Table
T2. Summary of lithologic and alteration features of units
described in Hole 1189A.
Unit
Core,
section
Curated
depth (mbsf)
Curated
length
(m)Lithology
Alteration
193-1189A-
1
1R-1
(1-4)
0.00
0.17
0.17
Fresh,
moderately vesicular, aphyric dacite.
Fresh
unit. Minor sulfate films coat vesicles. XRD mineralogy: plagioclase and
opaline silica dominant, minor augite, quartz, and spinel.
2
1R-1
(5-8)2R-1 (1-13)
0.179.70
0.3410.63
0.170.93
Moderately
to completely altered, moderately vesicular, aphyric dacite.
Bleached
unit. Vesicles are filled with anhydrite. Rare Fe oxide films. XRD
mineralogy: plagioclase, cristobalite, anhydrite dominant, minor pyrite,
chlorite/smectite-mixed-layer clays, and traces of chlorite and illite.
3
2R-1
(14)
10.63
10.71
0.08
Coarse-grained
quartz-sulfate vein.
Gray
silica-sulfate-clay-pyrite vein. Coarse-grained sulfate occurs as vuggy
cavity fill. Very fine grained pyrite is disseminated throughout and is
concentrated in vugs.
4
2R-1
(15-17)
10.71
11.07
0.36
Hydrothermal
breccia with completely altered, perlitic volcanic clasts.
Volcanic
rock with remnant perlitic texture altered pervasively to silica clay and
fractured by an anhydrite-silica-pyrite stockwork. Fragments are cut by
fine anastomosing networks of sulfate veinlets. Anhydrite occurs as
vesicle fill. Pyrite occurs in veins and as vesicle fill. XRD mineralogy:
anhydrite, cristobalite dominant, minor pyrite and chlorite, and traces of
illite.
5
3R-1
(1-9)
19.40
19.96
0.56
Highly
to completely bleached, moderately vesicular, aphyric dacite.
Pervasively
bleached unit. Pyrite occurs as fine disseminations, as vesicle fill with
anhydrite and on fracture surfaces. Veins also contain scattered,
coarse-grained anhydrite. XRD mineralogy: plagioclase, cristobalite
dominant, minor pyrite, and chlorite.
6
3R-1
(10)
19.96
20.03
0.07
Hydrothermal
breccia.
White
sulfate-rich volcanic clasts cemented in bluish green sulfate-clay-silica
altered material. Pyrite is disseminated throughout. A single blue clay
altered rounded fragment contains anhydrite laths that do not extend into
the body of the rock, implying earlier alteration. XRD mineralogy:
anhydrite, quartz dominant, minor pyrite, and traces of illite.
7
3R-1
(11-16)
20.03
20.36
0.33
Variably
bleached and silicified, sparsely to moderately vesicular, intensely
veined volcanic rock.
Silicified
bleached vesicular volcanic rock. Medium-grained anhydrite-quartz-pyrite
veins with silica-pyrite halos cut the rock. Pyrite occurs in vein halos,
but also scattered throughout the rock. XRD mineralogy: quartz dominant,
minor orthoclase, pyrite, and traces of illite.
8
4R-1
(1-3)
29.10
29.34
0.24
Completely
altered, moderately vesicular dacite.
Pervasive
green silica-clay alteration, cut by irregular quartz-pyrite veins.
Silicate fills vesicles, implying silica flooding of the rock. Rock cut by
late anhydrite vein. XRD mineralogy: quartz dominant, minor plagioclase,
chlorite, pyrite, and illite.
9
5R-1
(1-9)6R-1 (1-10)
38.8048.60
39.4249.29
0.620.69
Completely
altered, hydrothermal breccia with flow-laminated volcanic clasts.
Patchy
to pervasive multiphase alteration. Stage 1: alteration of volcanics to
white clay-anhydrite-silica (locally preserving flow banding). Stage 2:
hydraulic brecciation with chlorite alteration associated with anhydrite
veining. Stage 3: quartz-pyrite veining with associated chlorite
alteration. XRD mineralogy: quartz dominant, minor anhydrite, chlorite,
pyrite, and illite.
10
7R-1
(1-8)
58.30
58.88
0.58
Completely
altered, nonvesicular to slightly vesicular volcanic rock.
Pervasive
green silica-clay alteration overprinted by silicification, which is most
intense along quartz-pyrite veins. Anhydrite in the centers of some veins.
Elongate vesicles sometimes form tube-like structures that are lined with
quartz and pyrite and rare late anhydrite. XRD mineralogy: quartz,
plagioclase dominant, minor anhydrite, pyrite, chlorite, and illite.
11
7R-1
(9-10)
58.88
59.02
0.14
Completely
altered breccia with possible evidence of clast rotation of flow-laminated
fragments.
