8. SITE 5591

Shipboard Scientific Party2

HOLE 559

Date occupied: 14 October 1981

Date departed: 16 October 1981

Time on hole: 52 hr.

Position (latitude; longitude): 35°07.45'N; 40°55.00'W

Water depth (sea level; corrected m, echo-sounding): 3754

Water depth (rig floor; corrected m, echo-sounding): 3764

Bottom felt (m, drill pipe): 3766

Penetration (m): 301

Number of cores: 8

Total length of cored section (m): 63.0

Total core recovered (m): 23.5

Core recovery (%): 37.3

Oldest sediment cored:Depth sub-bottom (m): 249Nature: LimestoneAge: middle Miocene

Basement:Depth sub-bottom (m): 238Nature: Basalt

Principal results: Hole 559 (Site MAR-8) was drilled between Anoma-lies 12 and 13 on the west flank of the Mid-Atlantic Ridge midwaybetween Oceanographer and Hayes fracture zones (Fig. 1). Thesediments were washed down to basement, which was felt at 238 msub-bottom.

Aphyric pillow basalts were cored through the entire 63-m base-ment section. The principal macroscopic features are the variabili-ty in degree of alteration and the large amount of fresh glass recov-ered. These basalts belong to a single petrographic chemical group.The effects of alteration are clearly shown by chemical data. Theobserved variations in Sr are due in part to contamination inducedby alteration. These variations can be used for choosing sampleswhose inferred Sr contamination is less than 5 ppm for Sr isotopicstudies. The Sr concentration in fresh glass is 157 ppm.

Bougault, H., Cande, S. C , et al., Init. Repts. DSDP, 82: Washington (U.S. Govt.Printing Office).

2 Henri Bougault (Co-Chief Scientist), IFREMER (formerly CNEXO), Centre de Brest,B. P. 337 29273 Brest Cedex, France; Steven C. Cande (Co-Chief Scientist), Lamont-DohertyGeological Observatory, Columbia University, Palisades, New York; Joyce Brannon, Depart-ment of Earth and Planetary Sciences, Washington University, St. Louis, Missouri, David M.Christie, Hawaii Institute of Geophysics, University of Hawaii at Manoa, Honolulu, Hawaii;Murlene Clark, Department of Geology, Florida State University, Tallahassee, Florida; DorisM. Curtis, Curtis and Echols, Geological Consultants, Houston, Texas; Natalie Drake, De-partment of Geology, University of Massachusetts, Amherst, Massachusetts; Dorothy Echols,Department of Earth and Planetary Sciences, Washington University, St. Louis, Missouri(present address: Curtis and Echols, Geological Consultants, 800 Anderson, Houston, Texas77401); Ian Ashley Hill, Department of Geology, University of Leicester, Leicester LE1 7RH,United Kingdom; M. Javed Khan, Lamont-Doherty Geological Observatory, Columbia Uni-versity, Palisades, New York (present address: Department of Geology, Peshawar University,Peshawar, Pakistan); William Mills, Deep Sea Drilling Project, Scripps Institution of Ocean-ography, La Jolla, California (present address: Ocean Drilling Program, Texas A&M Univer-sity, College Station, Texas 77843); Rolf Neuser, Institut für Geologie, Ruhr Universitàt Bo-chum, 4630 Bochum 1, Federal Republic of Germany; Marion Rideout, Graduate School ofOceanography, University of Rhode Island, Kingston, Rhode Island (present address: Depart-ment of Geology, Rice University, P.O. Box 1892, Houston, Texas 77251); and Barry L. Weav-er, Department of Geology, University of Leicester, Leicester, LE1 7RH, United Kingdom(present address: School of Geology and Geophysics, University of Oklahoma, Norman,Oklahoma 73019).

Magmaphile element concentrations are enriched relative to chon-drites (Nb = 16, Zr = 100, Ti = 9000, Y = 35, and V = 300 ppm).Although this result agrees with the hypothesis of a boundary at thelatitude of Hayes Fracture Zone, no definite conclusion can be madebecause of the complexities revealed at Sites 558 and 556 on the sameisochron.

The following analyses were not done for Site 559: sediment ac-cumulation rates, pore water chemistry, and downhole measurements.

OPERATIONS

Approach to SiteAfter analyzing the results of drilling at Site 558, we

decided to drill Site 559 near the original location ofMAR-8 between Anomalies 12 and 13 south of the Ocean-ographer Fracture Zone. A tentative site was located,based on existing magnetics data, halfway between twosmaller fracture zones that are themselves sandwiched bythe Hayes and Oceanographer fracture zones.

The initial approach to the site began at 0220Z on 14October (Fig. 2) on a track parallel to the fracture zonesand crossing the prime target area. Although in generalthe basement relief was quite variable and the sedimentcover was greater than 0.5 s, a location was observed atO353Z (Fig. 3) where the sediment cover thinned to lessthan 0.25 s on the flank of a small basement high. Pro-filing was continued for 4 miles beyond this point untilthe location of Anomaly 13 was confirmed. The ship'scourse was then reversed and the site relocated. The bea-con was dropped on Site 559 at 0518Z.

On-Site OperationsSite 559 was spudded at 1238Z 14 October in 3766 m

of water. Sediments were washed to a depth of 238 msub-bottom where basement was reached. Between 1930Z14 October and 2230Z 15 October, 63 m of basementwere cored without any major problems (Table 1). Drill-ing was then discontinued because of time considerations.The Challenger was under way to Site 560 at 0730Z 16October.

SEDIMENT LITHOLOGY

At Site 559 the sediments were washed to basement at238 m. At that time a wash core was retrieved that con-tained 2 m of disturbed marly nanno fossil ooze (white2.5YN 8 and 10YR 8/2) and marly nannofossil ooze withvolcanic glass. The core includes upper Pliocene to uppermiddle Miocene sediments. No bioturbation or beddingwas observed, except for faint color changes.

The sediment components are calcareous nannofos-sils (20-40%), clay (35-55%), foraminifers (3-15%), un-specified carbonate (5-10%), trace amounts to 10% ofvolcanic-derived material, and micronodules. In 559-

215

SITE 559

216

Figure 1. Site location map for Leg 82.

Figure 2. Approach and site survey track for Site 559. Heavy line is ship track with hour marks in GMT.Thin line is magnetic anomaly projected perpendicularly from the ship's track. Circled numbers aremagnetic anomalies based on work at Lamont-Doherty Geological Observatory.

SITE 559

— 3

Droppedbeacon05182

0200Z 0230ZC/C 281°

I I I I I I0300Z 0330Z | 0400Z 0500Z

C/C 277° C/C 102° C/S 160/160

— 6

C/C 102c

Figure 3. Glomar Challenger seismic profile over Site 559. For location of profile, see Figure 2. C/C = course change.

Table 1. Coring summary, Hole 559.

