Figure F6. Simplified longitudinal section along the crest of Pual Ridge, illustrating salient features of the subseafloor hydrothermal alteration at PACMANUS as an aid to discussions in the text. Since Hole 1191A at Satanic Mills did not penetrate beyond largely unaltered lava, the lower boundary of the unaltered volcanic cap as drawn between Snowcap and Roman Ruins is hypothetical and there is no certainty that the alteration systems below Snowcap and Roman Ruins are linked at relatively shallow depth as depicted. The boundaries of pyrophyllite-bearing acid sulfate alteration zones below Snowcap are diagrammatic, and a transition zone between cristobalite-bearing and quartz-bearing domains at Site 1188 is not shown. As argued in the text, "part-altered" may be a misnomer for the Lower Sequence of Hole 1189B and for isolated intervals below Snowcap containing relict plagioclase. The fault shown between the Stockwork Zone and Lower Sequence of Hole 1189B corresponds to a marked change in fracture pattern revealed by borehole logging and core recovery, but no displacement has been proven.

Figure F6. Simplified longitudinal section along the crest of Pual Ridge, illustrating salient features of the subseafloor hydrothermal alteration at PACMANUS as an aid to discussions in the text. Since Hole 1191A at Satanic Mills did not penetrate beyond largely unaltered lava, the lower boundary of the unaltered volcanic cap as drawn between Snowcap and Roman Ruins is hypothetical and there is no certainty that the alteration systems below Snowcap and Roman Ruins are linked at relatively shallow depth as depicted. The boundaries of pyrophyllite-bearing acid sulfate alteration zones below Snowcap are diagrammatic, and a transition zone between cristobalite-bearing and quartz-bearing domains at Site 1188 is not shown. As argued in the text, "part-altered" may be a misnomer for the Lower Sequence of Hole 1189B and for isolated intervals below Snowcap containing relict plagioclase. The fault shown between the Stockwork Zone and Lower Sequence of Hole 1189B corresponds to a marked change in fracture pattern revealed by borehole logging and core recovery, but no displacement has been proven.