Table T4. Lithology and alteration of Units 27 to 72, Hole 1188F.

Table T4. Lithology and alteration of Units 27 to 72, Hole 1188F.

Unit Core, section
(Piece) Curated depth
(mbsf) Curated
length
(m) Lithology Alteration

Top

Base

193-1188F-

27 1Z-1 (1-5) 218.00 219.21 1.21 Completely altered, silicified, massive aphyric volcanic rock. Intensely fractured, pervasive pale gray silicified rock with minor greenish, chloritic intervals (remnant GSC domains) and softer, more clayey pieces. Cut by irregular anhydrite-pyrite ± silica veins with cyclically zoned, 1- to 2-cm-wide siliceous alteration halos. XRD mineralogy: quartz dominant, minor anhydrite, illite, and pyrite.

1Z-2 (1-4) 219.21 220.42 1.21

1Z-3 (1-2) 220.42 221.04 0.62

28 1Z-3 (3) 221.04 221.65 0.61 Completely altered, silicified, and green clay-bearing, massive aphyric volcanic rock. Pervasive pale gray silicification and abundant green material (remnant GSC domains?). Similar to Unit 27 but with a dominance of green material. Anhydrite-pyrite coated fractures show distinct, cyclically banded silicified alteration halos overprinting the chloritic alteration. Remnant kernels of groundmass domains encircled by such veins are green. XRD mineralogy: quartz dominant, minor anhydrite, illite, chlorite, and pyrite.

1Z-4 (1) 221.65 222.25 0.60

29 1Z-4 (2) 222.25 222.86 0.61 Completely altered, silicified, massive aphyric volcanic rock. Intensely fractured, pervasive pale gray silicified intervals intercalated with creamy-colored, softer, more clay-rich material. Thin, submillimeter anhydrite-pyrite-silica veins with well-developed, 10- to 15-mm-wide, gray siliceous alteration halos. XRD mineralogy: quartz dominant, minor anhydrite, illite, and pyrite. Sample 193-1188F-2Z-1, 73-74 cm, contains, additionally, calcite and probably traces of kaolinite.

2Z-1 (1-3) 221.50 223.00 1.50

3Z-1 (1-3) 222.60 224.04 0.44

30 3Z-2 (1-3) 224.04 225.59 1.55 Completely altered, brecciated, silicified volcanic rock with a clayey matrix. Hard, indurated, pervasively silicified and less abundant creamy-colored (more clay rich) fragments embedded in a light gray, clay-anhydrite matrix. Late pyrite-silica ± anhydrite veinlets cut larger pieces and have well-developed, banded (cyclic) siliceous alteration halos (as wide as 2 cm). XRD mineralogy: quartz dominant, minor anhydrite, illite, chlorite, and pyrite.

6Z-1 (1) 233.10 233.55 0.45

31 6Z-1 (2) 233.55 233.57 0.02 Highly altered, apparently spherulitic volcanic rock. Single piece of apparently spherulitic volcanic rock. Contains 50% isolated, white, round, altered apparently spherulites (as much as 1 mm in diameter, radiating crystal aggregates). Central vugs are common and often filled by pyrite crystals. XRD mineralogy: cristobalite and plagioclase dominant, minor chlorite and pyrite.

32 6Z-1 (3-4) 233.57 234.37 0.80 Completely altered, silicified, massive aphyric volcanic rock. Light gray indurated, silicified, and less-abundant creamy-colored more clay-rich pieces. Fracture surfaces with silica and sulfate. Trace disseminated pyrite tends to be more abundant in less strongly silicified pieces. Scattered Fe oxide spotting after sulfide. XRD mineralogy: quartz dominant, minor anhydrite and illite.

6Z-2 (1A-1B) 234.37 234.61 0.24

33 6Z-2 (1C-3) 234.61 235.39 0.78 Silicified volcanic fragments embedded in soft gray clay. Pervasively silicified fragments embedded in and/or coated by soft, gray clay. Fracture surfaces are mostly coated by white silica-anhydrite with zoned cyclic alteration halos (as much as 1 cm half-width). Trace pyrite disseminated and as vug fills. Quartz-pyrite spots may be remnant plagioclase phenocrysts. Piece 3A contains rare plagioclase phenocrysts. XRD mineralogy: quartz dominant, minor anhydrite, illite, and pyrite.

34 7Z-1 (1A-1G) 235.00 236.01 1.01 Silicified, massive aphyric volcanic rock. Rounded pebbles of silicified, sparsely microvesicular volcanic rock. Intensity of silicification decreases away from edges of pebbles, leaving less-altered kernels. Pyrite is finely disseminated in the less-silicified kernels but is absent from the intensely silicified piece margins. FeO_x spotting on white coated surfaces is after pyrite. Distinct blue amorphous surface coating (silica-clay?) on some fragments of Piece 1E. XRD mineralogy: quartz dominant, minor anhydrite and illite, and traces of pyrite.

35 7Z-1 (2A-2D) 236.01 236.51 0.50 Silicified volcanic rock with scattered plagioclase phenocrysts. Intensely silicified rock. White silica-sulfate coated fracture surfaces have distinct banded silicified alteration halos. Planar to convolute lamination is defined by silica and gray-greenish clay. It is unclear whether they are vein halos or possibly pseudomorphed flow banding. Remnant plagioclase phenocrysts are generally corroded to skeletal. Pyrite is present as very fine grained disseminations and as slightly coarser microvesicle fill (± quartz). XRD mineralogy: quartz dominant, minor anhydrite and illite, and traces of pyrite.

7Z-2 (1-3) 236.51 237.11 0.60

36 8Z-1 (1-2) 236.20 237.53 1.33 Silicified, massive aphyric volcanic rock. Intensely silicified rock. Flamelike zoned to patchy halo, sometimes cut by narrow pyrite veins. Whitish to light gray elongate patches in halos are soft and consist of silica-clay with some anhydrite and pyrite. XRD mineralogy: quartz dominant, minor anhydrite and illite.

9Z-1 (1A) 237.70 237.80 0.10

37 9Z-1 (1B) 237.80 237.86 0.06 Silicified clastic rock. Irregular white clasts(?) are soft, anhydrite-clay-quartz-pyrite-bearing material. The groundmass is light green and fine grained with disseminated gray silica-clay. There are dark gray completely silicified oval patches developed in the piece. XRD mineralogy: quartz dominant, minor anhydrite and illite.