Core

H112345678

Date(Oct.1981)

141415151515151515

Time(z)

160522250310051009201220155019302230

Depth fromdrill floor

(m)

3766.0-4004.04004.0-4013.04013.0-4022.04022.0-4022.54022.5-4031.04031.0-4040.04040.0-4049.04049.0-4058.04058.0-4067.0

Depth belowseafloor

(m)

0.0-238.0238.0-247.0247.0-256.0256.0-256.5256.5-265.0265.0-274.0274.0-283.0283.0-292.0292.0-301.0

Lengthcored(m)

0.09.09.00.58.59.09.09.09.0

63.0

Lengthrecovered

(m)

0.003.993.820.252.723.392.603.473.27

23.51

Percentrecovered

04442503238293936

37

H1-2, 20 cm there is a thin layer of volcanic glass (moder-ately disturbed). As in Hole 558, traces of authigenic do-lomite rhombs are present. The sediments retrieved at thissite represent Neogene ocean pelagic sedimentation be-ginning in middle Miocene time.

Throughout the basalt units, intrapillow basalt (volca-niclastic) limestone is common. It occurs either betweenpillow margins or as fillings in basalt cracks and vesicles.Geopetal structures were observed in some vesicles. Thelimestones are moderately bioturbated and occasionallyshow inclined bedding contacts. Colors vary from verypale brown (10YR 8/3) to pale brown (10YR 6/3) andlight gray (5YR 7/1) to pinkish white (5YR 8/2).

Volcaniclasts are derived from adjacent vitric rims ofpillow basalts. The original calcareous pelagic ooze hasbeen recrystallized to micritic calcite, although ghosts offoraminifers still persist. The limestones in places are in-tensely mineralized by manganese oxide (usually dendri-tic) and are commonly veined by sparry calcite.

BIOSTRATIGRAPHY

SummarySediments for microfossil study from Hole 559 are

wash cores. Based on the calcareous nannofossils, the ageof the sediment ranges from middle Miocene to late Pli-ocene. One tentative determination based on poorly pre-served nannofossils in Core 2 from a sediment streak be-low basement may be Oligocene.

Foraminifers in the wash core are from the latest Mio-cene to earliest Pliocene times. Although well preserved,they are not considered reliable age determinants.

Calcareous NannofossilsHole 559 was washed down to a depth of 238 m where

basement material was encountered. Core HI containsabundant and well-preserved nannofossils. Discoasterbrouweri and D. surculus without Reticulofenestra pseu-doumbilica occur in 559-H1-1, 14 cm. This suggests theupper Pliocene D. brouweri Zone, D. surculus Subzone

217

SITE 559

CN12b (NN16) for this sample. Sample 559-H1-2, 50cm (slightly above the first basement material) is attrib-uted to the D. hamatus Zone CN7 (NN9) because of thepresence of D. hamatus and D. neohamatus.

A layer of sediment below basement level (Core 2)contains very poorly preserved nannofossils. A possibleDictyococcites bisectus and Sphenolithus predistentus arecontained in this interval. Because they are so poorly pre-served, these specimens are only tentatively identified.If these species do in fact occur, the sample could belower Oligocene.

IGNEOUS PETROLOGY AND GEOCHEMISTRY

Hole 559 encountered basement at 238 m sub-bottomand penetrated 63 m of a single aphyric pillow basalt unit(Fig. 4). Basalts of this unit appear to belong to only onechemical group; a single, distinctive glass analysis may,however, indicate the existence of a second group.

Lithology

Pillow basalts of Site 559 are fine-grained, gray, aphy-ric basalts with localized small increases in grain size inthe upper part and an overall grain-size increase down-hole characterized by the presence of visible plagioclaseneedles (1-3 mm long) below about 286 m. Close to theirmargins, fine-grained pillow interiors grade over a fewcentimeters through a brown, altered variolitic zone toblack aphanitic basalt and fresh glass. At the tops ofmost pillows, vesicles are abundant in the aphanitic zoneand the outer few centimeters of the fine-grained zone.Two different types (generations?) of vesicles are present.Round vesicles up to 2 mm in diameter are commonlyunfilled but may be calcite filled in altered zones. Larg-er, irregular vesicles up to 10 mm are calcite filled.

Fine-grained pillow interiors are largely weatheredbrown to brownish gray, particularly along fractures andcalcite veinlets. Variolitic zones are generally altered lightbrown, but the outermost aphanitic basalt zones appearblack and unaltered. Glass rims are generally fresh withonly narrow palagonite rims along cracks and outer sur-faces. Fractures and calcite-filled or limestone-filled vein-lets are common throughout. Interpillow limestone is pre-sent above 266 m (Fig. 4).

Petrography

We examined seven thin sections of basalt from pil-low interiors throughout the section. All are identical inprimary mineralogy with only minor variations in grainsize and texture. All contain interstitial zeolite (probablyheulandite), replacing interstitial glass.

Site 559 basalts are composed of approximately 40%randomly oriented, elongate, hollow plagioclase laths(about An^). Some anhedral, interstitial plagioclase isalso present. Clinopyroxene occurs as relatively large pris-matic grains (up to 0.5 mm), as parallel aggregates ofsmaller prisms and occasionally as sheaves or branchingaggregates. Fresh olivine is present in only one sample,but relict outlines of small (1 mm) prismatic olivine grains,now completely altered to zeolite and brown clay, are al-ways present (about 5%). Interstitial glass (about 25%)

230-

240-

250-

1 260-.c

dept

Eo

bot

ja

M 270-

280-

290-

300-

Cor

e

H1

1

2

\I7

4

-

5

6

-

7

-

8

/ery

(%

) I

I R

eco'

I

Lithology

1̂

fc Q

H^2S

Marly nannofossil ooze

Aphyric pillow basaltin limestone matrix

Aphyric pillow basalt

Figure 4. Basement lithology column, Hole 559.

has been partially (one sample) or completely replacedby colorless to light brown zeolite. This mineral occursas aggregates of very fine, irregular, sometimes radiatinggrains with complex, sutured boundaries. Its low relief,moderately low birefringence (cf. quartz), straight or near-straight extinction, and length-slow character tentativelyidentify it as heulandite. Heulandite peaks are also pre-sent in the whole-rock X-ray diffraction pattern.

218

SITE 559

Heulandite is also present, with calcite, clay, and de-vitrified glass as vesicle fillings, and in some places itappears to have partly replaced plagioclase.

Geochemistry

Pillow basalts of Site 559 form a single lithologic unitas well as a single chemical group (Fig. 5). Analyses forglasses, pillow interiors, and altered outer zones of pil-lows are shown in Table 2.

In some cases, it was necessary to analyze altered outerzones of pillows (as evidenced by brown discoloration)because of a lack of fresh basalt in the core. In order toobserve chemical changes resulting from this alteration,a pillow interior (559-1-2, 56-59 cm, [Piece 5C]) and analtered variolitic zone (559-1-2, 36-39 cm [Piece 5B]) ofa single pillow were analyzed.

