Jurassic and Lower Cretaceous dinoflagellate cysts from India with some remarks on the concept of Upper Gondwana

Abstract

A critical re-evaluation of the known records of dinoflagellate cyst assemblages from Jurassic and Lower Cretaceous sediments of India is made and stratigraphically significant taxa are identified and tabulated. Emphasis is laid on integration of dinocysts and ammonite evidence for stratigraphy precision. Significance of dinocysts in age determination of Kimmeridgian-Tithonian sequences of Kutch and Malla Johar is recognized. Berriasian dinocysts are not known from India. It is suggested that dinocysts assemblages documented from subsurface of East Coast of India are not older than Hauterivian as no conclusive evidence for Valanginian age, assigned by earlier workers, is available.

The traditional view regarding coastal marine Lower Cretaceous sequences as part of Gondwana is not tenable. It is suggested that the term Gondwana be reserved for inland, predominantly non-marine, fluviatile-lacustrine sediments as a lithostratigraphic unit. In view of the lack of any definite evidence of Jurassic sediments in intracratonic basins and the prominent post-Triassic hiatus, Late Triassic is considered to mark the upper age limit of Gondwana sequences.