38 9Z-1 (1C-1F) 237.86 238.25 0.39 Silicified, massive, aphyric volcanic rock. Highly silicified rocks. Zoned halos consist of dark gray silicified bands alternating with softer bands that have a bleached appearance. Away from the halos, alteration is pervasive, but anhydrite-pyrite-rich as well as quartz-rich patches are developed. XRD mineralogy: quartz dominant, minor anhydrite and illite, and traces of pyrite.

11G-1 (1-6) 238.90 239.56 0.66

39 11G-1 (7-13) 239.56 240.40 0.84 Silicified slightly vesicular volcanic rock with scattered plagioclase phenocrysts. Highly silicified rocks. Trace to 1% plagioclase phenocrysts are replaced by soft, white, clayey material. Pyrite is abundant in groundmass and filling vesicles together with anhydrite. Zoned halos are associated with anhydrite veins, some of which are preserved on the surfaces of some pieces. Open vesicles are lined with clay-silica and pyrite and often filled with blocky anhydrite. Piece 8 has acicular, clear crystals overgrowing anhydrite and pyrite in vugs. XRD mineralogy: quartz dominant, minor anhydrite, pyrite, and illite.

13Z-1 (1-3C) 241.40 242.20 0.80

40 13Z-1 (4) 242.20 242.23 0.03 Highly altered, apparently spherulitic volcanic rock. Single piece of apparently spherulitic volcanic rock. Contains 50% isolated, white, round, altered apparently spherulites.

41 13Z-1 (5) 242.23 242.76 0.53 Silicified volcanic rock with scattered plagioclase phenocrysts. Remnant plagioclase phenocrysts replaced by bluish white clay. Microvesicles(?) filled by anhydrite and pyrite. Hairline to several-millimeter-thick anhydrite-pyrite veins and veinlets, predominantly with millimeter- to centimeter-wide siliceous alteration halo. Occasional round to bulbous, irregular dark gray siliceous patches within the groundmass. XRD mineralogy: quartz dominant, minor anhydrite, pyrite, and illite, and traces of chlorite. Sample 193-1188F-14Z-1, 134-139 cm, additionally contains probably brittle mica or illite-bearing mixed layer.

13Z-2 (1-4) 242.76 243.57 0.81

14Z-1 (1-9) 245.90 247.42 1.52

14Z-2 (1) 247.42 247.61 0.19

15Z-1 (1-6) 250.40 250.84 0.44

42 15Z-1 (7-15) 250.84 251.79 0.95 Silicified, aphyric volcanic rock. Irregular silica void fill. Pyrite and anhydrite crystals as vesicle fill. Pyrite is disseminated throughout. XRD mineralogy: quartz dominant, minor anhydrite, pyrite, and probably brittle mica or illite-bearing mixed layer.

43 15Z-1 (16) 251.79 251.90 0.11 Silicified volcanic rock with scattered plagioclase phenocrysts. Rocks contain 1% plagioclase phenocrysts replaced by bluish clay. Vugs and veins are filled by anhydrite and pyrite. Pyrite is also in the microvesicles.

15Z-2 (1-2) 251.90 252.09 0.19

16Z-1 (1A-1B) 254.90 255.09 0.19

44 16Z-1 (1C-3) 255.09 256.38 1.29 Silicified, brecciated, flow-banded, aphyric volcanic rock. Dominantly nonporphyritic rubble with remnant autoclastic and flow-banded textures. Some pieces contain rare plagioclase phenocrysts replaced by bluish clay. Sulfate vesicle fill and pyrite-anhydrite vug lining. Fine pyrite-anhydrite veinlets with narrow bleached halos are present. XRD mineralogy: quartz dominant, minor pyrite, illite, and probably brittle mica or illite-bearing mixed layers, and traces of anhydrite.

45 17Z-1 (1) 259.40 259.52 0.12 Silicified volcanic rock with scattered plagioclase phenocrysts. Unit 45 is characterized by 1%-2% plagioclase phenocrysts replaced by bluish clay. Some edges show bleached silicified halos. Elongate, aligned microvesicles are filled with pyrite. Fine pyrite veinlets have anhydrite selvages and silicified halos. Pyrite content ranges from 1% to 3%.

18Z-1 (1A-1C) 263.90 264.30 0.40

19Z-1 (1A-1E) 268.40 268.81 0.41

46 22Z-1 (1-11) 282.10 282.98 0.88 Completely altered, silicified, aphyric, volcanic rock. Unit 46 is characterized by several slightly brecciated rocks. Multiple dark gray bands border the brecciated zone. The remainder is often green and apparently chloritized. Pyrite is present mostly in veinlets, and fine-grained pyrite fills vesicles and voids. XRD mineralogy: quartz dominant, minor anhydrite, pyrite, illite, and chlorite.

47 22Z-1 (12-15) 282.98 283.36 0.38 Completely altered, green clay-bearing, aphyric, volcanic rock. Highly silicified and apparently chloritized rock. Some quartz blebs with pyrite are present.

48 23Z-1 (1-10B) 286.60 287.61 1.01 Silicified volcanic rock with scattered plagioclase phenocrysts. Silicified rocks with plagioclase phenocrysts altered to white clay. A bleached appearance is in most of the rocks. Veins and veinlets are filled by pyrite, whereas vugs are lined by pyrite-anhydrite-quartz. Halos are developed around the edges. XRD mineralogy: white halos—quartz dominant, minor anhydrite, illite, and pyrite, and small amounts of chlorite. Gray kernels—quartz dominant, minor chlorite, illite, and pyrite, and traces of anhydrite and smectite.

49 23Z-1 (11E-14) 287.61 288.09 0.48 Completely altered, silicified, green clay-bearing, aphyric volcanic rock. Apparently chloritized rock with light gray to gray alteration halos around vugs that are partly filled with anhydrite-pyrite. Some anhydrite-quartz-pyrite vugs are present. Pyrite is present in rare hairline veinlets and as microvesicle fill. Piece 2 of Section 193-1188F-23Z-2 is covered by a white crust of anhydrite. In Piece 2 of Section 193-1188F-26Z-1 very fine grained magnetite is disseminated throughout. XRD mineralogy: quartz dominant, minor anhydrite, chlorite, illite, and pyrite. Piece 4 of Section 193-1188F-25Z-1 additionally contains major plagioclase.

