3-D Structural Controls of Contractional Fault-Related Folds on the Patterns of Growth Stratigraphy: Implications for Petroleum Exploration in Fold and Thrust Belts

Corredor, Freddy¹, John Shaw² (1) Harvard University, Cambridge, MA (2) Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA

Contractional fault-related folds often control the patterns of deposition of syn-tecton-ic growth stratigraphy in fold and thrust belts of active and passive margins worldwide. We observe fault-related folds that grow by mechanisms such as kink-band migration, limb rotation, or a combination of both processes, and that in many cases present distinc­tive three-dimensional patterns of growth stratigraphy. In fault-related folds that grow by kink-band migration, growth strata, such as channelized systems, that drain and are deposited along the base of backlimbs are incorporated and translated to higher positions over the fold limbs with increasing shortening and fold growth. In the case of fault-relat-ed folds that grow by limb rotation, the growth strata deposited along the base of back­limbs are stacked vertically along the axial surface that limits the base of the limbs as no new material is added to the fold with continuous shortening and growth. These process­es alone or combined ultimately control the local and regional distribution of potential clastic reservoirs in fold and thrust belts, and thus it is of critical importance to under­stand and predict the contractional fault-related fold kinematics in these regions. As an example, we present a three-dimensional sequential restoration of a fault-related fold in the deep-water Niger Delta that has been constrained using the patterns of growth sedi­mentation interpreted from 3D seismic amplitudes extracted across the pre-growth and growth stratigraphy. Combined mechanisms of kink-band migration and limb rotation are invoked to explain the three-dimensional kinematics of this fault-related fold, and the resulting patterns of growth sedimentation.