upper part of the volcanic sequence (Bish
and Vaniman, 1985).
MATERIALS AND METtKIDS
Except for a few outcrop samples, mineral and bulk-rock analyses
were performed on core and, to a lesser txtent, cuttings collected
from drill holes shown in Fig. 1. Mineral compositions were deter-
mined on an automated Cameca electron microprobe operated at 15 kev
with a 15 to 20 nanoamp beam current. Standards consisted of a set of
natural feldspars and other minerals, Uavelengtn-d ispersive x-ray
counts were collected for 10 to 20 s or 30,000 counts. Compositions
were corrected for differential mdtrix effects using the methods of
dence and Albee (1968).
Sodium was counted first in the analytical sequence because it
tend! to migraie from the region excited by the electron beam. The
-4-
beam was rastered to a aiameter of 15 to 25 microns to minimize sodium
migration. Oespite this precaution, sodium loss remained a signifi-
cant problem for tl]eanalysis of Clinoptilollte and the reported sodi-
um concentrations may be low by 5-20Z of the amount present. MOving
the sample Deneath the electron beam decreases sodium loss, but crys-
tals large enough to F!low sample Mvement during analysis are limited.
Bulk-rock major elements were analyzed with an automated Rigaku
wavelength-dispersive x-ray fluorescence (XRF) spectrophotometer.
Samples were crushed and homogenized (10 g), dried at 900°C, and a l-g
split was fused with 9 g of lithium tetraborate flux. A library of
x-ray intensities for standard rocks was used to calculate elemental
concentrations (Valentine, 19a3). Bulk-rock sodium was determined for
a separate sample split by atomic absorption spectrophotometry
plazma emission spectrometry because of sodium loss during the
procedure for XRF samples.
RESULTS AND DISCUSSION
and/or
drying
Representative compositions for clinopti lolite-group minerals are
giken in TdDlt? ]. Triangular diagrams showin~ variations in
exchangeable-cation compositions are presented in Figs. 3, 4, and 6.
Histograms of Si/Al ratios in these minerals are presented in Fig. 5.
Uased upon composition and mode of occurrence, these zeolites can be
dlvlded into (1) an upper group of cl inoptilolites and heulandites
that have limited distribution and uniform Calclum-rich compositions
(Fig. 3), and (2) a lower group of clinoptilolites that occur in
thick, widespread zones of alteration and have highly variable compo-
sitions (Fig.4). The upper group contains volumetrically small
amounts of zenlites but IS impo?tant because of the proximity of these
-5-
zeolites to the repository. The lower group includes thick zeolitic
tuffs both above and below the watertable.
Tne upper group of calcic clinoptilolites occurs below the reposi-
tory horizon in fractures (Carlos, 1985) and in a thin (0.2-1.0 m) but
nearly continuous zone of zeolite and smectite alteration concentrated
at the top of the basal vitrophyre in the Topopah Spring Member of the
Paintbrush Tuff (Levy, 1984). Oespite their scattered distribution in
local zones of alteration, the minerals in this group are invariably
ralcium-rich (Fig. 3) and have silica-to-alumina rdt!os ranging be-
tween 4.0 and 5,0 (Fig. 5). Magnesium contents of these zeolites are
relatively high, ranging from 0.6 to 1.5% MgO by weight. Some of
tnese zeolites have a thermal stability characteristic of heulandite
(i%mpton, 1960; Levy, 19b4), while others have a thermal stability in-
termediate bet~een heulandite and clinoptilolite (Group 2 of Boles,
1972).
The lower group of clinoptilolites occurs in nonwelded tuffs in
which diagenetic alteration has completely replaced original volcanic
glass with zeolites. Tnese zeolite-rich tuffs occur at well-defined
stratigraphic intervals including: (1) the interval extending from
the base of the Topopah Spring Member, through the tuff of Calico
Hills, ~nd into the top of the Prow Pass Member, (2) the interval at
the b~se of the Prow Pass Member and top of the Bullfrog Member, and
(3) the Interval at the base of the Bullfrog Member and top of the
Tram Member (F!g, 2). Clinoptilolite compositions in this lower group
vary systematically both vertically and laterally (Fig. 4). On the
e~stern side of Yucca Mountain clinoptilolite compositions are calcic-
potassic and show a strong calcium enrichment trend with depth. In
contrast, clinoptilolite~ on the western side of Yucca Mountain are
-6-
sodic-pottissic and tend to become more sodium rich with depth. A
transition zone which separates the two suites has compositions simi-
lar to both suites. Silica-to-aluminum ratios are similar for both
compositional suites (Fig. 5) concentrating between 4.4 and 5.0. How-
ever, the silica-to-alumina ratios in the eastern clinoptilolite suite
are Dimodal with a small population of samples having ratios between
2.8 and 3.6. This smaller population of samples with low silica-to-
alumina ratios is associated with the most calcic clinoptilolites in
the deepest parts of the eastern suite.
