OCS Study MMS 95 - Data Center

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92 9128v.rRtIJN. 1,.-T 1~7iLI4v-. ERS1 11250, 1993 50 km .Space Shuttle LFC, 1989figure 2.2ERS1 11551 8851, 1993 Landsat TM, 1991Overlap between oil slicks detected in remote sensing images from different dates reveals the locations ofperennial oil seeps . (Rectangular outlines show coverage for individual remote sensing images .) ERS-1:European Radar Satellite 1, TM : Thematic Mapper, LFC : Linhoff Frame Camera .
Sites selected for dives were located in the Green Canyon 232, 287 and 321lease blocks (Table 2.2) .We were able to find chemosynthetic fauna at the first twoof these sites, but not at the third .The surface slick in Green Canyon 232 wasspotted from an airplane and was clearly visible to ship-board observers before itwas noted in the satellite data .During two dives to depths of 700 m, we noteddense aggregations of tube worms and seep mussels similar to assemblages at theBush Hill site (MacDonald et al ., 1989) .One of us (Guinasso) inadvertently causeda copious discharge of oil and gas from the sea floor by attempting to collect some ofthe mussels . The mussels were clustered within a field of authigenic carbonaterubble . Probing the mussel cluster with a scoop sampler disturbed the carbonatesubstratum and initiated a burst of gas bubbles followed by a flow of oil dropletsthat continued unabated for over 30 min . Arrival of the oil droplets at the surfacewas noted by the shipboard observers at a location about 100 m from thesubmarine's sea floor position .The surface slick at Green Canyon 287 was noted in the LandSat TM andERS-1 data sets . The site is the location is on a plateau that rises from a base depthof 1500 m to a crest depth of 760 m . A salt body has intruded to the near seafloorand salt movement has produced a series of shallow faults trending northwestsoutheastnormal to the salt (see Reilly et al ., this volume) . The Johnson Sea-Linkbottomed at a depth of 800 m and followed a southern course across the flank of theuplift block . This track took the submarine across a series of northwest-southeasttrending valleys . Clam shells, carbonate outcrops encrusted with tube worms, andoccasional gas seeps were observed in the floors of these valleys . Although clamshells were broadly distributed, the abundance of chemosynthetic fauna in thecommunities at this site was much less than at the Green Canyon 232 site .Although gas venting was evident at several locations, macro-seepage of oil was not2-15
Page 1 and 2: OCS StudyMMS 95-0022Northern Gulf o
Page 3 and 4: DISCLAIMER.This report was prepared
Page 5 and 6: Principal Investigators (*) and Ass
Page 7 and 8: 3 .5 .1 Acoustic Echo Types . . . .
Page 9 and 10: 6 .6 Gulf-Wide Patterns . . . . . .
Page 11 and 12: LIST OF FIGURESFigurePage2.1 Locati
Page 13 and 14: 5 .3 Relation between wet weight an
Page 15 and 16: 8 .25 The apportionment of paleoing
Page 17 and 18: 6 .4 Composition of upper and lower
Page 19 and 20: y diverse, but tiny burrowing anima
Page 21 and 22: Collectively, these sites were judg
Page 23 and 24: 2.0 The Regional Distribution of Ch
Page 25 and 26: estricted to the localized areas wh
Page 27 and 28: 981W 96°W 94°W 92°W 90°W 88°W
Page 29 and 30: of exploration; the envelope of occ
Page 31 and 32: everberation ("turbidity") .These a
Page 33 and 34: The Space Shuttle photograph was sc
Page 35: 53 27043.62' N 91026.19'W GC0230 82
Page 39 and 40: Oil floating on the sea degrades as
Page 41 and 42: When Y, the dimensionless crossplum
Page 43 and 44: Figure 2.3 Laser line scan image co
Page 45 and 46: 3.0 Geological and Geophysical Char
Page 47 and 48: 51'wgaysz4ow 9?20W 9TiQYY MOW 9190V
Page 49 and 50: with active salt movement and activ
Page 51 and 52: nodules (Behrens 1988) .This may al
Page 53 and 54: tracks suggests that for most of th
Page 55 and 56: each site .The paper side-scan reco
Page 57 and 58: Table 3.2 Description of push cores
Page 59 and 60: ::~ v^{TYPE 1~s ate`' ~~,;~v.F .r.,
Page 61 and 62: carbonate rock(diameter 410 cm)ligh
Page 63 and 64: eflector at this location may have
Page 65 and 66: Figure 3 .7 . Patterns of acoustic
Page 67 and 68: WNwFigure 3.9 Patterns of acoustic
Page 69 and 70: GC 234, which has no large mound st
