Site U1377 core descriptions Thin sections altered by smectite and brown clay altered by smectite and brown vesicle laths[330] sometimes centered zoning REPLACING/FILLING COMMENTS SIZE(mm) min. max. mode. m smectite group (dioctahedral s smectite group (dioctahedral VESICLESGROUNDMASSplagioclaseglassopaque mineralsSECONDARY MINERALOGY 84.5 15 25 15 44.5 10 100 0.1 1.1 0.3 0.2 0.15 0.1 0.1 laths[330] needle low[330] 70 smectite THIN SECTION:ROCK NAME:WHERE SAMPLED:GRAINSIZE:TEXTURE: 270 68_70-BILLET270-SLIDE 330-U1377A-3R-1-W lava body PRIMARY aphyric trachybasalt MINERALOGYPHENOCRYSTS No: Piece fine grained aphyric ORIGINAL PERCENT Unit:1 REPLACED 0.5 REL. VOL. min. SIZE(mm) max. mode. SECTION:SLIDE 270 OBSERVER:THIN MORPHOLOGY SPHERICITY [%] Infilling COMMENTS VESICLE VESICLE STRUCTURECOMMENTS DESCRIPTION SUMMARY altered; no structure in groundmass; vein (0.5 mm wide; goethite); highly MICROPHENOCRYST plagioclase 0.5 10 1 0.5 Site U1377 thin sections U1377A-3R-1-W 68_70

Proc. IODP | Volume 330 1 Site U1377 core descriptions Thin sections brown clay and smectite low and 90 smectite-filled elongated[EXP330] vesicle anhedral subhedral subhedral[330] subhedral[330] SIZE(mm) min. max. mode. REPLACING/FILLING COMMENTS m SECONDARY MINERALOGY smectite group (dioctahedral s THIN SECTION:ROCK NAME:WHERE SAMPLED:GRAINSIZE:TEXTURE: 271 2_4-BILLET271-SLIDE 330-U1377A-3R-2-W lava body PRIMARY moderately olivine-phyric[EXP330] trachybasalt MINERALOGYPHENOCRYSTS fine grained augite Piece No:olivine moderately phyric ORIGINAL PERCENT REPLACED Unit:2 REL. VOL. 8 0.8 5 0 100 min. SIZE(mm) max. mode. MORPHOLOGY SECTION:SLIDE 271 OBSERVER:THIN SPHERICITY [%] Infilling COMMENTS 2.8 2.8 VESICLE 1.6 1.2 VESICLE subhedral euhedral to plagioclaseolivineGROUNDMASSopaque mineralsplagioclase 1glass 2 82 0 3 100 20 59 0 100 0.9 0.6 0.9 0.5 laths[330] 0.1 euhedral to 0.02 0.2 0.1 laths[330] clots sieve texture, centered zoning, MICROPHENOCRYST augite 0.2 0 0.8 0.6 VESICLES 10 0.1 0.6 0.3 STRUCTURECOMMENTS DESCRIPTION SUMMARY no structure in groundmass U1377A-3R-2-W 2_4

Proc. IODP | Volume 330 2 Site U1377 core descriptions Thin sections altered by clay vesicle also filled with green clay subhedral by brown clay replaced SIZE(mm) min. max. mode. REPLACING/FILLING COMMENTS SECONDARY MINERALOGY carbonate STRUCTURECOMMENTS DESCRIPTION SUMMARY mostly horizontal; several straight & cross-cutting veins (max.0.28 mm; irregulars 0.08 mm) aligned bands of glass, THIN SECTION:ROCK NAME:WHERE SAMPLED:GRAINSIZE:TEXTURE: 272 45_47-BILLET272-SLIDE 330-U1377A-4R-2-W basalt lava lobe or pillow PRIMARY aphyric trachybasalt MINERALOGYPHENOCRYSTS No: Piece fine grained aphyric ORIGINAL PERCENT Unit:3 REPLACED 0.5 REL. VOL. min. SIZE(mm) max. mode. SECTION:SLIDE 272 OBSERVER:THIN MORPHOLOGY SPHERICITY [%] Infilling COMMENTS VESICLE VESICLE VESICLESGROUNDMASSplagioclaseglass 97.5 2 10 87.5 10 100 0.1 0.5 0.2 0.4 0.08 microlite[330] low[330] 100 green clay and some carbonate MICROPHENOCRYST olivine 0.5 100 0.8 0.3 U1377A-4R-2-W 45_47