23Z-2 (1-9) 288.09 289.00 0.91

25Z-1 (1-6) 295.60 296.08 0.48

26Z-1 (1-2) 300.10 300.36 0.26

50 26Z-1 (3-6) 300.36 301.19 0.83 Silicified volcanic rock with scattered plagioclase phenocrysts. 1%-2% plagioclase laths are partly replaced by white clay. White silica-sulfate crusts on some pieces have zoned alteration halos. Fine quartz-pyrite spotting appears to be vesicle fill (amygdules). Magnetite is present in Piece 2 of Section 193-1188F-27Z-1. XRD mineralogy: quartz dominant, minor plagioclase, chlorite, anhydrite, illite, and pyrite.

26Z-2 (1-4) 301.19 302.27 1.08

27Z-1 (1-2) 304.60 304.91 0.31

51 30Z-1 (1-4) 318.10 318.30 0.20 Completely altered, variably silicified breccia. This is a clastic or pseudoclastic unit of completely altered rock, presumably volcanic. Clasts are variably silicified. Matrix is variably clay- and anhydrite-bearing. Piece 4 is considerably darker than the other pieces and may contain more abundant magnetite. Clasts are generally hard to very hard. Late-stage anhydrite-pyrite crystals are in veins and pockets in the matrix. XRD mineralogy: quartz dominant, minor plagioclase, illite, and chlorite, and traces of pyrite.

52 31Z-1 (1) 322.60 322.69 0.09 Silicified, magnetite-bearing volcanic rock with scattered plagioclase phenocrysts. Pervasive silicification of the groundmass with disseminated magnetite and pyrite (very high alteration intensity). An anhydrite vein with a dark silicified halo and a magnetite-pyrite-quartz vein (1 mm wide) with a pale silicified halo are present. XRD mineralogy: quartz dominant, minor plagioclase, illite, and chlorite, and traces of pyrite.

53 31Z-1 (2-5) 322.69 323.02 0.33 Completely altered, variably silicified breccia. Clasts are variably silicified. Matrix is variably clay- and anhydrite-bearing. Pieces 3 and 4 (3-5 cm in diameter) are massive aphyric volcanic rock with diffuse light gray and light green domains resembling previous units (such as Unit 50). XRD mineralogy: quartz dominant, minor pyrite, illite, and chlorite, and traces of anhydrite.

54 34Z-1 (1-4) 336.40 336.64 0.24 Completely altered aphyric volcanic rock. Silicified rock with zoned halos. Pyrite and magnetite are disseminated in the quartz-dominated clayey matrix. Vugs are filled with quartz, anhydrite, and pyrite. XRD mineralogy: quartz dominant, minor anhydrite, illite, and pyrite, and traces of plagioclase.

55 34Z-1 (5-12) 336.64 337.11 0.47 Completely altered volcanic rock and breccia with variable black, late-stage magnetite-bearing alteration. Highly silicified, gray clasts of coarse-grained quartz ± pyrite, and tannish gray, clay-rich clasts are in a highly silicified and magnetite-impregnated matrix. Bluish fine-grained silica patches are present. Vugs are filled with pyrite, anhydrite, quartz, and red hexagonal plates of hematite. Piece 5 is a black silicified, slightly brecciated rock, which is heavily impregnated with magnetite. XRD mineralogy of Piece 5: magnetite dominant, minor di- and trioctahedral illite, quartz, plagioclase, chlorite, pyrite, and Fe spinel, and traces of brucite. XRD mineralogy of Piece 9: plagioclase and quartz dominant, minor illite, chlorite, pyrite, and magnetite, and traces of illite-bearing mixed layer.

56 34Z-1 (13-18) 337.11 337.73 0.62 Completely altered and variably silicified volcanic rock breccia. Silicified rock with patchy distribution of light gray more clayey and gray, more silicified areas. Magnetite-rich apophysis and veins filled with magnetite-quartz-pyrite are developed. Spherical, light gray and light greenish gray spots (possible vesicle fill) could contain chlorite or green clay. XRD mineralogy: quartz dominant, minor chlorite and illite, and traces of anhydrite and pyrite.

57 35Z-1 (1-3B) 340.00 341.50 1.50 Silicified, sparsely vesicular, aphyric, massive volcanic rock. Sugary silicified rocks with scattered, ovoid fine grained quartz amygdules. Banded textures are common and related to anhydrite ± pyrite veins. Prominent alteration halos along margins of several pieces. Traces of disseminated magnetite are present in Pieces 1, 2D, and 2E of Section 193-1188F-35Z-1. XRD mineralogy: quartz dominant, minor plagioclase, anhydrite, illite, pyrite, magnetite, and chlorite.

35Z-2 (1A-2B) 341.50 341.99 0.49

36G-1 (1-2) 344.50 344.75 0.25

37Z-1 (1-4) 344.50 345.81 1.31

37Z-2 (1-2) 345.81 346.10 0.29

58 37Z-2 (3) 346.10 346.16 0.06 Magnetite-rich, clastic rock. Disseminated magnetite (5%-8%) is present throughout the dark siliceous groundmass. Quartz-anhydrite pyrite domains have near massive, 2-mm-wide, magnetite alteration halos. The rock is similar to Piece 5 of Section 193-1188F-34Z-1. XRD mineralogy: plagioclase dominant, minor magnetite, illite, alunite, Fe spinel, chlorite, pyrite, and brucite.

59 37Z-2 (4-9) 346.16 347.28 1.12 Silicified, flow-banded, locally magnetite-bearing, aphyric, sparsely vesicular volcanic rock. Banded, variably colored, silicified rock with fine quartz amygdules. Darker bands and domains are magnetite-bearing. Pyrite is present as crystals in very fine unfilled vesicles. XRD mineralogy: quartz dominant, minor plagioclase, anhydrite, and magnetite, and traces of illite, chlorite, and pyrite.

60 38Z-1 (1-3) 349.00 350.30 1.30 Silicified, slightly vesicular volcanic rock with scattered plagioclase phenocrysts. Uniformly silicified light gray to greenish gray rocks. The groundmass is dominantly quartz with clay and very minor disseminated pyrite and magnetite. Vugs are filled with pyrite-anhydrite.