Radionucl ide-transport models generally distinguish between trans-
port processes in the unsaturated and saturated zones. Figure 6 shows
only those clinoptilolite compositions (lower group) that are likely
to be encountered below the repository block in the unsaturated zone.
On the western side of th}erepository unsaturated-zone clinoptilolites
are potassic-sodic containing between 40 and 70 mol.% potassium as
exchangeable cations. The eastern side of the repository block coin-
cides with the transition zone for all clinoptilolites shown in Fig. 4
and has variaDle exchangeable cation composition. Part of the clinop-
tilolites illthe eastern part of the repository ~lock nave potassic-
sodic compositions similar to those to the west. However, others are
calcic-putassic, containing only 15-45 mol.% potassium.
Representative bulk-rock compositions for zeolitic tuffs from
Yucca Mountain are given in Table 11, For comparison, tuff composi-
tions from tt,e eastern part of Yucca Mountain are paired with tuff
compositions from the west. A triangular plot of alkalis and alkaline
earths shows that bulk-rock compositions vary from east to west in
manner similar to clinoptilolite compositions (Fig. 7). Zeolitic
tuffs from eastern Yucca Mountain are relatively calcium-rich and
-7-
deviate more from unaltered tuff compositions than tuffs to the west.
Groundwater c~positions in the saturated zone also vary ?aterally in
manner similar to clinoptilolite and bulk-rock compositions (Benson et
al., 1983; Ogard and I(errisk, 1984). These groundwaters become more
calcic and less sodic eastward. The more calcic groundwaters may be
partially derived from Paleozoic carbonate aquifers underlying the
volcanic rocks, or the groundwater may become more calcic after ion
exchange with calcium-rich zeolitic tuffs in the eastern part of Yucca
!buntain.
The physical and chemical pro~}erties of clinoptilolites and their
host tuffs at Yucca Mountain will probably vary with composition. For
example, experimental studies have shown that thermal and ion-exchange
properties of clinoptilolite, both of which are of particular interest
for repository performance assessment, are StrOtIgly influenced by com-
positional differences. Variations in physical and chemical propcr-
ti6S Of ClinOptllOliteS and ClinOptl lOlite-!)earing tIJffS IIIdy affect
their behavior in the repository setting.
The ~hermal properties of clinoptilolite are strongly affected by
exchangeable-cation compositions (Bish, 1984 and 1985).
Compositional ly-dependant thermal properties in clinoptilolite
include: (1) contraction and expansion behavior, (2) dehydration and
dehydration properties, and (3) mineral stability. Tnest? therlndl
properties are important because during the thermal pulse induced by
radioactive-waste decay clinoptllolites wI1l be heated to varying
degrees depending upon their proximity to the repository. Modelling
of the thermal pulse is not yet completed, but heating above ambient
temperatures will probably affect (1) clinoptilolite In fractures near
the repository, (2) cllnoPtilolite and hculandite associated with
-8-
alteration at the top of the Topopah Spring basal vitrophyre, and
(3) clinopti lolite-rich ltiffsat the base of the Topopah Spring Member
and in the tuff of Calico Hills.
In a changing thermal environment, unit-cell volumes of clinop-
tilolltes expand and contract in manner governed by the size, amount,
and charge of the exchangeable cations (bish, 1984). Significant
volume changes in zeolites could affect fluid flow paths by opening
fractures sealed by zeolites and by increasing permeabilities or open-
ing new fractures in tuffs containing large amounts of zeolites.