Proc. IODP | Volume 330 3 Site U1377 core descriptions Thin sections altered by brown clay and smectite low[330] 60 filled by brown clay vesicle brown clay REPLACING/FILLING COMMENTS SIZE(mm) min. max. mode. GROUNDMASSglassplagioclaseSECONDARY clay 90 10 80 10 100 0.4 0.2 microlite[330] THIN SECTION:ROCK NAME:WHERE SAMPLED:GRAINSIZE:TEXTURE: 273 123_125-BILLET273-SLIDE 330-U1377A-5R-2-W basalt lava lobe or pillow PRIMARY aphyric trachybasalt MINERALOGY Piece No:PHENOCRYSTS fine grained MICROPHENOCRYST VESICLES aphyric ORIGINAL Unit:3 PERCENT REPLACED REL. VOL. 0 10 min. SIZE(mm) max. mode. SECTION:SLIDE 273 OBSERVER:THIN MORPHOLOGY SPHERICITY [%] Infilling COMMENTS 0.1 1.2 0.2 VESICLE VESICLE MINERALOGY STRUCTURECOMMENTS DESCRIPTION SUMMARY non-oriented thin section; irregular vein (0.2 mm) glass bands, U1377A-5R-2-W 123_125

Proc. IODP | Volume 330 4 Site U1377 core descriptions Thin sections 90 filled by carbonate and brown clay elongate[330] SIZE(mm) min. max. mode. REPLACING/FILLING COMMENTS GROUNDMASSglassolivineplagioclaseaugiteSECONDARY 91 MINERALOGY STRUCTURECOMMENTS 36 40 10 DESCRIPTION SUMMARY 5 sub-vertical moderate trachytic texture 100 5 100 0 0.9 0.3 0.4 0.2 0.07 0.04 microlite[330] subhedral anhedral aligned smectite replaced by brown clay and THIN SECTION:ROCK NAME:WHERE SAMPLED:GRAINSIZE:TEXTURE: 274 13_15-BILLET274-SLIDE 330-U1377A-6R-2-W lobe basalt lava PRIMARY olivine-phyric[EXP330] trachybasalt moderately MINERALOGYPHENOCRYSTS Piece No: grained fine olivineMICROPHENOCRYST phyric moderately VESICLES ORIGINAL PERCENT Unit:4 REPLACED REL. VOL. 6 6 3 100 min. SIZE(mm) max. mode. SECTION:SLIDE 274 OBSERVER:THIN MORPHOLOGY SPHERICITY Infilling [%] COMMENTS 0.3 2.1 3.2 VESICLE 1.2 1.2 VESICLE subhedral low to replaced by brown clay and smectite U1377A-6R-2-W 13_15

Proc. IODP | Volume 330 5 Site U1377 core descriptions Thin sections 100 carbonate and smectite by brown clay, filled rounded[330] vesicle with smectite and carbonate also filled SIZE(mm) min. max. mode. REPLACING/FILLING COMMENTS THIN SECTION:ROCK NAME:WHERE SAMPLED:GRAINSIZE:TEXTURE: 275 64_66-BILLET275-SLIDE 330-U1377A-6R-2-W lobe basalt lava PRIMARY olivine-phyric[EXP330] trachybasalt moderately MINERALOGYPHENOCRYSTS Piece No: grained fine olivineMICROPHENOCRYST phyric moderately olivineVESICLES ORIGINAL PERCENT Unit:5 REPLACED 16 REL. VOL. 10 10 6 100 100 min. SIZE(mm) max. mode. SECTION:SLIDE 275 OBSERVER:THIN MORPHOLOGY SPHERICITY Infilling [%] COMMENTS 0.9 4.8 1.1 VESICLE 9 0.9 VESICLE 1.2 0.8 subhedral subhedral moderate, and carbonate smectite altered by brown clay, smectite and carbonate altered by brown clay, GROUNDMASSplagioclaseolivineglassopaque mineralsaugite 74 SECONDARY MINERALOGY clay 40 5STRUCTURE 10COMMENTS 25 0 DESCRIPTION SUMMARY 4 100 (0.4 m wide). weak, sub-vertical trachytic texture; branched vein 100 0 0.3 0.1 0.1 0.2 0.05 0.05 microlite[330] 0.07 anhedral subhedral 0.03 anhedral aligned needle U1377A-6R-2-W 64_66

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