Borehole Elongation and Its Relation to Tectonic Stress at ...UCRL-53528 Distribution Category UC-1l Borehole Elongation and Its Relation to Tectonic Stress at the Nevada Test Site

. 11 ?I*. 5xI A44�-��-S-09�f/ W6100'.

UCRL-53528

Borehole Elongation and ItsRelation to Tectonic Stress at

the Nevada Test Site

J. E. Springer

R. K. Thorpe

H. L. McKague

April 1984

UCRL-53528Distribution Category UC-1l



J. E. Springer*

R. K. Thorpe

H. L. McKague

Manuscript date: April 1984

*U.S. Geological Survey, 345 Middlefield Rd., Menlo Park, California 94025

LAWRENCE LIVERMORE NATIONAL LABORATORY IlLUniversity of California * Livermore, California * 94550 I

Available from: National Technical Information Service * U.S. Department of Commerce5285 Port Royal Road * Springfield. VA 22161 * $8.50 per copy * (Microfiche 54.50

Contents

Abstract................................................................................... .Introduction ................................................................................. ISite Geology ..................... 3Methods and Terminology ..................... 3Results.................................................................................... 5

Persistence of Breakouts ..................... 5Directionality of Breakouts ..................... 7

Discussion ..................... 12Conclusions................................................................................ 13Acknowledgments........................................................................... 13References................................................................................ 14Appendix A: Borehole Breakout Logs ........................... 15Appendix B: Circular Histograms ........................ 39

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Abstract

This paper documents the borehole spalling pattern in relation to lithology, geologicstructure, stress, and depth of two Nevada Test Site (NTS) areas, Yucca Flat and PahuteMesa. Downhole movies and stereo photographs from 58 large-diameter test holes at rJTSreveal a strong NW-SE elongation due to sidewall spalling. This trend is found in YuccaFlat and Pahute Mesa, which have distinctly different geologies, and is parallel to thedirection of regional extension. The directionality is due to tangential stress concentrationat the wellbore, which has a peak value along the azimuth of minimum horizontal re-gional stress.

The percentage of borehole length affected by spalling varies from 5% near the sur-face to 30% at depths over 500 m. The severity of spalling is also a function of lithology;however, geologic discontinuities apparently have little effect on the orientation and oc-currence of elongations. Directional spalling was observed in relatively shallow alluvialdeposits, suggesting the persistence of horizontal stress differences at shallow depths. Ifthe elongations are truly controlled by the deviatoric stress field, this implies that theregional stress direction is fairly uniform throughout NTS. A simple relation is given forthe in situ stress and material strength conditions associated with borehole elongation.

Introduction

Borehole elongations, or breakouts, havebeen observed for a number of years in downholephotographs and 3-trace caliper logs of large-diameter test holes at the Nevada Test Site (NTS).Because of their general orientation, the elonga-tions are thought to be closely linked to the re-gional stress field. Lithology, geologic structure,and depth may also affect the occurrence ofbreakouts. This paper documents the boreholespalling pattern in Yucca Flat and Pahute Mesa,shown in Fig. 1, in relation to these factors.

Yucca Flat occupies an intermontane basin40 km N of Mercury. Pahute Mesa lies 20 km NWof Yucca Flat and is about 600 m higher in eleva-tion. Extensive drilling of 1.2- to 3-m diam testholes has been done in both areas to depths of 200to 600 m. The results presented here are basedmainly on the analysis of downhole movie logstaken with a fisheye automated cine camera(Brugman, 1979) recently developed by theNevada Test Site Department of the Lawrence

Livermore National Laboratory (LLNL-NTS).Downhole stereo photographs from LLNL-NTSfiles provided additional information for selectedportions of holes not covered by a movie log.

Several workers in the petroleum industryhave detected directional breakouts in the ori-ented caliper data from 4-arm dipmeter logs. Cox(1970) noted a strong NW-SE preferred orienta-tion of breakouts in oil wells throughout a215,000-km- area in the Alberta Plains of Canada.He demonstrated that the breakout orientationswere generally unrelated to structural dip, but thatthere were minor influences from fault zones, andrapid changes in dip and borehole drift. Babcock(1978) suggested that these breakouts were causedby a NW-striking set of vertical fractures. Bell andGough (1979), however, suggested that the break-outs were the result of a NE-SW regional com-pressive stress. Later, they showed that the trendcovered a larger area (400,000 km-) in Alberta andeastern British Columbia (Gough and Bell, 1981,

1

4- M lwo-'--'71'11' W MMMIPP:

Longitude

1180 1170 1160

37.50

31-I 37.00

0 20 40-. - -

km

Figure 1. Map of NTS showing location of Yucca Flat and Pahute Mesa.

1982), and that it was the apparent northwestwardextension of the midcontinent stress province de-scribed by Zoback and Zoback (1980).

Similarly, breakouts in the Rangely Oil Fieldof Colorado (Gough and Bell, 1982) were found tobe parallel to the minimum horizontal regionalstress as determined from fault plane solutionsand overcoring stress measurements. Northeast-southwest oriented breakouts in the Austin Chalkof South Texas were noted in zones of increasedsecondary porosity (Schafer, 1980). These havebeen interpreted as zones of NE trending joints;however, an overcoring measurement in theLlano uplift 225 km to the north suggests a mini-mum horizontal stress parallel to these breakouts(Gough and Bell, 1981).

In another case, Brown et al. (1980) reportedNW-SE oriented breakouts in the gas sandstonesof the Cotton Valley Group of East Texas. Whilein situ stress directions were not identified fromtheir data, it is likely that the breakouts were inthe direction of the minimum horizontal regionalstress.

On Yucca Mountain, near the SW comer ofNTS, Stock et al. (1953) used televiewer logs inthree holes to determine the orientation of drilling-induced hydraulic fractures. From this data, theyinfer a direction for the least horizontal stressranging from N55W to N75W.

At NTS, past studies of downhole stereo pho-tographs of some emplacement holes indicatedthat the long axes of elongations were directedroughly NW-SE. The 3-trace caliper logs showedelongations in 70 other holes; however, their ori-entations could not be determined. The NTS datawere reported by R. D. McArthur and L. D.Ramspott in an internal memorandum. Carr(1974) later cited some of these data in an analysisof the regional stress orientation at NTS. The daton the elongations reported in the NTS studieswere consistent with the NW-SE extension in-ferred by Carr on the basis of seismic data, stressmeasurements, surface features, and large-scalegeologic structures. This work supplements theseprevious studies with new and more detailed data.

2

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Site Geology

A summary of the NTS geology is providedfor an understanding of the lithologic and stressconditions that influence borehole breakout pat-tems. Hannon and McKague (1975) give a morecomplete discussion. Regionally, the basementrocks consist of Precambrian and lower Paleozoicsedimentary sequences, none of which were inter-cepted by the boreholes studied here. These rocksunderwent folding and thrusting during early andmiddle Mesozoic time. Calcalkaline and peral-kaline tuffs and lavas of Oligocene-to-Plioceneage unconformably overlie the pre-Cenozoicbasement (Hinricks, 1968). These are representedby tuff sequences encountered in the test holes inYucca Flat and Pahute Mesa.

The study area in Pahute Mesa overlies thelate Miocene Silent Canyon Caldera. The rockswithin the caldera consist of ash flow and ash falltuffs and rhyolite lavas with interbedded re-worked tuffs. The caldera is buried by youngervolcanics (Orkild et al., 1968) that include thePaintbrush Tuff, the Timber Mountain Tuff, andthe Thirsty Canyon Tuff. These units vary fromcompetent welded and zeolitized ash-flows andash-falls to poorly indurated or fractured tuffs andlavas. North- and Northeast-striking faults cutacross the area. Many of these have shown move-

ment that is related to underground nuclear test-ing (Snyder, 1971; Maldonado, 1977).

In Yucca Flat, the Tertiary rocks consist ofover 300 m of ash-flow and airfall tuffs. Late Ter-tiary and Quaternary fanglomerates and alluviumcomprise the upper 200-300 m. Yucca Flat is cutby several north-striking faults, the most signifi-cant of which are the Yucca Fault and the Carpet-bag Fault; both show normal and dextral move-ment. Geomorphic evidence suggests that the' listnatural movement on the Yucca Fault was duringHolocene time. The minimum age of the last natu-ral movement on the Carpetbag Fault is 37,000 yr(Knauss, 1981).

North-/Northwest-trending basin and rangefaults were probably well developed prior to 14million years ago (Carr, 1974). The stress episoderesponsible for the deep, closed basins observedtoday began less than 10 million years ago (Carr,1974), and the present stress field is probably lessthan 5 million years old (Zoback et al., 1981). Thisstress field is evidenced by regional extension andboth normal and strike-slip motion on faults(Zoback and Zoback, 1980). Tectonic patterns sug-gest that the loci of extension are in structuraltroughs, such as the one underlying Yucca Flat(Carr, 1974).

Methods and Terminology

Borehole breakouts were logged from 16-mmmovies produced with LLNL's downhole fish-eye camera (Brugman, 1979), shown in Fig. 2.Designed for use in 1.2- to 3-m-diam boreholes,the camera is equipped with an fl .9, 197-deg lensthat gives a downward panoramic view of theborehole and sidewalls. Continuous depth and az-imuth readings are recorded on the right side ofthe image, as shown in Fig. 3. The azimuth of the12 o'clock position on the image is measured witha fluxgate compass 'and corrected for magneticdeclination. The readout is given to the nearestdegree; however, the overall accuracy of the unitis within 5 deg.' The depth of the camera is givento the nearest tenth of a foot.

* A malfunction of the compass during a period from late1978 to mid-1979 caused it to be somewhat less accurate. Theproblem has since been corrected. Holes affected are U2fc,U2eh, U2em. U4ai. U8c, U9cq. U10bg& U20ad. and U20ae.

