LA-1U52-MS

UC-5WIssued: June 1989

LA— 11452-MS

DE89 015327

Statistical Test of Reproducibility andOperator Variance in Thin-Section ModalAnalysis of Textures and Phenocrysts in theTopopah Spring Member, Drill Hole USWVH-2, Crater Flat, Nye County, Nevada

L. M. MooreF.M.Byers,]r.D. E. Broxton

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United StatesGovernment. Neither the United States Government nor any agency thereof, nor any of theiremployees, makes any warranty, express or implied, or assumes any legal liability or responsi-bility for the accuracy, completeness, or usefulness of any information, apparatus, product, orprocess disclosed, or represents that its use would not infringe privately owned rights. Refer-ence herein to any specific commercial product, process, or service by trade name, trademark,manufacturer, or otherwise docs not necessarily constitute or imply its endorsement, recom-mendation, or favoring by the United States Government or any agency thereof. The viewsand opinions of authors expressed herein do not necessarily state or reflect those of theUnited States Government or any agency thereof.

W OF THiS DQCUMZK7

Los Alamos National Laboratory> Los Alamos.New Mexico 87545

STATISTICAL TEST OF REPRODUCIBILITY AND OPERATOR VARIANCE IN THIN-SECTION MODALANALYSIS OF TEXTURES AND PHENOCRYSTS IN THE TOPOPAH SPRING MEMBER,

DRILL HOLE USW VH-2, CRATER FLAT, NYE COUNTY, NEVADA

by

L. M. Moore, F. M. Byers, Jr., and D. E. Broxton

ABSTRACT

A thin-section operator-variance test was given to the 2 juniorauthors, petrographers, by the senior author, a statistician, using16 thin sections cut from core plugs drilled by the US GeologicalSurvey from drill hole USW VH-2 standard (HCQ) drill core. The thinsections are samples of Topopah Spring devitrified rhyolite tuff fromfour textural zones, in ascending order: 1) lower nonIithophysaI, 2)lower IithophysaI, 3) middle nonIithophysaI, and 4) upper Iitho-physa I. Drill hole USW VH-2 is near the center of Crater Flat, about6 miles WSW of the Yucca Mountain Exploration Block. The originalthin-section labels were opaqued out with removable enamel andrenumbered with alpha-numeric labels. The slides were then given tothe petrographer operators for quantitative thin-section modal(point-count) analysis of cryptocrysta11ine, spherulitic, grano-phyric, and void textures, as well as phenocryst minerals. Between-operator variance was tested by giving the two petrographers the sameslide, and within-operator variance was tested by giving the sameoperator the same slide to count in a second test set, administeredat least three months after the first set. Both operators wereunaware that they were receiving the same slide to recount.

The operator-variance test results presented in this reportindicate that operator differences, in addition to core variation,significantly affect the results of petrographic modal analysis ofthin-section slides. However, variability within operator asmeasured by multiple readings of a slide by the same operator doesnot appear to be a significant component of variation. Thus, it islikely that an individual operator would be able to reproduce point-count results within random error, but these results would probablybe significantly different from those of another operator.

One of the operators (Byers) visually estimated the majortextures and total phenocryst content of the entire 800-ft thicknessof devitrified rhyolite, using about 100 slides, including repli-cates. The estimated data agree qualitatively with the point-countdata. A significant discovery from this work is that, because of

burial below 2500 ft and below the static water level, the TopopahSpring is slightly hydrothermaIly altered with only quartz as thestable silica mineral and also sericitized plagioclase. The top ofthe Topopah Spring is faulted with only about 10 ft of quartz latiticcaprock remaining.

The operator-variance test results and the qualitative evalua-tion of all core available from USW VH-2 indicate, again, thatpetrography of thin sections varies in a consistent manner with zone.However, the results do not suggest the nature of any systematicstratigraphic variation or precisely how an operator's results mightbe used to determine the stratigraphic source of a sample. Signifi-cant variation with depth in zone and small-scale variation within asample may interfere with assessment of stratigraphic position aswell. Further study of petrographic variation with depth orstratigraphic position is suggested.

I. INTRODUCTIONPetrographic modal analysis of thin-section slides has been considered in

investigations of the potential nuclear waste repository site at Yucca

Mountain, Nevada, for the purpose of identifying the stratigraphic position or

zone from which a core sample was obtained (Byers 1985; Byers and Moore 1987).

As a result, investigation of the degree of consistency in modal point-count

results between different petrographic operators is of interest. Petrographic

thin-section categories may include fine or coarse textures, amount of

xenoliths (foreign rock fragments), phenocryst (crystal) assemblage, micro-

cavities characterized by different silica minerals (amygdules), and presence

or absence of granophyre or quartz veinlets. The classification of a point

count into texture or phenocryst categories depends on optical identification

by the operator reading the slide. The primary purpose of this report is to

present the design and initial analyses of an investigatory experiment to test

the consistency of point-count results on a series of slides read by two

operators, F. M. Byers, Jr., and D. E. Broxton, both of the Los Alamos National

Laboratory (LANL).

Although the primary purpose of the experiment was to evaluate differences

in point-count results between Byers and Broxton, it was hoped that additional

information on variation between multiple readings of a slide by the same

operator and variation between thin-section slides would be obtained. A suite

of core samples from drill hole USW VH-2, made available through the courtesy

of J. G. Rosenbaum of the US Geological Survey (USGS), provided a source of new

thin-section slides for analysis by the two operators. However, availability

of the operators during the course of these studies limited the number of

slides for which a complete modal analysis could be conducted. Thus, the

series of slides included in the operator-variance test were selected so that

some information about different potential sources of variability was obtain-

able while recognizing that only a limited number of slides could be point

counted by both operators. After both operators concluded the test series,

Byers qualitatively examined all slides produced from the core samples provided

from the devitrified zones of the Topopah Spring above the basal vitrophyre in

hole USW VH-2 in an attempt to obtain a stratigraphic perspective and a

generalized picture of the overall petrographic variation.

Part II of this report presents further background information on studies

of the potential waste repository at Yucca Mountain, Nevada, on the collection

of core samples used for the present studies and on the geologic setting of the

area involved. Part III provides information concerning slide preparation,

thin-section modal analysis, selection and modal analysis results on samples

used in the test series, and Byers' visual estimates. Statistical analyses of

the results on the test series, discussion of the overall variation in the core

hole on the basis of the visual and modal analyses, and conclusions are

presented in Part IV. This work was sponsered by the Yucca Mountain Project

Office as part of the Civilian Radioactive Waste Management Program. The

Project is managed by the US Department of Energy, Nevada Operations Office.

II. BACKGROUND AND PREVIOUS WORKA. The Potential Site for the Repository

Yucca Mountain, in the southwestern part of the Nevada Test Site and

adjacent area (Fig. 1), is being examined for a possible national underground

nuclear waste repository (Nuclear Waste Policy Act of 1982, Public Law 97-425,

January 7, 1983). The Yucca Mountain area is underlain by a lOOO-ft-thick

candidate host rock, the Topopah Spring Member of the Paintbrush Tuff, in the

lower part of the unsaturated zone, which is slightly less than 2000 ft thick

(US DOE 1986; US DOE 1988).

The Topopah Spring tuff within the Yucca Mountain Exploration Block (YMEB)

consists mainly of about 50 ft of basal vitrophyre (hydrated obsidian with

sparse crystals or phenocrysts) overlain by about 800 ft of devitrified high-

116°45' 116°30' 116° 37° 15

30 MILES 36°

10 15 20 25 30 KILOMETERS

Fig. 1.Index map of Nevada Test Site region, showing location of USW VH-2, otherdrill holes, and the Yucca Mountain exploration block.

silica rhyolite, which would contain the potential mine workings of the under-

ground nuclear waste repository. In outcrop and in drill core this devitrified

rhyolite can be subdivided according to the presence or absence of lithophysae

(small cavities, a few inches to 2 ft in long dimension, created by expanding

gas at time of formation) into four zones: 1) lower nonlithophysaI, 2) lower

lithophysal, 3) middle nonlithophysaI, and 4) upper IithophysaI (Scott and Bonk

1984; Scott and Castellanos 1984; Spengler and Chornack 1984). These zones are

overlain by a relatively thin crystalline zone of vapor-phase crystallization

in turn overlain by a crystal-rich quartz latitic caprock, which together total

about 150 ft in thickness. The four zones, especially the lower three, would

be difficult to identify in drill core or mine workings if the overall

stratigraphic position were unknown, such as when crossing a fault in a

horizontal drill hole or mine drift. Therefore, petrographic thin-section

categories, including fine or coarse textures, amount of xenoliths (foreign

rock fragments), phenocryst (crystal) assemblage, microcavities characterized

by different silica minerals (amygdules), and presence or absence of granophyre

or quartz veinlets, were applied not only to identify the devitrified rhyolitic

zone but also to estimate the stratigraphic position within the devitrified

zone (Byers 1985; Byers and Moore 1987).

B. Source of Core Samples for the Operator-Variance Tests

Early in 1987 a hierarchical variance test was planned to compare two

operators' modal analyses of thin sections (slides) taken from different

stratigraphic levels. The primary purpose of this test was to assess the

extent of agreement between different petrographers' optical identifications of

textures and minerals in thin section for Quality Level I work on samples from

Yucca Mountain. Because no access was permitted to outcrop and drill hole

samples, we obtained a suite of 89 1-in. core plugs of the Topopah Spring tuff

in USW VH-2 drill hole through the courtesy of J. G. Rosenbaum of the USGS.

These samples were collected for USGS paleomagnetic studies following

procedures described in NWM-USGS Technical Procedure GPP-06, R0 (Rock and

Paleomagnetic Investigations) and in Rosenbaum and Rivers (1985).

These 89 core plugs provided us with sufficient samples for the study and

were already shaped for thin sectioning, which not only saved time in drill

core sampling but also saved considerable time in thin-section preparation. An

excellent lithologic log of hole USW VH-2 (Carr and Parrish 1985) was avail-

able, and it was possible from Carr and Parrish's descriptions to infer

contacts between the nonlithophysaI and lithophysal zones. Table A-I in

Appendix A lists the sampling footages corresponding to the 89 core plugs and

indicates the zone that was assessed for each plug based on Carr and Parrish

(1985). Figure 1 indicates the far-field location of core hole USW VH-2

relative to the YMEB, suggesting a potential opportunity to study far-field

lateral petrographic variation of the Topopah Spring. Also, most of the 89

core plugs were collected at approximately 10- or 20-ft-depth intervals,

providing a much closer-spaced vertical sampling interval than that used in

Byers (1985) and Byers and Moore (1987). Study of as many as 89 samples of the

unit from VH-2 would reveal what changes occur within the Topopah Spring

5 miles WSW from the YMEB and in the unit between the unsaturated zone at the

YMEB and the saturated zone in VH-2. Therefore, the Topopah Spring core from

VH-2 was selected both for an operator-variance study and also for an

opportunity to learn more about lateral changes in the candidate host rock.

C. Geologic Sett i nq

The Topopah Spring tuff penetrated in USW VH-2 is deeper than that in any

other hole in the Yucca Mountain-Crater Flat region and is below the static

water level. Drill hole USW VH-2, which was cored to a depth of 4000 ft in the

center of Crater Flat (Fig. 1), is about 6 miles from the nearest core hole,

USW G-3/GU-3, in the YMEB. The original purpose of hole VH-2 was to explore

the possibility of Pleistocene, Pliocene, and latest Miocene silicic volcanic

rocks younger than about 10 million years and to find evidence regarding a

possible caldera under Crater Flat. No post-10-mi11 ion-year-old silicic rocks

were penetrated, only alluvium, minor basalt, and megabreccia that may have

come from Bare Mountain to the west (Carr and Parrish 1985).