Sodium Clinoptilolites decrease in volume by about 8% when heated from
25°C to 300”C in unsaturated conditions (Fig. 8a). Calcic and potas-
sic clinoptilolites are reduced in volume 3.6% and 1.6%, respectively,
under the same conditions. Although Yucca Mountain cl”lfloptilolites
have mixed rather tnan pure end-member compositions, their contraction
and expansion behavior snould be governed by the dominant cations in
exchangeable sites. Tne clinoptilolites closest to the repository, in
fractures and at the top of the Topopah Spring basal vitrophyre, ars
calcium-rich and contain only subordinate sodium and potassium.
During the thermal pulse, these calcium-rich clinoptilolites will
probably change volume by less than 4g. The potassic-sodic and
calcic-potassic clinoptilolites in unsaturated zeolite-rich tuffs at
the base of the Topopah Spring Member and in the tuff of Calico Hills
(Fig. 6) wi 11 probably undergo considerably less volume change because
of their potassium-rich compositions and because of tneir greater
distance from the repository.
The dehydration properties of clinoptilolites also are strongly
affected by the nature of their exchangeable cations. Dehydration
effects should be greatest in Cl inoptilolites near the repository
-Y-
during the heating and cooling cycle associated
pulse. Bish (1985) demonstrated that water loss in
rapid between 50°C and 130°C and slower a: higher
with the thermal
clinoptilolites is
temperatures (Fig.
8b). Calcic clinoptilolites give up about 27% of their original water
upon heating to 100°t, whereas sodic and potassic clinoPtilolit= lose
29A and 35%, respectively.
may be a significant source
environment if temperatures
Partially-dehydrated zeolites
These data suggest that clinoptilolites
cf water in the repository near-field
approach 100°C (Bish, 1985). These
could also act as significant sinks for
water durinq the cooling portion of the thermal pulse.
Ion exchange capacities in zeolites are largely controlled by tne
silica-to-aluminum ratios of their structural framework .(Sherry, 1969;
Breck, 1974). Substitution of A13+ for Si4+ causes a charge
deficiency in the mineral framework that requires a greater number of
exchangeable cations to maintain electrical Dalance. Therzfore,
zeolites with low silica-to-alumina ratios nave the high ion-excF1ange
capacities. For example, heulandite witn a silica-to-alumina ratio of
3.5 has a theoretical ion-exchange capacity 15% ~reater than clinop-
tilolite with a silica-to-alumina ratio of 5.0 (Mumpton,
Table 1). Yucca Mountain cl inoptilolites and heulandites have
19!31;
vari-
able silica-to-alumina ratios ranging from 2.3 to 6.0 (Fig. 5). Tne
calcic clinoptilolites and heulandites in fractures near the reposi-
tory and in the thin zone of zeolites at the top of tne Topopah Spring
vitrophyre tend to have slightly lower silica-to-alumina ratios thatl
cl inoptilolites deeper in the volcanic pile and, therefore, should
halve slightly higher iOn-exCllange CapaCit~eS. The deeper clinopti lo-
lites have similar silica-to-aluminum ratios despite their large
variations in exchangeable cation compositions (Fig. 5) and probab!y
-1o-
have similar ion-exchange capacities. The calcic clinoptilolites or
heulandites in the deepest clinoptilolite-bearing rocks in the eastern
part of Yucca Mountain are unusual in that they have very low silica-
te-alumina ratios (2.8 to 3.6) compared to other clinoptilolites found
at similar depths. These unusual zeolites should have relatively high
ion-exchange capacities but would only be effective in sorbing radio-
n~cl ides being transported deep within the sarurated zone on the east-
ern side of Yucca Wuntain.
The ion-exchange selectivity of zeolites for radionuclides can be
strongly affected by cations already in the exchangeable cation posi-
tions (Breck, 1974). Ames (1060) determined that the cation selectiv-
ity for clinoptiicilte is C. RbKBaSr Na Ca FeAl Mg Li. This
selectivity seq~ence is only qualitatively correct because selectivity
can varj with degree of exchange and the nature of cation speciation
in solution (il~cck, 1!]74). However. it does demonstrate that cl!nop-
tilolites in contact with groundwater solutions wili tend to selec-
tively sorb and retain radionuclides with large ionic radii. Also,
clinoptilolites already occupied by relatively large exchangeable
cations (e.g., potassium) may be less likely to exchange with radio-
nucl ides with smaller ionic radii (e.g., Sr), effectively reducing the
ion-exchange capacity of the zeolites for these elements.
