Differentiation of the significant Late Valanginian (Early Cretaceous) transgressive event in the Spiti Himalaya, India

摘要

Nearly continuous sedimentary succession of Early Cretaceous age has been long known in the Tethyan Himalayan belt without differentiation of the individual stages. We discuss here our just realised differentiation of a relatively thin well bedded sandstone interval with significant presence of the characteristic Late Valanginian-Early Hauterivian ammonoid genus Okostephanus. It lies within a dominantly sandy succession with shale interbeds of Giumal Sandstone Formation, near Gate in Spiti Himalaya. This is the first stratigraphically precise record of Okostephanus from the Cretaceous of India. It is here circumstantially age constrained to the Standard Tethyan Verrucosum Subzone Okostephanus expansion event to the High Himalayan belt.