In the logging process, we described break-outs as either elongate, incipient, symmetrical, orragged zones. We define elongate breakouts as.those where the borehole is noticeably enlarged inone direction. In some cases, the hole was en-larged in all directions with one direction having agreater degree of spalling. Incipient breakouts arezones in which directional spalling seems to beimminent due to braided, intersecting cracks andsmall nicks on opposite sides of the borehole.Symmetrical breakouts are spall zones with nopreferred orientation. Those of less than 0.5-mlength from top to bottom seemed to have re-sulted from the drilling operation and were ig-nored. Zones in which there were numerous con-secutive symmetrical breakouts were identified asragged zones.

In our logging, we also noted faults and jointsto study any potential connection with breakoutsand their directions. Natural fractures that

3

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-_ -- 4 .4X. OA- .a _ 0

-Cable connector

Centering rodsplaced 30 deg apart

Fluxgate compass

Debris shield

Logic andpower supplies

-Suspension spring

Hyperbolic mirror

Figure 2. Diagram of the LLNL downhole movie camera.

showed some evidence of shear movement werecharacterized as faults, while those showing nodisplacement were referred to as joints. We usu-ally logged only those fractures that extendedcompletely across the borehole; however, zones ofsmaller discontinuous fractures were included ifthey were in close proximity to breakouts.

The depths to the upper and lower portionsof each feature were recorded. In the case of elon-gate and incipient breakouts, the azimuth of elon-gation or spalling was recorded. The strikes ofnatural fractures were recorded, and their dip an-gles were calculated trigonometrically.

It was not possible to determine the maxi-mum diameter of breakouts directly from themovie logs. Instead, these measurements weretaken from Birdwell 3-trace caliper logs and re-

corded to the nearest 0.1 m. When borehole elon-gations were encountered, the largest caliper tracecoincided with the maximum diameter of theborehole due to the tendency of the opposing cali-per arms to expand into the spalled cavities. Weavoided confusing true breakouts with varioussidewall marks caused by the caliper tool, side-wall sampling device, and other geophysical log-ging equipment.

Downhole stereo photographs provided par-tial coverage of several holes not logged with themovie camera, and additional breakouts wereidentified. To obtain orientation, a rotating com-pass was placed on a frame in the center of thefield of view. However, because of poor lightingconditions, we could make only a rough estimateof the breakout orientations from these photos.