Drill hole VH-2 penetrated the Topopah Spring Member of the Paintbrush

Tuff; although minor faults intersected the core, no significant amount appears

cut out by faults (Carr and Parrish 1985). The Topopah Spring was penetrated

from 2550 to 3794.5 ft, a total thickness of 1244.5 ft, with a basal vitrophyre

155 ft thick. These are probably minimum thicknesses, but they are still

greater than those of similar units penetrated in holes within or near the

YMEB. Despite the increases in thickness, one of the petrographers (Byers) was

able to recognize the nonlithophysal and lithophysal zones in the devitrified

rhyolite above the basal vitrophyre from the descriptions of Carr and Parrish

(1985). However, based on thin-section examination, the upper 264 ft of the

Topopah Spring above the upper lithophysal zone is almost all nonIithophysa1

devitrified rhyolite, except for 13.4 ft of crystal-rich caprock zone. This

caprock zone is somewhat less than its true thickness because the top is in

fault contact with the overlying bedded tuff (Carr and Parrish 1985).

III. METHODSA. Slide Preparation

The 1-in. cylindrical core plugs were cut perpendicular to the core plug

axis, and polished thin sections were prepared following LANL QA Procedure

TWS-ESS-DP-04, R4. If a core plug was of adequate length, a second (replicate)

slide was taken at least 5 mm from the first cut. This procedure was adopted

to ensure little or no overlap between samples front the same plug (the largest

texture diameters are about 5 mm for the lithics; most are smaller). The thin-

section slides were labeled with the customary drill hole and footage number,

and replicate slides were, additionally, designated A and B (e.g., VH2-2591.1A,

-2591.IB). The resulting slides are therefore circular and parallel. They are

oriented in a vertical plane, inasmuch as they are cut perpendicular to the

axis of the cylindrical 1-in. core plug, which in turn is horizontal with

respect to the vertical larger-diameter drill core (HCQ - 3.937 in.). (See

Rosenbaum and Rivers 1985, their Fig. 4.) The downward direction was marked on

the core plugs and is marked on the slides in the usual manner described in

Procedure TWS-ESS-DP-04, R4. However, in the statistical tests described

herein, no utilization was made of orientation involving the down arrow. Four

core plugs at -2632.4, -2717.3, -2819.6, and -3327.8 footages were considered

inadequate samples and were not thin sectioned, but the other 85 core plugs

provided 141 thin sections, including replicates. Twenty-nine cores provided

only one slide, owing to insufficient material to provide good replicate slides

of near-equal area, 5 mm or more apart. Table A-I indicates the number of

slides obtained from each of the core plugs.

Table A-II in Appendix A indicates the number of replicate slides and

single slides obtained from the set of core plugs by stratigraphic zone. The

location of the potential waste repository is within the devitrified rhyolite

between the basal vitrophyre and the caprock of the Topopah Spring Member of

the Paintbrush Tuff. Highlighted in caps in Table A-II are the four zones

contained within the devitrified rhyolite: upper lithophysal (UL), middle

nonlithophysal (MN), lower lithophysal (LL), and lower nonIithophysaI (LN).

Because the availability of the operators necessarily limited the number of

slides that could be point counted, it was decided that only slides from these

four relevant zones would be incorporated into the operator-variance test. As

indicated in Table A-II, there were 79 slides (31 with replicates and 17

without replicates) available in these 4 zones. Moore selected 16 slides (2

replicate pairs from each of the 4 zones) for the operator-variance test. It

was expected that the footage reference on a slide could influence an

operator's reading of a slide if he recognized having read the slide previously

or if he had some preconceived notion of the texture composition of a typical

slide from the same zone or near footage. To eliminate this problem, the

footage indications on slides presented to the operators for analysis were

obscured with a removable enamel and numbered with ink on the enamel surface

for reference purposes.

After the operator-variance test, Byers qualitatively examined the 101

slides of the devitrified Topopah Spring above the basal vitrophyre. Thin-

section labels showing depth, however, were visible so that these estimates, to

be discussed further below, are not truly "blind.11

B. Thin-Section Modal Analysis

The petrographic thin-section methods used in counting the different

textures and phenocrysts have been described in an earlier report (Byers 1985).

The methods are in accordance with LANL QA Procedure TWS-ESS-DP-102, R0, dated

February 6, 1987. Paragraph 4.5.2 under Point-Counting Procedures suggests

12 000 total points per slide on a rectangular 3.0- x 2.0-cm slide of the

Topopah Spring tuff in order to obtain 12C points in phenocrysts in a slide

with 1% phenocrysts. This number of points assumes a traverse spacing of 0.5

mm and a point spacing of 0.1 mm, which are the settings on Byers' mechanical

stage. The circular thin sections of the core plugs used for this report are

1 in. or 2.5 cm in diameter, and therefore Byers was able to count 9000 to 9500

points, depending on marginal attrition, based on the above traverse and point

spacing. Phenocrysts usually are one of the lower-percent texture constitu-

ents, so if a slide of the Topopah Spring cuts only 1% phenocrysts, then only

90 to 95 phenocryst point counts would be expected from Byers' point-count

results. Broxton's mechanical stage was set for a point spacing of 0.163 mm

and a traverse spacing of 0.398 mm so that Broxton was able to count 7000 to

7800 points per circular slide used in the operator-variance tests.

In general, two different operators will likely use slightly different

point-count spacings, and thereby the total points counted will vary between

operators. The texture and phenocryst point-count results are presented as

percents of the total number of points counted so as to establish a comparable

scale between operators. It is expected that the total number of points

8

counted is large enough that any effect due to a difference in number of points

counted will be negligible. If this is not the case, then an effect due to

totai points counted would probably constitute an operator effect and

subsequent analyses should detect this.

During the period of time that the operators were point counting the

operator-variance test slides, there was no discussion of the qualitative bases

for identifying texture or phenocryst points. After the conclusion of the test

series, a list of terminology used to describe textures and phenocrysts was

extracted from the operators' lab notebook tabulations of their results. In a

joint meeting between the authors, this terminology list was subdivided into

texture and phenocryst classifications similar to those used in Byers and Moore

(1987). Texture classifications are lithic fragments, granophyre, spherulites/

microlites, cryptocrystaI Iine, voids, veins, calcite, and phenocrysts. Pheno-

cryst classifications are quartz, sanidine, piagioclase, biotite, opaque

oxides, and other mafics and accessories.

Since the two petrographers are colleagues at LANL, it is expected that

through collaborations previous to this test they may have discussed and

established some common ideas for classifying points observed into the texture

and phenocryst categories. This indicates that the results of comparison tests

between these two operators will not necessarily extend to other operators. On

the other hand, Byers has considerable familiarity with textural components

within the Topopah Spring Member based on his early work (e.g., Byers 1985;

Byers and Moore 1987). Broxton has experience in point counting phenocryst

components but was unfamiliar with the classification and analysis of ground-

mass textures within the Topopah Spring Member before this test. Therefore,

this test includes data collected by one experienced operator (Byers) and one

inexperienced operator (Broxton); these differences in previous experience

should probably influence test results more than the previous collaborative

efforts between the two operators. It is emphasized that this operator-

variance test is investigating the potential for different point-count results

by different operators and provides inconclusive results when there is no

difference between operators.

C. Slide Selection for the Operator-Variance Test

In the initial planning stage of an experiment, judgments of potential

sources of effects or variation are made and incorporated into an assumed model

that forms a basis for development of an experimental plan. Consideration of

methods that may be used in the analysis stage is of interest in the design

stage since the experimenter wants to be somewhat assured that the results

provide a sufficient base for evaluating the significance of the model compo-

nents of prime interest. Often the experimenter does not have a clear idea of

what analyses may be of interest and obviously does not know what unforeseen

problems will appear in the experimental results to confound analyses. There-

fore, an experimental plan is usually developed on the basis of both an assumed

model with standard distributional assumptions and an assumed primary purpose

for initial analyses. In this section, the model assumptions, the approach to

obtaining the slides to be read by the operators, and the operators' results

are presented and discussed.

1. Model Assumptions. Given the goals of the operator-variance test,

the following model was assumed for a specified texture percent response, y, as

part of the basis for selecting a sampling plan:

y . . , , = u + o. + z. + P i / . \ + r ,.v + s, , • ,x + e . - , ,J i j k l m ^ i j K k ( j ) m ( i ) l ( j , k ) i j k l m

where

y..k|m represents the m response (from multiple readings) by

operator i on the I slide from plug k in zone j. The effects in the model on

the right side of this equation represent the following:

fi is the mean response;

o. is the effect due to operator i;

z. is the effect due to zone j;

Pk(--v is a component of error due to random plug variation within

zone j;

rm(.. is a component of error due to replicate readings of the same

slide by operator i;

s.,. ... is a component of error due to random slide variation1 (j >KJ

within plug k in zone j; andeijkim 's a component of error due to random variation not

accounted for by the previous effects or components of

error.

Since resources for the operator-variance test include a) the two

petrographers Byers and Broxton, b) two slides, at most, cut per core plug

available from USW VH-2, and c) the previously stated restriction to the four

10

devitrified rhyolite zones (UL, MN, LL, LN), the indices ranges for the above

model description are restricted as follows:

i = 1 (Broxton) or 2 (Byers);

j = 1 (UL), 2 (MN), 3 (LL), or 4 (LN);

k(j); variable with j, is limited to the number of plugs available

within zone j;

1 (j jk) = 1 or 2, variable with plug within zone; andm(i|jjk,l), variable with operator (i) and slide (j,k,l), is

the number of replicate readings of the same slide by operator i.

The classification of effects as either fixed or random implies different

interpretations in the model. A fixed effect is assumed to be a fixed value

component of the model such that whenever, for example, operator 1 reads a

slide, then the mean, fi, is affected by adding the value of ox, the fixed

effect parameter corresponding to the appropriate operator. A random effect is

assumed to be a random fluctuation added into the model generated from a

distribution (usually assumed to be normal) with zero mean and a variance of

a . A random effect on the result will differ from slide to slide with 90% of

the fluctuations in the result due to the random effect being between -(1.96)0"

and +(1.96)a if the fluctuations are normally distributed. All random effects,

including that due to random error, are usually assumed to be independent. A

model with some random effects as well as fixed effects is called a mixed

model. The mixed model analysis of variance problems is usually concerned with

estimating the fixed effects and the variance components of the random effects.

Sear Ie (1971, pp. 382-383) provides motivation for the classification of

the effects used in the operator-variance model as fixed effects or random

effects. The effects due to operator and zone are considered fixed effects

since inferences that may be made from the resulting experimental data will

only pertain to the additive effect due to the particular operator or zones

involved. However, the effects due to plug, slide, and multiple readings are

random effects since these plugs, slides, and readings are assumed to represent

random members of their corresponding populations of possible plugs, slides,

and readings, and inferences from the experimental results will concern varia-

tion in readings due to these components. The components of variance due to

plug, slide, and multiple readings are denoted as follows:

p k ( > ) are independent with mean 0 and variance a ;

s,.. k] are independent with mean 0 and variance a R; and

r ,.s are independent with mean 0 and variance a .

11

Although the operators might be considered representative of petrographers

in general, we did not assume this for two reasons. Since Byers and Broxton

are colleagues, as discussed in the previous section, they are likely not

random representatives of the population of petrographers. Also, the particu-

lar comparison of Byers and Broxton was of interest in that experimental

results concerning operators would provide estimates of differences between

these two particular operators.

