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Table T3. Petrographic descriptions of thin sections from select lithified intervals to support macroscopic core descriptions, Hole M0028A.

Hole, core, section, interval (cm) Thin section Top depth
Comments Section
25R-1, 5–11 1 286.83 Glauconite-bearing medium silty sandstone. Though most grains are subangular to subrounded, angular or rounded grains are also found. Quartz and feldspar (microcline, perthite, and plagioclase) grains are the main detrital grains, and rock fragments (granitoids, quartzite, and schist/gneiss), opaque minerals (including hematite), and heavy minerals (zircon, etc.) are associated. 3131973 270071, 270072, 270073, 270074
25R-2, 3–9 1 288.10 Very fine to fine silty sandstone cemented with a large amount of calcite. Some mica and opaque minerals. Initially matrix-rich sediment. Most grains comprise monocrystalline quartz, subrounded to subangular, possibly derived from granitoid. Feldspar and rock fragments are also found. Many grains are coated with calcite. Matrix is filled with argillaceous and calcareous mud and clay. Framboidal iron sulfide occurs in matrix. 3131974 270063, 270064, 270065, 270066
67R-1, 15–19 1 389.61 Glauconitic silty fine–medium sand with calcite cement. Quartz is rounded to subrounded and well sorted. Quartz and feldspar (microcline, plagiclase, and perthite) grains are roughly oriented along the bedding. Matrix is cemented by calcite. Amorphous iron oxide minerals are developed along pore space. Glauconite pellets are formed in matrix, and authigenic magnetic grains occur along glauconite margins. An articulated small shell is observed to be perpendicular to the bedding plane. 3132103 270067, 270068, 270069, 270070

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