4

% I

~~~~~~1. ' -SF

Figure. 3. Typical frame from the downhole movie log of a 2.4-m diam test hole at NTS.The depth (ft) and azimuth reading are shown at right; directional breakout is visibledownhole.

Results

We studied 33 downhole movies of 1.64- to2.44-m diam holes, representing a total of about15 km of borehole length. Stereo, photographsfrom an additional 25 holes were examined, repre-sentinig about 4 km of borehole length. AppendixA contains all of the individual borehole logs. Atotal of 549 elongations, ragged zones, and incipi-ent breakouts were logged. The important findingis that over 80% of these features displayed cleardirectionality, either as enlargements or incipientbreakouts. The remaining enlargements wereclassed as symmetrical (nonoriented) breakouts orragged zones. In the following sections, we dis-cuss the frequency of occurrence, or persistence,of breakouts, and the factors related to breakoutorientations.

Persistence of Breakouts

Figures 4(a) and 4(b) show the relationshipbetween hole enlargement and depth for the

holes in Yucca Flat and Pahute Mesa. Persistenceis expressed as the percentage of hole lengt:h thatis enlarged for each 50-m increment. Incipientbreakouts are not included. Note that there is anoverall increase in the amount of spalling withdepth in both test areas, although the frequencyof breakouts in Yucca Flat is greater than that inPahute Mesa. The screened areas represent theproportion of symmetrical breakouts, which re-mains less than about 5% throughout the holes.At very shallow depths, oriented breakouts areless common, and most enlargements are of thesymmetrical type. In both areas, there seems to bea significant increase in the percentage of break-outs below 200-m depth.

Figure 5 shows the relationship between fre-quency of spalling and the major stratigraphicunits of Yucca Flat and Pahute Mesa. In YuccaFlat, enlargements are generally more prevalent indeeper volcanic units than in alluvium, which alsoreflects their greater persistence with depth. When

5

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60

JCZ 40

2020

60

.8

0

4-

40

20

I (b) IODue to directionalII breakouts_ Due to symmetrical

- |..|1breakouts

0 . . . . . . . .200 400 600

Depth (m)

0 200 400

Depth (m)

600

Figure 4. Histograms of borehole breakouts vs depth for (a) Yucca Flat and (b) Pahute Mesa.

204-

.8C4-

15

10

5

0Yucca Yucca Pahute

Flat Flat MesaAlluvium Tuff Tuff

Figure 5. Histogram of borehole breakouts fordifferent geologic media at NTS.

comparing similar rock types in the two differenttest areas, we observed that breakouts in the vol-canic units of Yucca Flat are more frequent than inthose of Pahute Mesa.

The amount of enlargement associated withindividual breakouts varies from zero to severaltimes the original hole diameter. Figure 6 showsan extreme example from hole number UlOBF.The hole was drilled with a 1.64-m bit in 1978.The original caliper log showed a maximum diam-

eter of 2.8 m at the depth shown. By 1981, cavinghad filled over 300 m of the hole, and a laser cali-per was needed to determine the width of the cav-itv. The maximum diameter shown is 13 m, morethan 8 times the original bit size. In another exam-ple, hole U2ES shows enlargement beyond thelimits of the standard caliper tool (greater than9.8 m) at 500-m depth in the NW and SE direc-tions. The NE and SW sides, however, are 2.4 m,the diameter of the original hole.

6

. N

W

Depth: 208.8 m S

Figure 6. Cross section of hole UlObf, as de-termined with a laser caliper.

Directionality of Breakouts

Previously, we reported mean breakout ori-entations based on the number and orientation ofdiscrete observations (Springer and Thorpe, 1981).In this report, the orientations have been

35, ,I I i

weighted according to the amount of boreholelength that is spalled in a given direction. The re-sults are generally similar, although there is somedifference in the averages for individual holeshaving relatively little oriented enlargement.

Figure 7 is a histogram of 32 breakout ori-entations in Yucca Flat, including both elonga-tions and incipient spallings. Values are weightedaccording to the length in a given direction andare normally distributed about a mean of N4IW-S41E (139 deg azimuth), with a standard deviationof 32 deg. Figure 8, which is similar, representsbreakouts in alluvium only. The mean orientationhere is N45W-S45E (135 deg azimuth). Ap-pendix B presents circular histograms of the datafor each downhole movie with breakouts.

Breakout orientations in the Pahute Mesaholes follow a similar trend, as shown in Fig. 9.Here, the azimuth distribution is slightly bimodal,but the major mode at 124 deg (N56W-S56E) isclose to the mean for Yucca Flat. The secondmode near 230 deg is apparently associated withpreexisting fractures, which we discuss later.

Figures 10 and 11 show the spatial variationsin breakout orientations for Yucca Flat and PahuteMesa, and the mean direction of elongation foreach of the logged holes. The length of the arrowsis weighted according to the amount of boreholelength with oriented breakouts. Heavy arrows in-dicate directions from movie logs and light arrowsindicate approximate directions from downhole

II I I I

South 600 E

._

C

400 ,

200 c

IL

£~~a

b.

-I.-

30

25

20

15

10

5

60 80 100 120 140 160 180 200 220

Azimuth (deg)

Figure 7. Histogram of breakout azimuths in tuff and alluvium from Yucca Flat. There are 2152 mof oriented breakout.

7

owl 3"---- - -. _' . .111: "�-- .. � ZWV� "". -_ - �- f�- - -, -r: - '-, A . * * t- -

A_ - ....... Lw - -

35

30I I

East

I I I 14

South

I I

t

919V W.Cr 0

0

25 _

20 _

E300 I

200 0

100 c

IL

15 1_

10 _

5 2-4-- erfi_L 5. .560 80 100 120 140 160 180 200 220

Azimuth (deg)

Figure 8. Histogramoriented breakout.

of breakout azimuths in alluvium only from Yucca Flat. There are 1065 m of

35

30

t 25

20

o, I 15

310i A

200 Ej.S

100 9

.Ut

5

060 80 1O0 120 140 160 180 200 220

Azimuth (deg)

Figure 9. Histogram of breakout azimuths from Pahute Mesa. There are 629 m of oriented break-out. The screened areas indicate breakouts associated with cooling joints.

stereo photos. The numerals next to each hole in-dicate the length of breakout upon which the on-entation is based.

These maps in Figs. 10 and 11 emphasize thestrong NW-SE direction of breakouts and indicatelittle systematic change, or spatial drift, in themean orientations throughout the two regions. -In

Fig. 11, holes U20ac and U20ae are considerablydifferent, having mean breakout orientations in aNE-SW direction. Jointing was not responsible forthese orientations. These holes, however, repre-sent oriented breakout lengths of only 27 and16 m, respectively, so their statistical significanceis minor. Boreholes with substantial deviation

8

37.200

. Area 12

N I

t I

I I Area 15

l H\i276)

Iv(5)K"23)

\(36)

-- I 10,Area 8I __ _

37.150 _- Area 2 I

4-

U-

..~1

- Area 10(18)

7 - 6 - -\ X(161 ) Area 9

(112)(67)

i 'l I

4'%-

(85),( 103)

/ r1EU

37.100 _- Area 4

----- Stereo photo data*- > 100* 50-100_ 20-50

we..

37.35

37.300

S

laPI

37.25°

37.20°

116.500 116.40° 116.30°

Longitude o 5 10

km

Figure 11. Map of selected Pahute Mesa test holes showing the mean orientations of the breakoutsfor each hole. The length of the lines is weighted according to the number of meters of the boreholeaffected by breakouts (shown in parentheses). The downthrown side of the faults is indicated by thebar and the ball.

from the overall mean direction appear to be ran-domly located in both areas. Figures 10 and 11also show that mean directions apparently are notinfluenced by major geologic structures, such asthe faults in Yucca Flat and Pahute Mesa.

Smaller scale geologic discontinuities, such asminor faults and joints, generally have little effecton either the occurrence or direction of breakouts.In Yucca Flat, only 6% of the breakouts occurs inconjunction with single natural fractures. Table 1describes these and Fig. 12 plots the azimuth ofeach breakout against thb. strike of the fracture as-sociated witn it. Figure 12 shows no correlationwith either the low-angle or high-angle fractures.

Data for Pahute Mesa, likewise, show littlecorrelation between single natural fractures andeither the occurrence or direction of breakouts.However, in a number of instances zones of dis-continuous, nearly vertical cooling joints werefound in conjunction with directional breakouts,as listed in Table 2. The strikes of these joints didnot show any obvious preferred orientation.Figure 9 shows that azimuths of the 10 associatedbreakouts are clustered around 230 deg (N50E-S50W), which coincides with the minor mode inthe histogram for breakouts in Pahute Mesa, a di-rection quite different from the overall NW-SEtrend.

10

Table 1. Directional breakouts associated with fractures in Yucca Flat..

Depth BreakoutHole (m) type,

Azimuth Fracture(deg) typeb Strike Dip Throw

Lithologicunit'

_ __ _

U2coLI2caIJ2cpU2cpU2ehU2eq1.2crU2fbU2feU9kU9cnU9cnU9cqL9cqu9cqLJ9cqU9crU~crUlObdUlObfUlObfUlObf