Incorporation of the plug and slide components into the model suggests two

sources of variation in slide samples. The slide component suggests a small-

scale variation within a handsample, for example, whereas the plug component

suggests variation on a larger scale of more than 10 or 20 ft. Note that the

assumption of a random plug effect in the model above does not account for the

possibility of a trend with depth in zone. The more restricted model (not

accounting for depth in zone) was assumed since evaluation of a trend with

depth was not the primary purpose of this experiment, and limitations on the

number of slides that the operators could read necessitated limiting the amount

of information that could be modeled. It was expected that, by assuming a

random plug effect, any trend with depth would surface in a significant plug

component of variance and not interfere with assessing the influence of other

effects, such as the operator effect. ;

2. Sampling Plan Development. As noted previously, the number of plugs

and slides that may be read is variable with zone and the number of readings

may be variable with operator and slide. Standard analysis of a mixed effects

model, such as that indicated for the operator-variance test, usually assumes

balanced data are obtained. This required that the number of plugs and slides

read in each zone be the same, but multiple plugs and slides are needed from

some zones to evaluate variation with plug or slide. Thus, the choice of

slides from two plugs per zone was minimal to obtain balance with respect to

plugs and obtain some information about variation within zone on the scale of

more than 10 or 20 ft as represented by plugs. To maintain balance with regard

to slides and obtain some information on small-scale variation (within a

handsample), plugs -from which replicate slides were produced were selected.

Replicate slides from 2 plugs per zone suggested 16 slides (2 pairs of

replicate slides per the 4 zones) be included in the study, and this was the

most that were considered since operator availability required some limitations

to the number of slides to be read.

12

The 16 slides to be included in the operator-variance test were selected

by choosing, randomly, 2 plugs from each zone from among those plugs with

replicate slides. Table A-II indicates that 5 plugs in the UL zone, 10 in the

MN zcne, 6 in the LL zone, and 10 in the LN zone produced replicate slides.

Table A-III indicates the sampled footages from which slides for the operator-

variance test were taken.

In order to obtain information from which to assess the variability of an

individual operator on multiple readings of a slide as well as some information

for operator comparison, each operator needed to read some slides twice as well

as read some slides that the other operator had read. To maintain balanced

data would have required that each operator read each of the 16 slides twice.

Given the limitations on the availability of the operators, 32 readings per

operator seemed excessive, so the balanced design requirement was relaxed.

With four slides per zone, it was decided that each operator would read one

slide twice, two slides once, and one not at all. This meant that each

operator made 4 readings per zone, or 16 readings total. This design ensured

that fixed effects and components of variance could be estimated, although

standard inference capabilities were limited. This seemed to be reasonable

given the amount of time the operators had to conduct modal analyses and the

investigatory nature of this operator-variance test. This design plan does not

preclude the possibility of conducting a follow-up test in which a balanced

data set couId be obta i ned.

Assignment of slides to the operator was random within the constraints of

the design plan (each operator read at least one slide from each plug in the

test). Table A-III indicates the number of times each slide was read by the

operators. The slides were presented to the operators in two stages. In the

first stage, eight slides were presented to each operator with the slide

footages hidden and the reference labels identifying the slides in random

order. When both operators concluded modal analysis of their first eight

slides, the appropriate slides were switched and relabeled again in random

order for presentation to the operators for the final stage of the test.

3. Modal Analyses Results. The results of the modal point-count

analyses of textures and phenocrysts on the 16 slides included in the operator-

variance test are shown in Table A-IV (a) and (b), and the percent of total

counts for textures and phenocryst components are presented in Table A-V (a)

and (b). These tables in Appendix A associate the point counts with the

footage and replicate marks (A or B) of the slide read and in addition

13

identify the operator from which the results were obtained. Additionally, the

zone assignment based on the lithologic log of hole USW VH-2 (Carr and Parrish

1985) is identified in the "True Zone" columns of these tables. While the

footage of the slide, and thus the "True Zone," were hidden from the operators

during point counting, each operator assigned the slide to a zone on the basis

of his point-count results, his limited examination of the thin section, and

prior experience with core from the four devitrified rhyolite zones. These

zone assignments by the operators are listed in the columns labeled "Placed

Zone." The remaining column headings in these tables are self-explanatory.

P. Visual Estimates of Constituents in Thin Section

In order to view the variance tests in strati graphic perspective and to

obtain a generalized picture of the overall petrographic variation, Byers

qualitatively examined the 101 slides, including replicates, that sample the

devitrified zones of the Topopah Spring above the basal vitrophyre in hole USW

VH-2. This petrographic examination consisted of making estimates of the

constituents, following but without consulting the results of the operator-

variance test. Thin-section labels showing depth, however, were visible to the

operator, so these estimates are not truly "blind." The estimates of various

constituents normally counted in the mode were made by viewing the thin section

under the petrographic microscope at low magnifications; namely, 10X and 35X.

The percentages of different textures and total phenocrysts can be reasonably

estimated, but only ranking estimates are made among the different phenocrysts.

Constituents in a few slides of cores from the lower part of the upper litho-

physaI zone are not estimated at all, owing to the introduction of quartz and

recrystalIization.

IV. RESULTS

A. Analyses of Operator-Variance Test Results

Figures 2-14 are graphs of the percent point-count results for each

texture and phenocryst component against the footages of the samples analyzed.

Because each slide was analyzed two times and each footage has two associated

slides, there are four observations at each of eight footages. The observa-

tions at each footage are labeled "F" if Byers was the reader and "D" if

Broxton was the reader. Also, each observation is labeled by a slide number: 1

identifies the slide read once by both operators and 2 identifies the slide

read twice by the same operator.

14

ooo

CDO)CO

So

2.9

3.0

3.1-

3.2-

3.3-

3.4-

3.5

F1

(o D 1

*\D2

rolF?D1

F2

D OF1F2

F1O OD1

OD1

OD2

OjO OF1

F1O

OD2

D20 OD2

F2 F2O O

F2 F2O O

010 OD2

01o

F1O

OF1

O D 1

O D 2

0.0 0.2 0.4

Fig. 2.

0.6 0.8 1.0 1.2

percent lithics

1.4 1.6 1.8

OO

o0

Soo

2.8

2.9-

3.0

3.1- 08 02

0 0 OF1

3.2-

3.3-

3.4-

3.5.

F20 OF2

L/2

01000 OF2

210200 00 F10 2

D1

«>F1 OOF2F2

D1O Fo2

D10 0F1

D20OD2D1O

F2OOF1

01 02o oo

F1OD2

0.0 4.0 8.0 12.0 16.0 20.0 24.0

Fig. 3. percent granophyre

28.0 32.0

Plots of the individual texture and phenocryst content with depth in slidesfrom USW VH-2. Fl-Dl indicates count of same slide by two operators; F2-F2indicates count of same slide by F. Byers, D2-D2 indicates count of same slideby D. Broxton.

15

2.8

2.9

ooo0

BOo

3.0

3.1

3.2

3.3

3.4-

3.5.

F1O D1OOD2 OD2

OD2

OD2

OD1

Dl

D1O

F2O

0 F1OCPF2

D10DF2

D20

F2 F2

D1O (DOD1

D28DF1

D2F 1 O 0 OD2

F1 F 2 , F 2

DIOO cc

O F l

OF1

33.0 40.0 47.0 54.0 61.0 68.0 75.0 82.0 89.0 96.0

Fig. 4. percent spherulites/microlites

ooo

0

#O

o

2.8n

2.9-

3.0-

3.1-

F1 F20 0 OD1

F2

3.2-

3.3-

3.4-

3.5

F1 01O O OD2

F2 F2OOO OD1

Fl

F1OOD2

D2 D2

O <JDF

F2 F10 0 0 OD1

F2

F2 D1O OF2

F1OOD2

OD2

O D 2

O D 2 OD1

0.0 5.5 11.0 16.5 22.0 27.5 33.0 38.5 44.0 49.5 55.0 60.5

Fig. 5. percent cryptocrystalline

16

(100

0

CDO)

foot

*

2.9

3.0

3.1-

3.2-

3.3-

3.4-

3.5

FlO

DlO

OD1

020 OD2

Fl0

F2O OF2

F20OF2

F2O

FlO

OF2

O D 2

Fl Dl

O~ FS0D F2

F1CDD1

O D l

O D l

D20

DZO

D20OD?

D2O

Fl Dl

o o

DZ FT

o o <

0.35 0.55

Fig. 6.

0.75 0.95 1.15 1.35 1.55 1.75 1.95

O D l

2.15

percent phenocrysts

ooo

CDO)COoo

c.o-

2.9-

3.0-

3.1-<

3.2-

3.3-

3.4-

3.5

F2 Dl3 OF2 0 OF1

ID1/ (F l5 O OD2

D2

°2 F10 CfODl

D2

F2 F2000 ODlFl

(DlHF2 OF1

D2OOD2

1

F1O

02O OD2 OF1

F1O ODl

OF2

OD1

I 1

O F 2

1

O D l

1 )0.00 0.15

F ig . 7.

0.30 0.45 0.60 0.75 0.90 1.05 1.20 1.35

percent voids

17

2.8

ooo^,CDCDiSOO

2.9

3.0-

3.1-

3.2-

3.3-

3.4-(

\

\

IF1

I

F1D lF2F2

F l[DllD2

FlD1F2F2FlCO

F1D1F2F2

FlF2F2

F1D1D2D2

3.5.0.00

OD2

D10

Fig. 8.

°O OD1D2O

D1O

0.05 0.10 0.15 0.20 0.25

percent veins

ooo

CDO )CO+-»oo

£..O

2.9

3.0-

3.1-

3.2-

3.3-

3.4-

3.5

I F2

/Dl> OF2

IF1

/D2ID2

L IF1

\)D1)D2(D2i ni

NF1

]F2lF2

D1

| F 1

\°l1 D2

OF2

OF1

OD2 OD2

OF2 OF2

I J

0.00 0.05 0.10 0.15

Fig. 9. percent calcite

0.20 0.25

18

2.9

^ 3.0

ooo

CDO)CO

•i—<oo

3.1-

3.2-

3.3-

3.4-

3.5.

OFl

D2OO OD2

Fi

D10 OF2F2

O) F1

o o

F1o o

D2

F2 D1O OOOF1

F2

F2O OD1

OD1

O F l

O D 2

Or1

0.00 0.05

Fig. 10.

OD1

F10 OD2

0.10 0.15 0.20 0.25

quartz percent of total

0.30

ft)

(100

0

Q>D)frt

foot

.