In the unsaturated zone, the calcic cl~noptilolites nearest to the
repository (upper group) should be highly selective for many important
r~dionuclides including cesium, rubidium, barium, and strontium. The
selectivity of heulandite for radionuclides is less well-known, but it
and other sorptive minerals such as smectttes and manganese oxides are
conmnly associated with the cdlclc clinoptilolites and should provide
additional sorptive barriers near the repository, In the lower part
-11-
of the unsaturated zone, potasslc-sodlc and potassic-calcic clinop-
tilolites (Fig. 6) occur in thick zones containing 50-75% clinoptilo-
lite, forming major sorptive barriers between the repository and the
watertable. Between 40 and 70% of exchangeable cation sites in these
clinoptilolites are occupied by potassium in the western p~-t of the
repository. Some clinoptilolites in the eastern part of the reposi-
tory contain only 15-40% potassium as exchangeable cations. The
potdssium in these cl inoptilolites may exchange readily with cesium or
rubidium but may exchmge poorly with cat!ons of small ionic radius
such as strontium and barium. Simple exchange w+thin these clinop-
tilolites may be further complicated by cation-sieving effects in
which large cdions such as potassium may oe locked into certain
structural positions during crystallization of the mineral (Breck,
1974). Nevertheless, these clinoptilolites, particularly thos~ on the
east side of the repository, also contain significant concentra~ions
of sodium and ca?cium which should exchange more readily with a wider
variety of radionucl ides. 3atch-sorption experiments nave shown that
Yucca Mountain zeolitic tuffs are highly sorptive of cati~nic radio-
nucl ides (Janiels et al., 1982; U.S. Ikpartment of Energy, 19U4)
despite their potassium-rich clinoptilolite compositions. Ultimately,
variations in ion-exchange selectivity with clinoptilolite composition
may be relatively unimportant given the large volumes of zeolites that
gwundwaters must pass through along transport pathways, tlowgver,
this remains to be demonstrated.
in the saturated zone, the ~otassium contents of clinoptilolites
decrease systematically with depth, Calcium and sodium become pro-
gressively enriched with depth on the eastern and western sides of
Yuccd Mountain, respectively. Because of their low potassium con-
-12-
tents, these clinoptilolites should have generally similar selectivity
properties and better Ion-exchange capacities for some small-radii
radionuclides than zeolites in the unsaturated zone.
CONCLUSIONS
The compositions of Yucca 140untain clinoptilolites and their host
tuffs are highly variable. Clinoptllolltes and heulandites in frac-
tures near the repository and in a thin, altered zone at the top of
the Topopah Spring basal vitrophyre have consistent calcium-rich com-
positions, Below this level, cl inoptilolites in thick zones of dia-
genetlc alteration on the east side of Yucca Mountain have calcic-
potassic compositions and become more calcium rich with depth.
Clinoptllol~tes in stratigraphically equivalent tuffs to the west have
sodic-potasslc compositions and become more sodic with depth.
Clinoptilolite properties important for repository performance
ass~ssment include thermal expansion/contraction behavior, hydration/
dehydration behavior, and ion-exchange properties. These properties
can be significantly affected by clinoptilollte compositions. Tne
compositional variations for clinoptllolites found by this study sug-
gest that the properties will vary vertically and laterally at Yucca
thuntain. Used in conjunction with experimental data, the cllnoptllo-
lite compositions presented here can be used to model the behavior of
clinoptllolltes in the repository environment and along transport
pdthways.
-13-
ACKNOWLEDGMENTS
I want to thank Roland Hagan and Gary Luedemann for analysis of
the bulk-rock samples by XRF. Lois Tilden typed the manuscript, and
Anthony Garcia and Sharon Mikkelson prepared the illustrations. I
also thank David 1...Bish, Kimberly W. Thomas, and David T. Vaniman for
their critical review of the manuscript.
REFERENCES
Nnes, L.L., Jr., 1960, The Cation Sieve Properties of Clinoptilolite:Amer. Mineralogist, Vol 45, 689-700.
Bence, A.E.; and Albee, A.L., 1968, Empirical Correction Factors forElectron Microanalysis ~f Silicates and Oxides: J. Geol., Vol 76,382-4d3.
Bens~n, L,V.; Robison, J.H.; Blankennagel, R.K.; and Ogard, A.E.,1983, Chemical Composition of Ground ‘Water and the Locations ofPermeable Zones in the Yucca blountain Area, Nevada: U.S. Geol, SurveyOpen-File Report, 83-854, 19P.
