Eocene Limestones Overlying Lower Cretaceous Deposits of Western lstria (Croatia): Did Some Parts of Present lstria Form Land During the Cretaceous?

Abstract

In the region of the western Istrian anticline, erosional remains of the transgressive Eocene Foraminiferal limestones overly shallow waterdeposits of Early Cretaceous age (Valanginian, Hauterivian andBarremian). This evidence, together with the ocurrencc of bauxitedeposits and Palaeogene beds overlying Albian, Cenomanian andSenonian limestones indicate the very high relief of the land transgressedby the Palaeogene sea. Contrary to the traditional connectionbeetween formation of the western Istrian anticline and the Laramiantectonic phase at the end of the Cretaceous (Maastrichtian), newinvestigations suggest sporadic tectonic movements with constanttectonic coordinate orientation from the Hauterivian to the end of theCretaceous. With these movements, formation of the anticline structurebegan in the Early Cretaceous, with the emerged apical parts representingland areas throughout most of the Cretaceous.