Micropetrographic characteristics of the studied sandstone and siltstone samples. (a–e) Pervasive to patchy cemented sandstones (a–c: 1/2; d and e: 1/4; f: 3/3). Well-cemented zones can grade to poorly cemented zones over distances of a few tens of micrometers. Pores are filled by blue epoxy resin. Dominant framework grains: quartz (i), micas (ii), and carbonate lithics (iii, note: limestone clasts and detrital calcite crystals show red or pinkish color after staining but dolomite is unstained); dominant cements: Fe calcite (iv), ankerite (v), and framboidal pyrite aggregates (vi). (f) Poorly cemented sandy siltstone sample with locally high (~20–25%) porosity. Abbreviation: PPL = plane polarized light.