121184328340396

46282330371213168288179184218261149344199324364401

135095125.130145155105090125150140100

135145115130115120070115130

110185120

120130

195180170175190125130155135080125175150135170165120150120070160155155155140180120120120

81SE72ESwd

75SW67NW90S6NE72NE65NE21SE485W67SW48NE545W60NE54NE745W605WSWd

59NW645W59SW375W645W90soW805W80SW90

I

SW down 0.3 m

E down 2 m

NE down 3 mE down'SW down I mSW down 3 m

QtaQtaTmrTmrQtaQtaTbgQiaQtaTtsTpTtbTpTp'TpTbgTplTmrTtbTpTpTpTbgTbgTtbTmrTmrTmrTmrTmr

VU10bfu9ctU9c1

U9ctu9ct

408316345

347354

E

' I - Incipient; E - ElF - Fault; I - Joint.

ongate; S - Symmetrical

'Qta - Alluvium; Tmr - Rainier Mesa Member; TbgTp _ Paintbrush Tuff; Ttb - Tunnel Beds and older tuffs.

d Dip is uncertain.I Throw is uncertain.

- Grouse Canyon Member; Tts - Tub Springs Member;

220

g 180

12 140V

0

. 100Ca- 60

-iI I I L0 < 60" Dip

- B ~~0 @. * 60 0 Dip

0 0

0 00 too 0

0

00

I I I __r Figure 12. Breakout azimuth vs orientation ofassociated fractures in Yucca Flat test holes..60 100 140 180 220Breakout azimuth (deg)

11

10 11a l . ~~~~ ~ ~~; w4A, 4,;e~ - .3-. -'. .-

A i. 4- - - .. -~~~~~~~~~~~~Z _ =_

Table 2. Directional breakouts associated with fractures in Pahute Mesa.

Depth Breakout Azimuth Fracture LithologicHole (mi type' (deg) type" Strike Dip Throw unit'

U19ai 112 E 050 1 175 SWd TmrU19aj 31 E 180 highly fractured zone TmaU19aj 83 E 210 J highly fractured zone TmrU19t 33 E 210 1 highly fractured zone TinaU19t 346 E 205 1 highly fractured zone TmrU19t 359 E 210 J highly fractured zone TmrUL2ac 235 E 100 1 130 515W TmrU20ac 523 E 050 F 090 61S S down 0.1 m TpU20ae 235 E 195 1 195 67NW TmrU20ae 253 E 210 1 195 70SE Tmr

'E - Elongate.bJ - Joint; F - Fault.'Tmr - Rainier Mesa Member; Tma - Ammonia Tanks Member; Tp -Paintbrush Tuff.d Dip is uncertain.

Discussion

As mentioned previously, Carr (1974) identi-fied regional extension (i.e., minimum horizontalstress) in the N50W-S50E direction on the basis ofgeologic structure. Numerous in situ stress mea-surements by both hydraulic fracturing andovercoring techniques have been made beneathRainier Mesa, which is 5 km NW of Yucca Flat(Haimson et al., 1974; Ellis and Ege, 1975; Tylerand Vollendorf, 1975, among others). The maxi-mum principal stress was consistently found to bevery nearly horizontal and oriented betweenN21E and N53E, which is consistent with theWNW-ESE to E-W regional extension reported byZoback et al. (1981) and Zoback and Zoback(1980) for the northern Basin and Range Province.

The strong NW-SE orientation of boreholeelongations reported here is clearly related to theregional stress pattern, particularly since the trendpersists in two separate areas of different geologicsettings. While this phenomenon is not surprisingin light of similar observations cited earlier(Gough and Bell, 1981, 1982), it is noteworthy thatthe elongations, and presumably the regionalstress field, are expressed at relatively shallowdepths in the alluvium. This indicates that the me-dium has sufficient strength to sustain some sig-nificant, long-term deviatoric stress at relativelylow confining pressures, that is, within 50-100 mof the surface [see Fig. 4(a)].

The magnitude of the horizontal stress differ-ence cannot be estimated solely from boreholeelongation data; however, understanding the

mechanism of formation should at least indicatethe relationship between the maximum and mini-mum horizontal stresses in the alluvium. Assum-ing the medium is homogeneous, isotropic. andelastic, the plane-strain stresses around a circularopening can be computed from the well-knownKirsch equations (see Jaeger and Cook, 1976). Inthe configuration shown in Fig. 13, the tangentialcompressive stress a,, at the wall of the holereaches a maximum at A and A', given by

a,- 3aHmax - oHmin (1)

I I

OH max

1 9 9 9`H min

Figure 13. Location of breakout points in rela-tion to in situ stress.

12

Yielding or spalling will be initiated at thesepoints when the tangential stress reaches somefraction of the unconfined compressive strengthqu:,

a,, - m X qu *(2)

This corresponds to the onset of stable crackgrowth, for which m equals about one-half(Goodman, 1980). A relation for incipient spallingis then

3cHmax - uHmin > m qu (3)

We emphasize that this relation can be used onlyin a qualitative sense, since it involves gross as-

sumptions regarding the nature of the medium.Without knowledge of either the material proper-ties or the stress conditions, it would be highlyspeculative to make quantitative interpretationsfrom breakout characteristics.

While the in situ stress field is clearly linkedto borehole breakouts, other factors probably af-fect their directionality as well, resulting in somedegree of scatter about the NW-SE mean (Figs. 10and 11). For example, heterogeneity of the me-dium could contribute some local randomness ofdirection. This would be particularly true in thecase of the Yucca Flat alluvium. Also, transientloading produced from nearby nuclear tests con-ceivably could cause spalling in directions unre-lated to the in situ stress field.

Conclusions

The majority of breakouts in emplacementholes in Yucca Flat and Pahute Mesa at NTSshows some directionality, which is indicative ofthe orientation of regional stresses. The mean di-rection for the long axes of these elongations isroughly NW-SE, coinciding with the direction ofthe minimum horizontal stress. This connection isfound in widely separated areas with differentgeologies, including volcanic and shallow alluvialenvironments. If the elongations are truly con-trolled bv the deviatoric stress field, the implica-tion is that the regional stress direction is fairlyuniform throughout NTS. Also, the presence ofdirectional breakouts in alluvium is noteworthy,since horizontal stresses are usually assumed to be

equal in such media. In this case, if the appropri-ate material properties were known, a lowerbound for the stress difference producing theelongation could be estimated.

Regardless of the rock type, geologic discon-tinuities generally do not influence the occurrenceor direction of breakouts, except in several in-stances where intense jointing patterns are associ-ated with NE-SW elongations. These are confinedto volcanic units in Pahute Mesa. In terms of onlythe occurrence of breakouts, they are more fre-quently found in the volcanic units of Yucca Flatthan in Pahute Mesa. In both areas, the number ofbreakouts increases dramatically over depthsgreater than 200 m.

Acknowledgments

We gratefully acknowledge the support of the LLNL Containment Program and F. Morrison, Man-ager. N. Howard, G. Pawloski, and J. Wagoner, LLNL, provided valuable geologic interpretations anddata. R. McArthur and W. McKinnis, LLNL-NTS, provided useful discussions and downhole photographs;their contributions are greatly appreciated. We also thank J. Healy and M. L. Zoback, U.S. GeologicalSurvey, Menlo Park, Calif., for helpful conversations and encouragement on this project.

13

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ReferencesBabcock, A. E. (1978), "Measurement of Subsurface Fractures from Dipmeter Logs," Amer. Assn. Pet. Geol.

Bull. 62(7), 1111-1126.Bell, J. S. and D. I. Gough (1979), "Northeast-Southwest Compressive Stress in Alberta: Evidence from Oil

Wells," Earth and Planetary Science Letters 45, 475-482.Brown, R. D., J. M. Forgotson, and J. M. Forgotson, Jr. (1980), "Predicting the Orientation of Hydraulically

Created Fractures in the Cotton Valley Formation of East Texas, Society of Petroleum Engineers,Paper 9269, presented at the 55th Annual Fall Technical Conference and Exhibition, Dallas, TX.

Brugman, V. P. (1979), "Fisheye Camera for Surveying NTS Boreholes," Energy and Technology Review,Lawrence Livermore National Laboratory, Livermore, CA, UCRL-52000-79-10, pp. 25-27.

Carr, W. 1. (1974), Summary of Tectonic and Structural Evidence for Stress Orientation at the Nevada Test Site,U.S. Geological Survey, Open-file Report 74-176.

Cox, J. W. (1970), "High-Resolution Dipmeter Reveals Dip-Related Borehole and Formation Characteris-tics," in Proc. 11th Ann. Logging Sym. (Society of Professional Well Log Analysts), pp. 46-57.

Ellis, W. L. and J. R. Ege (1975), Determination of In Situ Stress in U12g Tunnel, Rainer Mesa, Nevada Test Site,Nevada, U.S. Geological Survey, Report USGS-474-219.

Goodman, R. E. (1980), Introduction to Rock Mechanics (John Wiley and Sons, New York, NY), p. 65.Gough, D. 1. and J. S. Bell (1981), "Stress Orientations from Oil-Well Fractures in Alberta and Texas," Can.

four. Earth Sci. 18, 638-645.Cough, D. 1. and J. S. Bell (1982), "Stress Orientations from Borehole Wall Fractures with Examples from

Colorado, East Texas and Northern Canada," Can. four. Earth Sci. 19, 1358-1370.Hannon, W. 1. and H. L. McKague (1975), An Examination of the Geology and Seismology Associated with Area

410 at the Nevada Test Site, Lawrence Livermore National Laboratory, Livermore, CA, UCRL-51830.Haimson, B. C., J. LaComb, A. H. Jones, and S. J. Green (1974), "Deep Stress Measurements in Tuff at the

