The identification and classification of contourite features: methods using seismic reflection data

In recent decades the contourite paradigm has gained prominence in academic and economic circles. Although many contourite deposits are easily identified in seismic reflection data, with the advent of new higher quality datasets the picture has become more complicated. Many questions still remain regarding how to classify the continuous spectrum of interrelated bottom current generated depositional, erosive and mixed features, and whether the classifications need to be enhanced or modified in light of recent findings. This project uses 2D and 3D seismic reflection and well datasets from the Uruguayan, Argentine and northwest Iberian Margins to conduct analyses on four contourite systems. Both the Uruguayan and Argentine Margins have a complex oceanographic history where multiple water-masses have developed through time. This resulted in multiple bottom currents flowing at different depths and in opposite directions close to the seafloor, which generated expansive contourite systems during the Cenozoic. The northwest Iberian Margin formed a narrow seaway during the Late Cretaceous, and since that time enhanced bottom currents as well as a complex and changing oceanographic scenario have resulted in the formation of a large contourite depositional system. These studies allowed for the conventional diagnostic seismic criteria used to identify and classify contourite features and systems to be tested and enhanced. Recent interpretation techniques such as sedimentary stacking pattern analysis were employed to elucidate the depositional and oceanographic processes controlling the spatial and temporal evolution of these systems. The studies presented in this manuscript have aided in enhancing and refining interpretation and characterisation techniques for contourite features and systems. New conceptual models were developed for plastered and detached asymmetric drifts based on the Uruguayan and Argentine Margin projects, and a contourite depositional system [CDS] framework was developed for multiple contourite features on the northwest Iberian Margin, which links the systems evolution to continental breakup and the palaeoceanographic scenario of the region, this framework builds on recent research and could aid future work in the area.