<i>Nummulites solitarius – Nummulites burdigalensis</i> Lineage in Kutch with Remarks on the Age of Naredi Formation

Abstract

Abstract Three successive subspecies of Nummulites burdigalensis evolved from N. solitarius. These include N. burdigalensis keupperi, N. burdigalensis burdigalensis and N. burdigalensis cantabricus. The evolving lineage is traced in a borehole drilled through the Naredi Formation of Kutch. The associated taxa include N. solitarius and N. fraasi in the lower part and Assilina laxispira and A. spinosa in the upper part of the formation. The better stratigraphic resolution achieved by subspecies identification and the lately redefined Ilerdien Stage in the background of Early Eocene carbon isotope excursion marker, lead to constrain the age of Naredi Formation as Early Eocene, ranging from shallow-benthic zones SBZ6 to SBZ11.