Analysis of scattered, or diffraction energy (the seismic response of small-scale objects) in the seismic data from Canterbury Basin, New Zealand reveals additional geological information about depositional patterns in sedimentary deposits. Diffrac- tion images from the seismic response for Canterbury Basin provide complementary interpretation tools to the conventional specular reflection images. To image diffrac- tions for a dataset from Canterbury Basin, I take the following steps: First, I attenuate multiples using a surface multiple prediction algorithm to predict multiples and apply regularized nonstationary regression to adaptively subtract the predicted multiples. Next, I separate diffractions using the plane-wave destruction method. The plane- wave destruction method removes conventional reflected energy in order to enhance the diffracted energy. I then apply a velocity continuation method on diffraction data to estimate migration velocities and then migrate the data using Kirchhoff migration in the dip-angle-gather domain. The resultant conventional and diffraction images are improved images suitable for geological interpretation of prograding sediment drifts. / text

A Neogene contourite depositional system was identified and mapped along the DeSoto Slope in the northeastern Gulf of Mexico, U.S.A. A series of drift deposits comprising the larger contourite depositional system were interpreted from a 2-D industry seismic data set. The now subsurface drift deposits are adjacent to the anomalous seabed feature, the DeSoto Canyon, and these data suggest contourite deposition and ocean currents are in integral part of the canyon’s depositional history. The contourite depositional system is underlain by an extensive, middle Miocene aged, erosional unconformity formed by ocean currents. The timing of this erosional surface is in alignment with the widely accepted premise that the Miocene represented a transitional period in Gulf of Mexico basin circulation. The discovery of this contourite depositional system adds to an established list of Miocene-aged features pointing to the onset of enhanced Loop Current circulation in the Neogene Gulf of Mexico.