LITHOLOGIC DESCRIPTION. VOLCANIC SAND, MUDDY SILICEOUS OOZE, GRAVEL, SANDY CLAY, and BASALT PEBBLES

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SITE 73 HOLE B CORE D CORED INTERVAL 4878.3-4886.3 mbsl; 0.0-8.0 mbsf U BIOSTRAT.

1 SITE 73 HOLE B CORE D CORED INTERVAL mbsl; mbsf U BIOSTRAT. ZONE/ FOSSIL CHARACTER GRAPHIC LITHOLOGY LITHOLOGIC DESCRIPTION VOLCANIC SAND, MUDDY SILICEOUS OOZE, GRAVEL, SANDY CLAY, and BASALT PEBBLES Core was forcibly extruded from barrel. Major lithologies: a. VOLCANIC SAND, very dark grayish brown ( OYR 3/), 90% of this interval, in Section, 0-70 cm. Medium-grained sand grading to coarse-grained sand. Composition is 90% volcanic sand fragments and <5% calcareous and siliceous microfossils. Volcanic sand is well-sorted; -50% of grains are slightly rounded and 50% are angular to slightly rounded. MUDDY SILICEOUS OOZE, yellowish brown (YR 5/4), % of this interval. 40 to 50% siliceous microfossils, <5% coccoliths, <5% broken foraminifers and 50% clay. b. Clasts of GRAVEL and MUDDY SILICEOUS OOZE, plus distinct gravel pieces, in Section, cm. GRAVEL is black (YR /), - cm diameter, weathered basalt and serpentinite, and subrounded. MUDDY SILICEOUS OOZE is yellowish brown (YR 5/4). c. SANDY CLAY, brown ( OYR 5/3) to yellowish brown (YR 5/4), with - 0-% black volcanic gravel, cm diameter; and ~ % coarse sand, very dark grayish brown (YR 3/), in Section, cm. d. BASALT PEBBLES, black (YR /), cm diameter, with -% very dark yellowish brown (YR 5/4) MUDDY SILICEOUS OOZE, in Section, cm. Largest clast is plagioclase-clinopyroxene-olivine phyric basalt. Olivine is totally oxidized; other clasts are weathered aphyric basalt. e. PEBBLES, -3 cm diameter, angular to subangular, comprising pieces of micro breccia (greenschist facies), 4 pieces of weathered basalt, 5 pieces of greenstone, 9 pieces of diabase, piece of amphibolite gneiss, pieces of gabbro (including coarse-grained rodingtized gabbroic vein in serpentinite), and 0 pieces of serpentinite, in Section. 5 cm" of undifferentiated gravel (< cm diameter) to mediumgrained sand. Representative pieces of each rock type are described separately. SMEAR SLIDE SUMMARY (%),,,, 38 Sand Silt Clay 85- Clay Diatoms Feldspar Foraminifers Nannofossils Quartz Radiolarians Rock frag. Silicoflag. Spicules r Information on Core Description Forms, for ALL sites, represents field notes taken aboard ship. Some of this information has been refined in accord with post-cruise findings, but production schedules prohibit definitive correlation of these forms with subsequent findings. Thus the reader should be alerted to the occasional ambiguity or discrepancy.

2 " SITE 73; HOLE r CORE B CORED INTERVAL tnbsl; mbsf n BIOSTRAT. ZONE/ a RB. «ROCK U ME- *~ LU 3TOCEN NIFERS RAM "OSSILS z Z o (N ARIANS ATO Q MAGNETIC LEO PROPER! YS. I 33 «óc TER GRAPHIC LITHOLOGY NG DiSTL ILL TRUCTUR I0 DIATOM OOZE Mud scraped from bit. LITHOLOGIC DESCRIPTION Major lithology: DIATOM OOZE, white (YR 8/), x 5 er diameter, fine grained, with 3 or 4 basalt chips, each <0.5 cm in length. PLEI SMEAR SLIDE SUMMARY (%): cc, D TEXTURE: Sand Silt 8 Clay 90 COMPO: Ace. min. Foraminifers Diatoms 9 Spicules 5