Bish, D.L., 1984, Effects of Exchangeable Cation Composition on theThermal Expansion/Contraction of Clinoptilolite:Minerals, Vol 32, No. 6, 444-~6Z.—.
Clay and Clay
Bish, D.L,, 1985, Effects of Composition on the Dehydration Behaviorof Clinoptilolite md Heulandite: Proceedings for the InternationalConference on the Occurrence, Properties, and Ilization of datural’
Leolites, Budapest, Hunqary,
tlish, D,L.; and Vaniman, O.T., 1985, i~ineralogic Summary of YuccaMountain, Nevada: Los Alamos National Laboratory Report, LA-10543-MS,
Breck, D.d., 1974, Zeolite Molecular Sieves: Structure, Chemistry, andUse, John Wiley and Sons, NY, 771P,
Byers, F,M., Jr,; Carr, X,J,; Orkild, P.P.; Quinl ivan, W,D,; andSargent, K.A., 1976, Volcanic Suites and Related Cauldrons of TimberMountain-Oasis Valley Caldera Complex, Southern Nevada: u.S. Geol,Survey Prof, Paper, 919, 70p,
——
Christianson, R,L.; Lipman, P,W,; Carr, W,J,; Byers, F.M., Jr.;Lrkild, P,P,; Sargent, K,A., 1977, Timber Mountain-Oasis ValleyCaldera Complex ot Southern Nevada: Geul. Sot, Americ~ Bull,, Vol !38,943-959.
Daniels, WOR, et al, 1982, Summary Report on the Geochemistry of Yuccabbuntain and Environs: Los Alamos National Laboratory Report,LA-9328-MS, 364P,
-14-
.
‘. ~vy, S.S., lq84, Petrology of Samples from Dri11 Holes USW H-3, H-4,and H-5, Yucca Mountain Nevada: Los Alamos National Laboratory Report,LA-9706-MS, 77P.
Mumpton, F.A., 1960, Clinoptilolite Redefined: Amer. Mineral., Vol 45,351-369.
14impton, F.A., 1981, Natural Zeolites, in F.A. Mumpton, Ed.,Mineralogy and Geology of Natural Zeolites: Mineral Sot. AnericaReviews ;nMineraloqy, Vol 4, 1-17.
Ogard, A.E.; and Kerrisk, J.F., 1984, Groundwater Chemistry Along F1OWPaths 8etween a Proposed Repository Site and the A&cessibleEnvironment: Los Alamos Nationdl Laboratory Report-, LA-10188-MS.
Sherry, H.S., 1969, The Ion-exchange Properties of Zeolites, inJ.A. Maririsky, Ed., Ion Exchange, A Series of Advances, Vol 2, MarcelDekker, Inc., NY, 89-133,
U.S. Department of Energy, 1984, Draft Environmental Assessment, Yuccahbuntain Site, Nevada Research and Development Area, Nevada: Office ofCivilian Radioactive Haste Management Report, 00E/RW-0012.
Valentine, G., 1983, Procedures for Analysis of Silicate Rocks andMinerals at Los Alamos National Laboratory by X-ray Fluorescence: LosAlanms National Laboratory Report, LA-9663-MS, 33p.
Zielinski, R.A,, 1983, Evaluation of Ash-flow Tuffs as Hosts forRadioactive Waste: Criteria Based on Selective Leaching of YlanganeseOxides: U.S. Geol. Survey Open-Fi le Report, 83-480, 21p.
-15-
LIST OF FIGURES
1.
2.
3.
4.
5.
6.
7.
8.
Map showing location of Yucca Mountain, Nevada.
Schematic cross-section of Yucca Mountain, Nevada, showingposition of potential repository and principal zeol itic tuffs.
Exchangeab’s-cation compositions in Calcic Clinoptilolites andheulandites (upper group), Yucca Mountain, Nevada.
Summary of exchangeable-cation compositions in the lower group ofclinoptilolltes, Yucca Mountain, Nevada.
Silica-to-alumina ratios in clinoptilolites, Yucca Mountain,Nevada.
Clinoptilolite exchangeable-cation compositions (lower group )below the repository block in the unsaturated zone, YuccaMountain, Nevada,
Exchangeable-cation compositions in bulk rocks, Yucca Mountain.
