Stromatolites from Middle-Riphean Gangolihat Dolomites (Deoban), Berinag-Gangolihat Area, Pithoragarh District, Kumaun Lesser Himalaya

Gangolihat Dolomite (= Deoban) of eastern Kumaun Himalaya, predominantly made up of micrite, dolomicrite) pelmicrite, dolomitic limestone and talc-associated magnesite, has preserved a variety of stromatolites, of Colonnella group, in its uppermost horizons, best developed soulh of Berinag near Rain Agar, Bora Agar and near the township of Gangolihat. The paper describes four forms of stromatolites which are compared with similar forms described by earlier workers from different parts of Himalaya and the depositional environment has been deduced.

A middle Riphean age (1260 - 1000 m.y.) is assigned to these dolomites because of the presence of Colonnella and Baicalia baicalica. In the present structural superposition, the Gangolihat Dolomites are discordantly succeeded by quartzites and chlorite schist of Berinag Formation which have given a radiometric age of 725 m.y., thus confirming a structural break between the two formations.