title textures of volcanic products from lathrop … · day cinder cone. ii. task steps -take...

Scientific Notebook #870E

Owner: Nancy Adams Date: 4/23/07

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TITLE: TEXTURES OF VOLCANIC PRODUCTS FROM LATHROP WELLS CINDER CONE, NEVADA PERSONNEL: Nancy Adams is the Principal Investigator for this project. All entries in the scientific notebook were made by Nancy Adams unless otherwise indicated. PROJECT: This notebook documents procedures, data, and results used in evaluating volcanic textures of eruption products of the Lathrop Wells Cinder Cone under 20.06002.01.302, Support Prelicensing Transition to License Application Review – DIRECT1 ISI (Volcanic Disruption of Waste Packages) first under 20.06002.01.302, Support Prelicensing Transition to License Application Review – DIRECT1 ISI (Volcanic Disruption of Waste Packages) and continuing under 20.14002.01.360, Volcanic Disruption of Waste Packages (DIRECT1) (nka; 12/17/2008). This text and supporting files are provided herein to meet the CNWRA requirements of QAP-001. DATA: CNWRA data contained in this report meet quality assurance requirements described in the CNWRA Quality Assurance Manual. Data used to support conclusions in this report taken from documents published by the U.S. Department of Energy (DOE) contractors and supporting organizations were generated according to the quality assurance program developed by DOE for the Yucca Mountain Project. Additional data was gathered from peer-reviewed journals. EQUIPMENT AND SOFTWARE: Mass measurements were made using an Ohaus Adventurer Pro Precision electronic balance. Thin sections were made at laboratories designated in the text and examined using an Olympus BX51 polarizing microscope. Images were captured using an Olympus digital camera attached to the microscope, a flatbed scanner (see text for specs), and on a Scanning Electron Microscope (SEM) (details noted in text); they were processed and analyzed using Adobe Photoshop CS2 Version 9.0 and Scion Image for Windows (nka; 12/17/2008). Location maps were produced using GoogleEarth Version 3.0 and ArcGIS Version 9. OBJECTIVES AND APPROACH: The primary goal of this study is to better understand the nature of alkalic basaltic magma as it ascends towards the surface during an eruption that ultimately produces a monogenetic cinder cone. In response to a decrease in pressure during ascent, magma will exsolve volatiles and crystallize microlites. Thus, by studying the textures of eruptive products that represents the magma ejected during various stages of the eruption, i.e. the density, vesicularity, and crystallinity, changes that characterized the magma during ascent can be discerned.



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ENTRY 1 Filed a work plan following AP-013 with EM J. Stamatakos. Lathrop Wells is outside the boundary of the NTS, but as a precaution, 2 work plans were produced following Appendix A (DOE work plan) and Appendix D (Safety and Environmental Work Plan). Appendix A (DOE Work Plan) I. Introduction A. PI - Nancy Adams B. Other participant(s) - Mark Silver C. Date of Work - March 22, 2007 - March 27, 2007 D. Location - Lathrop Wells cinder cone, Nevada (see attached figure) E. Purpose of Work - To examine in situ volcanic features and collect samples that represent the different eruptive phases and products of the igneous activity that resulted in the present day cinder cone. II. Task Steps -Take qualitative observations, make stratigraphic logs, and collect samples at locations recorded with GPS units associated with the:

1. Strombolian phase of the Lathrop Wells eruption (look for plagioclase phenocrysts) a. Early lower cone: target agglutinated pyroclastic mounds on S lava flow field b. South lava flow field lavas

2. Violent Strombolian phase of the Lathrop Wells eruption (no plagioclase phenocrysts) a. Upper cone b. Rafted upper cone: target non-agglutinated pyroclastic mounds on NE lava flow field c. NE lava flow field lavas d. Fall deposits

-Ship samples collected from Nevada to San Antonio. -Record information in a scientific notebook and enter collected samples into a sample control log. III. Safety Issues A. Identification and mitigation of hazards -Terrain: access along dirt roads on BLM land; use 4-wheel drive vehicle. -Climate:

1. dehydration is always a concern in an arid environment; bring a minimum of 1 gallon of water per person per day in addition to drinks rich in electrolytes, e.g. Gatorade 2. lightening; follow procedures outlined in Appendix B of AP-013 Rev.2

-Fauna: avoid fauna such as rattlesnakes, scorpions, and spiders as well as the desert tortoise -Flora: avoid cactus D. Facilities - Beatty Medical Clinic, Amargosa Valley Medical Center; see Figure 1 and Appendix C in AP-013 E. Contact:



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-Nancy Adams cell phone (210) 771-1301 -Mark Silver cell phone (832) 466-2951 -Longstreet Inn and Casino (775) 372-1777 F. Emergency kit obtained from Don Bannon; Nancy Adams is certified in CPR/AED - Adult IV. Environmental Issues A. Transportation - 4 wheel drive vehicle on BLM/Cind-R-Lite (mining company) access roads B. Surface disturbance - no collection of fine-grained sediments planned V. Land Access - permission from Andy Coop, mine manager at Cind-R-Lite (702-277-8640). VI. Check In/Out - daily phone call to GED Appendix D (Safety and Environmental Work Plan) I. Introduction (see section I of DOE work plan) II. Responsibilities -Nancy Adams: PI and team leader; set fieldwork objectives, create sampling strategy, assess

individual field sites, supervise sampling activities -Mark Silver: assist Nancy Adams with navigation and sample collection in the field III. Itinerary (see attachment) IV. Logistics Requested 4-wheel drive from rental company Obtained maps of Las Vegas and Nevada for navigation Located convenient supply (gas, grocery, shipping) stores Created plan along with Don Bannon for shipping collected samples from Las Vegas to San

Antonio Gathered proper field equipment including emergency kit, shovel, rock hammer, GPS unit,

Brunton compass, hand lens, sample bags, markers, field notebook, sieves V. Communication (see section III-E of DOE work plan) VI. Equipment Field gear will be part of check-in luggage (see section III of Safety and Environmental Work Plan) Samples - shipped from Nevada to San Antonio via UPS VII. Medical (see section III-D of DOE work plan) VIII. Environmental Concerns (see section III-A of DOE work plan) attached itinerary 22 MAR 07 - THURSDAY AIR SOUTHWEST AIRLINES FLT:711 ECONOMY LV SAN ANTONIO 1145A EQP: BOEING 737 300 DEPART: TERMINAL 1 03HR 00MIN