<£.O

2.9-

3.0-

3.1-

3.2-

3.3-

3.4-

3.5

F1OODt

F1O D2®D2

D18DF1

1

F2 F2O O

OD1

01F1O O

D2 D2 F1O O D1OO

F2F2OO

D7F2OOF2 O O

Fl

1 I

F2 0DF2

D2O O D2

F1 010 O

D1 F1

D2O OOD2

0.0 0.2 0.4 0.6 0.8 1.0

Fig. i i . plagioclase percent of total

1.2

19

ft)

000

tage

oo

CO

2.9

3.0-

3.1-

3.2-

3.3-

3.4-

3.5

Fl F2 F2DlOO 0 O

F2OOF2 DlOOFI

O D1COF1

02 D202

D1OOF1 O 002

F20 OF2

F2 Dl

o a> OFIF2

02 O OD2

1 1

FlO O01

Dl FlO 0

D1OOF1

02O OD2

1 1 1

0.00 0.25 0.50 0.75 1.00 1.25

Fig. 12. sanidine percent of total

1.50 1.75

Ooo

O)CO

•«—>oo

C-.O

2.9-

3.0-

3.1-

3.2-

3.3-

3.4-

3.5

F2• o

F2O

FlOODl

FlO

0F2

002

Fl F2

X

OD2

D2OOD1

F1O

F20DF2

OF2

OFl

F1O

DlO

OD2

F1 Dl0 O

O D 2

1

Dl0

020

02O

010

1 1

02 Dlo o

01o

1 1

0.000 0.025 0.050 0.075 0.150 0.175

Fig. 13. opaques percent of total

20

+_,**~

ooo

0O)COOO

2.8

2.9

3.0

3.1

3.2-

3.3-

3.4-

3.5

F2 F2F 1O 0 OD1

D2D1O 0 OOF1

D2

D1 F2 F2F1O O O O

F1D2O 0 OD2 OD1

F1>D1 0 ©

D2 D2F2

D1OOF1 O OF2

F2 F2

FiO CD 0D1

D2Fit© OD2

J 1 I

O D 1

1 P

0.00 0.05 0.10 0.15 0.20

Fig. 14. biotite percent of total

0.25 0.30

Each texture and phenocryst component percent is analyzed individually by

fitting a mixed model analysis of variance to assess the significant components

of variance and estimate the fixed effects in the presence of the effects

corresponding to the significant variance components. Table A-VI (a) and (b) in

Appendix A lists the estimates of the significant fixed effects and variance

components for texture and phenocryst percents, respectively. Methods of

univariate analysis for a mixed model with unbalanced data are described in

Searle (1971), and the particular approach used in the following analyses is

referred to as the Fitting Constants Method or Henderson's Method 3 (Searle

1971). This method yields unbiased estimates of variance components, but since

the data are unbalanced, the standard distributional assumptions underlying

tests of significance are not valid. Usually a test of significance makes a

comparison between the estimate of the variance component and the error

variance estimate, so in the analyses conducted here a variance component was

judged significant if it was large relative to the error variance estimate. If

a variance component was not judged significant, it was dropped from the model

21

and the alternate model was fit and analyzed similarly. Since the data are

unbalanced, some estimates may change with the order of components in the model

or with exclusion of some components of the model. However, it is noted that

due to some aspects of balance in the data, the estimates of zone effects are

unchanged with model alteration. Since the operators did not read all slides

the same number of times, the estimates of operator effects wiI I change with

exclusion of r ..., or p.,.., or s.,. .., the multiple reading, or plug or sliderail / »UJ HJi")

components of variance. The components of variance estimates associated with

plug multiple readings and slides will be altered if their order is changed in

the model. These differences were taken into account in analyses, so several

model arrangements were considered to ensure that exclusion or inclusion of an

effect or component of variance did not change with these alterations in the

model. The final model contains those effects that wens judged significant,

and estimates are obtained on the basis of this model.

The operator effect is significant in the granophyre, spherulites/

microlites, cryptocrystalIine, phenocryst, and vein texture categories. In

Fig. 3, the graph of granophyre texture percents, it is noticed that Byers'

results on the slides read by both operators are consistently higher. Analysis

indicates an estimated expected difference in operators of about 2 percent

points with Byers' additive effect being higher. The estimated mean granophyre

percent count, across all slides, is 6.1%, with zones as a significant effect

and significant variation attributed to plug and slide as well. The estimated

expected difference between operators in spherulites/microlites texture

percents (graphed in Fig. 4) is about 12 percent points, Byers' percents being

typically higher, with an estimated mean, across slides, of about 835?. Zones

are the only other significant effects indicated by the spherulites/microlites

data. The dominant effect in the cryptocrystalIine results (graphed in Fig. 5)

is operator dependent with Broxton's expected results higher than Byers' by

about 12 percent points. This is significant when considering that the

estimated average percent cryptocrystalIine is about 9%, and no effect due to

zone is indicated. Figure 5, the graph of cryptocrystalIine percents, shows

that Broxton's results are noticeably higher than Byers'. The results for

phenocryst counts indicate significant variation due to plug and slide as well

as zone and operator differences. Figure 6 shows that slide 1 and slide 2

results are set apart one from the other for each plug. With the exception of

the operators' readings on the slide from footage 3137.3, Broxton's results

22

were typically greater than Byers' results with an estimated average difference

of 0.1 percent points relative to an estimated mean phenocryst percent of 1.1%.

In Fig. 8, the graph of the vein-percent results, it is immediately obvious

that Broxton has the only non-zero counts for veins. This is not merely an

artifact of slides read by Broxton since three of the seven non-zero vein

counts are on slides that Byers analyzed as well and two are replicate observa-

tions on slides that Broxton read once as having non-zero vein count. One

slide, from the plug at 3137.3 ft, Broxton analyzed twice with a non-zero vein

count. Since Broxton's counts on veins are low (<0.25%), it is hard to know

how much impact vein count might have on Broxton's strati graphic assessment of

a slide based on modal point counts. However, significant zone differences are

indicated for the vein-percent results with the UL zone having the lowest vein

counts and the LN zone having the highest vein counts. Also, vein-count

variation with plug is indicated as significant.

Plagioclase, sanidine, and opaque oxides are the phenocryst categories

with significant differences between operators. The plagioclase percents,

graphed in Fig. V , differed between operators with an estimated expected

difference of about 0.09%, Broxton's results typically being higher, relative

to an estimated average, across all slides, of about 0.55%. Sanidine percent

counts are graphed in Fig. 12. Byers' sanidine percents were typically higher

by an estimate of 0.06% on average relative to an estimated mean sanidine

percent of 0.40%. The opaque oxide percents, graphed in Fig. 13, differed

between operators with an estimated expected difference of about 0.04%,

Broxton's results being higher, relative to an estimated average, across all

slides, of about 0.05%.

The phenocryst counts are quite low relative to the total count. In the

case of the biotite (graph in Fig. 14) and the other mafics and accessories

categories (graph omitted due to low counts), the counts are not significantly

different from zero with random error variation. However, the other texture

categories do exhibit consistent variation with zone, and for these reasons the

phenocryst categories have been considered in past studies for use in

stratigraphic analysis (Byers 1985; Byers and Moore 1987).

The opaque oxides phenocryst category is the only one, among all texture

and phenocryst categories, in which the multiple reading component of variance

is significant. In this category, the multiple reading component of variance

is significant with an estimate of about 0.016% standard deviation relative to

23

an additional estimated random deviation of about 0.023%. This suggests that

either the operators are generally consistent in their evaluation of texture

and phenocryst categories or their inconsistencies are minor relative to other

sources of variation, sometimes including core variation with different plugs

and si ides.

The results of the plug and slide component of variance study suggest a

high level of variation in the core, possibly with respect to depth in zone but

also on a small scale. Plug and slide components of variation are significant

in granophyre, phenocryst, and calcite texture results and in plagioclase and

sanidine phenocryst results. Typically, in studying Figs. 2-14, one may look

for consistent discrepancies, such as one operator's results are always

somewhat higher than the other operator's or same slide results group away from

the results on the other slide at the same footage. For example, in Fig. 12,

the graph of sanidine percent results, the slide 2 results are typically offset

from the slide 1 results. In the statistical evaluation of the components of

variation for the sanidine texture results, the slide component of variation is

indicated as significant, in addition to the plug component of variation.

Additionally, the plug component of variation is indicated as significant in

the voids and veins texture results and the quartz and opaque oxides phenocryst

results. Further investigations of core variation with depth should probably be

pursued in future studies.

With the exception of cryptocrystalItne texture results and biotite and

other mafics and accessories phenocryst results, texture and phenocryst percent

results were significantly different according to zone. This is consistent

with previous studies (Byers 1985; Byers and Moore 1987), but a means of

determining zone or strati graphic position of a sample on the basis of the

petrographic point-count results is not immediately apparent from these

studies. However, it is noted that the lithic fragments, voids, and calcite

textural percents and the quartz phenocryst percent results (Figs. 2, 7, 9 and

10) do not indicate a significant operator effect. This suggests that operator

readings of these textures and quartz phenocrysts are fairly consistent, and

zone variation may be more clearly detected from these point-count results.

Further study of the nature of core variation with depth as well as a more

comprehensive approach to the use of petrographic point-count results for

strati graphic determination based on the compositional nature of these

multivariate observations should be pursued.

24

The analyses presented here are a first evaluation of the data obtained

from the operator-variance test. One assumption underlying these analyses is a

constant error variance independent of the magnitude of the expected result.

This assumption may be violated if the variation in texture percent increases

with an increase in texture percent. In previous studies such as Byers and

Moore (1985), a transformation of the data was employed to attain the property

of constant error variance. Analysis of transformed data yields estimates that

pertain to the transformed data. Relating these estimates back to differences

in the operators' percent results would then be difficult. Thus, in order to

obtain easily interpretable estimates of the differences in percent results

between the two operators and of the effects of the other factors on the

percent results, no transformations were considered. The impact of these

assumptions should be investigated in future analyses. In addition to

investigation of these arid other model assumptions, alternate methods to the

Fitting Constants Method for estimation of variance components and more

rigorous significance tests for unbalanced data might be considered.

The compositional nature of the results of modal analysis of a thin-

section slide was also not considered in these analyses. That is, since the

texture and phenocryst percents sum to 1OOJS, it may be of interest to consider

a comparison of the relative values of the percent results for the two opera-

tors and different slides. Research in and application of multivariate

techniques for compositional data analysis should be considered for evaluation

of modal analysis results.

B. Qualitative Petrographic Variation with Depth Above the Basal Vitrophyre

The petrographic modal analyses of the variance test and Byers' estimates

of the constituents are inserted at the proper strati graphic position in Table

B-I in Appendix B, which also shows strati graphic position of faults and

textural zones inferred from Carr and Parrish (1985). The graphical represen-

tation of five textural types selected from Table B-I is shown in Fig. 15 and

includes percentages of lithics, granophyre, cryptocrystalIine groundmass,

total phenocrysts, and quartz phenocrysts. These five textural categories were

chosen because they seemed to vary the most with depth of stratigraphic

position within the Topopah Spring.

Eight textural categories including the ones above were used to define

stratigraphic position within and near the YMEB (Byers and Moore 1987). The

three not used in Fig. 15 are spherulites, amygdules filled with Cristobalite

25

DEPTH (It)

2500-

2600-

2700-

2B00-

2900-

3000

3100

3200

3300-

3400-

3500

3600

3700

r

;;i--

~

-

rrrT

;Z.

Z_

:

-

-

;

:•

PRINCIPALZONES

Sampled tootayHS

TOP PAULTED

MIXED ZONE OF

RHYOLITE ANDOOatoQTZ LATITE

coniacl inferredirom petrography

RHYOLITIC ZONEOF VAPOR PHASECRYSTALLIZATIONLITHOPHYSAL INLOWEH PART

UPPER ,LITHOPHYSAL

ZONE ,

MIDDLE 'NONLITHOPHYSAL

ZONE

LOWERLITHOPHYSAL

ZONE

„ „ , LOWERNONUJHOPHYS^i

?ONE

BASALVfTROPHVRE

«-v-PAftTLY WELDE. . . . . . V/ITRIP

NONWELDED.

ZEOL'TJC

% LITHICS

0 5 10 15

O

O(none)

Q

Oa'fTlOBl

none)

. (net

O !ne>

o•oto *oo

«•-(+ Oto o

o 5

o ° o oI *o»: •

OO

o

(VITROPHYRE)

Thin SRCticins ininterval not estifnor counted

5.5-

(

10

3 -a

•

_?__

% GRANOPHYRE (LARGELY MICRO-

t?°°(Jo (

OD

offC£D»*

O

oV

S1

)»4

JTJ)

a>ooo

GRANULAR QUARTZ)

10

O

O

+

th snatea Q

•

+

B m i

20 30

o

me) • 4

(ne)

10

3 O

(3>*»o

y x «j

o • » +o

1

Sx .

