Salmari Fm

This name is proposed by Shukla et al (1993) to represent the first coal-bearing unit of the Lower Gondwana subgroup of Purnea Basin. Holo: Karandighi-1, Latitude 25o 40' 53" N, Longitude, 87o55' 15" E, Drilled depth: 3143 m. The top of the formation is at 2425 m and the bottom is at 2800 m.

Sandstone. This formation is broadly divisible into two lithounits: Lower unit is comprised of conglomerate, siltstone, sandstone, claystone, carbonaceous shale and coal. Upper part is mainly sandstone-siltstone unit with few coal bands. Sandstone is light grey to grey in color, fine to medium grained, very hard, compact and made up of angular and subangular grains of quartz, feldspar with few micaceous and opaque minerals. Carbonaceous shale is black, fissile, hard, compact and micaceous. Siltstone is greenish grey to grey, hard, compact and micaceous. Parallel lamination is the main sedimentary structure of the section. The coal is pitch black in color and sub bituminous to bituminous. Igneous Intrusive: Towards north, in the Lahil depression (Purnea-1 and Lahil-1), two igneous intrusive bodies are present. Thickness of the formation varies from 131 m to 375 m. A marked decrease in thick towards northeast is observed.

The palynological suite is characterized by: a) the dominance of Parasaccites; b) marked decline in the frequency of Plicatipollenites; c) rare presence of disaccate pollen Sahnites d) low representation of Trilete genera.