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AR LAS VEGAS 1245P NON-STOP ARRIVE: TERMINAL 1 CAR LAS VEGAS AVIS RENT A CAR INTER 4WD AUTO A/C PICK UP-1245 RETURN-27MAR RATE PLAN 5 DAYS 0 HRS USD MI/KM EX MI/KM DAILY RATE 68.00 UNL XTRA DAY- 56.83 UNL XTRA HOUR- 34.01 UNL MANDATORY CHARGES 124.33 APPROX RENTAL COST 464.33 UNL CONFIRMATION NUMBER 39008023US5 RATE-GUARANTEED ID-€WEB HOTEL SKED CHG - TCC XX LONGSTREET 5 NIGHTS OUT-27MAR HCR 70 1 ROOM AMARGOSA VALLEY, NV RATE-70.00 PER NIGHT FONE 775-372-1777 GUARANTEED LATE ARRIVAL CF 60134...CANCELATION POLICY IS 24HRS 27 MAR 07 - TUESDAY AIR SOUTHWEST AIRLINES FLT:847 ECONOMY LV LAS VEGAS 240P EQP: BOEING 737 300 DEPART: TERMINAL 1 02HR 40MIN AR SAN ANTONIO 720P NON-STOP ARRIVE: TERMINAL 1



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attached figure

Figure1 1.1 (nka; 9/5/07). Image of Lathrop Wells cinder cone located in southern Nevada.



ENTRY 2

Developed a strategy for collecting sample based on Valentine et al. (2005), Valentine et al. (2007), Perry et al. (1 998), and Crowe et al. (1 997).

ERUPTION OVERVIEW:

Information potentially subjected to copyright protection was redacted from this location.

The redacted material is a collecting sample based on Valentine et al. (2005), Valentine et al. (2007),

Perry et al. (1998) and Crowe et al. (1 997)

Strombolian eruptive phase: Short fissure now bmied by the cone - Strombolian explosions with little-to-no fallout beyond

the cone and effusion of South lava field lavas Early cone - dull red, massive to crudely bedded, partly welded bomb-and-coarse lapilli

agglutinate with plag phenocrysts Mounds of pyroclastic material dispersed across the lava field are rafted early cone material

(often agglutinated and retain original bedding); previously were interpreted as separate eruptive vents

South lava field -- buried by fallout; lavas initially flowed S around the W side of a small hill of Miocene ignimbrite and then SE around the E side of the hill; W part flow fronts are steep, blocky laiva and have plag phenocrysts

Violent Stromboliari phase: Activity focuses to single vent - sustained eruption column by violent Strombolian eruption(s)

builds cone and fallout covers South lava field

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Upper cone composed of beds of relatively well-sorted, loose, vesicular scoria lapilli; some beds show grain avalanching (inversely graded, clast supported) and some show roll-over (dip inward toward crater center) indicative of mantling the cone; at least one pdc deposit

Planar beds beyond cone; some massive, some show reverse-to-normal grading indicative of waxing and waning of eruption; some beds consist of angular, glassy, vesicular clasts that appear to be fragments of small ribbons interpret as juvenile clasts that might have been shredded from an annulus of magma; other beds have rounded, abraded clasts that appear to have been recycled by avalanching and churning in the vent; no real lateral correlation of individual fall units

Northeast lava field overlies fallout deposits; covered only by a veneer

Mounds of pyroclasts fairly aligned; previously interpreted as trend of fissure and vents for northeast flows; now interpreted as material rafted from the cone during the violent Strombolian cone-building phase (non-agglutinated)

Medial distal parts of NE lava field bend to S to form a platform that probably followed a paleochannel then thickened, lengthened, widened as lobes broke out along margins (see preserved along N and E margins); see down-stepping, terrace-like nature from breakouts along toes; see stacking of flows

Summit explosion – blocks of basalt-xenolith breccia around the cone base; also along cone rim and inner crater walls; possibly from late stage steam explosion that ejected part of the conduit plug SAMPLES WANTED: 1. Early lower cone (with plag phenocrysts) – at cone base?; pyroclastic mounds on South lava flow field 4 types of mounds:

a. crest of mound composed of partly welded, angular fragments; mound ranges from linear to circular lava-flow-top breccia that was uplifted as tumuli

b. consist of loose, scattered accumulations of decimeter-sized ribbon and spindle bombs as well as broken slabs or masses of partly welded agglutinate (Fig. 6a in Valentine et al., 2007)

pyroclasts deposited in the main cone curing early Strombolian eruptions that were subsequently dislodged by flowing lava and rafted

c. consists of a coherent mass of variably welded spatter and agglutinate that preserves original bedding (Fig. 6b,c in Valentine et al. 2007) pyroclasts deposited in the main cone curing early Strombolian eruptions that were subsequently dislodged by flowing lava and rafted

d. composed of jumbled blocks of very coarse spatter distributed in a circular pattern remnants of a hornito (rootless spatter vent)

Sample types b and c! Look for bedding and plag crystals!!! Consider dip of beds



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2. South lava flow field lavas (with plag phenocrysts) Caution: pyroclastic debris from mounds and fallout deposits obscure the flow surfaces; sample

at the distal edges where surface textures and flow fronts are preserved Think about sample orientation with respect to flow direction 3. Fallout from violent Strombolian phase (beyond the cone) BEWARE OF RECYCLED CLASTS! Some beds have angular or ragged, glassy and highly vesicular clasts juvenile clasts that

might have been shredded from an annulus of magma in the conduit by the eruptive jet Some beds have rounded and abraded scoria clasts recycled by avalanching and churning in

the vent Xenolith free except for layer near base of sequence with coarse ash-sized, Miocene tuff

xenoliths in N and NW quadrants (B, E, and F) Seems separate fallout units were dispersed in different directions 4. Late upper cone BEWARE OF RECYCLED CLASTS! Also, cone rim, inner crater walls, and the foot of the

cone have sparse blocks of welded breccia late stage steam explosion that ejected part of the conduit plug.

Planar to lenticular beds of relatively well-sorted, loose, vesicular scoria lapailli; no welding Cone is ~140m high; base ~820 m asl, W peak ~960 m asl, E peak ~940 m asl g In addition to recording elevation, think about how sampled beds are dipping 5. Pyroclastic mounds of NE lava flow field previously assigned to Chronostratigraphic Unit I (rafted material from late upper cone?)

& Pyroclastic mounds of NE lava flow field previously assigned to Chronostratigraphic Unit II Mounds rise 5-15 m above the surrounding lava surface and have rounded tops, and are

characterized by loose scoria clasts in the large lapilli to small block size range and are blocky in shape

Material not agglutinated 6. NE lava flow field lavas BE CAREFUL not to confuse individual lobe breakout associated with down-stepping with

pyroclastic mounds! Lobes preserved along northern and eastern margin (~10 m wide, ~10-20 m long, front 2-5 m

high) See down-stepping, terrace-like expression & flow stacking & probably inflation (tubes) Be aware of pressure ridges associated with axial lava channel Maybe try to distinguish between lava tube and channel lava?!