3D

° °

8 8» >o • a

0

• f(VITROPHYRE)

Fault or brecciated zone (Carrand Parrish 1965).

Estimated percentage ptot (Byers)

orM Two-operator count ol5 J same thin section

Broxtcn count of same thin sectionat different limes

% CRYPTOCRYSTALLINE(INCLUDES CLAY IN PART)

20 30 40 50

CD

4- (ne)

(ne)

+O

o •

o

° 8n o p° 8 o

oo ° + 8

[VITROPHYRE)

EXPLANATION

x * Byers count of same thin sectionat different times

7 5 -J Estimaled percentage off diagram;i doubled arrow, both estimated off

diagram

(ne) Not estimated, owing to veining andrecrystallization

% PHENOCRYSTS

0.5

OD

o

o

8c

o

1.0

o

8• o

o

» » „o

0 o00

°<&Qb °

? *o

o o

8o

8OQ

8o

o

ocPft

° fi8oa%

1.5 2.0 2 5

8 S ° ^o * #

o °

o

o

o• -IB

(nelO

++

• •

HO+ • •

% QUARTZ PHENOCRYSTS(COUNTED MODES ONLY)

0,1 0.2

Sampled lootages ^

\

none) -

-

none)-

c(none)

-

(xx * :

(none)

' *f + -

»* :

» 4 x :

¥ 4 + :

(VITROPHYRE) (VITROPHYRE)

L1

, Vertical (strat graphic) position otsampled lootages. Most tootages have

1 two thin sections. -A and -B. whichcan only be identified as two similarplots per constituent per footage, butnot as A or -B (See Table B-1).

BASE 3723 It

Thin-section comparison of estimated modal percentages and counted modal percentages within and betweenpetrographers of selected constituents most likely to vary with depth (stratigraphic position) in theTopopah Spring Member, drill hole USW VH-2. The estimates were made on all thin sections above thevityrophyre. Selected petrographer-counted thin sections were estimated percentages made by onepetrographer (Byers) with knowledge of the footage but without access to the modal data.

or tridymite, and voids. The reasons for not showing these three categories on

Fig. 15, other than space, are as follows: 1) Percent of spherulites is

generally the residual or "waste basket" category in a thin-section modal count

and adds nothing that is not shown by variation of cryptocrystalIine and

granophyre textures. 2) Neither Cristobalite nor tridymite was seen in thin

section. Whatever Cristobalite or tridymite may have been present has all

probably converted to the stable phase quartz, and the amygdule fillings are

counted as granophyre. The absence of Cristobalite and tridymite may be

related to the deeper burial of the Topopah Spring approximately 2000 ft

beneath the static water level. 3) Finally, with few exceptions, any voids

that may have been present originally are now filled with quartz, calcite, or

other mineral, probably again owing to deep burial beneath the static water

level. It is approximately at 600-ft depth, based on a measurement in nearby

USW VH-1 (Fig. 1; Thordarson and Howells 1987).

The overview of the results of the operator-variance tests (Fig. 15)

illustrates the following by appropriate symbol: 1) Byers' percentage

estimates of the 101 slides as background; 2) 2 percentage estimates of

constituents in the same slide, one by Byers and the other by Broxton (between

operators); and 3) 2 percentage estimates of constituents in the same slide,

each by Byers and Broxton at different times (within operators). Figure 15

does not distinguish between thin section A and thin section B nor how close

percentage counts agree between A and B, but Table B-I does show these

comparisons. An examination of Fig. 15, however, indicates there are signifi-

cant differences in some petrographic constituents between many sampled

footages, but unfortunately it is not clear whether one could consistently

identify strati graphic position within most of the devitrified Topopah Spring

rhyolitic tuff.

The open circles representing Byers' estimates of thin-section parameters

in Fig. 15 are in general agreement with the "hard" data generated by thin-

section modal counts at 10 different strati graphic levels through the devitri-

fied rhyolite. The worst agreement both between and within operators occurs in

the lowest sample at 3428.6 ft just above the basal vitrophyre. Both A and B

replicates of this sample had significant granophyre and also significant clay

alteration, which overprinted cryptocrystalIine textures related to cooling of

the Topopah Spring tuff at the time of emplacement.

27

About the only criterion that most reliably might indicate strati graphic

position is the recognition of quartz I atitic pumice lenticles within the mixed

zone of rhyolite and minor quartz labite in the upper 100 ft of drill hole VH-2

(Fig. 15). At the bottom part of the devitrif led rhyoiste just above the basal

vitrophyre, proper evaluation of a combination of higher cryptocrystaMine

groundmass, higher quartz phenocryst content, arsd higher iithic content might-

indicate the lower non I ithophysa! zo.:ie (Fig. 15).

A finer-grained middle zone, possibly related to the middle nonIithophysaI

zone, is suggested by cryptocrystai 1i ne values, both counted and estimated,

ranging from 5 to 31% through the uppermost part of the lower IithophysaI zone

and the lower part of the middle noniithophysaI zone (Fig. 15). Within this

increased cryptocrystaJIine zone, however, are two low estimates of crypto-

crysta I i inity just below 3100-ft depth. The general increase in the crypto-

crystalline values in this interval is aiso accompanied by reduced granophyre

values, mostly less than 3%. If this interval is indeed the middle noniitho-

physa I zone, it wouSd be moved downward on the basis of the petrography by

about 50 ft, in comparison to the geologist's contacts (Carr and Parrish 1985,

their Table 2 ) . However, the reverse situation occurs with respect to driil

hole USW GU-3 between the geologists and the petrographer (Byers) in that the

petrographer (Byers and Moore 1987, pp. 28-29, their Fig. 12) picked the lower

contact of the middle noriIithophysa! zone about 50 ft higher than that based on

geology (Scott and CasteManos 1984, p. 99).

In general, both quartz phenocrysts and lithic fragments tend to decrease

upward (Fig. 15) but onfy to the extent that the upper fithophysa! zone and

higher zones might be recognized. A few of the specimens through the upper

part of the devitrified rhyoiite above the middle non!ithophysaI zone do not

fit this trend; this problem emphasizes the need to collect three or more

specimens at any one strati graphic level in order to determine approximate

stratigraphic position.

C. Conclusions and Summary

The operator-variance test results presented in this report indicate that

operator differences, in addition to core variation, significantly affect the

results of petrographic modal analysis of thin-section slides. However,,

variability within operator as measured by multiple readings of a slide by the

same operator does not appear to be a significant component of variation. Thus,

it is likely that an individual operator would be able to reproduce point-count

28

results within random error, bub these results would probably be significantly

different from those of another operator.

The operator-variance test results srsd the qualitative evaluation of a!i

core available from USW Vri-2 indicate, again, that; petrography of thin sections

varies in a consistent manner with zone. However,, the results do not suggest

the nature of any systematic stratigraphic variation or precisely how an

operator's results might bs used to determine the stratigraphic source of a

sample. Significant variation with depth in zone and suiaIi-sca!e variation

within a sample may interfere with assessment of stratigraphic position as

well. Further study of petrographic variation with depth or stratigraphic

position is suggested.

ACKNOWLEDGMENTSDavid A. Mann participated in discussions on how best to cut the thin

sections from the core piugs and provided excellent thin sections of the core.

Anthony T. Garcia and C. James Archuleta prepared the illustrations. Barbara

E. Hahn prepared the typescript and assembled the report following LANL

editoriai and QA procedures. Richard J. Beckman reviewed the manuscript, but

the authors accept fu i ! responsibility for the accuracy of the data and the

interpretations contained herein.

REFERENCES

Byers, F. M., Jr., "Petrochemical Variation of Topopah Spring Tuff Matrix withDepth (Stratigraphic Level), Drill Hole USW G~4, Yucca Mountain, Nevada,"Los Alamos National Laboratory report LA-1O56I-MS (December 1985),HQS.880517.1103

Syers, F. M., Jr., and L. M. Moore,. "Petrographic Variation of the TopopahSpring Tuff Matrix Within and Between Cored Drill Holes, Yucca Mountain,Nevada," Los Alamos National Laboratory report LA-10901-MS (February1987). HQS.880517.2630

Carr, W. J., and L. D. Parrish, RGeology of Drill Hole USW VH-2 and Structureof Crater Flat, Southwestern Nevada," US Geological Survey Open-FileReport 85-475, 41 pp. (1985). HQS.880517.1918

Rosenbaum, J. G., and W. C. Rivers, "Paleomagnetic Orientation of Core fromDrill Hole USW GU-3, Yucca Mountain, Nevada: Tiva Canyon Member of thePaintbrush Tuff,fi US Geological Survey Open-File Report 85-48, 116 pp.(1985). HQS.880517.2846

29

Scott, R. B., and J. Bonk, "Preliminary Geologic Map of Yucca Mountain, NyeCounty, Nevada, with Geologic Sections," US Geological Survey Open-FileReport 84-494 (1984). HQS.880517.1443

Scott, R. B., and M. Castellanos, "Preliminary Report on the GeologicCharacter of Drill Holes USW GU-3 and USW G-3, Yucca Mountain, NyeCounty, Nevada," US Geological Survey Open-File Report 84-491, 119 pp.(1984). HQS.880517.1444

Sear Ie, S. R., Linear Models (John Wiley ft Sons, Inc. New York, 1971).

Spengler, R. W., and M. P. Chornack, "Stratigraphic and StructuralCharacteristics of Volcanic Rocks in Core Hole USW G-4, Yucca Mountain,Nye County, Nevada," with a Section on "Geophysical Logs" by D. C. Mullerand J. E. Kibler, US Geological Survey Open-File Report 84-789, 77 pp.(1984). NNA.870519.0105

Thordarson, W., and L. Howells, "Hydraulic Tests and Chemical Quality of Waterat Well USW VH-1, Crater Flat, Nye County, Nevada," US Geological SurveyWater-Resources Investigations Report 86-4359, 20 pp. (1987).

US Department of Energy, "Environmental Assessment, Yucca Mountain Site,"Vol. I, DOE/RW-0073 (May 1986). NNA.890327.0062

US Department of Energy, "Exploratory Shaft Test Plan," Rev. 1, DOE/NVO-224(January 1988).

30

APPENDIX A

STATISTICAL DATA ON REPRODUCIBILITY AND OPERATOR VARIANCE INTHIN-SECTION MODAL ANALYSIS OF SELECTED SLIDES FROM DRILL CORE OF

TOPOPAH SPRING DEVITRIFIED RHYOLITE, DRILL HOLE USW VH-2

TABLE A-I

SAMPLING FOOTAGES, ASSIGNED ZONES, AND NUMBER OF THIN-SECTION SLIDESCUT FROM USW VH-2 1-in. CORE PLUGS

Samp 1edFootage

25S9.22571.02581.12591.12601 . 82612.42632.426542668.22707.12717.32766.42776.32809.92819.62829.82849.02868 .72879.52889.62899.32909 .52919.22929 .82949.42959.12968.72978.82988.82998.83007.53020.23035.23046.23058.23068.83078.53088.33103.43115.33125.23137.33146.83175.83185.2

Zone*

CR'CR]'CR];CR]CRCR"CRgCRCR'CR'CR:

CRCRCR

L,O

D

kUL "ULULULULULULULULULULULULMNMNMNMNMNMNMNMNMNMNMNLLLLLLLLLLLLLL

SI idesCut

221222012202220112112221112222122222222122121

Samp 1edFootage

3213.43224.23246.23256.53266.83227.03287.13297.53307.53317.53327.83336.13346.43356.73378.43397.23408.03418.53428.13438.73458.63468.73496.73508.83518.83528.73538.83559.23569.63579.63590.53600.53610.5362O.53630.53640.23650.63660.63670.63680.63690.53700.63710.63720.6

Zone"

LLLLLLLLLLLNLNLNLNLN .LN b

LNLNLNLNLNLNLNLNBVBVBVBVBVBVBVBVBVBVBVBVBVBVBVBVBVBVBVBVBVBVBVBVBV

S1i desCut

21112221202222112211121121122221211222222222

Zone indicators (based on Carr and Parrish 1985):CR: cap rock. Those in brackets proved to be phenocryst poor,

devitrified rhyol ite, based on thin-section examination (Tab IB-I, Appendi x B) .upper Iithophysal.UL:

MN:LL:LN:BV: basal vitrophyre.