61 38Z-2 (1-4) 350.30 351.22 0.92 Completely altered, aphyric, amygdaloidal volcanic rock. Silicified, greenish gray rocks with disseminated very fine grained magnetite and pyrite (as much as 1% each) in groundmass. Groundmass is gray, greenish gray, or GSC. Plagioclase microlites are replaced by white clay. XRD mineralogy: quartz and plagioclase dominant, minor illite, chlorite, and anhydrite, and traces of pyrite and magnetite.

62 39Z-1 (1-6) 353.50 354.05 0.55 Silicified volcanic rock with scattered plagioclase phenocrysts. Silicified gray to light gray rocks. The groundmass is dominantly quartz with clay and very minor disseminated pyrite and magnetite (as much as 1%). The zoned halos are developed in Pieces 1 and 2 and consist of gray silicified and light gray, slightly softer bands. Plagioclase phenocrysts are replaced by white clay or dark gray clay and quartz. XRD mineralogy: quartz dominant, minor anhydrite, illite, chlorite, and pyrite, and traces of plagioclase and magnetite.

63 39Z-1 (7-10) 354.05 354.67 0.62 Completely altered, variably magnetite-enriched volcanic rock. Abundant magnetite (as much as 5%) imposes a dark gray to black color to the rock. Magnetite is intergrown with clay and quartz. Dark spots are soft and magnetic (i.e., clay + magnetite). Vugs are filled with pyrite and clay or pyrite and anhydrite. Pyrite in groundmass is rare. Plagioclase phenocrysts are altered to white clay.

64 39Z-1 (11-12) 354.67 354.93 0.26 Completely altered, aphyric volcanic rock. Silicified rock with quartz-clay dominated light gray groundmass. Rocks have a spotty texture, owing to pyrite + anhydrite filled vugs with clay-rich halos. Minor magnetite and pyrite disseminated in groundmass. Pieces 3 and 4 of Section 193-1188F-39Z-2 are greenish-gray rocks with tan alteration halos along anhydrite + pyrite veins (Piece 4). Plagioclase phenocrysts are replaced by white to bluish white clay. Vugs are filled/lined with pyrite and anhydrite. XRD mineralogy: quartz dominant, minor anhydrite, illite, chlorite, pyrite, and plagioclase.

39Z-2 (1-4) 354.93 355.38 0.45

65 40Z-1 (1) 358.00 358.16 0.16 Completely altered, magnetite-enriched, vesicular volcanic rock. Silicified microcrystalline groundmass. Vesicles lined/filled with green clay, anhydrite, pyrite, and magnetite. Commonly, pyrite is present in the centers of magnetite-filled vesicles. XRD mineralogy: quartz dominant, minor plagioclase, anhydrite, illite, chlorite, pyrite, and magnetite.

66 40Z-1 (2) 358.16 358.82 0.66 Silicified volcanic rock with scattered plagioclase phenocrysts. Silicified rock with quartz-clay dominated light gray groundmass. Rocks have a spotty texture, owing to pyrite + anhydrite filled vugs with clay-rich halos. Minor magnetite and pyrite disseminated in the groundmass. XRD mineralogy: quartz dominant, minor anhydrite, illite, and pyrite, and traces of plagioclase and chlorite.

67 40Z-1 (3) 358.82 359.39 0.57 Completely altered, clastic-textured volcanic rock. Brecciated with centimeter-sized angular highly silicified clasts that are surrounded by a light gray to tannish gray silica-clay matrix. The matrix is completely recrystallized, which makes distinguishing the original texture difficult. However, relict textures suggest it is composed of clay-silica altered clasts embedded in a silica-rich cement. Minor pyrite is disseminated throughout the rock. XRD mineralogy: quartz dominant, minor anhydrite, illite, and pyrite, and traces of plagioclase and chlorite.

40Z-2 (1-2) 359.39 360.22 0.83

68 41Z-1 (1-2) 362.50 362.67 0.17 Completely altered, magnetite-enriched volcanic rock. Magnetite is abundant (3%), finely disseminated in a silicified groundmass. A trace of fresh plagioclase phenocrysts (2 mm long, identified by perfect [010] cleavage reflections) is noted in Piece 2B.

69 41Z-1 (3-4) 362.67 364.05 1.42 Completely altered, aphyric, amygdaloidal volcanic rock. Silicified rock with finely disseminated pyrite and trace magnetite. Highly silicified very fine grained gray halos. Rocks are commonly spotty, owing to quartz-clay-pyrite vug fill. XRD mineralogy: quartz dominant, minor plagioclase, pyrite, illite, and chlorite, and traces of magnetite and anhydrite.

41Z-2 (1-6) 364.05 364.86 0.81

70 42Z-1 (1-7) 367.00 368.46 1.46 Completely altered, aphyric, sparsely amygdaloidal volcanic rock. Pale, silicified rocks with anhydrite veins and associated alteration halos. Banded structures are probably vein-related zoned alterations. Fine quartz ± pyrite and anhydrite ± pyrite amygdules form discrete bands. Pyrite also is present as very fine grained crystals in microvesicles. XRD mineralogy: quartz dominant, minor anhydrite, chlorite, illite, and pyrite, and traces of plagioclase.

42Z-2 (1-3) 368.46 368.75 0.29

71 43Z-1 (1) 371.50 372.06 0.56 Completely altered, aphyric, sparsely vesicular volcanic rock. Silicified rock with anhydrite-chlorite or quartz-chlorite lined vesicles and small (<1 mm) quartz, quartz-pyrite, and pyrite-chlorite amgydules. XRD mineralogy: quartz dominant, minor illite, pyrite, and chlorite, and traces of anhydrite and plagioclase.

72 43Z-1 (2-4) 372.06 372.64 0.58 Completely altered, magnetite-bearing, aphyric, sparsely vesicular volcanic rock. Pervasive silicification. Magnetite (1%-5%) is present throughout the rock as very fine grained disseminations and as vesicle fill with blue quartz and pyrite, and occasional late anhydrite. In the vesicles magnetite-quartz represents an early assemblage followed by pyrite ± anhydrite. Magnetite increases in abundance toward anhydrite-pyrite veins. XRD mineralogy: quartz and plagioclase dominant, minor chlorite, anhydrite, pyrite, and magnetite.