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Think about sample orientation with respect to flow direction REFERENCES: Valentine GA, Krier DJ, Perry FV, and Heiken G. (2007) Eruptive and geomorphic processes at

the Lathrop Wells scoria cone volcano. J Volcanol Geotherm Res 161: 57-80. Valentine GA, Krier DJ, Perry FV, and Heiken G. (2005) Scoria cone construction mechanisms,

Lathrop Wells volcano, southern Nevada, USA. Geology 33: 629-632. Crowe B, Morley R, Wells S, Geissman J, McDonald E, McFadden, L, Perry F, Murrell M,

Poths J, and Forman S. (1997) The Lathrop Wells volcanic center: status of field and geochronology studies. MOL.19980213.0044

Perry FV, Crowe BM, Valentine GA, Bowker LM (Eds.). (1998) Volcanism studies: final report

for the Yucca Mountain project. Los Alamos National Laboratory Report LA-13478-MS. 554 pp.

TO BRING LIST GPS (2) Extra batteries for GPS Tape measure Rock hammer (2) Sieves (brass and plastic) Shovel Sample bags Markers (sharpies) – fine tip for notebook, regular tip for samples Brunton compass Hand lens Paper/notecards (for samples) Camera Road maps Field maps/photos/satellite images Pocket knife Field notebook Clipboard Duck tape Purell



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ENTRY 3 Fieldwork 3/22/07-3/27/07 Sites were located using a handheld Garmin GPS V personal navigator unit. Accuracy ranged between 13-29 ft. Locations were marked as waypoints for each site, and UTM coordinates and elevations were recorded. They were named sequentially by date, e.g. the first site visited on March 23, 2007 is called 32307-1. Samples collected match location name, and if multiple samples were collected at one location, they are labeled alphabetically (a, b, c, etc.). These names match the C/CL (file: 3-07 LW sample-custody-log.wpd) saved on the CD attached to this notebook. Digital photos were also taken at each location and are named to match the site. These pictures are also saved on the attached CD (folder: LW 3-07 photos). March 23, 2007 Pyroclastic mounds, lavas, and fall deposits of the South lava field. The motivation behind sampling the mounds is to sample early/lower cone facies. 32307-1: UTM 11S 4059724, 543918; Elev. 818m. Pictures: LW 32307-1 001 – 005. Sample 32307-1. Pyroclastic mound ~4.6 m x 2.6 m comprised of layered massive lava with flow aligned vesicles and slightly oxidized, well-agglutinated/welded spatter like material. Type III mound described in Valentine et al. (2007)? Or lava-flow-top breccia uplifted as tumuli (Type I mound or something like it)? Welded spatter and massive lava layered more in a zone-like manner than continuous beds. 32307-2: UTM 11S 4059549, 544086; Elev. 810m. Pictures: LW 32307-2 006 – 008. Samples 32307-2a, b, and c. Fall deposits on N-NW side of Miocene bluff that divides South lava flow field. Close to point Z in Valentine et al. (2007). 32307-3: UTM 11S 4059608, 544023; Elev. 841m. Pictures: LW 32307-3 009 – 010. Sample 32307-3. Pyroclastic mound of moderately-densely welded agglutinate with a bedded appearance but no real discernable bedding; a few spindle bombs. Type III mound described in Valentine et al. (2007)? 32307-4: UTM 11S 4059446, 543868; Elev. 799m. Pictures: LW 32307-4 011 – 014. Sample 32307-4. Flow lobe/toe on E margin of S lava flow field. Flow top breccia with vesiculated flow interior. Definitely see evidence of vesicle elongation/oriented along flow. 32307-5: UTM 11S 4059365, 544140; Elev. 801m. Pictures: LW 32307-5 015 – 017. Sample 32307-5. Pyroclastic mound on SE flow field just E of Miocence Tuff bluff. Moderately-



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densely welded agglutinate and spatter with possible bedding (hard to discern bedding with certainty). Type III mound described in Valentine et al. (2007)? 32307-6: UTM 11S 4059570, 544255; Elev. 813m. Pictures: LW 32307-6 018 – 022. Sample 32307-6. Pyroclastic mound on SE flow field. Several slab like pieces of moderately welded agglutinate, and littered with fluidal shaped pieces (ribbon and spindle bombs). Highly oxidized appearance. Poorly vesicular small lava-dike like feature stands near/within bombs and agglutinated slabs. Type II mound (and same mound shown in Figure 6a) in Valentine et al. (2007). 32307-7: UTM 11S 4059344, 543639; Elev. 790m. Pictures: LW 32307-7 023 – 024. Sample 32307-7. Flow toe of lobe on W margin of S lava flow field (near road). Blocky flow appearance; some blocks have flow top breccia (aa clinkers?). Coarsely vesicular. Minor (≤ 1%) phenocrysts of olivine, maybe plag. March 24, 2007 Sampling the upper cone facies deposited during the violent Strombolian phase. To try to decipher the ascent history of the magma throughout the course of the eruption, we will study textures, i.e. vesicles and microlites, from samples representing eruptive stages/the eruptive sequence. For the Strombolian – violent Strombolian eruption that created Lathrop Wells, the main phase was marked by violent Strombolian activity (Valentine et al., 2007) that created the bulk (~2/3) of the cone (and the layers of the cone currently exposed), the N-NE lava flow field, and the fall deposits. The strategy for studying the eruptive sequence is to sample in situ layers of the cone. From current base to peak, the cone is ~140 m in height (Valentine et al., 2005; USGS topo quads 7.5” series Big Dunes and Amargosa Valley), thus we attempted to collect samples in 10-25 m increments dropping in altitude from peak (~3175 ft. asl) to base (~2720 ft. asl). Cind-R-Lite mining operations have created an access road to the peak. 32407-1: UTM 11S 4060681, 543664; Elev. 965m. Pictures: LW 32407-1 00245 (nka; 11/12/07) – 0028. Sample 32407-1a – large outsized volcanic breccia blocks along S facing N wall of inner crater near cone peak (products of throat clearing event of conduit plug (Valentine et al., 2007)?) Sample 32407-1b – clast supported non-agglutinated bed of coarse clast, highly oxidized; many of the clast appear rounded/abraded suspect recycling. 32407-2: UTM 11S 4060546, 543635; Elev. 933m. Picture: LW 32407-2 0029. Sample 32407-2. Along a SW bearing from peak, sampled a fairly continuous, oxidized bed in a S facing outer cone wall. Clasts definitely appear less abraded (recycled) than 32407-1b.