Insufficient material prohibited preparing slides from some plugs.

m i ddIe nonI i thophysaI .lower I ithophysal.lower nonIithophysal.

33

TABLE A-II

NUMBER OF REPLICATE AND SINGLE SLIDES PREPARED FROMTHE 89 CORE PLUGS AVAILABLE FROM USW VH-2 BY ZONE

Zone

[CR]ULMNLLLNBV

* [CR]:UL:MN:LL:LN:BV:

Plugs

141311121425

caprockupper 1m i dd1e1ower 1

Two s1i des

105

106

1015

(see footnote,ithophysa1.non1i thophysa1.ithophysa1.

lower noniithophysa1.basa1 v itrophyre.

One siide

2*7b16.3b

10

Table A-I).

Insufficient material or severe fracturing pro-hibited preparation of slides from some plugs.

Zone*

UL

MN

LL

LN

TABLE A-III

OPERATOR-VARIANCE TEST

Samp 1edFootage/SIide

2868.7/AB

2919.2/AB

2998.8/AB

3058.2/AB

3137.3/AB

3213.4/AB

3317.5/AB

3428.6/AB

TimesBroxton Read

0112101212011021

PLAN

TimesByers Read

2110121010211201

UL: upper IithophysaI.MN: middle noniithophysaILL: Iower Ii thophysaI.LN: lower noniithophysa!.

34

Samp 1edFootage

2868.7A2868.7A2868.7B2868.7B2919.2A2919.2A2919.2B2919.2B2998.8A2998.8A2998.8B2998.8B3058.2A3058.2A3058.2B30S8.2B3137.3A3137.3A3137.3B3137.3B3213.4A3213.4A3213.4B3213.4B3317.SA3317.0A3317. SB3317.bP3428.6A3428.6A3428.SB3428.SB

TrueZone

ULULULULULULULULMNMNMNMNMNMNMNMNLLLLLLLLLLLLLLLLLNLNLNLNLNLNLNLN

Operator

22121211122212111211221212221112

PlacedZone

LLLLLLLLLLULULULLNLLLLMNLLLLLNLNLNLLLNLNLLLLLNLNULLLLLLNLNLNLLLN

TotalCount

93009227759692337307938770477114737095119196897075469500735974557223914173437489936688067501930572359074949992517801718174649213

TABLE A-IV(a)

RESULTS: TEXTURE COUNTS

LithicFragments

01212000219021282963203845623848791641143170615512348100

Grano-phyre

531418698937170931117857831372323832363464592852631172147203152564273288804816681575317203460

Spherulites/Microlites

84338343638382144659551345435262668889478550832562168739676352214797848170027032878882286806863961938128815575676866335226368332

Crypto-crystal1ine

1623013770

7836131541890437208146303889198226

1866224436115426111721042636155619386964168

32824480115

Voids

957110045555836281218600063441063740800563129

Pheno-crysts

7993363699921351387597107103779660382843118111726114116466796859132101166177

Calcite

00000071100510000000000000514190000

Veins

000000020000600213016130000180000000

Operator 1 is Broxton; operator 2 is Byers.

00en

SampledFootage

2868.7A2868.7A2868.7B2868.7B2919.2A2919.2A2919.2B2919.2B2998.8A2998.8A2998.8B2998.8B3058.2A3058.2A3058.2B3068.2B3137.3A3137.3A3137.3B3137.3B3213.4A3213.4A3213.4B3213.4B3317.6A3317.6A3317.5B3317.5B3428.6A3428.6A3428.6B3428.6B

TrueZone

ULULULULULULULULMNMNMNMNMNMNMNMNLLLLLLLLLLLLLLLLLNLNLNLNLNLNLNLN

Operator

22121211122212111211221212221112

PlacedZone

LLLLLLLLLLULULULLNLLLLMNLLLLLNLNLNLLLNLNLLLLLNLNULLLLLLNLNLNLLLN

TotalCount

93009227759692337307938770477114737095119196897075469500735974657223914173437489936688067501930572359074949992517801718174649213

TABLE A-IV(b)

RESULTS:

TotalPhenocrystCount

7993363699921351387697107103779660382843118111726114116466796859132101166177

PHENOCRYST COUNTS

Quartz

0001612108213600044621233731116201016

Sanidine

383215204869104110263646202766111732271813467282010633225672

Plagio-clase

376610103081414414985834559352814187373404083824343363468646479

Biotite

3242374532107844202227623634454195

OpaqueOxides

13731271185212116232736184663361115

Other Maficsand Accessories

00000000005400000000000000220060

Operator 1 is Broxton; operator 2 is Byers.

O O O O IO O O O I

I O O (O O I> O O O O (

IOOC0OOC0C0OCMI>»OOOOUJOOOOOOOi o o o r "" "lOOOriONHOOOONOOOOOOO

oooooooooooooodoodoodoooooddoodd

OOOOOOOLOOOUJr-IOOOOOOOOOOOOOCOlOrHOOOOOOOOOO-liHOOOOOOOOOOOOOOOOOOrHCMOOOO

oooooooooooooooooooooooooooooooo

Or-IOOrHOi-lr-lr-li-l<-liHr-l«HOOOOrHWOOf-<r-tOOOO<-<rHCMf-l

tOVHOOIOO)VOO)OOOOOG4r(IOOOOOOOOOOOOOO^TCO

id^-idddddddddddddoooddooodooooooo

TOTA

L

u.o

2 y? S< 0.

(•>

ID

Spt

1o

>o

M

:ro

l i

•

CM <0

tnOVNMMrirlOlCOOVNOia

d<onHHriN<<)Hri

I-111.

35o oI - VJ

IIIa. rsil

C 01

ddddd^

I I I I t I I5li§§I§IIIdddddddd53535335

33S3S300 00 00 00 3v 3) 3 #) 00 00 00 00 00 00 00 00<Dtt)CD(DHHHHQtO)OtOtU}U)U)U) - _ . _ - _ . _ .00 00 00 00 (A 0) Oft Ok Ok Ob Ok Ok 3 O 3 0 H «H <*4 C"J OJ C4 OJ CO CO CO CO * * t" CMCMCMCMCMCMCMCMCMCMCMCMCOCOCOCOn>C9<a<OtOCOCO(0«>CQCOCQ<0(OCOCO

CM

t .

I&o

2.o

37

«m —o

— o<t- «m in3 •

U

OOOOOOMOOOOOOOOOOOOOOIo o oooooooooooooOOOOOOr»(NOOOOOOOOOOOOO_ _oncoogooggogggooooowOOOOOOOOOOVTOOOOOOOOOOOOOI

OOOOOOOOOOUJ^-OOOOOOOOOOOOOOCMCMOOOOOoooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo

a. x

o o

<o

oCO

xi a:s-t UJ> o.I

< I -(0

UJ >-CO U< OI- Z

UJI0.

is

o uo >-C 0

^•CDC)^COU3^U>< .

OOOOtHOtHi-IOOOOOOOOOOOOOOt-IOOOOOOOt-IO

dodddddddddddddddddddddddddododd

(^* ») ^ ^ f U) 00 J 00 ZJ oi C? 3 00 ^ ^ r 4 ) 9 tr 7* ^ v r 00 ^ ^

^A ^ ^ o^ c ) ^^j a oo ^ ^ oo ^ ) f C J ji v*4 ^ oo M! QO G V ) oo oo ^ ^ ^

OOOOOOOOOOtHoSoOOOOOOOOOOOOOOOOCMO

odododdooododdooooddoooooooodooo

00000000>U>0)CP^-U3<-<'oianoooicioiiDfHNiCO CD *"4 tH f O *H tH US 14} Ok Ok I f l CO CO i

doddddddddddddddddddddi-iddddddddd

ddddddrHiHododdddddoododo'dddodoooo

oooMON«aooNioorioooooia«««oii)Ns««atn

O C3 O >H 00 tH C4 tH C3 00 J T4 CO US 3 O O ^ IA 00 C*l **i M CO CO 4 Ok CO OOOOOOOOOOOOOOOOOOOOOOOOOOOt-!t-ICMtHfH

oooooooooooooooooooooooooooooooo

«o«nnaio)aiooriHoc)«ionY««N«ctr>a>oD««e?NaidHdoH'driHriHiHriririddddrtHddHriddddrirtNri

•P 3o o

SI

«a.ocoP

3 c1- oI— Ml

E oIf) U.I

o•P

o

38

TABLE A-VI(a)

ESTIMATES OF SIGNIFICANT FIXED EFFECTS AND VARIANCE COMPONENTSFOR TEXTURE PERCENTS

Effects/VarianceComponents

V-

°i

°2

Zl

Z2

Z3

Z4

%

ft

a

LithicFragments

0.4847

-

-

-0.4747

-0.2509

0.2766

0.4491

-

-

0.3605

Grano-phyre

6.1034

-1.2263

1.2263

7.4291

-2.6147

-4.6109

-0.2034

3.4195

2.9799

1.7888

Spheru1i tes/Microlites

82.5647

-6.1928

6.1928

-5.6872

5.7978

7.2128

-7.3234

-

_

12.9143

Textures

Crypto-crysta11i ne

9.

6.