Nevada Test Site," Advances in Rock Mechanics (National Academy of Science, Washington, D.C.),pp. 557-561

Hinrichs. E. N. (1968), Geologic Structure of Yucca Flat Area, Nevada, Geological Society of America, Mem-oir 110, pp. 239-246.

Jaeger, J. C. and N. G. W. Cook (1976), Fundamentals of Rock Mechanics (Chapman and Hall, London), 2nded.

Knauss, K. G. (1981), Dating Fault Associated Quaternary Material from the Nevada Test Site Using Uranium-Series Methlods, Lawrence Livermore National Laboratory, Livermore, CA, UCRL-53231.

Maldonado, F. (1977), Results from Fault-Monitoring Stations on Pahute Mesa. Nevada Test Site, from July1973 through December 1976, U.S. Geological Survey, Special Studies-94, Report USGS-474-242.

Orkild, P. P., R. M. Byers, Jr., D. L. Hoover, and K. A. Sargent (1968), Subsurface Geology of Silent CanyonCaldera, Nevada Test Site, Geological Society of America, Memoir 110, pp. 77-86.

Schafer, J. N. (1980), "A Practical Method of Well Evaluation and Acreage Development for the NaturallyFractured Austin Chalk Formation," Log Analyst XXI(1), 10-23.

Snyder, R. P. (1971), Composite Postshot Fracture Map of Pahute Mesa, Nevada Test Site, U.S. GeologicalSurvey, Special Studies-86, Report USGS-474-100.

Springer, J. E. and R. K. Thorpe (1981), Borehole Elongation Versus In-Situ Stress Orientation, LawrenceLivermore National Laboratory, Livermore, CA, UCRL-87018, presented at the Int. Conf. on In-SituTesting of Rock and Soil Masses, Santa Barbara, CA.

Stock, J., J. Healy, and J. Svitek (1983), "The Orientation of the Current Stress Field on Yucca MountainNevada, as Determined from Televiewer Logs, EOS 64(18),319.

Tyler, L. D. and N. C. Vollendorf (1975), "Physical Observations and Mapping of Cracks Resulting fromHydraulic Fracturing In-Situ Stress Measurements," Society of Petroleum Engineers, Paper SPE-5542, presented at the AIME Fall Meeting.

Zoback, M. L., R. E. Anderson, and G. A. Thompson, (1981), "Cainozoic Evolution of the State of Stressand Style of Tectonism of the Basin and Range Province of the Western United States," Phil. Trans.Royal Soc. London A300, 407-434.

Zoback, M. D. and M. L. Zoback (1980), "State of Stress in the Conterminous United States," I. Geophys.Res. 85(B11), 61136156.

GLE/sb

14

..

Appendix A: Borehole Breakout Logs

Appendix A gives the breakout logs from downhole movies (Part I) and stereo photos (Part 11). Part Ialso contains selected data fror i Birdwell 3-trace caliper logs and lithologic logs from the LLNL contain-ment group's data base. Abbreviations used in the logs are as follows:

L - total length of breakouts.M - mean azimuth of the oriented breakouts in the hole.SD - standard deviation about the mean orientation of breakouts in the hole.

Breakout types:E - Elongate breakout.I - incipient breakout.S - symmetrical breakout.R - ragged zone, nondirectional.

Structural controls:J - joint.F - Fault.B - Bedding contact.

Lithologic units:Qta - Alluvium.Tt - Tertiary Tuff Undifferentiated.

Thirsty Canyon TuffTs - Spearhead Member.

Timber Mt. TuffTma - Ammonia Tanks Member.Tmr - Rainier Mesa Member.Tp - Paintbrush Tuff.Trpr - Lavas of Scrugham Peak Quadrangle.

Belted Range TuffTbg - Grouse Canyon Member.Tts - Tub Springs Member.

Ttb - Tunnel Beds and Older Tuffs.

Tra-Tuffs and Rhyolites of Area 20Trab - Bedded and Ashflow Tuffs.Trau - Upper Rnyolite Lavas.Tpr - Pre-pah Canyon Rhyolite Lava.Tdh - Dead Horse Flat Lava and Tuff.

Tc - Buried Colluvium.

15

-. .,-* - ~~~., ~ I. - .W" " 7. - . -W "

Part I: Movie Borehole Breakout Logs

Breakout data Geologic structureMax Strike

Hole Depth Azimuth width Lith Depth azim DipNo. (Im) (deg) (m) Type unit Type (m) (deg) (deg) Comments

U2co121-122 135 1 Qta F 121-136 195 SISE157-166 130 2.9 E Qta B Ends on contact167-172 130 I Qta 8 Begins on contact14-184 095 2.6 E Qta F 184-192 160 72E Occurs at top of fault206-209 130 I Tmr B Begins on contact213-244 110 3.0 E Tmr B Ends on contact310-315 115 3.3 E Tp B Ends on contact315-329 135 3.4 E Tp B Between bedding contacts335-337 3.4 S Tp B Begins on contact337-340 120 2.9 E Tp B341-349 120 2.9 E Tp 8 Ends on contact349-353 110 I Tp B Begins on contact353-354 130 2.9 E Tp

General comments: 12 oriented breakouts; L -85 m; M -115; SD -12.Hole coordinates: N861,950, E657,375Drilling completed: 9/1S/S0Caliper log date: 9128/60Movie log date: 10/30/80Drill bit size: 24 rn


Hole Depth Azimuth width Wth Depth azim DipNo. (Im) (deg) Im) Type unit Type Im) Ideg) (deg) Comments

U2cp140-140 2.S S Qta a Begins on contact165-172 120 3.3 E Qta a Ends on contact176-200 120 1 Qta 8205-208 115 2Ls E Qta220-228 1IS I Tmr B Begins on contact230-257 135 1 Tmr305-327 130 3.0 E Tp B Ends on contact328-330 125 1 Tp F 330-335 170 75SW Breakout at end of fault342-345 115 3.S E Tp B Ends on contact365-365 130 26 E Tp B Occupies one layer374-378 135 2.6 E Tp B

General comments: 11 oriented breakouts; L -103 m; M -126; SD- 7.Hole coordinates: N861,113.85, E65,St33/61Drilling completed: 3/25/81Caliper log date: 3/26101Movie log date:Drill bit size: 2.4 m

16

IBreakout data Geologic structure

Max StrikeHole Depth Azimuth width Lith Depth azim DipNo. () (deg) (m) Type unit Type (ml (deg) (deg) Comments

U2eh106-109 1SS 1 Qta B Ends on contact

162-164 160 I Qta B

185-167 ISO I Qta 8 Ends on contact

17-190 170 1 Qta B Between bedding contacts

209-216 170 I Qta May be caused by logging tools

224-229 135 1 Qta

240-242 150 I Qta B Between bedding contacts

249-257 145 1 Qta Ends on contact

284-290 1S0 I Qta B Ends on contact

307-308 160 I Qta B Ends on contact

311-316 175 2.5 E Qta B Ends on contact


368-396 L6 S Qta B

396-400 145 3.4 E Qta J 395-400 190 67NW400-402 150 3.4 E Qta

403-411 145 2.9 E Qta

411-423 2.6 S Qta Too dark to see

General comments: 371-375 m. 389-391 m, and 401-402 m; 15 oriented breakouts; L -95 m; M -157; SD- 15.Hole coordinates: N874,060, E670,320Drilling completed: 1124175; hole was drilled 12/2/74 and redrilled 124/75.

Caliper log date: 12/3/74Movie log date: 8t14/79Drill bit size: 2.4 m


Hole Depth Azimuth width Lith Depth azim DipNo. (ml (degl (m) Type unit Type (ml (deg) (deg) Comments

U2em

General comments: No breakouts visible. No fractures visible. Bedding planes are horizontal. The only apparent caving issidewall samples and striations caused by logging tools. The azimuth reading remains 001 for most of the movie.

Hole coordinates: N869,517.20, E675956.49Drilling completed: 10/9/79Caliper log date: 10/7/79Movie log date: 10/16/79Drill bit size: 24 m

17

I - ~ ~ 111 -'ZWW -N'W-' 7

Breakout data Geologic tructureMax Strikc

tlole Depth Azimuth width Lith Depth azim DipNo. tmit deg) Imi Type unit Type IMn (deg) (deg) Comments

U 2e310-310 090 I Qta405-406 lS I QtA413.414 170 I Tma B423-424 IS0 I Tma B426-430 2.6 S Tmr B430-440 170 I Tmr472-475 175 I Tp553-556 205 2.3 E Tbg

General comments: 0-73-m film is badly damaged. Below 476 m. depths are approximate; depth counter is erratic. Drillingmud obscures the bottom 61 m of the hole. 7 oriented breakouts; L - 20 m; M - 174; SD - 23.Hole coordinates: N874,8500 E673,350Drilling completed: 11/17/78Caliper log date: 11/14/78Movie log date: 11/20178Drill bit size: 2.1 m


Hole Depth Azimuth width Lith Depth azim DipNo. (mi Idegi Iml Type unit Type tml Idegl (degl Comments

u2ep252-259 130 I Qta261-263 085 I Qt263-266 105 2.5 E Qta266-268 120 I Qta271-275 125 1 Qta291-294 100 2.5 E Qta296-301 085 2.5 E Qta 8301-309 090 I Qta B Becomes symmetrical

Ends on contact327-331 110 I Qta340-345 105 I Qta345-348 2.5 S Qta B Becomes symmetrical

Ends on contact348-350 085 I Qta350-353 2.6 5 Qta B Becomes symmetrical

-End on contact353-357 105 I Qta397-411 130 I Qta411-414 115 2.5 E Qta414-425 110 2.6 E Qta B426.433 115 I Qta42-454 125 1 Qta454-461 125 2.7 E Or: B461462 145 I QOf B Becomes incipient on contact500-505 123 I Qta505-520 095 3.3 E Qt.

General comments: 21 oriented brtzkouts: L 119 m; M -113: SD - 16.Hole coordinates: N863.649.95, E67J4951.6SDrilling completed: 3127/79Caliper log date: 3128/79Movie log date: 518179Drill bit size: 2.4 rr

18

~2ugg=


Hole Depth Azimuth width Lith Depth azim DipNo. (ml (deg) (m) Type unit Type (m) (deg) (deg; Comments

UZeq46-47 15S 2.6

130-135 195 2.9147-150 190 2.7170-177 190

177-181 155 2.7183-1S4 2.6216-219 090 2.7220-222 160 2.6

225-231 165 2.7231-234 155 3.4239-244 165 3.1245-248 160 2.7250-25S 160 2.9258-266 160266-271 160 2.8274-276 145 2.8276-279 150280-284 135284-287 160 3.0288-290 140 3.0

291-293 3.1294-297 145297-300 150 2.8300-306 150306-309 135 3.0315-320 150322-326 145348-352 SS 2.5366-369 145 2.5369-372 145375-380 135380-384 130 2.6354-392 135392-400 145 3.2433-435 2.8439-447 125449-453 145 2.8453-459 1S0459-472 120 3.0472-479 125479-495 140 3.2499-512 205 2.7

,Qta J 35-48 125 90 Tension fractureQta BQtaQtaQtaQta B Ends on contact

Qta B Ends on contactQtaQta BQta B Ends on contact

Qta B Begins on contact

Qta B Begins on contactQta B Ends on contact

Qta BQtU B Becomes elongated on contact

QtaQtaQtaQtUQta B Ends on contact

