Sivaganga Formation, its Sedimentology, Micropalaeontology and Sedimentation History

The textural study of the sand grains of Sivaganga Formation indicates that sedimentation commenced in a fluvial environment passing through the lacustrine-marsh conditions and ending with the influence of tidal estuary. The clayey sediments in the upper part have yielded an arenaceous foraminiferal assemblage having a low dominance and diversity value belonging to the Neocomian-Aptian (Early Cretaceous) age. The sedimentary basin was formed as a result of downwarping of the crystalline basement along the prominent Eastern Ghat trend during Late Jurassic and Early Cretaceous. The basin established its fragmentary connections with the open sea situated at some distance towards the east and southeast.