Raipur Gr

Claystone and limestone. Consists of two major clastic-carbonate cycles, the lower one consisting of Bijepur Shale Fm and Sarangarh Limestone Fm (Charmuria Limestone Fm), and the upper one consisting of Gunderdehi Shale Fm, and the overlying stromatolite-bearing carbonates of the Saradih Limestone Fm (Chandi Limestone Fm); then passes upward into the Churtela Shale Fm (Tarenga Shale Fm), a shallow shelf to offshore mud deposit with intermittent volcanism. That upper shale "in all likelihood represents a truncated cycle where carbonates were either not deposited or were removed by erosion during the sub- Kharsiya Gr unconformity. The carbonates are mostly micrite with minor dolomitization at places. Early lithified intrabasinal lime clasts occur as a subordinate constituent, and calcareous peloids occur in a very minor amount.

[Figure: Chattisgarh basin Field photographs illustrating lithology and sedimentary structures. (A) Lohardih Fm - Poorly sorted, matrix supported ungraded, conglomerate. Note the occurrence of large fairly rounded clast with relatively smaller angular clasts. (B) Gomarda Fm - Sand-mud heterolithic rocks. Note the successive fining upward cycles marking cyclic change in depositional environment. (C) Kansapathar Sandstone Fm - Cross-stratified sandstone. (D) Sarangarh Limestone Fm (Charmuria Limestone Fm) - Limestone-marl rhythmite. Bed thickness: 2-10 cm and separated by mm thin marl layer. (E) Gunderdehi Shale Fm - Upper part of with stromatolite bioherms appearing as isolated pockets. (F) Saradih Limestone Fm (Chandi Limestone Fm) - Stromatolitic limestone. Note that stromatolite columns are nonbranching and branching with two to six branches. Column height 5-15, width 1-3 cm. (from Saha et al., 2016)]

[Figure: Volcaniclastics from the Raipur and Kharsiya Groups, Chattisgarh basin. (A) Churtela Shale Fm (Tarenga Shale Fm) - Planar tabular-bedded, cross-stratified, coarse ash tuff bed. (B) Sarnadih Sandstone Fm - Pebbly sandstone with clast derived from underlying tuff units and from the basement. (from Saha et al., 2016)]

Two cycles of muddy tidal flat transitioning upward into a carbonate platform, then a truncated third cycle.