Qta B Between bedding contacts

Qta B Begins on contact

QtaQtaQtaQtaQtaQt"QtaQtaQtaQta

Qta

Qta Ends on contactQta B Ends on contact

QtaQta B Begins on contactQta B Becomes incipient on contactQta B Ends on contact

QtaQta B Ends on contact

Qta B Ends on contact

General comments: At 513 m, camera goes under wter. 38 oriented breakouts; L - 192 m; M - 150; SD - 14.

Hole coordinates: N862,000, E675,000

Drilling completed: S114180

Caliper log date: 531/80Movie log date: 6/13/S0Drill bit size: 2.4 m

19

-- I 110 WA" ,


Hole Depth Azimuth width Lith Depth azim DipNo. (m) (deg) (i) Type unit Type (ml (deg) (deg) Comments

U2er36-37 2.9 S Qta Undercuts casing52-53 2.7 S Qta B Ends on contact55-57 2.7 S Qta77-7S 2.7 S Qta B Ends on contact83-85 2.7 S QtbS8-S9 2.6 S Qtb B Ends on contact93-94 2.6 S Qta B Ends on contact99-100 2.7 S Qta B Ends on contact

242-244 135 2.S E Qta248-251 140 1 Qta2S2-258 120 2.7 E Qta258-262 125 2.S E Qta252-263 105 I Qta263-272 105 2.6 E Qta B Ends on contact273-278 100 30 E Tbg B Begins on contact262-292 105 2.9 E Tbg ] 262-2S5 130 S6NE292-296 130 I Tbg296-304 140 3.2 E Ttb305-315 145 I Ttb319-323 135 1 Ttb

General comments: 12 oriented breakouts; L -66 m; M -123; SD -17.Hole coordinates: NS77,920, E674U880Drilling completed: 5110/80Caliper log date: 5/111S0Movie log date: 6/131S0Drill bit size: 2.4 in


Hole Depth Azimuth width Lith Depth azim DipNo. (m) (deg) (In) Type unit Type (ml (deg) (deg) Comments

U2es363-3t4 115 2.6 E Qb394-395 2.6 S Qta B Ends on contact397-406 2.7 S Qta B Ends on contact422-425 065 2.5 E Qt B Ends on contact430441 220 I Tmr444-431 075 I Tmr453-457 105 I Tir464-469 090 1 Tmr475-481 3. S Tp B Begins on contact with Tp4S1-505 100 E Tp Broken out beyond the limits

of caliper tool

General comments 463-475-in view Is obscured by poor lighting. 479-505-m hole is completely caved in. 490-492-m camera isoff center. 7 oriented breakouts; L - 55 m; M - 119; SD - 12.Hole coordinates: N873,549, E673650.00Drilling completed: 1/22161Caliper log date: 2/20161Movie log date: 4/17/S1Drill bit size: 2.4 in

20


Hole Depth Azimuth width Lith Depth azim DipNo. Im) (deg) (ml Type unit Type (ml (deg) (deg) Comments

U2et220-245 105 3.3

245-254 090257-261 100 2.S263-266 110 2.7320-322 2.5328-334 150 2.8

336-337 2.6344-345 2.8349-351 130 2.6352-354 130 2.6397-398 2.7417-421 3.4

E Tt Breakout starts on NW side ofhole. There is much variationin amount and azimuth ofbreakout at 227 m. Breakoutbegins In SE quadrant at 235 m.There is pronounced 2-sidebreakout with 2700 azimuth.

IE

TtTt Circular at 259 m

Breakout on NW side of holeE TtSE Tt Breakout may be related to

fault at 229 mSSEES

TtTt

TtTt

S Tc/Pz ColluvlumfPaleozoicContact at 418 m

General comments: 6 oriented breakouts; L - 51 m; M - 110; SD - 1S.Hole coordinates: NS78,800, E675,S00Drilling completed: 11/3/81Caliper log date: 11/2/81Movie log date: 1115/81Drill bit size: 2.44 m


Hole Depth Azimuth width Lith Depth azim DipNo. (ml Ideg) (m) Type unit Type (m) (deg) (deg) Comments

U2fb308-326 120 I Qta327-329 090 I Qta330-334 090 1 Qta J 331-338 155 72NE3S3-354 070 2.5 E Qta

General comments: at 35-70 m, caliper log shows hole enlargement that is not visible on Image. Below 415 m, the lens isfogged and the Image is not usable. 4 oriented breakouts; L -25 m; M -111; SD -15.Hole coordinates: NS65,675S E669,900Drilling completed: 5/12/78Caliper log date: 7123/78Movie log date: S/17/78Drill bit size: 2.4 mn

21

17VF7 -'-w- 7-

--- - ~ ~ ~ ~ ~ ~ -- -- - ~ ~-- -.-- ~-


Hole Depth Azimuth width Lith Depth azim DipNo. ml (degl (In) Type unit Type (ml (deg) (deg) Comments

U2fc76-77 2.4 S Qta B Between bedding contacts

110-110 2.4 S Qta B Ends on bedding planes375-396 140 I QtA B Between bedding contacts417-422 125 I Qta B Between bedding contacts433-437 145 I Qta B Ends on bedding plane441-450 160 I Qta B Ends on bedding plane452-456 150 I Qta B Between bedding contacts459-466 155 1 Qta B between bedding contacts470-472 150 I Qta B Between bedding contacts474-485 150 2.3 E Qta B Begins on bedding plane486-487 130 2.4 E Qta B Changes at bedding plane487-558 155 3.4 E Qta B Changes azimuth

General comments: 10 oriented breakouts; L -135 m; M - 151: SD -8.Hole coordinates: N871,599.97, E668,800.00Drilling completed: 1017/78Caliper log date: 10/11/78Movie log date: 10/24/78Drill bit size: 2.4 m


Hole Depth Azimuth width Lith Depth azim DipNo. m) (deg) 4mn Type unit Type Wml Ideg) (deg) Comments

U2fd64-65 2.6 S Qta B Ends on contact

General comments: No oriented breakouts or fractures. All tuffaceous alluvium.Hole coordinates: N865,550.01, E668,549.95Drilling completed: 9/22/79Caliper log date: 9/26/79Movie log date: 10/5/79Drill bit size: 2.4 m

22


Hole Depth Azimuth width Lith Depth azim DipNo. Im) Ideg) Im) Type unit Type Im) (deg) (deg) Cc-rments

U2fe4S-52 2.S S QtA B Ends on contact

113-116 2.6 S Qta B Ends on contact311-313 2.5 S Qta B Ends on contact342-346 120 1 Qtb B Ends on contact361-370 130 1 Qta371-376 125 2.5 E Qta J 371-377 135 65NE376-391 120 I Qta391-405 115 2.6 E Qtb B Becomes incipient on contact405-408 10S I Qta B Ends on contact408-412 2.6 S QtA B Ends on contact416-416 2.7 S Qta B Between bedding contacts422-433 100 I Qta433-441 115 2.5 E Qta B Becomes elongated on contact444-444 120 1 Qta

General comments: 9 oriented breakout,; L mi M, - 117; SD- 9.Hole coordinates: N872,500. E668,300Drilling completed: 1/11180Caliper log date: 1/13/S0Movie log date: 4/21/80Drill bit size: 2.4 m


Hole Depth Azimuth width Lith Depth azim DipNo. (m) (deg) Iml Type unit Type Iml (deg) (deg) Comments

U4ai67-91 095 I Qtb B

130-195 225 1 QtA B195-199 150 2.7 E Qta199-207 135 1 Qta207-210 110 3.0 E Qta210-219 130 I QtA219-221 130 2.5 E Qta221-273 110 I Qb273-281 170 1 Qb283-314 175 I Qta373-381 115 I Qta392-397 105 I Qta399-406 120 1 Qta406-466 120 3.1 E QtalTma466-474 110 I Trna474-477 100 2.5 E Tma

General comments: 16 oriented breakouts; L -277 rn; M -150; SD _ 46.Hole coordinates: NSS3075.04, E674,074.97Drilling completed: 9/15/78Caliper log date: 9116178Movie log date: 105/78Drill bit size: 2.4 m

23

W

, Aqwat -


Hole Depth Azimuth width Lith Depth azim DipNo. In) (deg) Im) Type unit Type (m) (deg) (deg) Comments

USc23-38 R Qta41-42 2.7 S Qta43-44 2.7 S Qta B Between bedding contacts

210-213 145 I Ttb B Becomes elongated on contact213-223 135 3.5 E Ttb B Becomes incipient on contact223-230 115 I Ttb B Becomes elongated on contact230-233 110 2.6 E Ttb B Ends on contact

General comments: Drilling mud on sidewalls obscures geologic features. 4 oriented breakouts; L - 23 m; M - 127; SD - 12.Hole coordinates: N884,999.91, E670,000.42Drilling completed: 1/11/70; re-drilled 4/25/79.Caliper log date: 4/25/79Movie log date: 5/15/79Drill bit size: 2.4 in


Hole Depth Azimuth width Lith Depth azim DipNo. (ml (degl (ri) Type unit Type Em) (deg) (deg) Comments

USk36-S9 R Qta

213-214 150 1.9 E Ttb 1 213-214 080 21SE Tub Springs Member227-230 145 1 Trb231-235 140 2.4 E Ttb242-243 2.2 S Ttb243-245 150 1 Ttb2S1-282 1.9 S Ttb Caused by drilling284-285 165 2.1 E Ttb B Ends on contact256-293 145 2LS E Ttb B Ends on contact297-310 140 2.2 E Ttb Redrock Valley Member310-314 140 I Ttb Redrock Valley Member314-315 130 2.1 E Ttb B Redrock Valley Member

Ends on contact

General comments: Below 332 m, depth counter is Illegible. 9 oriented breakouts; L -36 m; M -143; SD - 5.Hole coordinates: NU84,046.34, E669,527.43Drilling completed: 8/14/S0Caliper log date: S/IS/80Movie log date: 6/27/S0Drill bit size: 1.S m

24


Hole Depth Azimuth width Lith Depth azim DipNo. (m) (deg) (m) Type unit Type (m) ideg) (deg) Comments

U8133-34 R Qta

132-133 1.7 S Ttb B Confined to one layer149-152 150 I Tib B Ends on bedding plane200-202 125 1 Ttb B Confined to one layer

General comments: 2 oriented breakouts; L 5 m; M- 140; SD -12.Hole coordinates: N885,708.67, E669,666.98Drilling completed: S/19/S0Caliper log date: 8/19/80Movie log date: 5116/S0Drill bit size: 1.6 m


Hole Depth Azimuth width Lith Depth azim DipNo. (m) (deg) Em) Type unit Type (Im) (deg) (deg) Comments

U9cn34-41 2.9 S Qta Large bit around casing60-66 155 2.3 E Qta/Tp J 63-69 150 71SW70-79 145 2.7 E Tp79-94 140 1 Tp96-98 130 2.5 E Tp98-108 110 I Tp B

108-110 125 2.3 E Tp B Becomes elongated on contact110-113 120 I Tp113-120 135 2.7 E Tp123-128 110 I Tp134-139 115 2.5 E Tp168-192 140 1 Tp J 173-176 125 4SSW

Thg/Ttb195-227 120 1 Ttb227-232 110 2.5 E Tlb277-279 It5 I Ttb B Ends on contact258-306 100 I Ttb 1 292-298 175 675W

General comments 15 oriented breakouts; L -145 m; M- 125; SD - 16.Hole coordinates: N867,199J.2, E6S9,S49.46Drilling completed: 9/6177Caliper log date: 9/4/77Movie log date: S/2117SDrill bit size: 2.2 m

25


Hole Depth Azimuth width Lith Depth azim DipNo. (m) (deg) (m) Type unit Type (m) (deg) (deg) Comments

U9cq40-41 2.6 S Qta

46-46 2.6 S Qta Caused by drilling49-51 2.7 S Qta53-55 195 I Qta56-5S R Qta

58-62 115 3.0 E Qta


119-123 195 1 Tmr

142-152 090 I Tmr

179-184 2.5 S Tp F 176-178 IS0 48NE Breakout begins on footwall offault

184-168 135 2.8 E Tp I 183-187 135 54SW Between two faults