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32407-3: UTM 11S 4060726, 543805; Elev. 910m. Picture: LW 32407-3 0030. Sample 32407-3. Along an E bearing from peak, sampled a fairly continuous bed in an E facing out cone wall; overall, a coarser bed than 32407-1a or 32407-2. Dark gray color (not oxidized; off the main fissure?). 32407-4: UTM 11S 4060661, 543898; Elev. 886m. Picture: LW 32407-4 0031. Sample 32407-4. Along an E bearing from peak, sampled a bed in E facing outer cone wall; bed seemed continuous and in situ, but overlain by a bed of fines (sand mostly). Gray colored clasts mostly (off main fissure?). 32407-5: UTM 11S 4060469, 543937. Outer cone slope facing SE; bedding exposed in quarried bench; beds dip 32o S62oE. Sample 32407-5 a, b, and c. Elev. 869m. Pictures: 32407-5 032 – 036. E side of cone/quarried bench. Bedding defined by fine-coarse clasts; see both normal and reverse bedding. Many clast appear abraded/weathered; abundant wall rock lithics. Sample 32407-5d. Elevation. 863m. Picture: 32407-5 0037. Bed outcrops ~5-10m below 32407-5a. Bed not as well sorted; shows fine scale layering (coarsening-fining over cm scale). Abundant wall rock lithics, and bed in general is more oxidized than 32407-5a, b, and c. 32407-6: UTM 11S 4060328, 543802. Elevation 857m. Same quarried bench as 32407-5; W-SW facing slope of outer cone. Beds in this section are highly oxidized and range in thickness (cm-m scale). Wall rock lithics present (maybe not as abundant as 32407-5). Beds dip 25oE. Sample 32407-6a. Pictures 32407-6 038 – 039. Coarse bed overlain by a much finer grained bed. Sample 32407-6b. Pictures 32407-6 040 – 041. Collected ~6m stratigraphically beneath 32407-6a. Beds still defined by size, but the beds are not as well sorted in this sequence. Pictures: 32407-6_6 042 – 045. Panoramic of quarried bench from W (6a, b 042) to E (5a, b, c, d 045). 32407-7: UTM 11S 4060173, 543788. Elev. 827m. Pictures: LW 32407-7 046 – 048. Sample 32407-7. Outer cone slope facing SE; close to location shown in Valentine et al. (2005) Figure 2b. Bedding defined by clast size (coarser beds, finer beds). Sample coarsest bed (≥ 16mm) in sequence directly under bed comprised of fines (≤ 8mm). Seemed to have plag phenocyrsts? According to Valentine et al. (2007), plag phenocrysts are an indicator of lower cone facies (early Strombolian phase of the eruption). Drove up gully on W side of cone to examine fall deposits near sites X and Y in Valentine et al. (2007).



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32407-8: UTM 11S 4060673, 543245. Elev. 828m. Pictures: LW 32407-8 049 – 050. Sample 32407-8. Fall deposits. Sample WSW of X in Valentine et al. (2007). Dug ~1m deep pit; did not reach contact or see distinct bedding (probably in massive bed). No discernable grading; poorly sorted bed of ash-fine lapilli sized particles. 32407-9: UTM 11S 4060815, 543219. Elev. 832m. Pictures: LW 32407-9 051 – 052. Sample 32407-9. Fall deposits. Sample located between J and Y of Valentine et al. (2007) (WSW of Y). Dug ~130cm in a series of 2 pits; did not reach contact. Lower bed (**sampled unit) is a massive bed with fine-medium clasts (≤ 4mm); upper unit is fine-ash / fine-medium sizes lapilli (≤ 4mm) bedded. March 25, 2007 Sampled fall deposit S of the cone. Confirmed rafted upper cone facies in pyroclastic mounds on the NE flow field, and sampled lava from the NE flow. 32507-1: UTM 11S 4059847, 543946. Elev. 826m. Pictures: LW 32507-1 053 – 055. Sample 32507-1a. very dark red (possibly wet), massive bed of small-medium sized clast Sample 23407-1b. definitely not wet, massive bed very similar to Sample A bed. 32507-2: UTM 11S 4059806, 543909. Elev. 821m. Pictures: LW 32507-2 056. Sample 32507-2a. high certainty it’s primary; crudely bedded; small-medium clasts in a fines matrix Sample 32507-2b. no discernable bedding (massive); small-medium sized clasts; not as fines rich as 32507-2a. 32507-3: UTM 11S 4059913, 543935. Elev. 823m. Pictures: LW 32507-3 057-062. Thick in situ sequence outcropping near quarry operations. Fine ash couplet near base of outcrop reminiscent of fine ash layers in 32507-2. Sampled massive bed containing the coarsest clasts seen in any of the sampled fall deposit localities. 32507-4: UTM 11S 4061053, 543803. Elev. 853m. Pictures: LW 32507-4 063 – 064. No sample collected. Pyroclastic mounds N of cone on NE flow field comprised of unconsolidated, non-agglutinated clast; clast themselves (size) and nature (unconcolidated) reminiscent of upper cone facies (rafted material). Lava push-up(?) located on W side of mound; lava transitional between aa and pahoehoe/massive. 32507-5: UTM 11S 4060969, 544796. Elev. 820m. Pictures: LW 32507-5 065 – 068. Sample 32507-5. NE lava flow field. Lavas DEFINITELY seem younger than S flow field lavas, e.g. better exposed, original flow features such as surface textures are preserved. A less weathered overall appearance; flow field features evident, e.g. terraced toes, draping, tubes(?). Flow toes



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comprised of blocky/aa or massive/aa lava. Previous studies (EPRI, DOE) have reported all flows aa, and them come directly from the vent as aa; what is the evidence they exit the vent/fissure as aa? NE flow field fissure covered by sand! Pictures: LW from NE 069 – 070 standing ENE of cone (N36o 41’ 33.25”, W116o 30’ 01.22”) looking almost due W; see lavas, sand dunes, and rafted upper cone facies (pyroclastic mounds) in foreground and cone in background. 32507-6: UTM 11S 4060023, 544989. Elev. 806m. Pictures LW 32507-6 073 – 074. Sample 32507-6. Lava toe along E margin of NE flow field.



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ENTRY 4 New objectives and additional desired samples were identified to supplement the fieldwork performed on 3/22/07-3/27/07.

