Figure F10. Fine-grained arkosic sandstone from Unit S-2, Hole SEG80B. A. Clear, dominantly angular quartz and feldspar grains with minor organic grains (opaque) and elongate mica grains (red brownish) (plane-polarized light). Clear alkali feldspar overgrowths on dusty cores are common. The limited deformation of mica grains suggests low amounts of mechanical compaction. The high porosity value of ~30% reflects the low compaction and widespread feldspar dissolution. B. Same view in cross-polarized light. Untwinned alkali feldspar overgrowths are cemented by sporadic calcite with high birefringence.

Figure F10. Fine-grained arkosic sandstone from Unit S-2, Hole SEG80B. A. Clear, dominantly angular quartz and feldspar grains with minor organic grains (opaque) and elongate mica grains (red brownish) (plane-polarized light). Clear alkali feldspar overgrowths on dusty cores are common. The limited deformation of mica grains suggests low amounts of mechanical compaction. The high porosity value of ~30% reflects the low compaction and widespread feldspar dissolution. B. Same view in cross-polarized light. Untwinned alkali feldspar overgrowths are cemented by sporadic calcite with high birefringence.