Clasts
show silica-sulfate-chlorite alteration and are cemented in fine grained
silica.
12
7R-1
(11-14)
59.02
59.22
0.20
Completely
altered sparsely vesicular volcanic rock.
Extensive
pervasive silicification overprinting silica-clay alteration. Vesicles are
lined with large euhedral quartz and pyrite crystals.
13
7R-1
(15-16)
59.22
59.29
0.07
Completely
altered breccia with possible evidence of clast rotation of flow-laminated
fragments.
Clasts
show green silica-clay alteration and are cemented in fine grained silica.
XRD mineralogy: quartz dominant, minor plagioclase, chlorite, and traces
of pyrite.
14
7R-1
(17)
59.29
59.32
0.03
Massive
silica-Fe oxide-pyrite with minor pale green altered clasts.
Rare,
whitish green altered clasts and fine pyrite euhedra are cemented in a red
jasperoid cement.
15
8R-1
(1-20)
68.00
69.28
1.28
Plagioclase-rich
sparsely vesicular volcanic rock with patchy poikiliblastic silicification
associated with a fine network of silica-pyrite veins.
Plagioclase-rich
rock overprinted by patchy poikiloblastic silicification. Veins are
abundant and are filled with quartz and pyrite in approximately equal
proportions. XRD mineralogy: plagioclase dominant, minor quartz,
K-feldspar, pyrite, traces of smectite, chlorite, and illite.
16
9R-1
(1-12)
77.70
78.56
0.86
Completely
altered hydrothermal breccia with abundant flow-banded clasts.
Rocks
are composed of green silica-clay altered material, which is cut by a
network of quartz and pyrite veins with heavily silicified in halos along
the veins. XRD mineralogy: anhydrite, quartz dominant, minor plagioclase,
pyrite, and traces of chlorite.
17
9R-1
(13)10R-1 (1-2)
78.5687.30
78.5987.37
0.030.07
Completely
bleached moderately vesicular volcanic rock.
Completely
bleached and slightly silicified. XRD mineralogy: quartz dominant, minor
plagioclase, pyrite and traces of chlorite.
18
10R-1
(3)
87.37
87.41
0.04
Completely
altered and mineralized breccia.
Clasts
of glassy volcanic rock and sulfide (pyrite + chalcopyrite) in a very fine
grained silica-pyrite cement.
19
10R-1
(4-14)
87.41
88.72
1.31
Completely
altered hydrothermal breccia with medium- to fine-grained clasts hosted in
a network of silica-sulfide veins with late anhydrite vug fill.
Silica-clay
alteration overprinted by silicification. Bluish gray domains in the core
are heavily silicified, while greenish domains are soft (clayey). Quartz
and pyrite veins often have anhydrite vug fill. XRD mineralogy: quartz and
anhydrite dominant, minor plagioclase and pyrite, traces of chlorite and
illite.
20
11R-1
(1-13)12R-1
(1-15)
96.90106.50
98.07107.70
1.171.20
Completely
silicified, massive, moderately vesicular volcanic rock.
Intense
silicification overprinting patchily preserved green clay alteration. Vugs
and vesicles are commonly lined with quartz and pyrite. Pyrite veins
commonly have silicified halos. XRD mineralogy: quartz dominant, minor
pyrite, illite, and chlorite.
21
12R-1
(16)
107.70
107.78
0.08
Completely
altered and mineralized volcaniclastic breccia.
Clasts
of glassy volcanic rock and sulfide (pyrite + minor chalcopyrite) in a
very fine grained silica-pyrite cement.
22
12R-1
(17-18)13R-1
(1-7)
107.78116.10
107.88116.61
0.100.51
Pervasively
bleached moderately vesicular volcanic rock with a patchy silica
overprint.
Vesicular
intensely bleached volcanic unit with patchily developed indurated
silicification. Widespread pyrite as vesicle lining. XRD mineralogy:
quartz dominant, minor chlorite, pyrite, illite.
23
13R-1
(8)
116.61
116.69
0.08
Polymict
volcaniclastic breccia, with rounded green clay, altered gray silicified
and bleached clasts cemented in silica.
Three
distinct clast types, all showing differing alteration types, suggesting a
polymict nature. Most of the more clay-rich pieces have silicified rims
adjacent to the silceous cement. Traces of disseminated pyrite. XRD
mineralogy: quartz dominant, minor plagioclase, pyrite and chlorite, and
traces of illite.
24
13R-1
(9-10)
116.69
116.82
0.13
Pervasively
bleached sparsely vesicular volcanic rock with a patchy silica overprint.
Vesicular
intensely bleached volcanic unit with patchily developed indurated
silicification. XRD mineralogy: quartz dominant, minor pyrite and, traces
of chlorite and illite.
Note: XRD = X-ray diffraction.