44Z-1 (1-3) 374.00 374.91 0.91

Unit	Core, section (Piece)	Curated depth (mbsf)	Curated length (m)	Lithology	Alteration
Top	Base
	193-1188F-
27	1Z-1 (1-5)	218.00	219.21	1.21	Completely altered, silicified, massive aphyric volcanic rock.	Intensely fractured, pervasive pale gray silicified rock with minor greenish, chloritic intervals (remnant GSC domains) and softer, more clayey pieces. Cut by irregular anhydrite-pyrite ± silica veins with cyclically zoned, 1- to 2-cm-wide siliceous alteration halos. XRD mineralogy: quartz dominant, minor anhydrite, illite, and pyrite.
	1Z-2 (1-4)	219.21	220.42	1.21
	1Z-3 (1-2)	220.42	221.04	0.62
28	1Z-3 (3)	221.04	221.65	0.61	Completely altered, silicified, and green clay-bearing, massive aphyric volcanic rock.	Pervasive pale gray silicification and abundant green material (remnant GSC domains?). Similar to Unit 27 but with a dominance of green material. Anhydrite-pyrite coated fractures show distinct, cyclically banded silicified alteration halos overprinting the chloritic alteration. Remnant kernels of groundmass domains encircled by such veins are green. XRD mineralogy: quartz dominant, minor anhydrite, illite, chlorite, and pyrite.
	1Z-4 (1)	221.65	222.25	0.60
29	1Z-4 (2)	222.25	222.86	0.61	Completely altered, silicified, massive aphyric volcanic rock.	Intensely fractured, pervasive pale gray silicified intervals intercalated with creamy-colored, softer, more clay-rich material. Thin, submillimeter anhydrite-pyrite-silica veins with well-developed, 10- to 15-mm-wide, gray siliceous alteration halos. XRD mineralogy: quartz dominant, minor anhydrite, illite, and pyrite. Sample 193-1188F-2Z-1, 73-74 cm, contains, additionally, calcite and probably traces of kaolinite.
	2Z-1 (1-3)	221.50	223.00	1.50
	3Z-1 (1-3)	222.60	224.04	0.44
30	3Z-2 (1-3)	224.04	225.59	1.55	Completely altered, brecciated, silicified volcanic rock with a clayey matrix.	Hard, indurated, pervasively silicified and less abundant creamy-colored (more clay rich) fragments embedded in a light gray, clay-anhydrite matrix. Late pyrite-silica ± anhydrite veinlets cut larger pieces and have well-developed, banded (cyclic) siliceous alteration halos (as wide as 2 cm). XRD mineralogy: quartz dominant, minor anhydrite, illite, chlorite, and pyrite.
	6Z-1 (1)	233.10	233.55	0.45
31	6Z-1 (2)	233.55	233.57	0.02	Highly altered, apparently spherulitic volcanic rock.	Single piece of apparently spherulitic volcanic rock. Contains 50% isolated, white, round, altered apparently spherulites (as much as 1 mm in diameter, radiating crystal aggregates). Central vugs are common and often filled by pyrite crystals. XRD mineralogy: cristobalite and plagioclase dominant, minor chlorite and pyrite.
32	6Z-1 (3-4)	233.57	234.37	0.80	Completely altered, silicified, massive aphyric volcanic rock.	Light gray indurated, silicified, and less-abundant creamy-colored more clay-rich pieces. Fracture surfaces with silica and sulfate. Trace disseminated pyrite tends to be more abundant in less strongly silicified pieces. Scattered Fe oxide spotting after sulfide. XRD mineralogy: quartz dominant, minor anhydrite and illite.
	6Z-2 (1A-1B)	234.37	234.61	0.24
33	6Z-2 (1C-3)	234.61	235.39	0.78	Silicified volcanic fragments embedded in soft gray clay.	Pervasively silicified fragments embedded in and/or coated by soft, gray clay. Fracture surfaces are mostly coated by white silica-anhydrite with zoned cyclic alteration halos (as much as 1 cm half-width). Trace pyrite disseminated and as vug fills. Quartz-pyrite spots may be remnant plagioclase phenocrysts. Piece 3A contains rare plagioclase phenocrysts. XRD mineralogy: quartz dominant, minor anhydrite, illite, and pyrite.
34	7Z-1 (1A-1G)	235.00	236.01	1.01	Silicified, massive aphyric volcanic rock.	Rounded pebbles of silicified, sparsely microvesicular volcanic rock. Intensity of silicification decreases away from edges of pebbles, leaving less-altered kernels. Pyrite is finely disseminated in the less-silicified kernels but is absent from the intensely silicified piece margins. FeO_x spotting on white coated surfaces is after pyrite. Distinct blue amorphous surface coating (silica-clay?) on some fragments of Piece 1E. XRD mineralogy: quartz dominant, minor anhydrite and illite, and traces of pyrite.
35	7Z-1 (2A-2D)	236.01	236.51	0.50	Silicified volcanic rock with scattered plagioclase phenocrysts.	Intensely silicified rock. White silica-sulfate coated fracture surfaces have distinct banded silicified alteration halos. Planar to convolute lamination is defined by silica and gray-greenish clay. It is unclear whether they are vein halos or possibly pseudomorphed flow banding. Remnant plagioclase phenocrysts are generally corroded to skeletal. Pyrite is present as very fine grained disseminations and as slightly coarser microvesicle fill (± quartz). XRD mineralogy: quartz dominant, minor anhydrite and illite, and traces of pyrite.
	7Z-2 (1-3)	236.51	237.11	0.60
36	8Z-1 (1-2)	236.20	237.53	1.33	Silicified, massive aphyric volcanic rock.	Intensely silicified rock. Flamelike zoned to patchy halo, sometimes cut by narrow pyrite veins. Whitish to light gray elongate patches in halos are soft and consist of silica-clay with some anhydrite and pyrite. XRD mineralogy: quartz dominant, minor anhydrite and illite.
	9Z-1 (1A)	237.70	237.80	0.10
37	9Z-1 (1B)	237.80	237.86	0.06	Silicified clastic rock.	Irregular white clasts(?) are soft, anhydrite-clay-quartz-pyrite-bearing material. The groundmass is light green and fine grained with disseminated gray silica-clay. There are dark gray completely silicified oval patches developed in the piece. XRD mineralogy: quartz dominant, minor anhydrite and illite.
38	9Z-1 (1C-1F)	237.86	238.25	0.39	Silicified, massive, aphyric volcanic rock.	Highly silicified rocks. Zoned halos consist of dark gray silicified bands alternating with softer bands that have a bleached appearance. Away from the halos, alteration is pervasive, but anhydrite-pyrite-rich as well as quartz-rich patches are developed. XRD mineralogy: quartz dominant, minor anhydrite and illite, and traces of pyrite.
	11G-1 (1-6)	238.90	239.56	0.66
39	11G-1 (7-13)	239.56	240.40	0.84	Silicified slightly vesicular volcanic rock with scattered plagioclase phenocrysts.	Highly silicified rocks. Trace to 1% plagioclase phenocrysts are replaced by soft, white, clayey material. Pyrite is abundant in groundmass and filling vesicles together with anhydrite. Zoned halos are associated with anhydrite veins, some of which are preserved on the surfaces of some pieces. Open vesicles are lined with clay-silica and pyrite and often filled with blocky anhydrite. Piece 8 has acicular, clear crystals overgrowing anhydrite and pyrite in vugs. XRD mineralogy: quartz dominant, minor anhydrite, pyrite, and illite.