Page 71 and 72: WNfigure 3.11 Side scan sonar mosai
Page 73 and 74: 0 201'45"NWNCDFigure 3 .13 Comparis
Page 75 and 76: 3 .5 .5 Connections to Deep FaultsI
Page 77 and 78: our data on the locations of chemos
Page 79 and 80: seen or turbidity (reverberation) w
Page 81 and 82: continuous layers beneath the GB 38
Page 83 and 84: 4.0 Geochemical Alteration of Hydro
Page 85 and 86: A fundamental feature of the chemic
Page 87 and 88:
98OC 70`~ o 0 GC-272 (CF)x GC-2340
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86o GC-272 (CF)x GC-234o Bush Hillf
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0-5 cmN~1 .0 m3-15 cm^'C4 / i'C4 va
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0-3cm1 .0 m 0.13-11 cm11 - 25 cm" P
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4.2 Experimental4.2 .1 SamplesSampl
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approximately 575 m .The clams cont
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Table 4 .1Concentrations of UCM (pp
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cCFigure 4.11 Examples of C15. chro
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ange . The i-C4/n-C4 ratios varied
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3AvcasQas2NWmtrolTotal Cj-CS (PPm)
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GC 185-2 Seep SampleNCnNAL OXDA110N
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at GC 185 was higher (24,775 ppm) t
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The C15+ chromatograms of sediment
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'PwFigure 4.17 . A C 15+ chromatogr
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were destroyed by bacterial oxidati
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3 . Sediment samples from an area w
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their chemical habitats, we also de
Page 121 and 122:
samplers employ stainless steel fil
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Marked mussels were retrieved in Au
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5.5 Statistical MethodsDue to the n
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6% with another 40% accounted for b
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lamellibrachids and eight escarpids
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varied from extremes of 1 .4 to 22.
Page 133 and 134:
Table 5 .2 Variability in replicate
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5 .7 .3 Vectimentiferan Condition a
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For each of the other three conditi
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(Rosman et al .1987) and while they
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Table 5 .6 Sulfide levels in Louisi
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Table 5 .7 Methane concentrations i
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1008060d 402000 20 40 60 80 100 120
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5 .9.2 SM Ia Population StructureTh
Page 149 and 150:
Table 5.8 Average growth rate of SM
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s4.,0 o =O 0000oO ~NNUM~M~N~NIpM~NM
Page 153 and 154:
5.9 .4 growth Rates and Ages of SM
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live a long time after reaching rep
Page 157 and 158:
65s*r43JC1,= 0U-1-240 50 60 70 80 9
Page 159 and 160:
Mean shell lengths of mussels from
Page 161 and 162:
the effects on condition and growth
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ed oxidation rates necessary to sus
Page 165 and 166:
6.0 Sessile Macrofauna and Megafaun
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common axis .Under ideal conditions
Page 169 and 170:
Table 6 .1 Continued3265 .04 08/09/
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articulated dead shells with no liv
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6.3.3 relationships With Provanna s
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species complex form the primary bi
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developmental stage or not .A compr
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organisms in the seep environment .