-6

10

.4347

.4247

.4247

-

-

-

-

-

-

.6973

Phenocrysts

1.1188

0.0525

-0.0525

-0.005

-0.1725

0.0125

0.165

0.3356

0.3378

0.1041

Voids

0.2406

-

-

0.4931

-0.1731

-0.1994

-0.1206

0.0817

_

0.1551

Veins

0.03

0.0304

-0.0304

-0.0263

-0.0163

0.0413

0.0013

0.0333

_

0.0503

Ca1c i tes

0.0228

-

-

0.0084

-0.0153

-0.0228

0.0297

0.0301

0.0336

0.0188

TABLE A-VI(b)

ESTIMATES OF SIGNIFICANT FIXED EFFECTS AND VARIANCE COMPONENTS FOR PHENOCRYST PERCENTS

Effects/VarianceComponents

/»

°i

°2

zi

Z2

Z3

Z4

^P

ar

°*a _

Quartz

0.0523

-

-

-0.0341

-0.0261

-0.0185

0.0787

0.0298

-

-

0.0350

Plagioclase

0.5470

0.0442

-0.0442

-0.2801

0.0767

0.1065

0.0969

0.1172

-

0.1991

0.0775

Phenocrysts

Sanidine

0.3984

-0.0300

0.0300

0.2996

-0.2042

-0.0408

-0.0547

0.2234

-

0.2063

0.0414

OpaqueOxides

0.0504

0.0176

-0.0176

0.0270

-0.0272

-0.0056

0.0058

0.0161

0.0155

-

0.0234

Other MaficsBiotite and Accessories

0.0548 0.0069

0 .0186

APPENDIX B

PETROGRAPHIC MODAL DATA FOR ALL THIN SECTIONS OF DEVITRIFIED RHYOLITEAND QUARTZ LATITE, TOPOPAH SPRING MEMBER, DRILL HOLE USW VH-2

41

TABLE B-I

ESTIMATED MODES (BY BYERS) OF ALL THIN SECTIONS OF CORES OF TOPOPAH SPRING DEVITRIFIED TUFF ABOVE VITROPHYRE, HOLE USW VH-2,COMPARED WITH COUNTED MODES BY OPERATORS (BROXTON, BYERS) OF UNKNOWN VH-2 THIN SECTIONS SELECTED BY STATISTICIAN (MOORE)

(Footage A and B are replicate thin sections cut at least 5 mm apart from same core plug. Welding zones: pmwt, partially tomoderately welded; mwt, moderately welded; mdwt, moderately to densely welded; dwt, densely welded. Microlitic/spheruliticestimates by difference from 100% Phenocryst estimates qualitative; Plag, plagioclase; San, sanidine; Q, quartz; B, Biotite; Maf,mafic pseudomorph; Cpx, clinopyroxene; Opx, orthopyroxene; A, allanite; opaque oxides not estimated; ne, not estimated)

FootageA & B Welding

Crypto- Microlitic/ TotalLithics Granophyre crystalline Spherulitic Phenocr. Phenocryst* (as percent of whole rock where counted)/

(X) (X) (X) (X) (X) Remarks (e.g., quartz vein lets)

Quartz latitic caprock: (Top of Topopah Spring Tuff, 2E50-ft depth, at fault, 10° dip, Carr and Parrish, 1985.)2659.2A pmwt 0.3 0.0 40 60 7 San>Plag>B>Cpx=: Perrierite. Mixture, rhy. A qtz lat.2559.2B pmwt 0.0 0.0 40 SO 8 San>Plag>B>Cpx=; Perrierite. Mix, rhyolite k qtz lat.

Rhyolitic vapor-phase crystallization zone, with less than 10X lenticles of quartz latite pumice:2571.0A2571.0B

pmwtmwt

2581.1 pmwt

2691.1A2591.IB

2601.8A2001.8A2601.8B2601.8B

2612.4A2612.4B

2654

2668.2A2668.2B

mwtmwt

0.00.1

0.1

0.50.0

53

1.6

1.01.0

0.00.0

0.0

1.01.0

9095

95

9595

2 San>Plag>B. Plag gone. Irregular quartz veinlet.

2.5 San>Plag>=: B>Cpx(?). Plag A Cpx altered k gone.

1.5 San>Plag- B. Plag altered; may exceed biotite.

2.0 San>Plag>B. Plag altered. Flattened vesicles ~2X.1.5 San>Plag2 B>Q. Plag alt. Flattened vesicles ~1X.(2595-2601 ft, several high-angle faults, clay and breccia; Carr and Parrish, 1985.)

mwt 0.0 6 1.0 90 1.0 San^ Plag>B. Quartz latite pumice ~3X.mwt 0.04 7.73 0.94 89.28 1.76 San, 0.96; Plag, 0.61; B, 0.12. (BYERS mode).mwt 0.0 3 3 95 1.0 San=s Plag>8. Quartz latite pumice ~8X.mwt 0.00 0.46 4.43 92.6 2.38 San, 0.76; Plag, 1.31; B, 0.20. (BROXTON mode).

pmwt 0.0 3 3 95 1.0 San=£ Plag>B>alt. mafic. Qtz. latite pumice ~5X.

mwt 0.0 2.6 3.6 90 1.5 San>Plag>B>Q. Quartz latite pumice ~6X.

mwt 0.0 0.6 1.0 96 2.0 San>Plag>B. Quartz latite pumice ~7X.

mwt 0.0 0.5 6 90 1.7 San>Plag>B>Q. Quartz latite pumice ~55t.pmwt 0.1 1.0 1.0 95 0.7 San^ Plag>B>alt mafic. Lithic(?), quartz latite.

Rhyolitic vapor-phase zone: (No quartz latite pumice below 2707-ft depth.)2707.1A2707.IB

2766.4A2766-4B

2776.3A2776.3B

dwtdwt

dwtdwt

mdwtmdwt

0.00.0

0.00.0

0.30.0

2010

106

44

0.00.0

0.0<0.6

<0.5<0.S

8090

9095

9695

0.2 Pfag>San- B. Granophyre veinlets, mostly Q.0.3 San>Plag>B. Granophyre veinlets, mostly Q.

1.0 San- Plag>B. Granophyre veinlets, mostly Q.1.5 San- Plag>B>Q. Smectite-Iined fractures.

0.6 Plag>Sans B>Q. Granophyre veinlet.1.0 San>Plag>B- Q. Granophyre veinlet.

TABLE B-I (cont)

FootageA * B Welding

Lithics

COGranophyre

Crypto-crystalIine

(*)

Microlitic/Spherulitic

TotalPhenocr.

(X)Phenocrysts (as percent of whole rock where counted)/Remarks (e.g., quartz vein lets)

2809.9A mdwt2809.9A mdwt2809.9B mdwt2809.OB dwt

0.20.010.20.00

2.04.972.03.45

1.02.521.03.97

9090.989091.54

1.5 S»n>Plag>B>Q. Clay aggregate ~5X.1.51 San, 0.97; Plag, 0.47; B, 0.01; 0, 0.0 (BYERS).1.2 San>Plag>8 >A(incl. w. Cpx below). Clay agg. ~6%.0.93 San, 0.47; Plag, 0.32; B, 0.01; Cpx, 0.05 (BROXTON).

Upper lithophysal zone: (Byers' interpretation of Cam and Parrish, 1985, drill log.)2829.8 dwt 0.2 1.0 1.0 90 1.2 San>Plag>B>Q. Clay aggregate ~5%.

2849.0 dwt 0.0 2.0 <0.E 90

2868.7A2868.7A2868.7A2868.7B2868.7B2868.7B

2879.5

2889.6

2899.3A2899.3B

2909.6A2909.5B

2919.2A2919.2A2919.2A2919.2B2919.2B2919.2B

2929.8

2949.4

2959.1

2968.7A2968.7B

dwtdwtdwtdwtdwtdwt

mdwt

mdwt

dwtdwt

dwtdwt

dwt?dwtdwtdwt?mdwtdwt

dwt

dwt

dwt

dwtmdwt

0.00.000.010.10.030.01

0.0

0.1

0.00.0

0.06

n*0.030.00ne0.000.00

3

0.0

ne

2.00.3

6.05.714.536.09.1910.15

3

3

65

103

ne23.3933.14ne11.1411.01

<0.S

5

ne

1.01.0

1.01.743.26<0.S4.960.00

1.0

<0.5

0.00.0

0.00.0

ne10.726.63ne21.8712.51

3

10

ne

<0.S<0.S

9090.6890.429084.0388.96

95

95

9090

8590

ne63.7658.73ne

64.4773.97

90

85

ne

9595

1.00.851.010.60.470.39

1.2

2.0

1.01.0

1.01.0

1.0?1.350.982.0?1.921.94

0.8

1.0

ne

0.70.8

2.0 San>Plag>B. Clay aggregate ~5X.

San>Plag>B. Clay aggregate, present.San, 0.41; Plag, 0.40; B, 0.03 (BYERS I mode).San, 0.35; Plag, 0.61; B, 0.02 (BYERS II mode).San>Plag= B. Clay agg. ~5X. Granophyre veinlet.San, 0.20; Plag, 0.13; B, 0.05 (BROXTON mode).

San, 0.22; Plag, 0.11; B, 0.02; Q, 0.01(BYERS mode).

San£Plag>B=; Q. Est. <2X clay agg. Granoph. veinlet.

San>Plag>B>Maf, possibly Cpx.

San>Q(l large)>Plag>B.San>Plag>B- Q. Clay more diffuse ft not in patches.San>Plag>B. Clay agg. Granophyre gash veinets.San>Plag>B>Q. Clay agg. Cognate lithic (Tpt?).

Tuff, fractured, recrystalIized, fcsilicified.San, 0.65; Plag, 0.41; Q, 0.08; B, 0.04 (BROXTON).San, 0.74; Plag, 0.09; Q, 0.01; B, 0.07 (BYERS).Tuff, fractured, recrystalIized, Asilicified.San, 1.48; Plag, 0.20; B, 0.06; Q, 0.03 (BROXTON I).

San, 1.65; Plag, 0.20; B, 0.07; q, 0.01(BROXTON II).

San>Plag>B- Q. Extreme welding like flow banding.

San>Plag>B>Maf. RecrystalIized quartz near fault?

Fractured, silicified; 2mm-wide quartz veinlet.

Sans: Plag>B>Q. Clay agg. ~5X. Cognate I ithic(Tpt?) .Plag>San>B>Maf(Cpx?). Clay aggregate ~3X.

TABLE B-I (cont)

FootageA * B Welding

Lithics

(X)Granophyre

(X)

Crypto-crystal1ine

(X)

Microlitic/Spherulitic

(X)

TotalPhenocr.

(X)Phenocrysts (as percent of whole rock where counted)/Remarks (e.g., quartz vein lets)

Middle nonIithophysal zone:2978.8A dwt 0.12978.8B dwt 0.0

(Byers' interpretation of Carr and Parrish, 1985, drill log.)3 <0.5 95 0.5 Plag>San=* B>Maf(Cpx?). Clay aggregate ~4%.3 <0.B 95 1.5 Plag>San>B. Clay aggregate ~4%.

2988.2988.

2998.2998.2998.2998.2998.2998.

3007.

3020.3020.

3035.3035.

3046,3046,

305830583058305830583058

30683068

30783078

30883088

8A8B

9A9A9A9B9B9B

6

,2A,2B

2A.2B

,2A.2B

.2A

.2A

.2A

.2B

.2B

.2B

.8A

.8B

.5A

.SB

-3A.3B

dwtmdwt

dwtdwtdwtdwtdwtmdwt

dwt

mdwtmdwt

mdwtmdwt

mdwtmdwt

mdwtdwtmdwtmdwtmdwtmdwt

dwtdwt

mdwtmdwt

mdwtmdwt

0.0.

0.0.0.0.0.0.

10

2.0.

0.0.

0,0,

000100

0<0

00

0<0

20

0280900002

.0,0

.0

.2

.0

.0

.5

.16

.08

.0

.39

.85

.0

.5

.0

.0

.0

.5

1.4

2.1.2.2.4.2.

<1.

1.1.

1.4

33

444433

33

11

11

0

0864401663

0

.0

.0

.0

.59

.83

.87

.53

.5

.0

.0

.0

2.<o.<o.5.2.<0.1.3.

<0.

1.2.

<l.<1.

2.1,

1,112<1325

11

65

1030

05

5931955838

5

00

0.0

.0

.0

.0

.58

.08

.0

.07

.02

.0

.0

9595

9590.7594.079592.9892.81

90

9590

9090

9090

9082.3791.999091.9070.03

9090

8585

8565

1.0 Plag=* San>B. Quartz-caIcite veinlets.0.7 Plag>San>B. Clay aggregate present.

1.0 Plag- San>B>Q. Sparse calcite in vert, fracture.1.02 Plag,0.56; San,0.35; B,0.04; Q,0.00 (BROXTON mode).1.02 Plag,0.52; San,0.38; B.0.02; Q.,0.08 (BYERS mode).1.0 Plag>San2 B>Maf (Opx?). Open fract. with calcite.1.18 Plag,0.92;San,0.04;B,0.11;M»f,0.05;Q,0.02 (BYERS I).1.15 Plag,0.93;San,0.07;B,0.08;Maf,0.04;Q,0.01(BYERS II).

