Relationship Between Seismic Facies and External Morphology of Mass Transport Deposits and Their Influence from Subsequent Depositional Systems

Katerina Garyfalou¹, Benjamin Kneller¹, and Mason Dykstra^2
1Geology and Petroleum Geology, University of Aberdeen, Aberdeen, United Kingdom
²Geology and Geological Engineering, Colorado School of Mines, Colorado, CO

Possible variations of bulk sediment concentrations and differences in the rheology within Mass Transport Deposits (MTDs) are responsible for the generation of irregular topography on the upper surface of these deposits. This irregular topography may lead to the creation of accommodation space which can later be infilled by subsequent turbidite systems.

The interaction between the scale of turbidity flows and the height of the topography on top of MTDs determines whether subsequent turbidites form isolated ponded units, whose extent is determined by the wavelength of the topography (‘underfilled’ case), or whether they swamp the entire surface forming continuous, potentially connected units (‘overfilled’ case).
We present an integrated approach in studying the affect that MTD topography may have on potential reservoir units by using spectral analysis of 3D seismic data combined with outcrop data. The methodology involves: a) Identification and classification of distinct internal facies of MTDs based on seismic data and their relationship with their external morphology, b) Fourier analysis of extracted sea-floor topography along depositional strike and dip lines through the MTDs and, c) Field data from seismic scale outcrops (Guandacol Formation, NW Argentina) which illustrate the presence of ponded facies above MTDs.
By understanding the effect MTD generated topography on the overlying depositional systems we are able to predict the distribution of potential reservoir units overlying MTDs. Topography on top of MTDs may be the result of several factors including the spatial distribution of internal structures and facies and the morphology of their basal surface. Spectral analysis applied on seismic data indicates the presence of discrete scales of wavelengths, with different composite wavelength spectra for different types of MTDs.

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