干旱区生态环境知识资源中心

The Upper Cretaceous succession of the northwestern desert in Egypt comprises two distinctive formations distributed throughout the studied subsurface succession. These formations are the Abu Roash and the Khoman from base to top, respectively. The examination of the studied samples resulted in the identification of thirty-six calcareous nannoplankton species belonging to twenty-three genera. Based on calcareous nannoplankton assemblages, the studied El-Noor-1 borehole succession was subdivided into seven calcareous nannoplankton biozones. These biozones were correlated with those recorded in Egypt and in other parts of the world. The analyses of calcareous nannofossils revealed the presence of hiatuses between the Late Santonian and Late Campanian. Abundance, diversity, preservation, fertility indices and temperature indices of the Late Cretaceous calcareous nannofossils were analyzed to determine the paleoecology of the studied succession. According to the calcareous nannoplankton content, the studied successions are subdivided into five ecozones. The environment of each ecozone is interpreted. The environmental indicators point to warmer climate oligotrophic environments for the Lucianorhabdus cayeuxii, Reinhardtites levis, Arkhangelskiella cymbiformisand Micula murus zones and cooler climate eutrophic environments for the Quadrum trifidum, Tranolithus orionatus and Lithraphidites quadratus zones.