Table 1.

General sample description including depth, lithological unit, onboard sample description, and in which group in the hierarchical cluster analysis the microbial community is located.

Sample	Depth (mbsf)	Unit	Specific sample description	Cluster
1382A
2R_1C	110	I	Massive, minor red-yellow-brown alteration	4
3R_2B	115	I	Massive, yellow-white-brown alteration in vein	4
3R_3A	117	I	Massive, patchy orange-brown alteration	4
3R_4B	117	I	Massive, mostly brown oxidized halo	4
4R_1B	123	II	Aphyric cryptocrystalline basalt, gray-brown alteration	4
5R_1B	133	II	Massive, aphyric, red alteration	4
6R_1A	142	II	Aphyric, cryptocrystalline, less vesicular, patchy alteration	4
7R_2B	153	III	Aphyric, glassy margin, red, and orange-brown alteration	4
8R_1A	161	IV	Ultramafic, pyroxene, evidence of low-temperature alteration	1
8R_1B	161	IV	Porphyritic basalt	4
8R_2F	162	IV	Orange-brown sediment with small (< 1 mm) basalt clasts	2
8R_3G	163	IV	Gray-brown + orange-brown sediment with small (< 1 mm) basalt clasts	1
8R_4D	163	IV	Sedimentary breccia with basalt clasts, rusty colored, extensive carbon	2
9R_1C	172	IV	Sediment near serpentinized breccia	3
10R_3D	183	V	Medium-grained basalt, massive, porphyritic, pervasive alteration	4
12R_1A	199	VI	Porphyritic basalt, minor alteration	4
1383C
2R_2E	72	I	Aphyric basalt, highly altered, vein with red alteration, light brown alteration	5
3R_1B	77	I	Aphyric basalt, slight alteration, tan alteration deposits	4
4R_1B	87	I	Light tan micrite breccia with altered glass clasts	4
5R_1B_I	97	I	Aphyric basalt, moderately altered, vein with red alteration	5
5R_1B_II	97	I	Aphyric basalt, moderately altered	5
6R_1A	105	I	Aphyric basalt, slight alteration, altered chilled margin, ochre alteration	6
10R_1A	144	II	Light tan micrite with large clasts of altered glass	5
10R_1D	145	II	Phyric basalt, moderately altered, multiple veins, slight red alteration	5
11R_1C	154	II	Phyric basalt, extensive alteration, orange, and olive alteration	5
19R_1B	212	III	Aphyric basalt, highly oxidized, light brown alteration, relatively brittle	5
19R_1A	212	III	Two small pieces, mostly glass, rust alteration	5
20R_1A	219	III	All basalt glass, rust alteration	5
24R_1B	257	III	Aphyric basalt, oxidized, dark orange-brown alteration, fractured	5
24R_1A	256	III	Aphyric basalt glass with rust alteration, vesicles	5
27R_1A	285	III	Aphyric massive basalt, alteration	4
29R_1A	300	III	Aphyric basalt, highly oxidized, thin carbonate veins	6
30R_1A	304	III	Aphyric basalt, oxidized, some fractures, dark orange alteration	5

Cluster number corresponds to numbers in Figure 4. The sample description presented here is modified from IODP 336 site summaries (Expedition 336 Scientists, 2012a,b).