Revision and reasseessment of a dinoflagellate cyst assemblage from Sangchamalla Formation (Upper Flysch), Malla Johar area, Kumaon Himalaya, India

Abstract

A dinoflagellate cyst assemblage described by Mehrotra and Sinha (1981) from Sangchamalla Formation (Upper Flysch) of Malla Johar area in the Tethyan zone of higher Kumaon Himalaya is critically re-evaluated.

The taxonomic revision of the assemblage on its face value indicates total absence of Areosphaeridium diktyoplokus (Klumpp) Eaton, A. arcuatum Eaton, Homotryblium tenuispinosum Davey & Williams, Hystrichokolpoma unispinum Williams & Downie, Diphyes colligerum (Deflandre & Cookson) Davey & Williams and Deflandrea speciosa Alberti based on which a Lower Tertiary age was assigned by Mehrotra and Sinha (1981). Instead, it is characterized by the predominance of Oligosphaeridium with the common occurrence of Coronifera, Gonyaulacysta, Hystrichosphaerina, Tityrosphaeridium and Cordosphaeridium. A new species, viz., Hystrichospheridium himalayaensis proposed by Mehrotra and Sinha (1981) is treated as a junior synonym of Oligosphaeridium complex (White) Daey & Williams.

The revised dinocysts assemblage is devoid of exclusive Tertiary taxa and indicates an Upper Cretaceous age. The possibility of Lower Cretaceous reworking in the ‘Upper Flysch’ assemblage is suggested. The occurrence of dinocysts in the deep oceanic environment of the ‘Upper Flysch' sediments is considered to be most probably due to transportation from shallower regions through sedimentary processes.