3 SITE 73 cm 0- Q "S 8 I I a- δ. s.9- i- GD *C o rr o TS UNIT: RUBBLE Piece : Mylonite 8 73A D- COLOR: Green-brown. LAYERING: -5 mm, compositional, sequence cannot be determined (sample too small). Contact rather sharp between layers. Azimuth and dip cannot be determined, but are parallel to foliation. DEFORMATION: Very strong mylonitic foliation, marked by flattened opaques. Lineation not visible. Azimuth and dip cannot be determined. Rotated augens indicate that simple shear was active during deformation. No variation in grain size visible. : Olivine, clinopyroxene(?), and oxides. Completely altered. : Total percent: 0%. Texture: Approximately -mm-thick layer of actinolite + mixture of amorphous oxides in a finegrained smectite(?). Rotated augens of opaques + actinolite and chlorite. Flattened opaques with chlorite rims in a matrix of fine-grained serpentine)?). Percent vein material: Not determined. Vein material: Not determined CORE/SECTION 7

4 SITE 73 cm : ö UNIT : GRAVEL* Type : Micro Breccia ( pieces) 8-73B-D- GLASS: Not determined. PHENOCRYSTS: None. GROUNDMASS: Aphyric basalt grains and clasts, < mm, and albitized clasts, < mm, are all subangular in a gray-green aphoritic matrix. COLOR: Gray. VESICLES: Not determined. STRUCTURE: Massive, undeformed. Matrix supported breccia with 50% clasts. ALTERATION: Moderately altered replacement in clasts and matrix by chlorite, albite, and clay minerals. VEINS/FRACTURES: None Type : Aphyric to Sparsely Phyric Basalt (4 pieces) PHENOCRYST: Single crystals. ace (-3%), - mm, subhedral, weathered, dull white surfaces. GROUNDMASS: Microcrystalline. COLOR: Gray, gray-brown, red-gray. VESICLES: Rare. Less than mm. STRUCTURE: Rubble ALTERATION: Weathered. Dull white, altered to clays. Groundmass also altered to clays. VEINS/FRACTURES: None. Type 3: Metabasalt (5 pieces) PHENOCRYSTS: None. GROUNDMASS: Microcrystalline. COLOR: Red, gray, gray-green. VESICLES: None. STRUCTURE: Rubble. ALTERATION: Moderately to heavily altered appear to be metabasalts. Secondary mineralogy inferred to be chlorite, albite, actinolite, and some clays. Probably more than 50% of the original rock is altered. VEINS/FRACTURES: None. 0 Type 4: Diabase (9 pieces) PHENOCRYSTS: None. GROUNDMASS: Fine-grained. Random orientation. Intersertal to intergranular texture. 0-40%, less than mm, euhedral, slightly altered to clays. -40%, less than mm, subhedral, fresh. COLOR: Gray, gray-brown, brown-gray. VESICLES: None. STRUCTURE: Layering. Massive. ALTERATION: Groundmass moderately altered to clays<?), and chlorite(?). VEINS/FRACTURES: None. Type 5: Amphibolite Gneiss ( piece working half only) COLOR: Layers of white and green-black. LAYERING: <- mm thick, discontinuous, lenticular alternating layers of fine-grained and amphibole. Sharp contacts. DEFORMATION: Foliation defined by phase layering. No lineation. Uniformly recrystallized. : and clinopyroxene completely altered. : Total percent: 0%. Texture: < mm aggregates of amphibole and. Percent vein material: None. Vein material: None. 50- CORE/SECTION 8

