Foraminiferal distribution and sequence stratigraphy of Oxfordian successions in the Wessex/Anglo-Paris Basin
The use of micropalaeontology within a sequence stratigraphic context is rapidly emerging as a valuable tool for the recognition of ancient cycles and sequences. This study shows how micropalaeontology can be used to develop insights into sequence stratigraphic interpretations. A micropalaeontology study of two Upper Jurassic, Oxfordian successions from the South . Dorset Coast, U.K. and the Normandy Coast, France provide the basis for this study. A near continuous succession of the Oxfordian from South Dorset and Normandy were obtained, and foraminifera extracted. Examination of the fauna revealed representatives from 23 families, comprising 36 genera and 126 species. All species were identified and the taxonomy of each studied and described. The abundance and distribution patterns of the foraminifera were used to identify sequence stratigraphic horizons (such as Maximum Flooding Surfaces) and the correlation between the two successions was carried out. Detailed research and examination of the >63µm size fraction lead to the discovery of Oxfordian planktic foraminifera from samples in South Dorset. These are the first known occurrences of planktic foraminifera from the Oxfordian of England and are coeval with previously reported occurrences of planktic taxa in the Oxfordian of Normandy and Seine Maritime (France). This study demonstrates how detailed micropalaeontological data can be combined with sequence stratigraphy to reveal a more accurate picture of the controls on basin fill than can be provided by sedimentology alone. It has demonstrated the importance of the preservation upon the fossil assemblages recovered and how this can influence the establishment of biozones.