Effect of composition on clinoptilolite thermal properties.
-16-
Tale 1. REWRESEKTATIVE CLIKWTILOLITE CWOSITIONS, TUCCA MAIN. WVAOA
kuk ihit—.—
~le rn.a
Si02
Ti02
“203 ~
‘=203
w
cdl
hi)
~o
K,(J.
TOTM
Si
TI
Al
Fe”’
*
Ca
ea
M
K
K
Ra
[~*Pq
.---------------------------ibsatmated Zone---------------------------- ------------Saturated Zme------------
Prm Pass *..
10wWI Spring -., Tuff of Calico Hilh, luff of cdifC~ Hills, crater Flat Tuff,
Paintbrmh luff. East sf&of Ust Sitiof CastSi& ofTopof Basal Vitmph~e Repository Block i?e!wsitw~lodt— —— Repository Bled.——. ——
J-13-1335 LE25a#I-132- Usu 6-1-1774 UE i?5afl-2oE7
66.0
0.02
13.1
0.47
o.~1
4.49
O.in
1.07
1.05
m.7
72.6
0.02
17.0
0.39
0.84
5.39
0.922.28i-413
66.1
0.03
11.6
0.02
0.38
4.01
0.15!
0.67
1.78
84.7
74.0
0.03
i5.j
0.02
O.M4.07
0.07
1.47
2.57
68.1
0.00
12.2
0.00
0.09
Ill
0.03
2.84
4.20
80.5
CATiON PERCENT—-----—71.9
0.00
15.2
0.00
0.14
1.26
0.015.82
5.66
SilAl
64.1
o.m
12.0
O.(M3
0.71
3.78
0.05
n.47
I .54
82.7
74.3
O.al
16.4
O.(YJ
1.23
4.70
0.02
1.06
2.28
4.3 4.8 4.7 4.5
*1.X EXCHAWEA8LE CATIOHS.--.—15 27 — 44 25
23 15 45 11
62 58 11 64
PraPlss Pbr.,C-alterFlat luff,
tkst SideiifRepository 810ck
Usu 6-1-2083
67.3
O.m
11.7
0.00
0.07
0.78
0.08
3.13
3.34
IM.4
72.8
0.0014.9
0.00
0.11
0.91
0.03
6.574.61
4.9
38548
——.- __
a~le ndmr cm,sists of drill hole d@5ivatfm followed by depth of saqle in feet beneath the surface.
bTotdl irm calculated as Fe203
TAUE 1[. RE~ESC~ATIVC R4AK-R(XK C~OSITIONS FM 91 AIXNETICALLY ALTERED TuFFS, YKCA MOUNTAIN, WVAEIA
Rock Unit—. .-— ToPp.M SpricgMm,
Paintbrush Tuff .--------Tuff Of c~lico H~lls.--------Pr* Pass Mder,
----------c~ater Flat TUff--.---.-.---Ehllfrog -m,
-..--.-.-.-cr~ter Flat TUff -----------
A.Nonuelded Zeolitfcluff, East Si@ of
Repository Ellock
B.Ncmeldd Ztolit{cTuff, Uest Side ofRepositoryBlocc.—
Zeollu- and
Clay-Rich Zme●t Top of
Basal Vitroptlyre
A.naMel(M ZmlltlcTuff, East Side of
Repository Elock
tE75&#l-1667
72.1
O.oa
11.3
1.00
0.05
O.lz
2.67
1.47
3.47
0.02
7.68
99.9
B.Ncwmelded Zeol~tlcTuff. Mest Side of
Reposlt~y Block
Usu 6-1-1771
A.kmwelded ZeollticTuff, East Side of
Reposltmy 810ck
B.Ibuelded ZeolitlcTuff, Wst Side of
Reps itcwy Block
U5M G-4-1314 UW G-4-2226
66.4
0.14
13.2
1.45
0.05
0.25
2.43
2.15
3.70
0.01
Usw 6U3-19C166
67.9
0.10
12.4
1.23
0.07
0.11
0.87
3.44
3.72
0.02
10.2
Km.]
N25b/lH-2879A
67.3
o.~5
11.2
1.82
0.04
:.30
3.13
1.18
3.75
0.09
7.24
USU G-3-2577
Si02 m.?