5 SITE 73 g CD DC > O ^ Ü XRF TS UNIT : RUBBLE Pieces -6 Piece : Phyric Basalt 8-73C-D- PHENOCRYSTS: cm, partly altered. GROUNDMASS: Fine-grained. COLOR: Not determined. VESICLES: None. STRUCTURE: Rubble. ALTERATION: Reddish oxide. phenocrysts partially altered. VEINS/FRACTURES: Calcite vein coats part of one surface. No other veins U0 Piece : Sparsely Phyric Basalt PHENOCRYSTS:. GROUNDMASS: Very fine-grained. COLOR: Not determined. VESICLES: None. STRUCTURE: Metabasalt<?). ALTERATION: Red oxide. Two phenocrysts have recrystallized rims. VEINS/FRACTURES: None. Piece 3: Highly Phyric Basalt PHENOCRYSTS: %, cm, one megacryst cm long. GROUNDMASS: Fine-grained. Acicular microlites. COLOR: Dary gray, reddish tint. VESICLES: None. STRUCTURE: Not determined. ALTERATION: Minor oxidative alteration to reddish oxides. VEINS/FRACTURES: None. Piece 4: Aphyric Basalt PHENOCRYSTS: <% small phenocrysts. GROUNDMASS: Fine-grained, microlitic. COLOR: Gray. VESICLES: None, but some tiny, irregular cavities or pores can be seen. STRUCTURE: Not determined. ALTERATION: Faint reddish o idative halo at one end, filling pore spaces in rock. VEINS/FRACTURES: None. Pieces 5 and 6: Indurated Mafic Sandstone Cemented by iron-oxyhydroxides. Sand grains are polymict basalt,, serpentine, and more. Grains are quite angular but well sorted. 50- CORE/SECTION 9

6 SITE 73 o eg c 3hic rese 03 CL ö rr (J o ntati δ CO "D E Q _C CO UNIT: RUBBLE Pieces -7 Piece : Aphyric Basalt No description. 8-73C 3D 0 D TS XRF TS Piece : Gabbro COLOR: Not determined. LAYERING: Massive. DEFORMATION: locally deformed and crystal edges granulated. Sample cut by fractures. : Mode: 68%. Crystal size: 5- mm. Crystal shape:. Preferred orientation: Locally deformed. Percent replacement: 60% by clays and albite. Mode: 7%. Crystal size: 5- mm. Crystal shape:. Preferred orientation: Not determined. Percent replacement: -0% by amphibole with epidote. 50 Mode: 5%. Crystal size: -4 mm. Crystal shape:. Preferred orientation: Not determined. Percent replacement: Slightly altered to spinel. : Total percent: -70%. Texture:, amphibole, clays, and epidote present. Percent vein material: Not determined. Vein material: Hematite/smectite vein. Also chlorite veins, chlorite + epidote veins, chlorite + epidote + amphibole veins, and epidote + amphibole + sphene veins. Piece 3: Sparsely Phyric Basalt No description. Piece 4: Metagabbro 0 COLOR: Not determined. LAYERING: Massive. DEFORMATION: Mortar texture. Sample cut by fractures. : Mode: 44%. Crystal size: -6 mm. Crystal shape:. Preferred orientation: Not determined. Percent replacement: -50% by chlorite, epidote, hornblende, and albite. Mode: 4%. Crystal size: 3-5 mm. Crystal shape:. Preferred orientation: Not determined. Percent replacement: -50% by chlorite, amphibole, and hornblende. Mode: %. Crystal size: Not determined. Crystal shape:. Preferred orientation: Not determined. Percent replacement: 50%. 50- CORE/SECTION Hornblende Mode: %. Crystal size: < mm. Crystal shape: Euhedral. Preferred orientation: Not determined. Percent replacement: 50%. : Total percent: -60%. Texture:, epidote, hornblende, and albite replaces. Albite forms an anastomosing network. Magnetite in pseudomorphs with amphibole. replaced by chlorite, amphibole, and hornblende. Percent vein material: Not determined. Vein material: Not determined.

7 SITE 73 Piece 5: Gabbroic Gneiss 8-73C-3D- (continued) COLOR: Not determined. LAYERING: Gneissic. DEFORMATION: Foliated. Sample cut by fractures. : Mode: 60%. Crystal size: - mm. Crystal shape: Porphyroblasts, crushed or locally recrystallized. Preferred orientation: Not determined. Percent replacement: -50% by chlorite, epidote, and amphibole. Green hornblende Mode: 40%. Crystal size: - mm. Crystal shape: Porphyroblasts, kinked and recrystallized. Preferred orientation: Not determined. Percent replacement: -5% by amphibole. : Total percent: -55%. Texture: is crushed and locally recrystallized into very small grains (<0. mm) or replaced by epidote-amphibole aggregates. Green hornblende replaced by amphibole. Epidote found in aggregates elongated in the foliation. Percent vein material: Not determined. Vein material: Epidote. Piece 6: Lithic Sandstone No description. Piece 7: Aphyric Basalt No description. 3

