Planktonic microfossils recovered from the deep marine shales and marls of the Fiqa Formation, Oman, deposited through ∼15 Ma, from the late Coniacian to earliest Maastrichtian provide a window into Late Cretaceous tropical, pelagic ecosystems. In this thesis I present new records based on well-preserved calcareous nannofossil assemblages and inorganic geochemistry to provide new information on the chronostratigraphic subdivision, palaeoenvironments, high-resolution correlation and sequence stratigraphy of the Fiqa Formation. This study is based on the examination of 341 cuttings and side core samples from 11 hydrocarbon exploration wells distributed across a palaeobathymetric gradient within the Upper Cretaceous Aruma Basin. Results include the first detailed taxonomic analysis of Late Cretaceous nannofossils from the Fiqa Formation including the identification of two new species; a new biozonation scheme for the Fiqa Formation that is correlated into the global UC biozonation scheme of Burnett et al. (1998); new biostratigraphic correlations across the basin and integration with regional sequence stratigraphy; and finally, integration of nannofossil assemblage data with detailed bulk rock carbon isotope and element composition analysis and the reconstruction of long-term palaeoenvironmental change and basin evolution, both in space across Oman and through time.