Tp F 187-190 155 S45W. 1-i gouge

I88-217 110 I Tp F 215-221 145 69NE

224-231 155 I Tp B

218-238 145 1 Tp/Tbg F 230-234 170 60NE Begins on footwall

238-250 140 2.8 E Tbg B Ends on contact

261-261 115 I Tbg F 258-261 165 54NE Begins on footwall

284-290 135 1 Ttb B

290-291 S Ttb B Becomes symmetrical ancontact

291-301 125 1 Ttt, B

325-332 125 1 Tto J 329-332 020 56NW Two joints

General comments: 14 oriented breakouts; L -111 m; M 137; SD - 26.

Hole coordinates: N860,200.19. E688.949.79Drilling completed: 5/16179Caliper log date: 5/6/79Movie log date: 5123/79Drill bit size: 2.4 m

26


Hole Depth Azinmnth width Lith Depth uzim DipNo. (mW (deg (m) Type unit Type (m) (deg) (deg) Comments

U9cr38.39 2.7 S Qta a40-41 2.8 S Qta B

54-S5 2.7 S Qta B55-57 2.7 S Qta B59-59 2.6 S Qta B

S4-86 S Qta B149-l15 130 3.4 E Tmr F 141-i1O 120 74SW Breakout occupies footwall of

fault

200-205 215 2.9 E Tp B Begins on contact

210-212 225 I Tp B

228-237 120 1 Tp B Begins on contact

241-247 130 1 Tp B Ends on contact

253-257 110 I Tp B Begins on contact

259-261 130 I Tp263-269 130 3.2 E Tp

273-276 120 1 Tp B Ends on contact288-298 115 2.8 E Tbg B Begins on contact

299-303 130 1 Ttb B Begins on contact

327-330 115 I Ttb334-339 210 I Ttb B Ends on contact

344-350 115 3.3 E Ttb F 342-346 150 60SW Breakout begins on footwall offault

General comments: 14 oriented breakouts; L -67 m; M 130; SD - 31.

Hole coordinates: N866,400.26, E684,500.19

Drilling completed: 6/27/S0Caliper log date: 6129/80Movie log date: 6/30/S0Drill bit size: 2.4 m

27


Hole Depth Azimuth width Lith Depth azim DipNo. (m) (deg) (ml Type unit Type (m) (deg) (deg) Comments

U9ct66-68

237-238

267-269272-275275-284284-290290-291316-321

3.5.5

S

SQtaQta

Circular washout in alluviumBreakout covers 75% of hole;only WSW to WNW sideremains

3.33.4

135135 3.1

2.718 2.6

SSIESE

QtaQtaQtaQtaQtaTmr 316-321 140 90 Breakout on SE side of hole

only, along jointBreakout only on NW side ofhole

337-344 135 I Tmr

345-347 120

347-349 120349-354 130354-363 130

387-388 150 2.5389-390 170

390-393 150 2.7393-399 155 3.4399-402 3.4402-405 150

412-414 2.5414-418 120 2.5419-420 135 2.8421-424 170 2.8424-425 170435-436 2.5446-453 380 2.5454-456 160 3.3458-460 150 2.9467-471 160

471-486 160 2.5

I Tmr J 346j 346

I Tmr - J

I J

180 BoW120 SOSW Two perpendicular joints120 805W Breakout along joint

SE side of hole only120 90 Two joints, breakout on NW

sideBreakout on both sides of holeBreakout on SE sides of holeonly

E

I

EE

S

EEEISEEEI

TmrTmr

TpTpTpTp Predominant breakout in SE

directionTpTpTp

Tp

TpTpTpTpTp

Highly variedBreakout in NW quadrant only

Poorly definedNW side only, at 469 m bothsides continuous 467 to 503 mBreakout parallel to joints at483 m

E l

486-488488-489489-491491-500500-503

130

150

12.5 S52.7 S

I

2.9 I/E/S TP Complex and irregular

General comments: 24 oriented breakouts; L - 112 m; M - 149; SD - 18.Hole coordinates: N869600, E677,550Drilling completed: 6/11/81Caliper log date: 6/5/S1Movie log date: 10/20/S1Drill bit size: 2.44 m

28

. ~ ~ ~ ~ ~ ~ ~ ~ ~ -_-N X2p


Hole Depth Azimuth width Lith Depth azim DipNo. (I (deg) Inl Type unit Type (In (deg) Ideg) Comments

U9itsu2923-3S R Qha95-96 IgO 1.9 E Qta

123-137 150 LO E Tp B Begins on Tp contact137-139 1.8 S Tp Becomes incipient139-140 160 1 Tp149-153 165 1 Tp155-158 165 1.9 E Tp B Between bedding contacts178-180 '60 1 Thg197-199 175 I Tbg223-224 165 1 Tbg B Begins on contact232-234 1.9 S Tbg234-243 135 2.2 E Tbg B Ends on contact248-250 145 I Thg253-256 140 1 Thg256-261 130 1.9 E Tbg B Ends on contact with Ttb274-277 1O5 I Ttb277-280 115 1.9 E Ttb B Ends on contact267-292 105 I Ttb304-305 140 1.8 E Ttb B Between bedding contacts308-310 130 1.8 E Ttb B Begins on contact

General comments: 17 oriented breakouts; L -61 m; M -141; SD - 19.Hole coordinates: N871,599.85, E683,200.00Drilling completed: 2/0S/71Caliper log date: 12/13/74Movie log date: 8/6/81Drill bit size: 1.6 m


Hole Depth Azimuth width Lith Depth azim DipNo. fin) (deg) Iml Type unit Type (ml Ideg) (deg) Comments

UlObd36-37 2. S Qta42-43 5 Qta49-50 2LS S Qta62-62 26 S QtaS8-95 170 I Qta May be related to logging

108-109 150 I Qta113-114 130 1 Qta123-129 170 1 Qta130-131 2.7 S Qta134-136 R Qta199-202 120 3.1 E Tp J 200 300 SW Dip angle uncertain

General comments: 5 oriented breakouts; L -18 m; M -160; SD - 20.Hole coordinates: N876,000.1S, E683,149.J2Drilling completed: 4/20/77Caliper log date: 4/19177Movie log date: 7/26/79Drill bit size: 2.4 m

29

1111

�. . �W

Breakout data Geologic ctureMax WU

Hole Depth Azimuth width Lith Depth &rim DipNo. gm) ideg tIml Type unit Type ml idetgl IdegI Comments

U1O_

44-52 2.0

tl0-81 1.7

205-206 205

208-228 215 2.8

22tt-237 205 2.6

238-243 21524V-266 215 2.8

-26 190

2e7 273 145 J.4273-75 170275-280 160 2.8

281.2U4 175

284-285 155 1.7

285-288 2.8

213-291 l65

291-300 165 2.'

300-311 125 2.7

311-31t -135

216-321 230 2.1

321-324 130

324-325 070 I.7

325 32- 110 1.6327332 130

332-334 165 2.

339-348 155

348-359 130 2.0

359-362 130

364-368 115 2.1

3-2-377 095 1.9

377 -32 130 2.0

312-384 120

384-389 115 2.2

392-401 100 1.9

401-408 130 1.9

40W-46b 110425-427 100

441-443 120

446-457 120

457.459 115 1.8

460-462 110

462-463 1.7

463-464 100

465-467 110

467-470 2L0470-473 215

473-475 110 1.7

475-477 5O0

479488 125

488-491 140 I,'

491.498 215

498-511 105 2.4

513-515 1t7

515-516 105 2.0

517-523 115

526-540 105 2.1

Qta S Ends on contactQta B Ends on contactQta B Begins on contactQlaOt B Changes azimsuth

Ends on contactQtat-pTpTp 3 Ends on contacttpTp

TpTp B Becomes elongated on contactTp B Begins on contactTp

Tp B Changes azimuthEnds on contact

Tp B Becomes incipient on contactTpTpTp 1 323-326 070 57NW Parallel to Strike O ointTp Changes azimuthTp * Becomes incipient on contactTp B Becomes elongated on contactTp B Becomes incipient on contactTp B Becomes elongated on contactTp B Becomes Incipient

Ends on contactip I 361-368 160 645WTpTpTpTp B Becomes elongated

Ends on contactTbgtbS ji 3t4-368 160 t4SW Changes azimuthTbg 402.405 155 59SWTbg 1 407-408 155 375WTtbTtbTib B Ends on contactTibTtb Bitb * Becomes symmetrical on

contactttbteb

TitbTitbntb

tb B Becomes IncipientEnds on contact

Ttb aTtb Becomes elongated on contactTtbTitb B Becomes elongated

Ends on contactitb a Begins on contactTitbTtb * - Ends on contactTtb

_ _ _

Genera: comments: 49 oriented Ireakouts; L - 27e t; M - 148; SD . NRole coordinates Nt888650 E68300Drilling completed: 8/28/78Caliper to date: *1251/7Movie lg date: 9114178Drill bt sit . I.t m

30


Hole Depth Azimuth width Lith Depth azim DipNo. tIM) deg) (Im) Type unit Type (m) (deg) Ideg) Comments

UlObg175-177 155 I Ttb180-1l2 2i S Ttb B Between bedding contacts197-200 075 1 Ttb B210-212 2.6 S TIb B Begins on contact212-213 080 2.8 E Ttb

General comments: Last two directional breakouts are parallel to the dip of bedding; controlled by bedding structure;3 oriented breakouts; L - 6 m; M - 103; SO - 37.Hole coordinates: N875,549.97, E684,060.44Drilling completed: 1107/79Caliper log date: 1109/79Movie log date: 1119179Drill bit size: 2.4 m


Hole Depth Azimuth width Lith Depth azim DipNo. gm) (deg) ' m) Type unit Type (m) (deg) Ideg) Comments

U19ai112-114 050 2.6 E Tmr J 98-115 90

J 116-124 90 Major joint in zone that ex-tends to 127 m

264-271 180 2.8 E Tmr B Begins on contact314-316 3.5 S Tp B Between bedding contacts330-334 165 3.3 E Tp B Between bedding contacts335-336 2.8 S Tp B Between bedding contacts

340-341 2.7 S Tp B

427-428 210 1 Tp448-457 050 2.9 E Tpr480-490 070 1 Tpr490-498 075 3.2 E Tpr498-502 060 1 Tp502-505 080 3.0 E Tp508-511 3.5 S Trab B Between bedding contacts511-513 1 Tdh B Between bedding contacts516-520 105 2.9 E Tdh520-554 105 I Tdh562-578 125 1 Tdh

General comments: 12 oriented breakouts; L -102 m; M -101; SD -35.Hole coordinates: N937,400, E602200Drilling completed: 4113/80Caliper log date: 4/15/80Movie log date 7/2/80Drill bit size: 2.4 m

31

* t~ .FIX


Hole Depth Azimuth width Lith Depth azim DipNo. (ml (deg) Iml Type unit Type (ml (deg) (deg) Comments

UI9aj31.34 180 2 9 E Tma J 16S53 90 Zone of cooling joints63-67 2.6 S Tma B Between bedding contacts83-86 210 2 9 E Tmr j 82-109 90 Zone of cooling joints

343-346 2.7 S Tp B Between bedding contacts354-355 155 2.7 E Tp355-363 170 I Tp B Ends on contact363-377 155 3.5 E Tp B Ends on contact377-380 190 I Tp B Begins on contact383-386 135 1 Tp456-459 095 1 Tp B Begins on contact462-470 090 1 Tp470-475 070 3.5 E Tp475-478 1o0 I Tp479-484 120 3.4 E Tp B Between bedding contacts484-486 095 I Tp B Ends on contact486-490 095 2.6 E Tpr B Begins on contact490-494 120 I Tpr516-518 100 I Tpr541-554 125 1 Tpr598-599 2.e S Trab B Between bedding contacts600-602 29 S Trab B Occupies one bed605-607 130 I Trab B Between bedding contacts

General comments: 18 oriented breakouts; L - 76 m; M -134; SD- 3.Hole coordinates: N929,600.30, E599,199.60Drilling completed: 10/101S0Caliper log date: 10/14/80Movie log date: 11117/10Drill bit size: 2.4 m