8 SITE D D cm 0- co o er o ú 0* 0 ö TS TS TS RF UNIT: RUBBLE Pieces -5 Piece : Sparsely Phyric Basalt PHENOCRYSTS: < cm. GROUNDMASS: Fine-grained. Has two -0.5 cm gabbroic<?) clots. COLOR: Not determined. VESICLES: -% filled by chlorite(?). STRUCTURE: Rubble. ALTERATION: phenocrysts partly altered to clays. <?) replacing groundmass. VEINS/FRACTURES: Veins of quartz, oxides, and chlorite<?). Piece A: Aphyric Basalt No description. Piece B: Pyroxene Gabbro 50 COLOR: Not determined. LAYERING: Not determined. DEFORMATION: Not determined. :, pyroxene, and oxides. Very coarse-grained. : and amphibole. Rock only slightly altered. Piece 3: Serpentinized Harzburgite COLOR: Not determined. LAYERING: Not determined. DEFORMATION: Pyroxene elongation defines a rough foliation. : Olivine and pyroxene. : Serpentine. Rock is completely altered. Piece 4: Diabase with Basalt Dikelet GLASS: Not determined. PHENOCRYSTS:. GROUNDMASS: Fine-grained., pyroxene, and oxides. COLOR: Gray. VESICLES: None. STRUCTURE: Not determined. ALTERATION: and amphibole. VEINS/FRACTURES: cm thick dikelet cuts sample. Piece 5: Phyric Basalt No description CORE/SECTION 3

9 SITE 73 S => 8 73E R cm 0- o er o UNIT : RUBBLE Pieces -3 Pieces and : Diabase No description. Piece 3: Highly Phyric Basalt TS PHENOCRYSTS: 5%, -6 mm, euhedral, slightly altered to chlorite and prehnite. GROUNDMASS: Fine- to medium-grained., pyroxene, and opaques. COLOR: Not determined. VESICLES: ace. Mostly filled by chlorite with minor prehnite and actinolite. STRUCTURE: Rubble. ALTERATION: Slightly altered to chlorite, actinolite, and prehnite. VEINS/FRACTURES: Veins of zeolite(?) and chlorite<?) CORE/SECTION 33

10 SITE 73 o E 8-73F-R- cm 0- σ rr o UNIT: RUBBLE Pieces -7 Piece : Moderately Olivine Phyric Basalt PHENOCRYSTS: Homogeneous distribution. Olivine, 3-5%, 0.5 mm, subhedral, 0% altered to clay minerals. GROUNDMASS: Microcrystalline. COLOR: Dark gray. VESICLES: None. STRUCTURE: Rubble. ALTERATION: Slightly altered. Olivine 0% altered to clay minerals. VEINS/FRACTURES: None. O XRF Pieces, 3, 5, and 6: Aphyric Diabase PHENOCRYSTS: None. GROUNDMASS: Fine-grained. COLOR: Dark gray. VESICLES: None. STRUCTURE: Rubble. ALTERATION: Slightly altered. VEINS/FRACTURES: Piece 3: Oxidation halo along empty(?) fracture. 50 Pieces 4 and 7: Aphyric Basalt PHENOCRYSTS: None. GROUNDMASS: Fine-grained. COLOR: Gray. VESICLES: None. STRUCTURE: Rubble. ALTERATION: Fresh. VEINS/FRACTURES: Small fracture in each piece CORE/SECTION 34