Changes in major element concentration (mole%), nor-malized to constant TiO2 between the pillow interior andthe altered variolitic zone are shown in Table 3. Relativeto the assumed chemical immobility of such elements asTi and Zr, significant chemical changes induced by al-teration appear to be a decrease in SiO2 and MgO andan increase in MnO, K2O, P2O5, Sr, and V content. With

the exception of the increase in P2O5, these changes areconsistent with those observed in other comparative stu-dies of alteration occurring at a low temperature (Mat-tey et al., 1981; Rice et al., 1979). These changes arecomparable to those between the average of fresh pillowinteriors and the average of altered basalts (shown in Ta-ble 4). Again, SiO2 and MgO contents decrease, whereasMnO, K2O, P2O5 and V increase. Because these visiblyaltered outer pillow areas are not representative of thefresher pillow interiors, we caution against the use of thealtered outer pillow areas as representative samples ofthis chemical unit.

The chemical uniformity of fresh basalts at Site 559is demonstrated by average statistical analysis of 15 pil-low interiors, which are only slightly to moderately al-tered (Table 5). Average statistical analysis of seven visi-bly altered basalts is also given in Table 5.

Glassy pillow rims are abundant. Two distinct glasscompositions are shown in Table 5. The average compo-sition of three glasses is virtually identical to that of theaverage basalt. One glass (559-1-4, 20-22 cm [Piece 2])is quite distinct in composition from all other samples atSite 559 (Fig. 5). It contains significantly less CaO, V,

Core

Sr(ppm)

160 180 200I I I I I I I

Zr(ppm)

100 120I I I

Ti(ppm)

8000 10,000i i I

AI 2 O 3

(wt.%)

15 17I I

CaO(wt.%)

9 11I I 1

1 3I I

Fe2°3(wt.%)

13I I

MgO(wt.%)

3 5 7I I I I I

H1

240-

2 5 0 -

260-

280-

290-

3 0 0 •

Glass

Glass-

Glass

Figure 5. Downhole variations in chemical abundances, Hole 559. Some data appearing in Table 2 was not included in thisfigure because of the high degree of alteration.

219

SITE 559

Table 2. Analyses of major elements (in wt.%) and trace elements (in ppm) for Hole 559 basalts.

Core-Section(interval in cm)(piece number)

Depth(m)

Type ofgroup SiO2 Tiθ2 A12O3 Fe2C>3 MnO Mg' CaO K2O P 2 O 5 Total Mg Ti Sr Zr Nb

HI, CC(1)1-1, 120-123 (9B)1-2, 36-39 (5B)1-2, 56-59 (5C)1-3, 0-3 (1A)1-3, 44-47 (3B)1-3, 76-79 (5A)1-3, 129-132 (8C)1-3, 148-150 (9)1-4, 20-22 (2)2-1, 1-3 (1A)2-2 24-28 (IB)2-3, 75-79 (4C)3-1, 13-14(2)4-1, 125-129 (9B)4-2, 92-96 (5D)5-1, 45-48 (3B)5-2, 35-39 (4A)5-3, 25-29 (2)6-2, 25-29 (IB)6-3, 27-31 (1)7-1, 137-140 (12D)7-2, 143-146 (8C)7-3, 110-113 (7B)8-1,48-51 (IB)8-3, 19-21 (1A)

239.2239.8240.1241.0241.5241.8242.3242.5242.7247.0248.8250.8256.1257.7258.9265.5266.8268.3275.8277.3284.4286.0287.1292.5295.2

GB

ABB

ABABABABGGBBBGBBB

ABABBBBBBBB

50.6250.0346.5249.5447.3446.7048.1647.8249.8648.9649.9348.9049.8050.3550.3549.4249.5947.8648.7250.0250.0049.6749.6650.0650.2249.96

1.491.571.721.521.691.601.581.691.491.741.551.501.471.481.521.541.491.661.581.521.471.491.511.481.501.49

15.2015.8017.2615.6017.3116.5915.9416.9314.6315.6515.6215.3114.9115.0215.3315.4714.9816.7616.0115.3314.8714.8115.1414.8415.1014.80

11.7012.0513.6111.1712.8112.3111.8312.7911.4013.1211.0611.3611.7811.2511.0211.1511.0512.5912.1111.5110.8611.3311.2010.9010.6611.51

0.180.150.210.140.210.160.180.230.180.180.140.160.170.180.140.150.140.160.150.160.140.170.160.140.140.15

8.296.953.287.244.383.975.225.917.947.006.937.087.557.817.366.677.444.385.108.017.587.467.497.347.397.46

11.3211.7613.2611.6511.2314.1513.1912.9710.888.8911.8812.4511.7810.9211.6312.7611.4513.0913.1911.7311.4711.5511.6111.5411.6011.44

0.300.490.740.400.890.640.380.500.370.970.380.400.490.400.340.430.360.340.440.390.380.420.350.340.310.41

0.190.230.430.200.370.290.260.290.190.160.200.170.180.180.210.200.190.260.230.200.190.190.190.180.180.20

99.2999.0397.0397.4696.2396.4196.7497.1396.9496.6797.6997.3398.1397.1997.9097.7996.6997.1097.5398.8796.9697.0997.3196.8297.1097.42

6156355943425041615558585961605760444961616060606159

318317409305341374404404301

10,440 2439300 30490008820

89409420

10,3209120

10,14096009480

10,1408940

248288

8880912092408940996094809120882089409060888090008940

301300302283369352314298290307297304284

162172215166181199200187157172172173169157168176169181185171167166166167167168

36.837.343.736.437.637.045.839.233.432.535.933.636.333.935.337.935.437.339.136.035.935.135.334.634.034.5

102105111104108108110108101119102105106100106109

97106115104102

9910098

10096

14.817.517.115.215.717.317.414.916.018.416.916.116.616.516.016.715.516.717.615.316.316.115.814.016.115.6

Note: Group types: G = glass, B = basalt, AB = altered basalt. Mg' is the atomic ratio of 100 × (Mg/[Mg + Fe2 + ]) calculated using an assumed Fe2θ3/FeO of 0.15. Measurementswere made on board using ignited samples. Onshore analyses show loss on ignition to be less than 1%. The concentrations listed in the tables of compiled data (Appendix at end ofvolume) include volatile contents. Total Fe as Fe2θ3

Table 3. Assessment of chemical change during alteration of apillow rim.

Table 4. Chemical changes during alteration based on

average Site 559 compositions.

