Palynology (pollen, spores and dinoflagellates) and cretaceous stratigraphy of the Dakhla Oasis, central Egypt

Abstract

A re-assessment of the Cretaceous succession in the Dakhla area, central Egypt, is presented on the basis of new palynological evidence from the Six Hills and Maghrabi Formations. Miospore ages for the Six Hills Formation range from Early Neocomian to late Barremian-Early Aptian(?). The upper Six Hills (to lower Abu Ballas?) interval is the only unit that yielded marine dinoflagellates in addition to terrestrially derived miospores. Marine influence was thus effective below the base of the marine Abu Ballas Formation, which is here regarded as Early Aptian in age. The overlying Sabaya Formation could range down into the Aptian. Miospore assemblages from the Maghrabi Formation in the Dakhla area contain the new species Retimonocolpites variplicatus, tricolpates and tricolporates, but no triporates, which favours an Albian to Early Cenomanian age. Maghrabi assemblages in the Kharga area include triporates, which is broadly consistent with a Late Cenomanian to Turonian age. The formation may thus be diachronous, becoming younger from west to east. It is concluded that an eastward shift of the depocentre took place from the Dakhla area in Early Cretaceous time to the Kharga area in Albian to Late Cretaceous time.