11 SITE A-D- (Piece, 0- cm) ROCK NAME: Serpentinized peridotite/mylonite TEXTURE: Mylonitic GRAIN : Fine OBSERVER: DCK Olivine Pyroxene Ferric chromite Fine-grained aphanitic. Completely altered to serpentine. Chromite now altered to ferric chromite with chlorite rims. Serpentine Amphibole(?) Magnetite 80 5 amphibole Chromite Ol, px Px(?) Ol, px Honey colored mineral. Very fine-grained. Represents possible alteration of relict ol or amphibole. Coarser#amphibole is stained brown suggesting that the honey-colored mineral is partially replacing amphibole rims. Rims around ferric chromite (which has replaced spinel). Identification questionable, possibly smectite. Typically very fine-grained. Defines foliation.. Intergrown with serpentine. : Fine-grained mylonite. Occasional augen consist of serpentine after px + ferric chromite after spinel. Amphibole<?) schileren also present; probably represent a replacement of smeared out primary px. Foliation defined by amphibole(?) laths, schlieren, serpentine replacing oriented, elongated ol crystals, and rotated serpentine sheaves. 8-73B-D- (Piece, 5-6 cm) ROCK NAME: Gabbro gneiss TEXTURE: Gneissic GRAIN : Fine OBSERVER: STA COMMEN Orthopyroxene (?) Granular Cores are replaced. Corroded. Relict igneous crystals Bastite Hornblende 50 8 Opx Cpx Crystal size ranges mm. Granular texture. Metamorphic, Fine-grained. Replacing cpx cores. Brown. : Most of the cpx could be metamorphic. Two stages of deformation: ^recrystallization of plag + cpx, granulite facies; )replacement of opx by bastite. Cpx is recrystallized during deformation, but not opx. 35

12 SITE B-D- (Piece, 6-7 cm) ROCK NAME: Diabase TEXTURE: Subophitic GRAIN : Medium OBSERVER: STA, CAN Magnetite Olivine L(max) = 3.5 W(max) =.0 L(max) =.5 W(max) =.0 <0.5 Clear sodic rims. Locally replaced by actinolite. Replaced by clay and epidote. Fresh. Epidote Actinolite 8 Ol Cpx Fe-stained smectites. Pale, blue interference colors. Yellow, very small grains. Acicular. : Greenschist facies overprint. 8-73B-D- (Piece, 7-8 cm) ROCK NAME: Aphyric diabase TEXTURE: Equigranular, holocrystalline GRAIN : Fine OBSERVER: KEM Oxides Olivine Fe-Ti, blocky, equant, equant Replaced-by clays. Dusty appearance Replaced by clay. 0 Ol Occurs along veins and cracks. Brown. Interstitial. Replaces ol. 8-73B-D- (Piece, 8-9 cm) ROCK NAME: Serpentinite TEXTURE: Mesh texture GRAIN : OBSERVER: KEM Chromian Partially replaced by serpentine. Magnetite Serpentinite 96 Bastite. Replaces all primary phases. : Possibly after peridotite. 36

13 SITE B-D- (Piece, 9- cm) ROCK NAME: Vein from metagabbro<?) TEXTURE: No longer apparent. GRAIN : Coarse OBSERVER: KEM Orthopyroxene Actinolite Prehnite Serpentine Px (?) Colorless. Replaces cpx(?). Forms whiskers on cpx pseudomorphs. Ghost outlines of plag and plag twins in prehnite. : This rock is composed totally of secondary minerals. Primary texture and most primary mineralogy is no longer apparent. Orthopyroxene is the only primary mineral remaining. Cpx pseudomorphs are composed of actinolite + serpentine. 8-73B-D- (Piece, - cm) ROCK NAME: Aphyric basalt TEXTURE: Intergranular GRAIN : Microcrystalline OBSERVER: STA, CAN Magnetite Glass Olivine 40 <0. < Euhedral, laths Euhedral, laths Extensively altered to colorless clay. Partially altered to Fe-stained clays. Fresh. Altered to clay. Replaced by red Feoxyhydroxide + clay(?)., ol, glass Fe-stained clay replacing cpx. in a magnetite crystal. Clay (smectite?) also replaces an inclusion(?) : Low temperature oxidation. 8-73B-D- (Piece, - cm) ROCK NAME: Metagabbro TEXTURE: Holocrystallin GRAIN : Coarse OBSERVER: STA >3 3 Euhedral Euhedral Cut extensively by veins. Amphibole pseudomorphs after cpx. Albite Epidote Actinolite 5 (?) (?) Veins, cpx Filling veins in cpx. One larç : Feldspar percentages based on the following distinctions: plag, twinned cores; albite, clear pseudomorphs or turbid regions due to epidote inclusions. One large vein of clinozosite(?). Grains are crushed, but not deformed. 37

