| The Lower Cretaceous (LK) section in the offshore Alabama and Mississippi area has been a petroleum target since the 1970s in the Main Pass and the Viosca Knoll areas. To date, no comprehensive stratigraphic analysis of this section in these locations has been published.; This work focuses on the characterization of the sequence stratigraphy and seismic stratigraphy of the LK strata offshore Alabama and Mississippi, through the study of seismic, well-log, and core data. Furthermore, different cores were analyzed from wells onshore Mississippi and Louisiana in order to perform a paleogeographic reconstruction, with particular focus on microbial deposits. Microbial deposits occur largely in the LK section.; Eight major third-order depositional sequences were recognized. The LK section overlies a Valanginian unconformity associated with a significant hiatus and is overlain by a mid-Cenomanian unconformity associated with a deposition hiatus of more than 10 million years in the Main Pass 253#6 well. The three older sequences exhibit a strong retrogradational trend. The younger sequences show an aggradational-retrogradational trend in the northwestern part of the study area and exhibit an aggradational-progradational trend in the southeastern part of the study area. The LK shelf was rimmed by extensive reefs in the Main Pass area, whereas less significant reefs occurred in the Viosca Knoll area.; Shelf-edge lithofacies are represented by rudist and microbial boundstones in the southeastern part of the study area and by carbonate sand banks and microbial boundstones in the northwestern part of the study area. Microbial structures were divided into peloidal, alveolar, laminated, micritic massive, and micritic irregular microstructures and oncolitic, patchy, micritic massive, and laminated mesostructures. Microbialites occur in most of the depositional environments investigated.; The methodology for carbonate sequence and seismic stratigraphic interpretation developed in this study includes three step: first, the seismic data are interpreted without the support of the well-log and core data. Once the main seismic sequence boundaries and systems tracts are recognized, they are projected onto the well-log records. Eventually, seismic, well-log, and core data are integrated in order to improve the preliminary interpretation and to perform a sequence stratigraphic and seismic stratigraphic analysis. |