0.5 Ptag>San>B>Q. Calcite veinlet, 1 mm wide. Cognate I.

0.5 Plag>San>B=: Q. Calcite veinlet, 0.1 mm wide.0.8 Plag>San=: Q>B. Clay aggregate ~5X.

0.6 PI»g>S»n>B. Clay aggregate present. -1.0 Plag>- San>B. Clay aggregate present.

0.7 Plag>San>B>Q. Clay aggregate present.0.5 Plag>San>B. Clay agg. pros.

0.5 Plag>San>B. Granophyre veinlets. Clay aggregate.1.02 Plag, 0.60; San, 0.27; B, 0.11; Q, 0.04 (BROXTON).1.01 Plag, 0.62; San, 0.28; B, 0.04; Q, 0.05(BYERS mode).0.5 Plag>San>B. Granophyre veinlets. Clay aggregate.0.68 Plag, 0.48; San, 0.08; B, 0.05 (BROXTON mode I).0.51 Plag, 0.38; San, 0.08; B, 0.03 (BROXTON mode II).

0.4 Plag- San>B. Granophyre veinlets. Clay aggregate.0.5 Plag^ San- Q>B- Maf. Granoph. veinlets. Clay agg.

0.5 Plag>San>B. Granophyre veinlets. Minor clay agg.0.5 Plag- San>B>Q. Granoph. veinlets. Minor clay agg.

0.5 PlagK San>B>Q. CryptocrystalIine incl. clay agg.1.2 Plag>San>B>Q. Cryptocrys. includes clay aggregate.

Cn

TABLE B-I (cont)

FootageA A 8 Welding

Lithics

<*)Granophyre

(*)

Crypto-crystal1ine

(X)

Microlitic/Spherulitic

(X)

TotalPhenocr.

(X)Phenocrysts (as percent of whole rock where counted)/Remarks (e.g., quartz veinlets)

Lower lithophysal zone: (Byers' interpretation of Carr and Parrish, 1985, drill log; fault at 3091 ft.)3103.4A mdwt 3 <1.0 <1.0 95 0.8 Plag=^ San>B. Shard walls fuzzy and indistinct.3103.4B mdwt 0.0 1.0 <1.0 95 1.0 Plag>San= B=i Q. Shard walls indistinct as in .4A.

311E.3 mdwt 0.0 2.0 95

3125.2A3125.2B

3137.3A3137.3A3137.3A3137.3B3137.3B3137.3B

3146.8

3175.8A3176.8B

3185.2

3213.4A3213.4A3213.4A3213.4B3213.4B3213.4B

mdwtdwt

dwtdwtdwtdwtdwtdwt

dwt

mdwtmdwt

mdwt

mdwtdwtmdwtmdwtdwtmdwt

<0.5<0.5

1.00.280.420.30.610.69

0.0

0.00.1

1.0

0.50.730.551.01.051.76

<1.1.

1.1.2.<1.0.0.

4

64

5

332<000

00

062340.1027

.36

.91

.5

.56

.78

5.0<1.0

1031.073.95102.103.49

20

<0.6<0.S

2.0

1.01.252.382.05.683.88

9095

8566.92.9095.93.

75

9596

90

959393959091

4178

3690

.83

.44

.73

.77

1.0.

0.0.0.1.1.1,

0,

00

0

000111

08

439470.61.48

.5

.8

.5

.5

.5

.77

.69

.2

.88

.76

3224.2 mdwt <0.6 1.0 3.0 95

0.6 Plag>San>B>Q. Shard walls indist. Clay aggregate.

Plag>S»n>B>Q. Shard walls indist. Clay aggregate.Plag>S»n>B- Q. Granophyre veinlet.

Plag>San>B- Q. Cryptocr. incl. clay agg. Gr. veinlet.Plag, 0.20; San, 0.15; B, 0.00; Q, 0.00 (BR0XT0N).Plag, 0.20; San, 0.19; B, 0.02; Q, 0.04 (BYERS mode).Plag- San>Q>B. Cryptocr. incl. clay agg. Gr. veinlet.Plag, 1.00; San, 0.44; 0,, 0.05; B, 0.03 (BROXTON I).Plag, 0.97; San, 0.36; Q, 0.08; B, 0.03 (BROXTON II).

Plags: San>B>Q. Shard walls distinct. Granoph. vein I.

Plag- San>B. Shard walls not identifiable.Plag- San>B. As above. Typical lower lithophysal.

Plag>S»n>B= Q. As above. Typical lower lithophysal.

Plag>S»n>B>Q. Discontinuous granophyre veinlet.Plag, 0.43; San, 0.19; B, 0.07; Q, 0.02 (BYERS I).Plag, 0.46; San, 0.15; B, 0.07; Q, 0.01 (BYERS II).Plag- SirOBs; Q. Granophyre veinlet.Plag, 1.11; San, 0.61; B, 0.03; Q, 0.03 (BROXTON).Plag, 0.88; San, 0.77; 6, 0.03; Q, 0.03 (BYERS mode).

1.0 Plag- San>Q>B. CryptocrystalIine largely clay.

3246.2

3256.5

(Many fractures from 3223 to 3235 ft, C»rr and Parrish, 1985.)dwt 3 2.0 IS 80 1.2

dwt

3266.8A dwt3266.8B dwt

1.02.0

1.0

36

10

65

85

9085

0.5

0.50.8

Plag>San>B. Cryptocryst. incl. ~l/2 clay.

Plag- San>Q>B. Crypto, incl. clay. Granoph. veinlet.

Plag- San>Q>B. Granoph. v. No clay in cryptocrys.Plag- San>Qs Maf>B. Granophyre veinlets. No clay.

Lower nonlithophysal zone: (Byers' interpretation of Carr and Parrish, 1985; also fault at 3272 ft.)3277.OA dwt 10 3 5 80 0.7 Plag>San>R>B. No clay in cryptocrystalIine.3277.0B dwt 0.5 2.0 10 85 0.5 Plag>San^ Q>B. Granoph. v., 0.1 mm wide, mostly Q.

San>Plag- Q>B. Granophyre v. No clay, see above.Plag- San>B>Q. Granophyre veinlets. No clay.

3287.1A3287.IB

dwtdwt

1.0<0.5

2.04

105

8590

0.80.7

GO

VE

RN

ME

NT

PB

INT

II IG O

FFICE

:

!<bu

t

FootageA * B

3297.6A3297.5B

3307.5

3317.5A3317.6A3317.5A3317.5B3317.6B3317.6B

3336.1A3336.IB

3346.4A3346.4B

3356.7A3356.7B

3378.4A3378.4B

Welding

dwtdwt

dwt

dwtdwtmdwtdwtmdwtmdwt

dwtdwt

Lithics(X)

1.6Z

1.0

1.680.340.00.740.66

1.06

Granophyre(X)

33

6

53.988.8668.596.28

33

Crypto-crystal1ine

(X)

2016

20

57.680.21104.0610.42

2530

(3336-3340 ft, fault zone, Carr and Parrishdwt 1.0 3 20dwt 2.0 3 30

dwtdwt

dwtdwt

2.07

2.6

43

63

630

6060

TABLE B-I

Micro!itic/Spherulitic

(X)

7580

75

9085.6089.578585.8581.80

7060

, 1985.)7566

9060

4636

(cont)

TotalPhenocr.

(X)

1.01.0

0.5

0.7C.910.870.60.610.64

0.71.0

1.00.6

0.61.0

0.51.0

Phenocrysts (as percent of whole rock where counted)/Remarks (e.g., quartz vein lets)

Plag- San>B)Q. Granophyre veinlets up to 0.1 mm wide.San>Plag>Q— B. Granophyre veinlets up to 0.1 mm wide.

Plag— San>B— Q. Granophyre v. No clay, see above.

g^ San>Q=? B. Granoph. v. No clay, see above.Plag, 0.59; San, 0.11, Q, 0.04, B, 0.08 (BROXTON).Plag, 0.47; San, 0.22, Q, 0.08, B, 0.03 (BYERS mode).Plag>San>Q- B. Granophyre A calcite veinlets. Clay.Plag, 0.38; San, 0.10; Q, 0.03; B, 0.04 (BYERS I).Plag, 0.37; San, 0.05; Q, 0.12; B, 0.04 (BYERS II).

Plag=! San>Q>B. Granoph. veinlets. Little or no clay.Plag= San>Q>B. Granoph. veinlets. Little or no clay.

Plag= San>q>B. Granophyre veinlets. No clay,l San>Q^ B. Granophyre veinlets. No clay.

g= San>B. No Q. No clay in cryptocrystalIine.San>Plag>Q>B. Granophyre veinlets. No clay see above.

Plag— San>Q- B. Granoph. veinlets. No clay see above.Plag>San= 0,>B. Granoph. v. No clay in cryptocryst.

(3387-3391 ft, highly fractured, calcite and MnO coated, some breccia, Carr and Parrish, 1985.)3397.2 dwt 3 2 75 20 1.0 Plag>San>Q= B. Granoph. veinlets. No clay, see above.

(3401-3403 ft, highly fractured, calcite and MnO coated, some breccia, Carr and Parrish, 1985.)3408.0 mdwt 4 6 40 60 1.0 PlagK San>q=! B. One granoph. v. No visible clay.

San>Plag^ Q>B. Granoph. veinlets. No visible clay.Plag>San>Q>B. Granoph. veinlets. No visible clay.

Plag^ San>0.~ B. No granoph. veinlets or visible clay.Plag, 0.87; San, 0.42; Q, 0.19; B, 0.06 (BROXTON I).Plag, 0.76; San, 0.31; Q, 0.28; B, 0.06 (BROXTON II).San>Plag>Qs B. No granoph. veinlets or visible clay.Plag, 0.86; San, 0.75; Q, 0.13; B, 0.26 (BROXTON).Plag, 0.85; San, 0.78; Q, 0.13; B, 0.05 (BYERS mode).

(3436-3437 ft, highly fractured and brecciatod, calcite and MnO coated, Carr and Parrish, 1986.)Top of basal vitrophyre, 155 ft thick, at 3438-ft depth (Carr and Parrish, 1985.)

3418.5A3418.SB

3428.6A3428.6A3428.6A3428.6B3428.6B3428.6B

mdwtmdwt

mwtdwtdwtmdwtmwtmdwt

616

60.711.711.00.641.09

31.0

37.374.412.02.724.99

6030

602.1646.702060.021.25

4065

4088.0146.687633.9890.44

1.01.0

1.01.691.411.52.221.92

The following number is for Office of Civilian Radioactive Waste Management purposes only and shouldnot be used when ordering this document:

Accession Number: NNA. 890502.0089

Printed in the United Stites of AmericaAviitible from

National Technical Information ServiceUS Department of Commerce

5285 Port Royal RoadSpringfield, VA 22161

Page Range

001 025026-050051 075076 100101 125126-150

NTISPrice Code

A02A03A04A05A06A07

Page Range

151 175176-200201 225226-250251-275276300

Microfiche (A0I)

NTISPrice Code

A08A 09AI0A l lAI2AI3

Page Range

301 325326 350351 375376 400401 425426450

NTISPrice Code

AI4AI5A 16AI7A18AI9

Page Range

451 -475476500501 525526-550551 575576600601 up*

NTISPrice Code

A 20A2IA22A23A24A25A99

•Contact NTIS Tor a price quote.