Element

SiO 2

TiO 2

A1 2O 3

F e 2 O 3

MnOMgOCaOK 2 O

P2O5

Total

Pillow interior(mole%)

56.41.30

10.54.80.13

12.314.20.290.10

100.01

Altered rim(mole<Vo)

56.01.59

12.26.20.215.9

17.10.570.22

99.93

Normalizedrim (mole%)

45.81.30

10.05.00.174.8

14.00.470.18

81.7

Relativechange (%)

- 1 90

- 5+ 4

+ 31- 6 1

- 1+ 62+ 80

- 1 8

Note: Pillow interior sample is 559-1-2, 56-59 cm (Piece 5C); altered vari-olitic rim from same pillow is 559-1-2, 36-39 cm (Piece 5B); "normal-ized rim" composition is normalized to 1.3 mole% TiO 2 (interior val-ue); "relative change" is the change between normalized rim and pil-low interior (normalized rim-pillow interior)/pillow interior. Analysesassume TiO 2 immobility.

and Y and more Fe2O3, K2O, Zr, and Nb than the aver-age basalt. This sample may be the only representativeof a second, distinct chemical unit. Pillow interiors ad-jacent both above and below this 6 cm-diameter glasspiece have compositions close to the average of Site 559.No crystalline basalt analyzed at Site 559 has this uniqueglass composition. Further investigation of this sampleis certainly required.

The relatively fresh sample (559-1-2, 56-59 cm [Piece5C]) of the interior of a pillow and the strongly alteredsample of the variolitic zone of the same section (559-1-2, 36-39 cm [Piece 5B]) were chosen to study the effectof alteration on the major element composition. Thesetwo samples were also chosen to study the effect of al-

Element

SiO 2

TiO 2

A1 2O 3

F e 2 O 3

MnOMgOCaOK 2 O

P2O5

Total

Fresh(mole%)

56.51.29

10.24.80.12

12.414.30.280.09

99.98

Altered(mole%)

56.31.47

11.75.60.197.6

16.50.450.15

100.01

Normalizedaltered

(mole%)

49.41.29

10.34.90.176.7

14.50.390.13

87.78

Relativechange (%)

- 1 20

- 1+ 21+ 42- 4 6

+ 1+ 39+ 44

- 1 2

Note: "Fresh" is average fresh pillow interior; "altered" is aver-age altered basalt; "normalized altered" is average alteredbasalt normalized to 1.2 mole% TiO 2; "relative change" ischange between normalized altered basalt and fresh.

teration on the abundances of the trace elements thathave been chosen to describe the enrichment or deple-tion of magmaphile elements in terms of mantle hetero-geneity: Nb, Zr, Ti, Y, and V. Rare earth elements havealready been shown to be immobile in slightly to moder-ately altered basalts during low-temperature alteration(Rice et al., 1979), as have non-rare-earth magmaphileelements (Joron et al., 1979). However, because of theimportance of measuring these elements on board in or-der to test for mantle heterogeneity, it was absolutelynecessary to demonstrate on samples of this hole thatlow-temperature alteration has not modified the relativeabundances of these elements. In the altered sample(559-1-2, 36-39 cm [Piece 5B]), the concentrations areincreased by a factor of 1.15 ± 0.05 relative to the fresh

220

SITE 559

Table 5. Average analyses of Site 559 basalts. Major elements ex-pressed in wt.%; trace elements in ppm.

Element

SiO2TiO2A12O3Fe2O3MnOMg'CaOK2OP2O5

TiVSrYZrNbMg

Fresh basalt(15)

×49.8

1.5115.211.20.157.3

11.80.390.19

900030016936

10216.059

S

0.40.030.30.40.070.30.40.050.07

200203140.81

Altered basalta

(7)

47.61.65

16.712.60.194.3

13.00.60.30

990038019040

1091743

S

0.80.060.60.60.030.70.90.20.07

300301033I5

Glass(3)

×50.3

1.4915.011.50.188.0

11.00.360.19

892031015935

10115.861

b

S

0.40.010.30.200.20.20.050.01

30103210.90

Glassc

(1)

48.961.74

15.6513.120.187.008.890.970.16

10,44024317232.5

11918.455

Note: Numbers in parentheses are number of analyses. X = mean; S = standard de-viation (lσ). Mg' is the atomic ratio of 100 × (Mg/[Mg + Fe2 + ]) calculated us-ing an assumed Fe2θ3/FeO of 0.15. Averages are calculated from data listed inTable 2 and are rounded.

a Samples 559-1-2, 36-39 cm (Piece 5B); 559-5-2, 35-39 cm (Piece 4A); 559-5-3, 25-29 cm (Piece 2); 559-1-3, 0-3 cm (Piece 1A); 559-1-3, 44-47 cm (Piece 3B); 559-1-3,76-79 cm (Piece 5A); and 559-1-3, 129-132 cm (Piece 8C).

b Samples 559-H1, CC (Piece 1); 559-3-1, 13-14 cm (Piece 2); and 559-1-3, 148-150cm (Piece 9).

c Sample 559-1-4, 20-22 cm (Piece 2).

sample (559-1-2, 56-59 cm [Piece 5C]), except for V (forwhich the increase is somewhat higher). The factor 1.15accounts for the leaching out of major elements (MgO,SiO2), and its accuracy (0.05) relative to the differentmagmaphile trace elements agrees with the precision ofthe concentration measurements. Thus, the relative abun-dances of magmaphile elements investigated on boardare not affected by low-temperature alteration. Their rela-tive abundances can be interpreted in terms of mantleheterogeneity and/or melting processes.

Figure 6 illustrates the effects of low-temperature sea-water alteration on strontium and calcium concentrations.As the degree of alteration increases, strontium concen-tration increases. The less-altered samples of Site 559 lo-cated at the bottom of the hole are grouped in the vicini-ty of 165 ppm Sr and 11.6 wt‰ CaO. Altered samples,denoted by squares, show increasing Sr and CaO con-centrations. Glass samples have the lowest Sr and CaOcontent; glass from Section 559-1-4 (the triangle) is againunique. The two glass samples collected within the ba-salt section (559-1-3 [Piece 9] and 559-3-1) have exactlythe same CaO and Sr contents (10.9 wt.% and 157 ppm,respectively), whereas Core HI collected at the sediment/basement interface shows slightly higher concentrations(11.3 wt.% and 162 ppm). "Fresh" glasses showing thelowest Ca-Sr concentration are a good indication of thelowest contamination in Sr for 87Sr/86Sr ratio measure-ments.

The following table shows calculated Sr isotopic ra-tios for various degrees of seáwater contamination of abasalt that has an initial Sr concentration of 160 ppmand Sr isotopic ratio of 0.7020.