• Examine pyroclastic mounds on the E side of the S flow field (ESE of cone) • Re-examine 32407-1, especially considering elevation of sample 32407-1b • Additional upper cone samples for elevations 910 m asl and 886 m asl, but at different

bearings/sectors than 32407-3 and 32407-4 • Additional upper cone samples between 830 m and 860 m elevations (32407-5/6 and

32407-7) • Sample additional strata at 32407-7 • Examine(/sample?) fall deposits/cone strata near X and Y sites identified in Valentine et

al (2007); in general, examine deposits on NNW side of cone Following the same general field plan produced for the 3/22/07-3/37/07 trip, a follow-up field investigation was conducted on 5/12/07-5/14/07. The participants were Nancy Adams and Saurav Biswas (618-203-9130 cell), both of whom stayed at the Motel 6 in Beatty, NV (775-553-9090) during the field-trip. Fieldwork 5/12/07-5/14/07 Sites were located using a handheld Garmin GPS V personal navigator unit. Accuracy ranged between 13-21 ft. As for the 3-07 fieldwork, locations were marked as waypoints for each site, and UTM coordinates and elevations were recorded. They were named sequentially by date, e.g. the first site visited on May 12, 2007 is called 51207-1. Samples collected match location name, and if multiple samples were collected at one location, they are labeled alphabetically (a, b, c, etc.). If a sample was collected at a site originally sampled and described during the 3/22-3/27 work, the sample was named to match this site (e.g. 32407-7b). These names match the C/CL (file: 5-07 LW sample-custody-log.wpd) saved on the CD attached to this notebook. Digital photos were also taken at each location and are named to match the site. These pictures are also saved on the attached CD (folder: LW 5-07 photos). May 12, 2007 Examined pyroclastic mounds on the S flow field. On the E side of the S flow field, many of the mounds look like the mounds due E of the cone and ENE on the NE flow field, i.e. large hills of loose pyroclastic material with little to no agglutination (32507-4 pics 063-064). 51207-1: UTM 11S 4059599, 544222. Elev. 821m. Pictures LW 51207-1 003 – 008. Sample 51207-1. Pyroclastic mound as described on ENE of the NE flow field, i.e. large hill of mostly



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non-agglutinated pyroclasts; mix of textures, e.g. spindle bombs, ribbons, rubble (either a’a’ flow or agglutinate); near 32307-6 (pic 51207-1 008 is taken standing on 32307-6). 51207-2: UTM 11S 4059820, 544215. Elev. 822m. Pictures LW 51207-2 009 – 011. No sample. Pyroclastic mound on E side of the cone overlaying the S flow field; very similar to 51207-1 (large hill, mix of textures including fluidal, e.g. ribbons, and agglutinate); no fall deposits overlaying mound. 51207-3: UTM 11S 4059930, 544259. Elev. 818m. Pictures LW 51207-3 012 – 017. Sample 51207-3. Pyroclastic mound capped by a large dike-like wall of agglutinate (~3-4 m in height and 10 m in length); maybe loosely bedded; could be rafted and pushed up, but could this also be a hornito or rootless vent?; on same mound E of the wall is a small “lava-fence” similar to 32307-6 51207-4: UTM 11S 4060058, 544256. Elev. 818m. Pictures LW 51207-4 018 – 020. No sample. Slab of agglutinate similar to 51207-3; possible bedding or zonation where denser lava in the center of the slab is mantled by rubbly texture. Drove vehicle to the top of the cone to collect additional upper cone samples; collected data during descent. 51207-5: UTM 11S 4060673, 543632. Elev. 964m. Pictures LW 51207- 15 (nka; 9/7/07) 021 – 022 (see also SB photos\2007_05_12_LasVegas_LathropeWell 0181-0184). Sample 51207-5. Near 32407-1 (re-examined and determined previous description, including elevation, was good); top of cone, outer wall, N-facing; poorly sorted bed with large eolian contribution; highly oxidized and significant presence of caliche coating; recycled appearance. 51207-6: UTM 11S 4060553, 543816. Elev. 935m. Pictures LW 51207- 16 (nka; 9/7/07) 023 – 024 (see also SB photos\2007_05_12_LasVegas_LathropeWell 0188). Sample 51207-6. Near top of cone, outer wall, S-SW facing; poorly sorted (some very large outsized clasts ~0.3 m in length), semi-continuous bed of highly oxidized clasts with an abraded appearance; no significant presence of caliche. Drove down to 32407-5_6 bench; took pics showing stratigraphic relationship between samples 32407-6a and 6b. In pictures LW 5-07_32407-6 025 – 027, Saurav’s hand is on 6a, and in pictures LW 5-07_32407-6 028 – 030, his hand is on 6b. Also see SB photos\2007_05_12_LasVegas_LathropeWell 0189 – 0198, 0202 – 0203. Sampling between 830 m and 860 m not really feasible because of very steep slopes and fairly fine-grained deposits.



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51207-7: UTM 11S 4060510, 543489. Elev. 850m. Pictures: LW 51207-7 031 – 036 shovel is in front of sample a; LW 51207-7 037-040 shovel is in front of sample b. Samples 51207-7a and b. On same bench as 32407-5 & -6, drove around to WNW side of cone; deposits dark gray (minimum – no hydrothermal alteration…off the main fissure?); sequence of nicely sorted, reversely graded, fairly continuous beds of outer cone (reversely grading indicative of grain avalanche sequence?). Drove down to 32407-7; took pics LW 5-07_32407-7 041-047. Sample 32407-7b. Sampled coarse grayish layer, moderately-poorly sorted overlain by the layer sampled on 32407 (sample 32407-7); layers fairly continuous. May 13, 2007 Examined cone layers exposed in close proximity to quarry operations SSE of cone which we believe to be products of the Strombolian phase (early/lower cone) based on previous descriptions. Valentine et al. (2005, 2007) described early/lower cone products as dull red, massive-crudely bedded, partly welded bomb-and-coarse-lapilli aggluntinate with plag phenocrysts; fluidal spindle and ribbon bombs are abundant. Also, this early cone-building facies is in sharp contact with, and mantled by, overlying beds of well-sorted scoria lapilli of the later violent Strombolian eruptions. Also visited NW side of cone near sites X and Y of Valentine et al. (2007). 51307-1: UTM 11S 4060241, 543988. Elev. 830m. Red, rubbly, lightly agglutinated, poorly sorted, crudely bedded exposure on SE base of cone; fluidal textures abundant (ribbons, spindle bombs, toothpaste); some clasts have abundant plag crystals Sample 51307-1a. Pictures LW 51307-1 048 – 055 (shovel at sampled bed). Sample 51307-1b. Pictures LW 51307-1 056-059; 064 – 065 shows 1b prominently, but also 1c [also see SB photos/2007_05-13_Lathropewell 173_7310 through 173_7314 (in 7311, 7312, and 7314, Nancy Adams is sitting in front of sampled bed)]. Sample 51307-1c. Pictures LW 51307-1 060 – 062. [also see SB photos\2007_05_13_Lathropewell 173_7317 through 173_7319 (Nancy Adams and shovel are sitting in front of sampled bed)]. 51307-2: UTM 11S 4060100, 544021. Elev. 829m. Pictures: LW 51307-2 063, 066 – 070 (063 is taken looking at 51307-2 from 51307-1b) [also see SB photos\2007_05_13_Lathropewell 173_7320 through 173_7322 and 7331 (in 7321 and 7322, Nancy Adams’s hand is on sampled bed)]. Sample 51307-2. Proximal to (just S of) 51307-1 and very similar in appearance; did not immediately find clasts with abundant plag crystals.