0-1/
16.7
1 .U
71.8
0.10
11.8
1.40
O(n
0.24
1.20
2.79
3.76
0.00
5.64
%.8
72.7
0.08
14.1
I .07
0.03
0.36
1.30
5.48
4.s
0.00
66.3
0.12
12.9
Ti02
Al$3~ ~
Fe703 1.32
0.10ho
wCdo
Na70
0.09
0.90
3.51
1-m
0.27
2.34
2.43
3.61
0.02
K2i
W5CLOI
0.72
0.02
5.91 9.40 9.83
TOTAL 101.5 99.2 99.2 99.3
CATION PERCENT--——--
69.8
0.1116.31.15
0.040.392.744.3.85.070.01
Si
Ti
Al
69.6
0.10
19.5
1.07
o-m
1.33
3.73
3.65
0.91
0.02
74.7
0.06
13.7
0.78
0.04
0.19
2.%
2.95
4 59
0.02
70.7
0.08
15.2
0.97
0.05
0.17
0.97
6.54
4.94
0.02
69.5
0.19
16.0
1.42
0.03
2.00
3.46
2.36
4.94
0.08
69.8
0.10
16.1
1.05
0.07
0.42
2.64
4.%
4.85
0.02
Fe+l
m
--———-●~le rider cwsists
Zielinskl (1983).
of drill hole desfgndtion folloued by depth of sqle In feet beneath the surface. Sample analfiis USU 6-1-1771 from
blotal irm as Fe20>
Vw?H
al1-Z H I
sTATi~Iy$TE~TABLE
- -. , ,-----.-..” .. .. .. ..+m$.’..m.....
h-’
\p
‘ ‘ ● *... +,.!.!.:,:,:.....0..:,;.,,;’$@j:q~; :
5E?ULLFROG MEMBER
:1
.,....,,.....,..’>,,$’.“!”,’.,.%?,4,,,,,,,,, ,,
I& ,,.. >,,,:’:::::,y~,’ .............,~t.,!,.,.,#,,,.,..,.,!...,,..,.,.,<,..’4.,,,,,,,....Abk&....6..~~*.*:s,. t,...,.:.;,;.;,;,l<.,,4.:’:.;,,..,’..,.,’,4:<..~,...,.:.,,,,,,,,,!,,!,>...$
..’*., .~.,.+4’’..,..,..’.,’,.,.,.,,,,,,..,,.!..,,,,t.,....,~...t.,,.,.,’..,’.,.,..’~,...’.,...‘,,,,$>,.,.,,,,,,.,’..., ,.,.,..>.,‘ ,,..,,,,!,.,!,,,..!.,.,.,.$.,.,,,.,,,$..,! .,,$,.$, ,,,,....,,,,.,,....,,,,...,..,,.,.,,:.:.:.:,.,.a?,.>;,~,.,<,.m.,,,,,,~,.,!,t,.,.,,..............,.~,.’,>,,.,.,,,.,J’~AM ?vIEMOE~--J?W?WA%9X.’,,, ...%’,.,...,.,, ....,,.,.,.,.,...,.,,.,,,,...!,..,,. .,, ,, --+’.+.’.,,.,.,,’.’~,.’+’$........,+,.,,,<...,.,.,,.............,,,,.,..~,...,,.!.,.,,,..!,,..,.,,,,...,,!,.,.,,.,.:.,,.,.,.,.:,:..,...>.,i4..i4.,,,,.,’,,,...,.,.,.,.,.,~,~,.,!,.,.,,,,,..t.,.,,,,..$,$:,.;,.,!..:tyf’,.<....4...,..,... ..............$....4......,,,,..,,.,.,,,..,..,.4.‘..,,..................,,!,,,.....‘ .,., .,.,...,,,,,,,,.,,’,..,.,,........,,,>$,.......’........,’,:,:,.,,,.,.;.:,::...,......,“.+,..,..,,.,,,,,,,,..,,,,,,,,’.4,+,:,::.:4;.:,:.;
%a\ 4I0 II
‘—’——————
il,’, fWiOPOSED 13EP0SlT0HY‘*4 ~REAK~UT HORIZO~i
GALGiC CLl@PTILOLITES AND MEULANDITES AT lC?PD of yOp&AH SPFlft@8A$$ALVITffOPti’@C{lJPPE~GFiOUP)
,* 2@’4E= (?FABUNOANT GLU’JQPTILQLITEIN131AGENETICALLYSa ALT~!?E~rJ@WELDEO TUFFS (LCIWERGHOUP}
I
..●
EXCHANGEABLE-CATIONS IN Ca-CLINOPTILOLITEAND HEULANDITE (UPPER GROUP), YUCCA
MOUNTAIN, NEVADA
K
●
✼
Na Ca + Mg
,- !:..’ .