	13Z-1 (1-3C)	241.40	242.20	0.80
40	13Z-1 (4)	242.20	242.23	0.03	Highly altered, apparently spherulitic volcanic rock.	Single piece of apparently spherulitic volcanic rock. Contains 50% isolated, white, round, altered apparently spherulites.
41	13Z-1 (5)	242.23	242.76	0.53	Silicified volcanic rock with scattered plagioclase phenocrysts.	Remnant plagioclase phenocrysts replaced by bluish white clay. Microvesicles(?) filled by anhydrite and pyrite. Hairline to several-millimeter-thick anhydrite-pyrite veins and veinlets, predominantly with millimeter- to centimeter-wide siliceous alteration halo. Occasional round to bulbous, irregular dark gray siliceous patches within the groundmass. XRD mineralogy: quartz dominant, minor anhydrite, pyrite, and illite, and traces of chlorite. Sample 193-1188F-14Z-1, 134-139 cm, additionally contains probably brittle mica or illite-bearing mixed layer.
	13Z-2 (1-4)	242.76	243.57	0.81
	14Z-1 (1-9)	245.90	247.42	1.52
	14Z-2 (1)	247.42	247.61	0.19
	15Z-1 (1-6)	250.40	250.84	0.44
42	15Z-1 (7-15)	250.84	251.79	0.95	Silicified, aphyric volcanic rock.	Irregular silica void fill. Pyrite and anhydrite crystals as vesicle fill. Pyrite is disseminated throughout. XRD mineralogy: quartz dominant, minor anhydrite, pyrite, and probably brittle mica or illite-bearing mixed layer.
43	15Z-1 (16)	251.79	251.90	0.11	Silicified volcanic rock with scattered plagioclase phenocrysts.	Rocks contain 1% plagioclase phenocrysts replaced by bluish clay. Vugs and veins are filled by anhydrite and pyrite. Pyrite is also in the microvesicles.
	15Z-2 (1-2)	251.90	252.09	0.19
	16Z-1 (1A-1B)	254.90	255.09	0.19
44	16Z-1 (1C-3)	255.09	256.38	1.29	Silicified, brecciated, flow-banded, aphyric volcanic rock.	Dominantly nonporphyritic rubble with remnant autoclastic and flow-banded textures. Some pieces contain rare plagioclase phenocrysts replaced by bluish clay. Sulfate vesicle fill and pyrite-anhydrite vug lining. Fine pyrite-anhydrite veinlets with narrow bleached halos are present. XRD mineralogy: quartz dominant, minor pyrite, illite, and probably brittle mica or illite-bearing mixed layers, and traces of anhydrite.
45	17Z-1 (1)	259.40	259.52	0.12	Silicified volcanic rock with scattered plagioclase phenocrysts.	Unit 45 is characterized by 1%-2% plagioclase phenocrysts replaced by bluish clay. Some edges show bleached silicified halos. Elongate, aligned microvesicles are filled with pyrite. Fine pyrite veinlets have anhydrite selvages and silicified halos. Pyrite content ranges from 1% to 3%.
	18Z-1 (1A-1C)	263.90	264.30	0.40
	19Z-1 (1A-1E)	268.40	268.81	0.41
46	22Z-1 (1-11)	282.10	282.98	0.88	Completely altered, silicified, aphyric, volcanic rock.	Unit 46 is characterized by several slightly brecciated rocks. Multiple dark gray bands border the brecciated zone. The remainder is often green and apparently chloritized. Pyrite is present mostly in veinlets, and fine-grained pyrite fills vesicles and voids. XRD mineralogy: quartz dominant, minor anhydrite, pyrite, illite, and chlorite.
47	22Z-1 (12-15)	282.98	283.36	0.38	Completely altered, green clay-bearing, aphyric, volcanic rock.	Highly silicified and apparently chloritized rock. Some quartz blebs with pyrite are present.
48	23Z-1 (1-10B)	286.60	287.61	1.01	Silicified volcanic rock with scattered plagioclase phenocrysts.	Silicified rocks with plagioclase phenocrysts altered to white clay. A bleached appearance is in most of the rocks. Veins and veinlets are filled by pyrite, whereas vugs are lined by pyrite-anhydrite-quartz. Halos are developed around the edges. XRD mineralogy: white halos—quartz dominant, minor anhydrite, illite, and pyrite, and small amounts of chlorite. Gray kernels—quartz dominant, minor chlorite, illite, and pyrite, and traces of anhydrite and smectite.
49	23Z-1 (11E-14)	287.61	288.09	0.48	Completely altered, silicified, green clay-bearing, aphyric volcanic rock.	Apparently chloritized rock with light gray to gray alteration halos around vugs that are partly filled with anhydrite-pyrite. Some anhydrite-quartz-pyrite vugs are present. Pyrite is present in rare hairline veinlets and as microvesicle fill. Piece 2 of Section 193-1188F-23Z-2 is covered by a white crust of anhydrite. In Piece 2 of Section 193-1188F-26Z-1 very fine grained magnetite is disseminated throughout. XRD mineralogy: quartz dominant, minor anhydrite, chlorite, illite, and pyrite. Piece 4 of Section 193-1188F-25Z-1 additionally contains major plagioclase.
	23Z-2 (1-9)	288.09	289.00	0.91
	25Z-1 (1-6)	295.60	296.08	0.48
	26Z-1 (1-2)	300.10	300.36	0.26
50	26Z-1 (3-6)	300.36	301.19	0.83	Silicified volcanic rock with scattered plagioclase phenocrysts.	1%-2% plagioclase laths are partly replaced by white clay. White silica-sulfate crusts on some pieces have zoned alteration halos. Fine quartz-pyrite spotting appears to be vesicle fill (amygdules). Magnetite is present in Piece 2 of Section 193-1188F-27Z-1. XRD mineralogy: quartz dominant, minor plagioclase, chlorite, anhydrite, illite, and pyrite.
	26Z-2 (1-4)	301.19	302.27	1.08
	27Z-1 (1-2)	304.60	304.91	0.31
51	30Z-1 (1-4)	318.10	318.30	0.20	Completely altered, variably silicified breccia.	This is a clastic or pseudoclastic unit of completely altered rock, presumably volcanic. Clasts are variably silicified. Matrix is variably clay- and anhydrite-bearing. Piece 4 is considerably darker than the other pieces and may contain more abundant magnetite. Clasts are generally hard to very hard. Late-stage anhydrite-pyrite crystals are in veins and pockets in the matrix. XRD mineralogy: quartz dominant, minor plagioclase, illite, and chlorite, and traces of pyrite.
52	31Z-1 (1)	322.60	322.69	0.09	Silicified, magnetite-bearing volcanic rock with scattered plagioclase phenocrysts.	Pervasive silicification of the groundmass with disseminated magnetite and pyrite (very high alteration intensity). An anhydrite vein with a dark silicified halo and a magnetite-pyrite-quartz vein (1 mm wide) with a pale silicified halo are present. XRD mineralogy: quartz dominant, minor plagioclase, illite, and chlorite, and traces of pyrite.
53	31Z-1 (2-5)	322.69	323.02	0.33	Completely altered, variably silicified breccia.	Clasts are variably silicified. Matrix is variably clay- and anhydrite-bearing. Pieces 3 and 4 (3-5 cm in diameter) are massive aphyric volcanic rock with diffuse light gray and light green domains resembling previous units (such as Unit 50). XRD mineralogy: quartz dominant, minor pyrite, illite, and chlorite, and traces of anhydrite.
54	34Z-1 (1-4)	336.40	336.64	0.24	Completely altered aphyric volcanic rock.	Silicified rock with zoned halos. Pyrite and magnetite are disseminated in the quartz-dominated clayey matrix. Vugs are filled with quartz, anhydrite, and pyrite. XRD mineralogy: quartz dominant, minor anhydrite, illite, and pyrite, and traces of plagioclase.