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Trench dug E of 51307-2 as trash pit shows sharp contact between lower cone facies and upper cone/fall deposits. Pictures LW trench near 51307-2 071 – 074 (also see SB photos\2007_05_13_Lathropewell 173_7324 through 173_7330). Pictures LW near 51307-1 075 – 081 (see also SB photos\2007_05_13_Lathropewell Panorama2, Panorama2b, and Panorama3) taken from 51307-2 looking towards (and just E of) 51307-1 at contact between lower cone facies and upper cone/fall deposits. 51307-3: UTM 11S 4060595, 543423. Elev. 848m. Pictures: LW 51307-3 085 – 089 [see also SB photos\2007_05_13_Lathropewell 173_7382, 7386-7388 (in 7386-7388, Nancy Adams is sitting/standing directly in from of sampled bed)]. Sample 51307-3. Fall deposits/grain-avalanche deposits on NW side of cone near site X of Valentine et al. (2007); non-agglutinated, dark gray, poorly-moderately sorted, inversely graded.



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ENTRY 5 Lab equipment and space was secured in Building 51 to measure the density of samples collected from Lathrop Wells cinder cone. Acquired materials included:

(i) Ohaus Adventurer Pro Precision Electrical Balance (Model AV3102, Weighing Range 0 to 3100g, Readability 0.01g, Pan Size 16.8 x 18cm)

(ii) Kiwi Camp Dry Heavy Duty Water Repellent (contains 13% silicon) (iii) Parafilm M Laboratory Wrapping Film (1 roll: 4” x 250’)

Additional non-specific supplies included white-out pens, a plastic dish tub, a plastic bucket, aluminum baking pans, index cards, markers, and sheets of butcher paper. Following Houghton and Wilson (1989), density of individual clasts were measured by determining weights in air and in water (Archimedes’ principle) and converted to vesicularity using a dense-rock equivalent (DRE) density of 2.65 g/cm3. Also, a whole (2”x 2” square) wax sheet was measured in water and determined to weigh 0.1 g. The equipment set-up used to accomplish measuring weight in water is shown below.

Figure 5.1 (left) Clast is placed inside the suspended basket; the ballast (mesh cage) can be turned upside down (as shown) for clasts that float. Figure 5.2 (right) Basket is positioned in water so that it is completely submerged and is not in contact with the sides or bottom of the container.



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Figure 5.3 Set-up used to measure clast density following Archimedes principle and outlined in Houghton and Wilson (1989). Scott Rubio was the primary tech to measure density; the instructions supplied to and followed by him are shown below: 1. Wash sample in sink with tap water; take care not to clog drain (use the plastic tub). The wet clasts of one sample should be placed in an aluminum tray along with the sample number (written with a magic marker on an index card). Think about saving the sample bag; move the bag to certain spots to indicate where the sample is in terms of processing, e.g. in the oven, on butcher paper. Also, if the bag is in decent shape, you can reuse it when the processing is complete. Don’t just leave the bag near the sink! 2. Place the aluminum tray with the sample in the oven at 110 oC. Leave in the oven for at least 24 hours to drive off all water. 3. Spread the sample out on a sheet of butcher paper, taking care to note the sample number (write on butcher paper, keep sample label with sample). Make qualitative observations. Look for things like caliche, abrasion, agglutination/welding. If possible, separate clasts into subgroups distinguishable by your qualitative observations. Write down a basic description of each subgroup on lab sheet. Arrange the clasts biggest to smallest per subgroup. Number each clast, 1-1XX; note the limits of each subgroup on the lab sheet. Caution! When numbering clasts, consider how a thin section might be made/positioned (ideally, the cross-section of the clasts with the largest area will be used so that a slide is filled as much as possible). This might entail not choosing the easiest face of the clast on which to write. Also, be sure to underline numbers when appropriate, e.g. 18, 69. 4. Weigh each clast and record the weight in the dry column on the lab sheet. 5. Seal the vesicles of each clast either by:



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(i) if vesicles are <1mm, spray with silicon spray. After spraying, allow to dry for at least 24 hours. Be sure to go outside to spray, and leave the samples outside for the first few hours after spraying. Don’t leave them outside overnight, and be cautious of rain. [Given the 24 hour wait-period, it might be easier to spray the clasts directly out of the oven, i.e. immediately after step 2. If the vesicles are too large and spraying doesn’t seal the clasts (see step 7), after re-drying them in the oven, use the wax sheets (see step 5-ii).] (ii) if vesicles are >1mm, wrap in wax sheets. Cut the sheets into wholes (2”x2” square) or halves (triangles) and record the number of sheets used in the wax column. 6. Put the ringstand on the balance with the clast-basket attached to the arm hanging into 2L of water. The basket should be completely submerged and suspended so that it in no way touches the bucket walls. Tare the setup. 7. Weigh the sealed clasts in water; place a clast in the basket, making sure the clast is sealed (no bubbles are rising from the clast) and that it is completely submerged in the water. If the clast floats, you must use the ballast, thus, first weigh the ballast in water. Put the ballast on top of the basket making a cage; make sure the ballast is completely submerged in water. Record the weight of the ballast in the ballast column. Then put the rock in the cage and record the weight in the wet column. 8. Enter the measurements into the spreadsheet to calculate density and vesicularity. The lab sheet(s) and spreadsheet(s) referred to in the above instructions are worksheets in the file LW07 density_distributions.xls included on the attached CD. The samples initially chosen for density measurements were collected from different elevations on the cinder cone itself (Figures 5.4-5.6). Histograms illustrating the distribution of densities of individual clasts within a sample were produced to illuminate peaks and troughs in the data. The mean density, average of the three minimum density clasts, and average of the three maximum density clasts were also determined per sample. Worksheets (the spreadsheets previously referenced) set-up and identified by sample name within the file LW07 density_distributions.xls contain not only all the density/vesicularity measurements but also these calculated data for each sample. Density variation with elevation for the cinder cone samples was also plotted (worksheet density with elevation in file LW07 density_distributions.xls) and included the average minimum, the average maximum, the peak, and the mean values for each sample. Since each sample was chosen from a vertically narrow range/single bed, this plot illustrates trends in the average and peak density values as well as variation in density ranges of erupted products with eruption time.



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Figure 5.4. East view of Lathrop Wells cone with collected samples.

Figure 5.5. West view of Lathrop Wells cone showing collected samples.