220

210 -

200 -

190 -

180 -

170 -

160 -

150

1 1

-

-

A 1-4

I L

I I 1

1-2 (3.3)

5-3 (5.1) r

p

. C] 4-2 (6.6)

o / ^ 2 (7.0)

8g°p\λλ,CC (8.2) Glass

P3-1 (7.8) Glass

i i i10 11

CaO (wt.%)

12 13 14

Figure 6. Sr versus CaO for altered and slightly altered basalts (squares)to unaltered basalts (circles). The triangle represents the unique glasssample (559-1-4, 20-22 cm [Piece 2]). Hyphenated numbers next tosymbols represent Core-Section (in Hole 559); numbers in paren-theses are Mg' -values (rounded to the nearest tenth) for these sam-ples. Mg' is the atomic ratio of 100 × (Mg/[Mg + Fe2 + ]) calcu-lated using an assumed Fe2O3/FeO of 0.15. Overly altered data inTable 2 has been excluded from this figure.

Seáwater Sr added(ppm) 8 7Sr/ 8 6Sr

015

1015202530

0.70200.70200.70220.70240.70260.70280.70290.7031

The Sr isotopic ratio can only be reliably interpreted asreflecting the mantle source composition if the amountof Sr added from seáwater is lower than 5 ppm. To theextent that there is no Sr exchange between glass andseáwater (which is a possibility mentioned by Rice et al.,1979), the lowest Sr concentrations (157 ppm) found intwo glasses compared to 165 ppm in relatively fresh ba-salts allows us to postulate that the true concentration inSr—and thus the true 87Sr/86Sr ratio—could be reachedwith a precision better than 5 ppm. In addition, care hasto be taken in separating clean fragments of glass (1 mmsize) and then leaching the powder with HC1 or HNO3solution several times: the Sr concentration of the pow-

221

SITE 559

der could be checked after each leaching by X-ray fluo-rescence measurements on the powder itself, until a con-stant value is found. The true Sr and 87Sr/86Sr could bereached this way only if glass-seawater exchange of Srhad occurred without other detectable modifications ofthe glass composition.

The extended Coryell-Masuda diagram is presentedin Figure 7. The enriched pattern (Nb in respect to otherelements) is typical of transitional basalts found in theAzores Triple Junction area. This result by itself wouldagree with a boundary between an Azores-type sourcenorth of Hayes Fracture Zone and a depleted sourcesouth of Hayes Fracture Zone. Nevertheless, the resultsobtained at Site 558 (where depleted, flat, and enrichedpatterns were found) force us to be cautious in any at-tempted interpretation of geochemistry and geodynam-ics. A confident interpretation of this type can only bemade when we know why such different patterns arefound at Site 558.

MAGNETICS

Basalt Paleomagnetism

Eight samples of basalt were taken for the study ofpaleomagnetic properties. The intensity of natural re-manent magnetization and initial susceptibility were mea-sured and Koenigsberger ratio (Q) calculated. The resultsare given in Table 6. Six samples have low intensity (0.1-0.8 × 10"3 emu/cm3), whereas only two samples havehigh intensity values (1.0-1.3 × 10~3 emu/cm3). Twosamples from Sections 559-6-1 and 559-7-2 have thelowest intensities and also low Q values, but susceptibili-ty values are moderate to high. Demagnetization was notdone on board so that further properties could be stud-ied onshore.

Zr Ti

Figure 7. Extended Coryell-Masuda diagram for an average basalt com-position, Hole 559.

The inclination values are shallower than the expect-ed dipole inclination for the latitude of this site, whichsuggests tectonic rotation of the ocean crust since the ac-quisition of remanance. The negative values of inclina-tion are in agreement with the location of this site be-tween Anomalies 12 and 13.

PHYSICAL PROPERTIES

No sediment samples have been measured because noundisturbed sediment was recovered in the wash core.Samples from the basement cores were measured routine-ly for sonic velocity, density, and water content. The da-ta are presented in Table 7.

Alteration of basalt specimens produces a wide rangeof densities and sonic velocities. Densities measured bythe 2-minute GRAPE technique are systematically lowerthan those determined by the gravimetric technique. Thisis due to the core condition, which only allowed rathershort minicores to be prepared. These were rather short-er than the minimum length (2.5 cm) required for an ac-curate determination by the GRAPE method. The lime-stone sediment with glass fragments measured from Sec-tion 559-1-4 has little acoustic impedance compared tothe altered basalts, mainly because of its high sonic ve-locity of 3.84 km/s.

The data show no systematic variation down the hole.

SUMMARY AND CONCLUSIONS

Hole 559 is located between Anomalies 12 and 13 mid-way between the Oceanographer and Hayes fracture zones.The upper 63 m of the basement were cored and consistof aphyric pillow basalts belonging to a single magmaticunit. The effects of low-temperature alteration are varia-ble and randomly distributed in the recovered samples.Fresh glasses are very common at the pillow margins;calcite is present in cracks and veins. MgO concentra-tion (about 8% in fresh samples) decreases to 3% inbadly altered samples. The loss of MgO and SiO2 in-duces higher concentrations of other major elementsand of magmaphile trace elements (e.g., Nb, Zr) in al-tered samples. We think that fresh glasses—which havea lower Sr concentration (157 ppm) than the freshest ba-salts (165 ppm)—should be suitable, after leaching pro-cesses, for Sr isotopic ratio measurements. A fresh glasssample with a different and unusual composition has beenfound (SiO2 = 48.96, TiO2 = 1.74, A12O3 = 15.65,Fe2O3 = 13.12, Mg' = 7.0, CaO = 8.89, and K2O =

Table 6. Paleomagnetic properties, Hole 559.

Core-Section(interval in cm)

JNRM(× 10-3 emu/cm3)

NRMdec.

NRM

x v(× 10-6emu/cm3 Oe) (= J N R M / 0 4 5 X)

1-2, 134-1362-1, 113-1154-2, 82-846-1, 76-787-2, 60-627-3, 145-1478-1, 37-398-3, 15-17

0.750.331.000.210.150.770.761.28

216.3186.9325.0277.1183.4180.980.3

270.9

-32.7-22 .9-29.5-22 .2-27 .0-26 .9

- 7 . 0-22 .9

7265768464945864

23.1511.2829.24

5.565.21

18.2029.1244.44

Note: JNRM = intensity of natural remanent magnetization (NRM); dec. = declination; inc. = inclination;X = susceptibility; Q = Königsberger ratio.

222

SITE 559

Table 7. Physical properties, Hole 559.

Core-Section(interval in cm)

1-1, 93-1071-4, 0-7

2-3, 93-1074-1, 35-375-3, 35-366-1,76-78

6-2, 15-177-2, 58-617-2, 70-728-3, 13-17

Sub-bottomdepth (m)

239.0242.5

251.0256.9269.4274.8

275.7285.1285.2295.2

Sonic velocity(km/s)

V. H.

4.733.84

4.52

4.47

4.46

4.71

Tempera-ture (°C)

22.022.0

22.0

22.0

22.0

22.0

Thermalconductivity

(meal/[cm deg . s])

GRAPE density(g/cm3)

V. H.

2.552.24

2.55

2.25(?)

