Figure F117. Close-up of hydrothermally altered sediment above a diabase sill in the lower part of Subunit 5C. The background sediment was originally burrowed mudrock (30-39 cm and 50-60 cm) and graded calcareous sandstone (40-50 cm). The sandstone has been strongly altered and replaced as noted in the text. The porous and permeable calcareous sandstone was probably the focus of hydrothermal fluid flow related to the sill intrusion (Subunit 5C: interval 210-1276A-98R-3, 30-60 cm).

Figure F117. Close-up of hydrothermally altered sediment above a diabase sill in the lower part of Subunit 5C. The background sediment was originally burrowed mudrock (30-39 cm and 50-60 cm) and graded calcareous sandstone (40-50 cm). The sandstone has been strongly altered and replaced as noted in the text. The porous and permeable calcareous sandstone was probably the focus of hydrothermal fluid flow related to the sill intrusion (Subunit 5C: interval 210-1276A-98R-3, 30-60 cm).