14 SITE C-D- (Piece 3, 4-7 cm) ROCK NAME: Moderately phyric basalt TEXTURE: Porphyritic GRAIN : Fine OBSERVER: KEM PHENOCRYSTS Olivine Microphenocrysts. Altered to clays. Skeletal overgrowths. Zoned and twinned crystals. Altered to clays. GROUNDMASS Olivine Cryptocrystalline groundmass Oxides < , skeletal Quench overgrowths. Occurs in interstices of plag crystals. Altered to clays and red mineral (oxide?). Unidentified groundmass. Elongate habit, acicular. Zeolites 3 Ol, plag Ol Filling thin cracks and veinlets in phenocrysts. Substantial replacement of groundmass ol. Local replacement of groundmass plag. Spherical morphology. Replaces some ol. 8-73C-D- (Piece 4, 9- cm) ROCK NAME: Aphyric basalt TEXTURE: Microporphyritic GRAIN : Microcrystailine OBSERVER: KEM PHENOCRYSTS Olivine 0 < Augite, skeletal, skeletal Totally replaced by calcite. Partially altered to albite<?) + clays. GROUNDMASS Cryptocrystalline groundmass Oxides = 0.5 <0.0 Magnetite(?) <0. Augite Skeletal, sheaves. equant Quench texture. Unidentified mineralogy. Interstitial between plag sheaves. Carbonate Albite Ol : Rapidly cooled basalt with quench crystallization textures. 38

15 SITE C-3D- (Piece, 5- cm) ROCK NAME: Metagabbro TEXTURE: Holocrystalline GRAIN : Coarse OBSERVER: KEM Dusty appearance. Altered to clays + albite. Completely replaced by amphibole ± epidote. Albite Epidote Actinolite Sphene Veins Veins, plag Cpx, veins Fe-Ti oxides Also in large patches in between granulated plag. Replaces plag in a network fashion associated with chlorite and epidote. Green to yellow pleochroism. : locally deformed and crystal edges granulated (incipient mortar texture). Veins include chlorite, chlorite + epidote, chlorite + epidote + amphibole, epidote + amphibole + sphene. enolith(?) quench basalt on margin. 8-73C-3D- (Piece 4, 5-8 cm) ROCK NAME: Metagabbro TEXTURE: Mortar GRAIN : Very coarse OBSERVER: STA Hornblende Red-brown. Albite Epidote Actinolite Hornblende Prehnite Magnetite Cpx, hbd, plag, cpx Anastomosing pattern. Epidote + chlorite replaces plag. Occurs with chlorite, along plag-cpx boundaries. Green and brown. Granular. Mortar structure. In pseudomorphs with amphibole. 8-73C-3D- (Piece 5, 0-3 cm) ROCK NAME: Foliated metagabbro TEXTURE: Porphyroclastic GRAIN : Fine to coarse OBSERVER: CAN Hornblende Green. Partially recrystallized. Kinked crystals. Actinolite<?) Epidote 5 5, hbd Composition could be an actinolitic hornblende. Some porphyroclasts. Crushed or locally recrystallized in very small grains or in an epidote + actinolite aggregate. Found in aggregates defining foliation and in the crosscutting veins. : The gabbro was first metamorphosed in the green hbd + plag facies. The crushing deformation developed in the actinolite or actinolitic hbd plag + epidote facies. Epidote crystallization in veins continued after deformation. 39