2.55

2.70

Gravimetric density

Wet-bulkdensity(g/cm3)

2.72.4

2.62.82.8

2.8

2.62.8

Watercontent

58

7< l

2

4

64

Φ%)

1420

17< l

7

10

1612

Acousticimpedance

(×105g/[cm s])

12.89.2

11.8

10.1

—11.4_

13.2

Lithologyor remarks

BasaltInterpillow

sedimentBasaltPillow basaltBasaltHeavily altered

basaltBasaltAltered basaltAltered basaltBasalt

Note: V. = vertical, H. = horizontal; water content is corrected; Φ = porosity. All values measured at laboratory temperature and pressure. For details of techniques, see Explana-tory Notes chapter (this volume).

0.97, all in wt.%). Site 559 is characterized by a typicalenriched abundance pattern for magmaphile elements([Nb/Zr]ch = 1.65).

This result would agree with a geochemical boundarybetween an Azores-type source north of Hayes FractureZone and a depleted source south of Hayes FractureZone. Nevertheless, the results obtained at Site 558 (whereenriched, flat, and depleted materials were found) ne-cessitate further analyses before a definite interpretationcan be made.

REFERENCES

Joron, J. L., Bollinger, C , Quisefit, J. P., Bougault, H., and Treuil,M., 1980. Trace elements in Cretaceous basalts at 25°N in the At-

lantic Ocean: Alteration, mantle composition, and magmatic pro-cesses. In Donnelly, T. W., Francheteau, J., Bryan, W., Robinson,P., Flower, M., Salisbury, M., et al., Init. Repts. DSDP, 51, 52,53, Pt. 2: Washington (U.S. Govt. Printing Office), 1087-1098.

Mattey, D. P., Marsh, N. G., and Tarney, J., 1981. The geochemistry,mineralogy, and petrology of basalts from the West Philippine andParece Vela Basins and from the Palau-Kyushu and West MarianaRidges, Deep Sea Drilling Project, Leg 59. In Kroenke, L., Scott,R., et al., Init. Repts. DSDP, 59: Washington (U.S. Govt. PrintingOffice), 753-800.

Rice, S., Langmuir, C. H., Bender, J. F., Hanson, G. N., Bence, A.E., and Taylor, S. R., 1980. Basalts from Deep Sea Drilling ProjectHoles 417A and 417D, fractionated melts and a light rare-earth de-pleted source. In Donnelly, T. W , Francheteau, J., Bryan, W ,Robinson, P., Flower, M., Salisbury, M., et al., Init. Repts. DSDP,51, 52, 53, Pt. 2: Washington (U.S. Govt. Printing Office),1099-1112.

223

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CORED INTERVAL 0.0-238.0 m

GRAPHICLITHOLOGY

— - _—

— -

£÷-L|-L-

- L _ l _ - J

-1- , -JL _

Basalt

' "-rs

z ^ IS

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T i t

LITHOLOGIC DESCRIPTION

2 ' 5 Y N 8 Section 1, 10-60 cm: MARLY NANNO OOZE.

Section 1. 60 cm-Section 2, 20 cm: MARLY NANNO OOZEwith volcanic 9lass.

Volcanic glass in DOMINANT LITHOLOGY MARLY NANNOFOSSIL OOZEwashed residue(for forams) White (2.5Y N8), 10YR 8/2 in Section 2, 32-42 cm

Λ Soft or soupy to firm

No bioturbation or bedding except sharp color change at Section

10YR 8/3 2, 20 cm, and faint color change at Section 2. 32

10YR8/2

— b a s a " Minor lithology:

Marly nanno ooze with volcanic glass

Marly limestone (CCI, white (10YR 8/2) with si

Note: glass makes up about 5-10% of the material

2. 20 cm.

htly darker

rom Section

1, 60 cm to Section 2. 20 cm, but fragments are large and do not

appear in smear slide analysis.

SMEAR SLIDE SUMMARY (%):1, 20 1.55 1, 140 2,20 2,31 ,40 CC

Clay 50 40 49 50 43 50 35-55

Volcanic glass 1 Tr 3 Tr

Palagonite - - - 2 - -

Micronodules 2 1 3 Tr Tr Tr 1-2

Zeolite - - - 5 -

Carbonate unspec. 5 8 7 10 5Foraminifers 5 9 8 8 15

Calc. πannofossils 35 40 30 20 35 'Diatoms 1 Tr 1 Tr -

Radiolarians 1 Tr 1 Tr Tr

Sponge spicules — — — — —Dolomite - Tr Tr-1 - Tr?

-

5 22-353 -

0 20 -28

rr Trfr

rr

rr Tr

SITE

- R

OC

NIT

TiM

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FOSSCHARAC

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2

3

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-

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;

:

-

CORED INTERVAL 238.0-247.0 m

GRAPHICLITHOLOGY

Basalt

t —1—'—•—

Basalt

NI?

T

10YR8/3

10YR 8/3

10YR8/3

V rincrea

Mangmicro

The rrof mi

ale brovse towards

nese minnodules or

icritic limrospar.

Throughout theinfiltr ated crack

n (10YR 8/3).the margin of th

ralization occurdendrites.

estone has been

pillow basaltss and vesicle wi

O N

T h e

epillo

thro

ecrys

sedimh the

v o ,

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a l l

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l a t

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patches

ne) hasng geo•

toto

SITE 559. CORE HI Depth 0.0-238.0 m

SECTION 2

APHYRIC PILLOW BASALT FRAGMENTSColor dark brown (10YR 3/3) to brown (10YR 4/3); moderately to badly altered. Fresh black aphanitic to

glassy basalt in Piece 1 with variolitic zone grading to altered basalt (size of varioles < 1 mm). Vesicles are scatteredthroughout the rock (size*C 1 mm, few<[3 mm) and often filled with calcite.

CORE-CATCHER

APHYRIC PILLOW BASALT FRAGMENTSPieces 1 and 3.1-4 cm: Black vesicular basalt glass. Vesicles (<1.5 mm) are round and empty.

13-23 cm: Moderately to badly altered aphyric basalt. Color brown to dark brown (10YR 4 /3 -10YR 3/3).- Round vesicles f<1 .5 ) and irregular shaped vesicles ( < 1 0 mm) are empty or calcite-filled. Some small veinlets are

cemented by calcite, too.

SITE 559, CORE 1 Depth 238.0-247.0 m

SECTION 1

APHYRIC PILLOW BASALT SEQUENCE

0 - 1 0 cm: Limestone, very pale brown (10YR 8/3), dendrites throughout the limestone (MnO).10-30 cm: Variolitic basalt, dark gray (2.5Y N4/0).10-22 cm. Pieces 2 and 3: 30-40% vesicles, unfilled.2 2 - 3 0 cm. Piece 4 : Glass r im, 10% unfilled vesicles.3 0 - 8 4 cm: Aphyric basalt, grayish brown (10YR 5/2), fine grained, highly altered, thin calcite filled fractures,

84 -150 cm: Aphyric basalt, dark gray (5Y 4/1), fine grained, alteration as noted at top of Pieces 7, 8, and 9B,

Unfilled round vesicles ( 51 mm) in Piece 7 and upper 2 cm of Piece 8. Weathered areas are brown (10YR 5/3).Pieces 5B, 6. and 8 contain irregular shaped vesicles ( 2 - 8 mm) filled with calcite.

