Seismic expression of contourite depositional systems

The seismic character of contourite features is to a large extent depending on the methods used in acquisition and processing of the seismic data. Prerequisites for an adequate seismic study of contourites are therefore:•identification of the type of seismic sources (LR, HR or UHR), acquisition parameters (SCS or MCS; 2-D or 3-D), processing sequences (e.g. filtering, deconvolution) and display parameters (e.g. twtt versus depth, axes scale, polarity);•recognition of how these factors affect the interpretation and level of detail resolved by the seismics in the contourite study;•careful attention for the seismic-to-geology conversion when using core and borehole information (seismic resolution versus core data, velocity estimation);•specification of the definitions and use of interpretational methods and terms (seismic sequence or unit, seismic facies) relevant for the current-controlled depositional environment. Seismic identification and stratigraphic breakdown of a contourite depositional system embodies three aspects, which reflect the increasing level of detail of interpretational seismic elements:•first-order seismic elements (large-scale features):the overall architecture of the drift focusing on the gross geometry and large-scale depositional units;•second-order seismic elements (medium-scale features):the internal architecture (drift structure) resolving the sub-units that build up the large-scale depositional units;•third-order seismic elements (small-scale features):the seismic attributes and seismic facies configuration of the depositional subunits. An overview of the correlation between the seismic methods, frequency of the seismic source and the seismic characteristics is shown in Figure 16.11.