16 SITE D-D- (Piece, 0-5 cm) ROCK NAME: Sparsely phyric basalt TEXTURE: Porphyritic, vesicular GRAIN : Fine OBSERVER: KEM PHENOCRYSTS Large patches altered to chlorite + epidote. GROUNDMASS Oxides Olivine Skeletal, acicular <0. <0.0 Fe-Ti, equant Sheaf texture. Pinkish-brown color. Intersertal texture. Completely replaced by chlorite. Epidote Quartz Oxides 3 0, plag,, veins, veins Veins Also fills vesicles and veins. Occurs with chlorite in veins. Occurs with epidote, replacing plag. Deformed during vein filling. Fe-Ti oxides. Yellowish brown to red oxides. Occurs with chlorite in veins. VESICLES/ CAVITIES Vesicles Even LOCATION SHAPE Round Filled by chlorite. : Difficult to determine how much matrix has been altered due to greenschist facies metamorphism. Phenocrysts and microphenocrysts may be albitized. 8-73D-D- (Piece B, 7-9 cm) ROCK NAME: Ferrogabbro TEXTURE: Orthocumulate GRAIN : Very coarse OBSERVER: STA Orthopyroxene Hornblende Apatite < Replaced by actinolite. Replaced by serpentine + magnetite. Brown. Late, intercumulus. Serpentine Actinolite 5 3 Opx(?) Hbd Hbd, plag, px 40

17 SITE D-D- (Piece 3, -8 cm) ROCK NAME: Serpentinized harzburgite TEXTURE: Porphyroclastic GRAIN : Coarse OBSERVER: CAN Olivine Pyroxene Lobate Completely altered to serpentine. Coarse mesh texture. Altered to magnetite. Partially plucked during polishing. Bastite pseudomorphs after both opx and cpx. Difficult to distinguish between the two px pseudomorphs; rough estimation 5% opx, 5% cpx. Serpentine Magnetite 93 Ol, px Ol, spinel Bastite pseudomorphs after both opx and cpx. Occurs as rims around spinel and as scattered grains in serpentine after ol. : Elongation of px aggregates defines a rough foliation. 8-73D-D- (Piece 4, -5 cm) ROCK NAME: Moderately phyric basalt TEXTURE: Subophitic, intersertal GRAIN : Fine OBSERVER: BLM PHENOCRYSTS 5:5 5:5 Euhedral One large crystal in host. One crystal in dike. Crystal in dike may be originally from host rock ( based on cpx and opaque inclusions). Amphibole + epidote ± albite occur along rectilinear fractures in the plag. GROUNDMASS Mesostasis 3: 39:43 4: 0.0 3: : : : Pronounced alignment in host. Skeletal crystals occur in dikelet. Albite Actinolite 3(?):0 : : 5:8 Mesostasis Mesostasis Mesostasis Probably smectite. Occurs along fractures in plag. Pale green patches after mesostasis. Also in fractures in plag. : cm dike cuts sample (constitutes approximately 0% of the slide). Percentages refer to ROCK:DIKE estimates. Dike has higher percentage of opaques, and is generally finer-grained (0. mm average grain size). Dike has a fine-grained border on one side that looks like recrystallized host rock (equigranular, mm grain size). 4

18 SITE E-R- (Piece 3, 7-0 cm) ROCK NAME: Highly phyric diabase WHERE SAMPLED: TEXTURE: Porphyritic, ophitic GRAIN : Medium OBSERVER: MEY, STA 3INAL PHENOCRYSTS <0. Chromian Euhedral Euhedral Homogeneous cores. Narrow, strongly zoned rims. Altered melt inclusions in cores. Inclusions in plag. GROUNDMASS Oxides Fe-Ti Small oikocrysts ophitically enclose plag. Actinolite Prehnite, veins, cpx, veins Also in interstitial areas. VESICLES/ CAVITIES Vesicles LOCATION.0 ± prehnite ± actinolite SHAPE Spherical One vesicle. Mostly filled with chlorite except for small interior spheres of prehnite. : Percentages based on 750 point counts. 4

Lithology: Olivine-rich gabbro medium grained Observer: Texture: granular Ave. grain size: medium grained [345] Shape Habit Comments

Lithology: Olivine-rich gabbro medium grained Observer: Texture: granular Ave. grain size: medium grained [345] Shape Habit Comments THIN SECTION LABEL ID: 179-1105A-1R-2-W 88/91-TSB-TSS Piece no.: #02 TS no.: Igneous Medium-grained olivine gabbronorite; plagioclase chadacryst within orthopyroxene oikocryst; rims of olivine and clinopyroxene