55	34Z-1 (5-12)	336.64	337.11	0.47	Completely altered volcanic rock and breccia with variable black, late-stage magnetite-bearing alteration.	Highly silicified, gray clasts of coarse-grained quartz ± pyrite, and tannish gray, clay-rich clasts are in a highly silicified and magnetite-impregnated matrix. Bluish fine-grained silica patches are present. Vugs are filled with pyrite, anhydrite, quartz, and red hexagonal plates of hematite. Piece 5 is a black silicified, slightly brecciated rock, which is heavily impregnated with magnetite. XRD mineralogy of Piece 5: magnetite dominant, minor di- and trioctahedral illite, quartz, plagioclase, chlorite, pyrite, and Fe spinel, and traces of brucite. XRD mineralogy of Piece 9: plagioclase and quartz dominant, minor illite, chlorite, pyrite, and magnetite, and traces of illite-bearing mixed layer.
56	34Z-1 (13-18)	337.11	337.73	0.62	Completely altered and variably silicified volcanic rock breccia.	Silicified rock with patchy distribution of light gray more clayey and gray, more silicified areas. Magnetite-rich apophysis and veins filled with magnetite-quartz-pyrite are developed. Spherical, light gray and light greenish gray spots (possible vesicle fill) could contain chlorite or green clay. XRD mineralogy: quartz dominant, minor chlorite and illite, and traces of anhydrite and pyrite.
57	35Z-1 (1-3B)	340.00	341.50	1.50	Silicified, sparsely vesicular, aphyric, massive volcanic rock.	Sugary silicified rocks with scattered, ovoid fine grained quartz amygdules. Banded textures are common and related to anhydrite ± pyrite veins. Prominent alteration halos along margins of several pieces. Traces of disseminated magnetite are present in Pieces 1, 2D, and 2E of Section 193-1188F-35Z-1. XRD mineralogy: quartz dominant, minor plagioclase, anhydrite, illite, pyrite, magnetite, and chlorite.
	35Z-2 (1A-2B)	341.50	341.99	0.49
	36G-1 (1-2)	344.50	344.75	0.25
	37Z-1 (1-4)	344.50	345.81	1.31
	37Z-2 (1-2)	345.81	346.10	0.29
58	37Z-2 (3)	346.10	346.16	0.06	Magnetite-rich, clastic rock.	Disseminated magnetite (5%-8%) is present throughout the dark siliceous groundmass. Quartz-anhydrite pyrite domains have near massive, 2-mm-wide, magnetite alteration halos. The rock is similar to Piece 5 of Section 193-1188F-34Z-1. XRD mineralogy: plagioclase dominant, minor magnetite, illite, alunite, Fe spinel, chlorite, pyrite, and brucite.
59	37Z-2 (4-9)	346.16	347.28	1.12	Silicified, flow-banded, locally magnetite-bearing, aphyric, sparsely vesicular volcanic rock.	Banded, variably colored, silicified rock with fine quartz amygdules. Darker bands and domains are magnetite-bearing. Pyrite is present as crystals in very fine unfilled vesicles. XRD mineralogy: quartz dominant, minor plagioclase, anhydrite, and magnetite, and traces of illite, chlorite, and pyrite.
60	38Z-1 (1-3)	349.00	350.30	1.30	Silicified, slightly vesicular volcanic rock with scattered plagioclase phenocrysts.	Uniformly silicified light gray to greenish gray rocks. The groundmass is dominantly quartz with clay and very minor disseminated pyrite and magnetite. Vugs are filled with pyrite-anhydrite.
61	38Z-2 (1-4)	350.30	351.22	0.92	Completely altered, aphyric, amygdaloidal volcanic rock.	Silicified, greenish gray rocks with disseminated very fine grained magnetite and pyrite (as much as 1% each) in groundmass. Groundmass is gray, greenish gray, or GSC. Plagioclase microlites are replaced by white clay. XRD mineralogy: quartz and plagioclase dominant, minor illite, chlorite, and anhydrite, and traces of pyrite and magnetite.
62	39Z-1 (1-6)	353.50	354.05	0.55	Silicified volcanic rock with scattered plagioclase phenocrysts.	Silicified gray to light gray rocks. The groundmass is dominantly quartz with clay and very minor disseminated pyrite and magnetite (as much as 1%). The zoned halos are developed in Pieces 1 and 2 and consist of gray silicified and light gray, slightly softer bands. Plagioclase phenocrysts are replaced by white clay or dark gray clay and quartz. XRD mineralogy: quartz dominant, minor anhydrite, illite, chlorite, and pyrite, and traces of plagioclase and magnetite.
63	39Z-1 (7-10)	354.05	354.67	0.62	Completely altered, variably magnetite-enriched volcanic rock.	Abundant magnetite (as much as 5%) imposes a dark gray to black color to the rock. Magnetite is intergrown with clay and quartz. Dark spots are soft and magnetic (i.e., clay + magnetite). Vugs are filled with pyrite and clay or pyrite and anhydrite. Pyrite in groundmass is rare. Plagioclase phenocrysts are altered to white clay.
64	39Z-1 (11-12)	354.67	354.93	0.26	Completely altered, aphyric volcanic rock.	Silicified rock with quartz-clay dominated light gray groundmass. Rocks have a spotty texture, owing to pyrite + anhydrite filled vugs with clay-rich halos. Minor magnetite and pyrite disseminated in groundmass. Pieces 3 and 4 of Section 193-1188F-39Z-2 are greenish-gray rocks with tan alteration halos along anhydrite + pyrite veins (Piece 4). Plagioclase phenocrysts are replaced by white to bluish white clay. Vugs are filled/lined with pyrite and anhydrite. XRD mineralogy: quartz dominant, minor anhydrite, illite, chlorite, pyrite, and plagioclase.
	39Z-2 (1-4)	354.93	355.38	0.45
65	40Z-1 (1)	358.00	358.16	0.16	Completely altered, magnetite-enriched, vesicular volcanic rock.	Silicified microcrystalline groundmass. Vesicles lined/filled with green clay, anhydrite, pyrite, and magnetite. Commonly, pyrite is present in the centers of magnetite-filled vesicles. XRD mineralogy: quartz dominant, minor plagioclase, anhydrite, illite, chlorite, pyrite, and magnetite.
66	40Z-1 (2)	358.16	358.82	0.66	Silicified volcanic rock with scattered plagioclase phenocrysts.	Silicified rock with quartz-clay dominated light gray groundmass. Rocks have a spotty texture, owing to pyrite + anhydrite filled vugs with clay-rich halos. Minor magnetite and pyrite disseminated in the groundmass. XRD mineralogy: quartz dominant, minor anhydrite, illite, and pyrite, and traces of plagioclase and chlorite.
67	40Z-1 (3)	358.82	359.39	0.57	Completely altered, clastic-textured volcanic rock.	Brecciated with centimeter-sized angular highly silicified clasts that are surrounded by a light gray to tannish gray silica-clay matrix. The matrix is completely recrystallized, which makes distinguishing the original texture difficult. However, relict textures suggest it is composed of clay-silica altered clasts embedded in a silica-rich cement. Minor pyrite is disseminated throughout the rock. XRD mineralogy: quartz dominant, minor anhydrite, illite, and pyrite, and traces of plagioclase and chlorite.
	40Z-2 (1-2)	359.39	360.22	0.83


