The Use of Spectral Decomposition for Interpretation of Outcrop Based Forward Models of Mass Transport Complexes
Mass Transport Complexes have been broadly studied and recognized on most continental margins. Throughout those deposits typically three main geological features are recognizable on conventional seismic data: a) continuous blocks without apparent internal deformation represented by high-amplitude continuous reflections; b) low- and high-amplitude reflections geometrically characteristic for slump deposits; c) low-amplitude, semitransparent chaotic reflections indicative of debris flow.
Our study investigates the accuracy of this interpretation by analysis of synthetic seismograms based on outcrop data of two end member MTC’s: debris flow and slide. Results of our studies show that the seismic expression of these deposits is much more complex and our ability to interpret them correctly is far from satisfying. As expected, the capability to interpret these deposits on seismic shows strong dependency on the burial depth and physical parameters, therefore vertical resolution. However, the impact of internal geometry: size and orientation of the individual blocks in compilation with acquisition parameters has a profound effect on seismic expression, especially in the shallow setting. Therefore, an interpretation focused only on analysis of reflection amplitude can provide very misleading results. Additional use of spectral decomposition allowed us to develop a set of rules and predictions about the general structure of MTC’s and their internal geometries which can lead to improving our understanding of these deposits, their role in oil reservoirs and their influence on other depositional systems via the creation and destruction of accommodation space.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009