Thin Section at 120-123 cm.

' SECTION 2

APHYRIC PILLOW BASALTS1-4 cm: Strongly altered variolitic aphyric basalt, color brown (10YR 5/3). Size of varioles < 4 mm.6 - 1 1 cm: Limestone, color pale brown (10YR 8/3). Black dendrites of Mn-O×ide are grown throughout the

(Piece 2).

31 -149 cm: Separate pillow of fine-grained aphyric basalt, color dark gray (10YR 4/1). High amount of round

• Pieces 5A and 12: Fresh glass rims on aphanitic, black basalt.

• SECTION 3

" APHYRIC PILLOW BASALTS

Moderately to highly altered aphyric basalt (highly altered brown [10YR 5 /3 ] , moderately grading to dark gray-ish brown [10YR 4/2] I. Two generations of vesicles suggested, esp. in 0 - 6 0 cm interval. Large vesicles 2 - 5 mm,

to very dark gray (7.5YR IM5/0) aphanitic, aphyric basalt grading to altered variolitic brown basalt. Calcite veining

relative to Sections 1 and 4 is striking.'Some larger cavities are present with the longitudinal calcite veining. calcite lined, in Pieces 1A -C , 3C, 7B, and

8CI.

J SECTION 4

BASALT GLASS AND LIMESTONE0-13.5, 3 5 - 3 8 , and 4 3 - 4 5 cm. Pieces 1A and B, 5, and 6: Limestone with glass clasts ( 1 - 3 cm in diameter).

Limestone shows dark "dendri t ic" pattern (MnO or Mn[OH) n). Glass clasts are slightly altered to very pale brown(10YR 8/4) palagonitβ around the rims and within the cracks.

(Λ J Jβ SS H Jft •"

i l l i .1 1 * I 1 t i l i I 1 i l l i l lε i § • ° g E I •i "E § ε f i " s c E I I "s § ε I •i •E § ε i .2 •s § E i ° "5 gz •s 8 I § a z £ 8 Js S β z •s 8 JS1 8 s I f 8 c § £ z s j | St J •? a Js S I .s 8 H § sslls-af s|Li i s f l . i f l s f l . i f l s l l 1 f i s i l l f i s SS .1 * I£ o c r θ « < C L O C C O C Λ < £ o c c o w < i O c c o c o < T U C C O C Λ < i u < r o w < £ u c c θ c o <

SITE 559, CORE 2 Depth 247.0-256.0 r

SECTION 1

APHYRIC PILLOW BASALT

0-147 cm: Dominantly aphyric dark gray O0YR 4/1) basalt. Fine grained. Grading through variolitic to blac

(10YR 5/3). Sparsely vesicular with small, round, unfilled vesicles (1-2%) concentrated (^5%) near pillow margin

Scattered irregular larger vesicles (—5 mm) generally calcite filled.

tone (46, 54-58, and 93-95 cm). Interpillow sediment: very pale brown (10YR 7/3)

with black MnOdendri

Basalt glass (135-145 cm). Thick rinds black, : r>tl , th black~aphanitic basalt. Only u

'HYRIC PILLOW BASALT AND LIMESTONE

— Aphyric pillow basalt, moderately/highly altered. Altered to brown (10YR 5/3) (highli

It; dark gray (7.5YR N4/0) to very dark gray (7.5YR N5/0). V

- ~lcite filled (3-7 mm) and small, empty K 1 - 2 mm). Large

C PILLOW B

0-64 and 104-140 cm: Aphy

altered) grading to dark grayish b

aprtanttrc Dasait pillows; dark gray (/.bYK N4/U) to very dark gray (7.bYK N5/0). Vesicles throughout section, tw

generations possible: large, calcite filled (3-7 mm) and small, empty ( < 1 - 2 m m ) . Larger vesicles are concentrate

in the highly altered upper sections of Pieces 1A and 3A, and a few in 4B; smaller vesicles are scattered.

60-102 cm: Limestone with glass clasts. 1-3 cm in length. Bioturbation is faint but present m majority of lim.

stone pieces. Piece 1G is limestone with glass fragment 63.0-64.5 cm. Glass is black (10YR 2.5/1). Limestone grade

from very pale brown (10YR 8/3) to light gray (10YR 7/2).

SECTION 3

APHYRIC PILLOW BASALTS

/vnhole. Small ( < 2 mm)

SITE 559. CORE 3

SECTION 1

BASALTIC PILLOW RIM PIECES

0-5 cm: Aphyric fine grained basalt altered grayish brown (10YR 6/2).

5-30 cm: Black basalt glass grading through black, aphanitic, spi

Limestone (11-13 and 28-30 cm): brown (7.5YR 5/2) limestone filling ii

SITE 559. CORE 4

SECTION 1

APHYRIC PILLOW BASALT, INTERPILLOW LIMESTONE

0-4, 24-62, and 70-144 cm: Aphyric pillow basalt sequence: black

black aphanitic, aphyric basalt (same color). Aphanitic basalt grades into

( <C 1 mm—1 mm in diameter) are present through this zone (aphanitic/variolitic), dem

Variolitic to aphyric altered basalt ranges in color from yellowish brown (10YR 5/6) to g

Within this brown altered basalt are found larger vesicles (2-7 mm in length) filled with Ci

Depth 256.0-256.5 r

Depth 256.5-265.0 π

(10YR 2.5/1) grading i

JSSL,

phyric basalt veds lin the brown H hnsal

(10YR 6/8) at 5-8 cm to very pale brown (10YR 8/4) at 8-12 cm to white I10YR 8/2) at 12-22 cm to very pale brr

(10YR 8/3) at 64-69 cm to light gray (10YR 7/1) at 146-150 cm. Dendritic patterns (of Mn-O×ides or

hydroxides?)are present in all pieces. Glass is palagonitized along cracks and edges.

SECTION 2

APHYRIC PILLOW BASALT, INTERPILLOW LIMESTONE0—5 and 99—106 cm: Limestone as in Section 1. Piece 6 contains a targe glass fragment. Palagonitized along

6-96 and 108-139 cm: Aphyric pillow basalt sequence as in Section 1. ILess total glass on aphyric basalt ascompared to Section 1.) Vesicles pattern the same, all but fewer large vesicles about calcite veins. Gradation ofbrown altered basalt to cores of unaltered basalt is less clear than in Section 1; much more subtle and fuzzy.

SECTION 3

APHYRIC PILLOW BASALT0-42 cm: Aphyric pillow basalt

Section 2.