Hole Depth Azimuth width W4th Depth azim DipNo. lm) Ideg) (m) Type unit Type Im) (deg) Ideg) Comments

U19t33-35 210 2.9 E Tma J 24-61 90 Controlled by cooling joints38-41 105 3.0 E Tma J 24-61 90 Controlled by cooling joints

346-355 205 3.1 E Tmr J 334-363 90 Controlled by cooling joints359-361 210 2.7 E Tmr J 334-363 90 Controlled by cooling joints363-371 115 3.0 E Tmr B Between bedding contacts386-412 090 35 E Tmr B Ends on contact412 421 3.5 5 Tp B Between bedding contacts421-441 IS0 3.5 E Tr B Begins on contact442-451 150 I Tp451-453 125 2.9 E Tp a Begins on contact453-454 175 1 Tp Ends on contact

General comments: 10 oriented breakouts; L -3 n; M -135; SD -40.Hole coordinates: N924,000, E607400Drilling completed: 6/6/78Caliper log date: S124178Movie log date: 6/25/78Drill bit size: 24 n 32

Breakout data - Geologic structureMax Strike

Hole Depth Azimuth width Lith Depth azim DipNo. (ml (deg) Cm) Type unit Type (ml (deg) (deg) CornfIts

U20ab57-64

139-142202-205207-212212-246246-276276-297297-303303-308370-377413-430439-444449-451453-466470-483492-497497-527532-534538-543554-562S66-569569-602

3.4 S045 1

3.4 S110 3.4 E120 1120 E140 1130 2.8 E150 1135 1ISO 1

145 1125 1140 1170 1140 1125 3.5 E105 1

095 1055 1060 1

3.5 E

TmrTmr

Tmr/TpTmrTpTp

TplTprTprTprTprTraTraTraTraTraTraTnaTeaTraTraTraTra

Between bedding contactsBegins on contactB

B Ends on contact

BB

Ends on contactEnds on contact

General comments: 20 oriented breakouts; L - 247 m; M - 109; SD - 36.Hole coordinates: N918,600. E574,600Drilling completed: 7127/78Caliper log date- 7/10/7SMovie log date: 8/1017SDrill bit size: 2.4 m


Hole Depth Azimuth width Lith Depth azim DipNo. ml (deg) (i) Type unit Type (in Ideg) (deg) Comments

U20ac235-238 100 2.9 E Tmr J 225-237 125 78SW284-291 200 I Tmr413-416 205 I Trpr441-446 180 2LS E Trpr523-527 230 2.7 E Tp B/F 524-S49 090 675 Bigins on contact548-5S1 195 2.6 E TpS56-558 175 I Tp B

General comments: 7 oriented breakouts; - 27 n; M- 188; SD - 3S.Hole coordinates: N909,501.11, E571,095.67Drilling completed: 9/29J79Caliper log date: 9/30/79Movie log date: 10/23/79Drill bit size: 2.4 m

33

-I * . . . ..

11��--


Hole Depth Azimuth width Lith Depth azim DipNo. (m) (deg) (m) Type unit Type (ml (degI (deg) Comments

U20ad158-159 155 2.6 E Tma B Between bedding contacts455-514 100 3.6 E Tp B Begins on contact

528-534 3.6 S Trau564-570 205 1 Trau B Begins on contact576-579 210 E Trau B Begins on contact

General comments: 121-138 m and 174 m; zones of open, continuous, nearly vertical cooling joints. 4 oriented breakouts;L - 69 m; M - 115; SD - 34.Hole coordinates: N924,500.00, E561499.99Drilling completed: 3/7/79Caliper log date: 3/10/79Movie log date: 3/16/79Drill bit size. 2.4 m


Hole Depth Azimuth width Lith Depth azim DipNo. ml (deg) Wm) Type unit Type (m) (deg) (deg) Comments

U20ae233-234 110 I Tmr235-241 195 2.6 E Tmr J 235-241 195 67NW253-256 210 3.2 E Tmr J 255-262 195 70SE428-434 Ot; I Tmr

General comments: 4 oriented breakouts; L -16 m; M -220; SD - 28.Hole coordinates: N912,300, E5S4,200Drilling completed: 1/2/79Caliper log date: 10/9178Movie log date: 1/11/79Drill bit size: 2.4 m

34

Part 11: Stereo Photo Breakout Logs

Hole LengthNo. Depth (m) Type covered (ml Azimuth Remarks Date

U2ao 169-1U2 E 13 NNE Shallow 1ii1i20Photograph length: 185-197 E 12 NNW169-275 m 206 E 3 N

211 E 3 NW217 E 2 NNW229 E 3 NNE Poorly defined, shallow240 E 3 NNE Poorly defined, shallow

U2bs 305 E 5 WNW 1/19/82Photograph length: 352 E 3 WNW One side shown244548 m 363 E 6 WNW One side shownInot continuous) 380 E 3 WNW One side shown

388 E 6 WNW Shallow397 E 3 NW One side rpalled477 E 5 E-ENE One side shown, shallow486 S 3Sit S 3523 I Continuous WNW

U2do 254-343 No breakouts 1/19/82Photograph length:254.343 m(not continuous)

U2dp 240-306 - No breakouts 1/19/82Photograph length: Scrape marks on N side240-306 m only

U2dq 74 E 3 NW One side only, small 1/19182Photograph length: 123 S 3 Deep34-363 m 128 E 3 NNE Shallow(not continuous) 163 E 3 N-NNW One side only, scrape mark

178 E 2 NNW One side only, scrape mark182 E 3 NNW One side only, scrape marklSS E 3 NNW One side only, scrape mark200 2 N-W. One side only, scrape mark209 E 3 NNW One side only, scrape mark222-268 Continuous NNW Scrape mark, no breakout277 E 5 E-W Deep283 E 6 NNW Deep314-320 1 6 NNW326 E 6 NNW331 E 2 NE One side only334 E 2 N One side only335 E 2 NW One side only340 S 3343 1 2 WNW349 E 3 WNW354 E 6 W-WNW.358 S 3

U2dsPhotograph length:343-349 m

343

345

349

EEE

Continuous

6

WNW

NW

NNW

Nearly symmetricalOne side only, shallowOne side only, shallow

11191/2

35

EM IE IM0" 11 7 "Ir..."T - P.-%- ----.. W N,

mmm�s

U2dv 446-468 22 No breakouts 1119182Photograph length:446-468 m

U2dw 98 E 3 NW One side only, shallow 1/19/82Photograph length: 105 E 5 NNW One side only, shallow31-378 m

U2dy 302 1 Continuous WNW 1119/62Photograph length: 314 E WNW262-414 m 317 1 WNW

329 E WNW345 E NW352-360 E WNW367 E NNW Spalls not opposite

378 E NW Very shallow382 E WNW391 E WNW-NW402 E WNW409 E NW414-415 E 113 WNW

U2ea 92-123 No breakouts 1120/82Photograph length:92-123 m

U3ja 62 E 6 WNW 1/20/82Photograph length: 126 E a WNW-EW62-63 m; 160 E 9 WNW Deep126-126 m; 175 E 12 WNW Deep160-289 in 192 E 12 WNW Deep

215-289 E 74 EW-WNW

U4af 225 E 8 NWN 1/20182Photograph length: 274 E 8 WNW-EW148-154 m;222-302 m

U4ah 120 S 3 1/20/82Photograph length: 203 E 6 NW37-342 m 222 E 9 NW-NNW

243 E 3 NW255 E 3 NW Deep280 E 3 NNW Shallow292 E a NW Shallow314 1 3 NW320-342 E 22 NW

U7akPhotograph length:346-495 mn(not continuousl

346351394431452495

£EEE£E

I1536

6

WNWWNWNWNWNW

WNW-NW

One side shown, shallowOne side shown, shallowShallow

1/20/82

ShallowShallow

V

36

Uqcg 142 E 3 NWN Shallow 1/20/82Photograph length: 165 E 3 NNW111-160 m 194 E 6 NW Deep

243 E 6 NW232 E S NW

U9ci 111 E 6 WNW-EW Deep 1121t82Photograph length: 117 S 3 Shallow111-120 m; 157 1 2 WNW152.157 m; 215-218 E 3 NW Shallow214-252 m 222 E S E-W

U9ck 89-237 E Continuous WNW Shallow 1/211/2Photograph length: 237-246 E WNW Deep89-265 m 255-265 E 176 WNW Very deep

U9cl 86 l 3 WNW Radial crack 1/21/82Photograph length: 95 E 3 WNW One side only86-348 m 105 E 2 N-W One side only

109 E 3 NW One side only112 E 2 WNW One side only153 E Continuous WNW164 E NW Deep197 E NW Shallow203 E WNW Deep209 E NW Deep215 E NW Shallow (contact)222-246 E WNW252 E NW258 E 105 E-W265 1 WNW One side only277 E 3 WNW335-349 E 14 NW Shallow

U9cm

Photograph length:31-345 m

31405565-S2U369

10t13516016917222824324625525826S271-277277-289317

WEEEIIEEE£IEIEEI£

EI

1/21/829

2Continuous

WNWWNW

366336

Continuous

346

123

E-WE-W

WNW

E-WE-W

WNWWNWWNWNW

WNWWNWWNWNWNW

E-WWNW

ShallowOne side onlyShallow

Very shallowShallow

Shallow, sides scrapedShallow, sides scraped

Very shallowVery shallow

No breakoutsShallow

37

PM Now. ."W'W777 " "w""ITA77'.

-- A. : A - - -- -

U9itsw24.S S3 E 3 NWN Continues from above 1121/82Photograph length: 95 E 3 WNW Continues from above83-207 m 115 E 6 WNW Continues from above

123 E 9 WNW Deep162 E Continuous WNW172 E WNW Shallow175-207 E 45 WNW Deep

UlOas 85 E 2 NW Shallow 1/21182Photograph length: 270 E Continuous WNW Shallow62-215 mn; 277 E WNW Deep271-283 m 280 E 10 WNW Deep

286 E 6 E-W

UlOaw 289 E Continuous WNW 1121/82Photograph length: 292 E WNW212-311 m 298 E WNW Deep

305 E WNW Large cavity311 E 22 WNW Large cavity

UlObb 275 E 2 NW Scrape mark 1/21/82Photograph length: 277 E 3 NW157-285 m

UlObc 192 E 6 No compass 1/21/82Photograph length: 215-254 E 38+ No compass85-285 m 254 1 No compass

262 E 6 WNW

38

Appendix B: Circular Histograms

Appendix B contains circular histograms of breakout orientations for each hole that has orientedbreakouts.

U2co LW8Srn M-IIS0 SD-120 U2cP Lin103m M=126* SD-70

% length

U2eh L-95m M=157° SD-IS* U2eo L-20m M-1740 SD-230

31

U2.eP Lin1 9m M n113 0 SD'u16 0 U2eQ LinIQ2m Mm150 SDm14 0

I

39

V I 0 -On - 1. .. M_ Z! . - T ,.".v f7 .!W _.51 ff -,. WYMAF, , -. � ... -..:,-- --- .- __ -- , -,, . . I I -1 _._P Aff, , --�_ I ',� , .

U2er L-66m M=123 SD=170 Ue SmffI9 D2U2es L-56m M=1190 SD=12'0

UMet L-Sim M=1teP SD-18 0 U2fb Lin25m M=1 I10 SDt1S0

U2fc Lin13Sm M1ISI0 SD=80 U2fe L-80m M=117' SD=GP

40

U4al L-277m M-'Se SD-4B 0 UcL2m Mi7SD 0USc L-23m M-1270 SD-12"

U8k L-36m Ma 1430 SD-5 0 USI LmSmn M I 4e SD-1 20

Ugcn Lint4Sm Mmu1250 SD"16 0 U9cq L-I1lm M-1370 SD-26a

v length

41

-I- I -.

-...-. 7- . ! -."-#W-i -- 11- .7 : O'.,�,!. . - ,, M. . :- -:. , ;W-.-- -, ,;,

Uger L-67m M- 1 30' SD=3 10 U~er L7m t1300 Sz~310Ugct L-iil2m M-i4g0 SD-180

UgitsU29 L-61m M-1410 SD-19 0 UI~bd L-18m M-ul0& SDa200

Ut~bf L-276m Ma1480 SD'380 U10bg L-6m M-1030 SD-370

42

-- I

Ul90i LinI02m M-1010 SD-3S0 Ul9oj Lin76m M.1340 SD-38 0

% length

UI9i Lin83m Mut3S0 SD=40' U20ob, Lin247m M-1090 SD-360

% length

U20ac Lin27m M=1880 SD=350 U20od LinB9m M= I IS SD=340

% length

U20a. Lin16m M-220 0 SD:280

LLNL- 8184

% length

-~~~... ...W! . Or -

I ; .t '. , - p 7 .2 i j K ? > ' .

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