Page 181 and 182:
Although Aluinocaris stczc tophilia
Page 183 and 184:
however, the bathymetric range of s
Page 185 and 186:
Table 6 .4Continued .ECHINODERMSAst
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changes bathymetrically, geographic
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might trip the balance in populatio
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typical chemosynthetic fauna at eac
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parent image . Rotation, etc . was
Page 195 and 196:
Table 7.2 .Classifications of commu
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sections, and the remaining sides c
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mechanical arm of NR-1 and was left
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photomosaics encompassed a total of
Page 203 and 204:
Grid M . 1 . Tm2 . Msb3 . M-dGrid N
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7 .3 .5 Photomosaics at GC 272 : Si
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designated labeled A through F . Fe
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7 .4.2 GC 234A single cage was depl
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marker . Between 1991 and 1992, thi
Page 213 and 214:
15th .Comparison of photographs and
Page 215 and 216:
408 .535V3071NU°... 8.0aEt' 7.5V1V
Page 217 and 218:
concentrations of dissolved methane
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On a larger scale, submarine observ
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fauna, the rods in the brine have e
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a matter for speculation, but clear
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8.0 Evidence for Temporal Change at
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where B is biomass-at-death in g as
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ased on consideration of the locati
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were alive .The degree to which thi
Page 233 and 234:
Lucinid biofades-coat slopeLucfnotn
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A .Lucinoma n .Vesicomya cordLucino
Page 237 and 238:
Following taphonomy, the guild stru
Page 239 and 240:
Ludnid biotaclea-cont.slope120lbyss
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the size classes were redefined acc
Page 243 and 244:
Paleoproduction by biofaciesFigure
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appearance for paleoingestion becau
Page 247 and 248:
Paleoproduction by biofacieslou9pe0
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containing the remains of much olde
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in its size-frequency composition .
Page 253 and 254:
Paleoproduction by biofacies1009080
Page 255 and 256:
Numerical abundance by biofaciesFig
Page 257 and 258:
Paleoingestion by biofaciesip090806
Page 259 and 260:
contribution to tier structure, whe
Page 261 and 262:
GC-184 Lacinid biofictes12(Y1GC-234
Page 263 and 264:
Numerical abundance by core interva
Page 265 and 266:
Paleoingestion by core intervalloo9
Page 267 and 268:
Paleoproduction by core intervalloo
Page 269 and 270:
8.28 with Figure 8 .25 for example)
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top of the core . In-between, epifa
Page 273 and 274:
GC-184 Core 1Lucinid biofacies05101
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272 was nearly identical to that ob
Page 277 and 278:
paleoproduction and paleoingestion,
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diameter piston cores were taken in
Page 281 and 282:
ange of conditions from distinctly
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habitat was invariantly suboptimal,
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Guild and tier structure varied lit
Page 287 and 288:
Faunal succession was not observed
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Recovery times are simply too long
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Table 9 .1 Seep sites from which oc
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Figure 9.1Major bands and minor ban
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Figure 9 .2Cross section of axial r
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colonies and one male colony were o
Page 299 and 300:
LS =rFigure 9 .4Rows of maturing sp
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2000 = GC 234 NE 1991t = VK 828 199
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One-way ANOVA's were performed to d
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= FEMALE COLONIES0 = MALE COLONIESw
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spawning event by these geographica
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10.0 An Ecological Characterization
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otherwise overlain by a less fractu
Page 313 and 314:
lower concentrations of hydrocarbon
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10 .1 .6 Temporal ChangeThe paleont
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original resolution .A modest level
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in a format that would augment the
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11.0 Literature CitedAllen, A.A .,
Page 323 and 324:
Cavanaugh, C .M ., S.L . Gardiner,
Page 325 and 326:
A. Newton, M .A . Powell, G .N . So
Page 327 and 328:
Jackson, M.P.A . and C .J . Talbot
Page 329 and 330:
MacDonald, I .R ., N.L . Guinasso,
Page 331 and 332:
Rosman, I ., G.S . Boland, and J.S
Page 333 and 334:
Tunnicliffe,V . 1992 . The nature a
Page 335:
~Q S~,ENT OF Ty ~The Department of
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