Characterizing the growth of structures in three dimensions using patterns of deep-water fan and channel systems

Abstract

Channel and fan systems in deep-water continental slopes respond to active deformation creating patterns within growth strata that record the history of deformation. These patterns provide important constraints on the timing and kinematics of structural deformation. We show how the location and orientation of depositional systems are affected by the emergence and growth of fault-related folds. We develop two end-member three-dimensional kinematic models to describe the reaction of channels to growing structures. In the first model, structures grow through lateral propagation, causing channels to migrate laterally outward through time. In the second model, structures grow with fixed lateral limits, and channels maintain relatively fixed positions through time. We compare our models with structures in the outer fold–thrust belt in the Niger Delta. The initiation of structural growth is recorded by a dramatic change in channel architecture with a reduction in sinuosity followed by deflection around the lateral edges of folds. Subsequently, in some examples, channels maintain relatively fixed positions through time, reflective of fold growth with fixed lateral limits, whereas other examples show channels that migrate laterally outward through time, reflecting fold growth by lateral propagation. We corroborate our interpretations by comparing our analysis of channel distribution to isopach and structure contour maps. Results indicate that structures in close proximity can grow through different mechanisms or a combination of mechanisms over different stages in their development. The resolved patterns of channel and fan systems provide insight into the complex distribution of reservoir facies, which has important implications for reservoir characterization.