.
WESTERNALKALIC GROUP
EASTERNTRANSITIONAL CALCIC GROUP
~....... . . L&_.-d_... . . . . . \ t--- —------- .
0
c1
A
●
Cm+Mg Na Ca. Mg N8 C, + Mg
NONWELOED BASE OF TOPOPAH SPRING MBR TUFF OF CALICO HILLS, AND TOP
OF Pi-iOW PASS MBR
NONWELDED BASE OF PROW PASS MBR AND TOP OF BULLFROG MBR
NONWELDED TOP OF BULLFROG MBR, AND TRAM MBR
PRE. TRAM VOLCANIC ROCKS
NOTE, SMALL ARROWS WITHIN PLOTS INDICATE CHEMICAL rRENDS WITH INCREASINGOEPTH
SCALE
o ! mile— ——
●
301
UPPER GROUP OF CALCIC CLINOP-TILOLITES AND HEULANDITES
LOWER GROUP OF CLINOPTILOLITESON EASTERN SIDE OF YUCCA MTN.
LOWER GROUP OF CLINOPTILOLITESON WESTERN SIDE OF YUCCA MTN.
IL20 :,’...’.’
. .. . . .
, (-j :;:.}::;
, :.....,.. ,.,,, :,.., ,,.,,..,. ,: ..,!.;,,’..,..”, .,, ,, ..,.. ,,,. ..,.
4.0 5.0
701
3:0 4:0 5.0 6,CJ
SilAl
40- ,,t’.,’::”:’,,:;;’.,..:..,:.”.:,,.,,.,!,’:.‘,.,,,
30-.................,..,., :,,’.....,;.“.,:,.,,’$,,,,,,
20-,:,’,,,,,,,,:,”.,,.;,;,,:”‘:,,,,,’:.,.,,,,,
lo-,,,’,,,,.,.,‘.,,,,:.,.,,,,,.:,,,,.,,,.,,,
,,,,., ,, :,A-kL I I 1 1 ! I --r*~—ll—r—,!
r-; l
3:0 4:0 5.’0 6s0
Si/Al
. .
CLINOPTILOLITE EXCHANGEABLE-CATION COMPOSITIONS BELOWTHE REPOSITORY BLOCK IN THE UNSATURATED ZONE
K
o
WESTERN PARTREPOSITORY BLOCK
EASTERN PART OFREPOSITORY BLOCKI
%\
/0
0-0
00%
~~oQ9 Om
QoO.O 0 00 0
0 Cp 000
0
[ 1 1 I 1
Na Ca+Mg
EXCHANGEABLE-CATION COMPOSTIONS IN BULK ROCKS,YUCCA MOUNTAIN, NEVADA
K
Po&
00 ●
FIELD OF UNALTERED o dTUFF COMPOSITIONS 00 ~ ●0
Oodo
\
\
o WESTERN YUCCAMOUNTAIN
● EASTERN YUCCAMOUNTAIN
/!!1 ~s
1 1
Na Ca + Mg
!
h>CLINOPTILOLITE UNITCELL VOLUMES AS A FUNCTION OFCOMPOSITION AND TEMPERATURE
em<
1>,
Na+XCHANt3ED ‘t1DSG CLINOPTILCILITE ‘*,
h. . ..--------------------------
~
J--A~o--4c4cFROM 81SH, 1944
RT. ROOM.tEMPERATUREVAC = VACUUM
!)DEHYDRATION PROPERTIES OF CLINOPTILOLITE AS AFUNCTION OF COMPOSITION AND TEMPERATURE
UJ
duNSATURATED CONDITIONS
z96 -
Al.<1 ‘,\gg 92 . ‘. \
V.EXCHANOEO CLINOPTILOLITE
(?JLu-3
‘,, \
!5
sODIUM.EXcHANOEO” ‘ “ ‘~1= kuu+. _,: .::, ... ,.,,,
CLINOPTILOLITE ——.
$ I 1 1 1 1 I 1
200 a Soa 800
TEMPERATURE (*C)