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Figure 5.6. Plan view of Lathrop Wells volcano showing all cone samples collected.



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ENTRY 6 Considering the density distributions and density variations with cone height, groups of clasts from specific samples were selected to represent different vesicularities and photographed (folder LW density pics included on attached CD), and subgroups were further selected from which thin sections were made. No standards exist by which to measure the quality of a thin section to be used for textural quantification. Thin sections received therefore are judged by visual inspection. Examinations of the thin sections require a petrographic microscope, and the following guidelines are used to assess quality: • Intact vesicle (glass) walls – Scoria and pumice clasts can be very friable, but integrity of the

glass walls surrounding the vesicles is critical to textural quantification. To minimize the amount of vesicle wall breakage, the vesicles should be filled by the epoxy or resin, i.e., the vacuum impregnation of the epoxy into the vesicles should be thorough.

• Empty vesicles – As mentioned previously, vesicles should be filled entirely with epoxy so that they appear “empty”, i.e. there should be no grit or broken bits in the vesicles.

• Evenness of sample thickness - All thin sections should be 30 µm over the entire surface, and none should have edges or corners ground too thin. There should be minimal relief between hard (crystals and glass) and soft (vesicles) phases, and sections should be polished completely and uniformly center to corner.

• Integrity of crystals – Crystals should be intact and undamaged (no cracking or spalling during lapping and polishing). No crystals should be plucked or missing in the final section as the void might be mistaken for a vesicle and the textural data misrepresented.

13 samples were shipped to Mineral Optics Laboratory, accompanied by the following letter: To: Marco vanGermeren

Mineral Optics Laboratory 29 A Street / PO Box 828 Wilder, Vermont 05088

Date: 10/8/07 Order: I would like to place an order for standard, polished thin sections made from each of these clasts (27x46 mm, 30µm thick). The thin sections will be used on an electron microprobe, a



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petrographic microscope (reflected and transmitted light), and a SEM. They should be vacuum impregnated with clear epoxy, but care should be taken. These are highly vesicular clasts (scoria and pumice), and I am mostly interested in the clast textures, so I will be studying not only the crystals but the shapes of the bubbles. While I know some breakage of the glass walls is inevitable, it should be minimized as much as possible. Most clasts are not large enough to completely cover a 27x46 mm area, but please try to make the thin sections with coverage maximized. Also, please label the blanks and return them with the completed thin sections. The thin sections themselves should also be labeled. Below is a complete inventory of clasts included in this shipment: 32407-1b 2 32407-1b 9 32407-1b 12 32407-1b 76 32407-1b 83 32407-1b 119

32407-5a 5 32407-5a 13 32407-5a 49 32407-5a 67

32407-5b 6 32407-5b 11 32407-5b 24

If you have any questions or problems, please feel free to contact me. Thanks, Nancy Adams (210) 522-2161 [email protected]



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ENTRY 7 Additional groups of clasts were selected from specific samples based on density distributions / variations with cone height and depositional facies (lower cone vs. upper cone); one clast from a fall deposit was also selected for comparison. Photographs were taken of these clasts to document macroscopic textural features (folder LW density pics included on attached CD), and subgroups were further selected from which thin sections were made. 19 samples were shipped to Wagner Petrographic, accompanied by the following letter: To: Wagner Petrographic

122 North 1800 West, #7 Lindon, UT 84042

Date: 2/26/08 Order: I would like to place an order for standard, polished thin sections made from each of these clasts (24x46 mm, 30µm thick). The thin sections will be used on an electron microprobe, a petrographic microscope (reflected and transmitted light), and a SEM. They should be vacuum impregnated with clear epoxy, but care should be taken. These are highly vesicular clasts (scoria and pumice), and I am mostly interested in the clast textures, so I will be studying not only the crystals but the shapes of the bubbles. While I know some breakage of the glass walls is inevitable, it should be minimized as much as possible. Most clasts are not large enough to completely cover a 24x46 mm area, but please try to make the thin sections with coverage maximized. Also, please label the blanks and return them with the completed thin sections. The thin sections themselves should also be labeled. Below is a complete inventory of clasts included in this shipment: 51207-6 33 51207-6 37 51207-6 5 32407-5c 24 32407-5c 21

51307-1c 27 51307-1c 31 51307-1c 16 51307-1c 42 51307-1a 60 51307-1a 61 51307-1a 89 51307-1a 78

32407-7 39 32407-7 19 32407-7 22 32407-7b 15 32407-7b 5

32507-1b 25



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I would also like one thin section slide box (25 slide capacity) to accompany this order and am requesting they be processed using your rush-service (1 week). If you have any questions or problems, please feel free to contact me. Thanks, Nancy Adams Geosciences & Engineering, CNWRA Southwest Research Institute 9503 W Commerce San Antonio, TX 78227-1301 (210) 522-2161 [email protected]



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ENTRY 8 To characterize the heterogeneity in vesicle and microlite populations seen in a single thin section, resolutions of the digital images required for textural characterization ranged from 50 – 5,000 pixels/mm (lowest to highest magnification). The lowest magnification images were collected by scanning the thin sections on a Hewlett-Packard flatbed scanner at 1,200 dpi resolution (50 pixels/mm). Backscatter electron (BSE) images with a resolution of 72 dpi were collected using a JEOL-840A scanning electron microscope (SEM) owned by the Biology Department at UTSA operating at a 20 kV accelerating voltage for the higher magnifications. Areas within which these higher magnification images were collected were chosen because they represented the range of vesicle and microlite populations present in the entire thin section, therefore images were not centered over large phenocrysts or bubbles. The strategy used for acquisition of images at higher magnifications involved nested sets of images. For each thin section, a minimum of two 120 pixels/mm images were taken, and within these images, additional images were taken at a slightly higher magnification (usually at 500 pixels/mm), and within these images, still higher magnification images were captured (up to 5,000 pixels/mm). Between nine to twenty-four images were taken each for twenty-four of the thin sections (see list below). Images were captured in grayscale; in the higher magnification images taken using the flatbed scanner, glass and crystals are gray to black and vesicles are white, and in the higher magnification images taken using the scanning electron microscope (SEM), glass and crystals are gray to white and vesicles are black. BSE images were collected from 24 clasts: 32407-1b 12 32407-1b 9 32407-1b 2 32407-1b 76 32407-1b 119 51207-6 37 32407-5c 21 32407-5b 24 32407-5b 11 32407-5b 6 32407-5a 67 32407-5a 49

32407-5a 13 32407-7 39 32407-7 19 32407-7 22 32407-7b 15 32407-7b 5 51307-1c 31 51307-1c 42 51307-1a 60 51307-1a 61 51307-1a 78 32507-1b 25

Dr. Stuart Birnbaum in the Geological Sciences Department and Dave Olmos in the Biology Department assisted with the image collection.