. Aphanitic basalt bort

SITE 559 HOLE CORE 2 CORED INTERVAL 247.0-256.0 m

LITHOLOGIC DESCRIPTION

10YR8/3

10YR8/3

10YR 7/3

10YR 7/3

INTRAPILLOW-BASALT (VOLCANICLASTIC) LIMESTONE

Very pale brown (10YR 8/3) to pale brown (10YR 6/3)

Section 2, 60-102 cm: Moderascoured contact (dip - 3 0 " ) lighti

SITE 559 HOLE CORE 5 CORED INTERVAL 265.0-274.0 r

LITHOLOGIC DESCRIPTION

Piece No. 45YR 8/2

INTRAPILLOW-BASALT (VOLCANICLASTIC) LIMESTONE

Pinkish white (5YR 8/2) with manganese mineralization as blaflecks possibly (doubtful) bioturbated.

SITE 559 HOLE CORE 4 CORED INTERVAL 256.5-265.0 r

LITHOLOGIC DESCRIPTION

10YR8/3-10YR7/8NTRAPILLOW-BASALT (VOLCANICLASTIC) LIMESTONE

•om vellow (10YR 7/8) very pale brown (10YR 8/3)to light gray (5YR 7/1) and pinkish white (5YR 8/2)

Moderately bioturbated

Manganese mineralization occurs as dendrites and vein

5YR 7/1-5YR 8/2

NJto-J

tooo

SITE 559, CORE 5

SECTION 1

APHYRIC PILLOW

4-90, 98-112.highly altered (palesome cases (black o

14-20 and 119liticpart. Minor call

IBASP\LTand 118-145 cm: Aphyricbrowr

n diagr-126 c:itevei

1-4 and 112-118 cm:

i - 10YR 6/3). Variiam). In aphanitic bas;m: Rounded and irrtning throughout.

Mostly fresh glass cl

basalt pillow

alt: roundedigular calcite

asts (with pi

s ranging frorr> grading to bliempty vesicle!filled vesicles

alagonitized ri

I moderatiick aphan: (1-2mn

(1-2 mr

ms) in pir

Bly alter!itic basali ) .

n, some

Depth 265.0-274.0 m

id (gray- 10YR5/1)tot grading to glass rims in

up to 1 cm) in the vario•

ikishgray (7.5YR 6/2) limestone

Hm

SECTION 2APHYRIC PILLOW BASALT

23-150 cm: Aphyric pillow basalts as in Section 1. Round, empty vesicles (1-2 mm) in black aphanitic basalt.78—88 cm: Round and irregular vesicles (1 —2 mm up to 1 cm).113-124 cm: Filled with calcite in the more altered cares of the pillows and top variolitic edges.56-58, 71-72, 76-78, and 104-110 cm: Mostly fresh black glass rims with calcite veining and some alteration

to clays grading into black aphanitic basalts (filled with rounded empty vesicles).

SECTION 3

APHYRIC PILLOW BASALT

As in Sections 1 and 2.5-12 cm, 39-40, 70-77, and 101-104 cm: Glass rims grading to black aphanitic basalt (some with rounded,

empty [1—3 mmj vesicles as in Sections 1 and 2) and variolites.111-119, 46-47, 80-89, and 106-115 cm: Rounded to irregular calcite vesicles (1-2 mm up to 1.2 cm) in

SITE 559, CORE 6 Depth 274.0-283.0 m

APHYRIC PILLOW BASALT

Similar to Core 5. Moderately-heavily altered aphyric basalt ranging from dark gray (10YR 4/1) through grayishbrown (10YR 5/2) to brown (10YR 5/3). Several areas grading from altered core through variolitic texture through

SECTION 2

APHYRIC PILLOW BASALTModerately to badly altered, fine grained aphyric basalt: color dark gray (10YR 4/1) to brown (10YR 5/3).

Vitric cooling margins occur at 46—47, 65—70, 78—84, 90—92, 105—110, and 122—124 cm. Some pieces show

b) irregular shaped (size < 1 0 mm); if vesicles are located in fresher parts of the basalt, they are mostly empty,

SECTION 3

APHYRIC PILLOW BASALT

Moderately to badly altered aphyric, fine grained basalt with some glass margins (Pieces 2. 4, and 5), Variolitesin Pieces 2 and 5.

SITE 559, CORE 7

SECTION 1

Depth 283.0-292.0 m

APHYRIC PILLOW BASALT

0—14 cm: dlack glass and aphaπitic basalt. Vesicles are common and mostly empty. Veinlets are filled with

16-150 cm: Fine grained, aphyric basalt; color dark gray (2.5Y N4/0) to dark grayish brown (2.5Y 4/2I in

< 1 . 5 m m a n d b) irregular, < 1 . 2 c m . They are mostly filled with calcite,

SECTION 2

SECTION 3

APHYRIC PILLOW BASALT

0-12 cm: Moderately altered, gray (2.5Y N5) aphyric fine grained basalt with glass chill margin of 10 cm(as in Sections 1,and 2).

New Unit:120-150 cm: Coarser grained (but still fine) yellowish gray (6Y 5/1), aphyric basalt with very fine ( < 3 mml

vine(>). Upper part (10-85 cm) is moderately altered, lower part (85-150 cm) is fresher.

33-42 and 63-74 cm: 5% round and irregular calcite filled vesicles (<;3 mm) in altered part; and 2% round

SECTION 4

APHYRIC PILLOW BASALT

SITE 559, CORE 8 Depth 292.0-301.0 m

SECTION 1

APHYRIC PILLOW BASALT

0-54 and 69-132 cm: Fine grained (coarser grained than previous unit), slightly to moderately to heavily(79-103 cm) altered, aphyric basalt as in Section 3, 12 cm and Section 4.

54-79 cm: Black aphanitic basalt with glass chill margins and 2% round, empty ( < 2 mm) vesicles. There is

79-86 and 105-113 cm: 5% round and irregular ( < 3 mm) calcite filled vesicles in altered parts of pillows.

SECTION 2

(filled with calcite in altered regions of rock) are common at 39— ~— 45 and 107 — 145 cm (size ̂ C 3.5 mm) Color

SECTION 3

APHYRIC PILLOW BASALT

Same unit and characteiistics as in Sections 1 and 2 with usual calcite-füled vesictes in altered part of rock (63—67 and 75-82 cm).

U0

Htn

SITE 559

r - 0 cm H1-1 H1-2 H1,CC 1-1 1-2 1-3 1-4 2-1 2-2 2-3 3-1 4-1

- 2 5

— 50

—75• *%,,

—100

—125

1—150:

230

r—0 cm

— 25

— 50

—75

—100

—125

1—150

4-2 4-3 5-1 5-2 5-3 6-1 6-2 6-3 7-1 7-2 7-3 7-4

231

SITE 559

r—0 cm, 8-1 8-2 8-3

- 2 5

— 50

•75

—100

—125