68	41Z-1 (1-2)	362.50	362.67	0.17	Completely altered, magnetite-enriched volcanic rock.	Magnetite is abundant (3%), finely disseminated in a silicified groundmass. A trace of fresh plagioclase phenocrysts (2 mm long, identified by perfect [010] cleavage reflections) is noted in Piece 2B.
69	41Z-1 (3-4)	362.67	364.05	1.42	Completely altered, aphyric, amygdaloidal volcanic rock.	Silicified rock with finely disseminated pyrite and trace magnetite. Highly silicified very fine grained gray halos. Rocks are commonly spotty, owing to quartz-clay-pyrite vug fill. XRD mineralogy: quartz dominant, minor plagioclase, pyrite, illite, and chlorite, and traces of magnetite and anhydrite.
	41Z-2 (1-6)	364.05	364.86	0.81
70	42Z-1 (1-7)	367.00	368.46	1.46	Completely altered, aphyric, sparsely amygdaloidal volcanic rock.	Pale, silicified rocks with anhydrite veins and associated alteration halos. Banded structures are probably vein-related zoned alterations. Fine quartz ± pyrite and anhydrite ± pyrite amygdules form discrete bands. Pyrite also is present as very fine grained crystals in microvesicles. XRD mineralogy: quartz dominant, minor anhydrite, chlorite, illite, and pyrite, and traces of plagioclase.
	42Z-2 (1-3)	368.46	368.75	0.29
71	43Z-1 (1)	371.50	372.06	0.56	Completely altered, aphyric, sparsely vesicular volcanic rock.	Silicified rock with anhydrite-chlorite or quartz-chlorite lined vesicles and small (<1 mm) quartz, quartz-pyrite, and pyrite-chlorite amgydules. XRD mineralogy: quartz dominant, minor illite, pyrite, and chlorite, and traces of anhydrite and plagioclase.
72	43Z-1 (2-4)	372.06	372.64	0.58	Completely altered, magnetite-bearing, aphyric, sparsely vesicular volcanic rock.	Pervasive silicification. Magnetite (1%-5%) is present throughout the rock as very fine grained disseminations and as vesicle fill with blue quartz and pyrite, and occasional late anhydrite. In the vesicles magnetite-quartz represents an early assemblage followed by pyrite ± anhydrite. Magnetite increases in abundance toward anhydrite-pyrite veins. XRD mineralogy: quartz and plagioclase dominant, minor chlorite, anhydrite, pyrite, and magnetite.
	44Z-1 (1-3)	374.00	374.91	0.91

Note: GSC = green silica-clay, XRD = X-ray diffraction.