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The digitals scans of all the thin sections are included in the folder: LW thin section scans (see attached CD), and the digital BSE images captured on the SEM are included in the folder: LW SEM images.



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ENTRY 9 To accurately characterize the general petrology of the samples and the microlites specifically, areas captured in selected SEM images were examined using an Olympus BX51 polarizing microscope with an attached digital camera. The areas examined were captured on the SEM in sets of nested images, i.e., an area within a thin section is captured at 25x magnification (~120 pixels/mm resolution) using the SEM, and an area within the 25x image is captured at 100x magnification (~500 pixels/mm resolution), etc. For 7 nests, pictures that corresponded to the SEM images were shot with the camera attached to the microscope and are in folder: LW petrography pics (see attached CD); UnX = uncrossed polars/plain light; X = crossed polars/polarized light; small = 25x mag SEM image; medium = 100x mag SEM image; large = 750x mag SEM image. Eight nests were examined in total: 32407-1b 12 scan-25a-100ab-micro750 (pictures taken) *32407-1b 2 scan-25b-100ba-micro600 (pictures taken) 32407-1b 119 scan-25a-100aa-micro600 (pictures taken) *51207-6 37 scan-25a-100aa-micro700 32407-7 19 scan-25c-100ca-micro500 (pictures taken) *32407-7b 15 scan-25a-aa micro600 (one picture corresponding to aa micro600; magnetite on

the far right and plag in the middle in plain light) *32407-7b 5 scan-25b-ba micro450 (one picture corresponding to ba micro450; cpx xtls in

crossed-polarized light) *51307-1c 42 scan-25b-100bc (two pictures corresponding to 100bc) * SEM images have been annotated General descriptions by Scott Rubio: 32407-1b 12 2% olivine phenocrysts (forsterite and fayalite) 40% groundmass (20% plag, 2% olivine, 15% cpx, 3% magnetite) 58% vesicles 32407-1b 2 5% olivine phenocrysts (forsterite and fayalite) 50% groundmass (plag 20%, olivine 1%, cpx 25%, magnetite 4%) 45% vesicles 32407-1b 119 7% olivine phenocrysts (forsterite and fayalite) 70% groundmass (plag 30%, olivine 5%, cpx 30%, magnetite 5%)



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23% vesicles 32407-7 19 7% olivine phenocrysts (forsterite and fayalite) 60% groundmass (plag 50%, olivine 2%, cpx 5%, magnetite 3%) 33% vesicles 51207-6 37, 32407-7b 15, 32407-7b 5, 51307-1c 42 Materials observed: glassy matrix, magnetite (oxides), augite (clinopyroxene), plagioclase, and forsterite/fayalite (olivine) In SEM pics: Glassy Matrix appears medium gray w/ very little textural characteristics Magnetite appears white w/ triangular cleavage Clinopyroxene appears light gray w/ usually “stubby” hexagonal crystal growth. Sometimes

they look like abnormally shaped “blobs” Plagioclase appears dark gray w/ long rectangular crystals Olivine appears a swirl/mixture of whites and grays w/ almost holographic imaging



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ENTRY 10 In a presentation to the ACNW in February 2007, Dr. RSJ Sparks from the University of Bristol, UK, discussed volcanic analogs for Yucca Mountain (presentation included on attached CD as Sparks_ACNW_2007.pdf). In this context, he compared the Lathrop Wells volcano to the Eldfell volcano in Iceland and Mt. Etna in Italy. In August of 2008, samples were collected from the Eldfell volcano to compare to Lathrop Wells samples by N. Adams. Eldfell volcano was created during an eruption on Heimaey Island in 1973. The initial phase of the eruption was purely explosive, with lava fountaining occurring along a 1.9 km fissure oriented SSW-NNE on the east side of the island. Within a few days, activity focused at the NNE end of the fissure, resulting in a cinder cone 200m in height. Activity then became purely effusive. In total, eruptive activity spanned 5 months and produced 0.23 km3 of material, mostly as a’a hawaiite flows (Higgins and Roberge, 2007; Self et al., 1974; Thorarinsson et al., 1973).

Figure 10.1 Heimaey Island (USGS map); available at http://maps.unomaha.edu/Peterson/funda/Pictures/Iceland/photos/Hmap.gif and

http://www.geokem.com/OIB-volcanic-iceland.html

To collect samples comparable to Lathrop Wells, scoria from the Eldfell cinder cone and from the extension of the fissure south of the cone were targeted. The fissure samples were acquired to compare to the lower cone samples at Lathrop Wells. Quarry cuts have not exposed the inner



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layers of the Eldfell cone, so the fissure samples were necessary to examine the early stages of the eruption. Also, to most accurately represent changes to the textures of eruptive products throughout the cone-building activity, care was taken to collect from different beds at different elevations during ascent of the cone. Fieldwork 8/23/08 The route began at the northern end of flow field and trended south up the cone. Push-up structures litter the flows, which appear mostly a’a – transitional in nature. Beds in the cone vary in color (red to black) and degree of agglutination (nonwelded to moderately-highly welded). Agglutination seemed much more prominent in the products found along the fissure. Sites were located using a handheld Garmin GPS V personal navigator unit. Sample locations were marked as waypoints for each site, and UTM coordinates, elevations, and accuracy were recorded. They were named sequentially by date, e.g. the first site visited on August 23, 2008 is called 82308-1. These names match the sample log (file: Eldfell sample log.xls) saved on the CD attached to this notebook. Digital photos were also taken at each location and are named to match the site. These pictures are also saved on the attached CD (folder: Eldfell photos). 82308-1: UTM 27V 537308, 7034102. Elev. 143m. Pictures 82308-1 001 – 002. Sample 82308-1. Scoria from cone. 82308-2: UTM 27V 537354, 7033985. Elev. 178m. Pictures 82308-2 001 – 002. Sample 82308-2. Scoria from cone. 82308-3: UTM 27V 537354, 7034236. Elev. 102m. Pictures 82308-3 001 – 002. Sample 82308-3. Scoria from cone. 82308-4: UTM 27V 537222, 7034457. Elev. 88m. Pictures 82308-4 001 – 003. Sample 82308-4. Scoria from cone. 82308-5: UTM 27V 537195, 7033389. Elev. 121m. Pictures 82308-5 001 – 003. Sample 82308-5. Scoria from fissure. 82308-6: UTM 27V 537164, 7033211. Elev. 108m. Pictures 82308-6 001 – 003. Sample 82308-6. Scoria from fissure.



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Figure 10.2 Sampled sites at Eldfell volcano.

ADDITIONAL INFORMATION FOR SCIENTIFIC NOTEBOOK NO. 870EDocument Date: 04/23/2007

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