Karnapur Fm

Shahjahanpur-1, Latitude: 27o 57' 58" N, Longitude: 79o 54' 41" E. Drilled depth: 3351.8 m. The top of the formation is at 1843 m and bottom at 2150 m (Shukla et al., 1993)

Siltstone. In the type section, the formation is divisible into three lithounits.. The bottom part is predominantly greenish grey, reddish brown, non-calcareous fissile shale with minor light bluish grey, pale brown siltstone. The middle part is characterized by sandstone, the unit consisting of dark grey to bluish grey, occasionally dirty white, fine to medium grained sandstone. The upper part consists of alternations of brownish grey to light grey, feebly calcareous siltstone and consists of alternations of brownish grey to light grey, feebly calcareous siltstone and brownish grey, non-calcareous claystone.

In Gandak-1 also this formation is divisible in to three lithounits. The lower 120 m comprises dominantly of shale. The middle part (140 m) is predominantly siltstone, minor sandstone and traces of marl/limestone. The upper part (190 m) is represented mainly by siltstone, maroon, chocolate brown to greenish grey. Occasionally pyretic with subordinate limestone/marl and minor sandstone. Thickness: In Puranpur depression, maximum thick is encountered in Shahjahanpur-1, where it is 307 m thick. This formation is extensively eroded as evidenced by its complete absence in Tilhar-1 and Ujhani deep-1. Thin development of this formation is seen in Puranpur-2 (52 m) and Ujhani structural-1 (72 m). In Gandak depression this formation attains thick up to 450 m.

Palynomorph assemblage recorded are Leiosphaeridia sp. Granomarginata sp., Lophosphaeridium tentatitum, Ellipsaletes sp., Dictyotidium sp.