3D Structural Controls of Contractional Fault-Related Folds on the Patterns of Growth Stratigraphy in Passive Margins: Examples from the Deep-Water Niger Delta

Freddy Corredor¹, John Shaw², Chris Guzofski¹, and Frank Bilotti^3
1 Harvard University, Cambridge, MA
² Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA
³ Unocal Corporation, Sugar Land, TX

Contractional fault-related folds that accommodate the gravity-driven extension from the shelf often control the patterns of growth stratigraphy in the deep-water regions of passive margins. In the deep-water Niger Delta we observe fault-related folds that grow by multiple mechanisms including kink-band migration and limb rotation, and that in many cases present distinctive patterns of growth stratigraphy. In fault-related folds that grow by kink-band migration, growth strata deposited along the base of backlimbs are incorporated over the fold limbs with increasing shortening and fold growth. For instance, as the fold grows, channelized systems that drain along the base of backlimbs are translated to a higher position along the fold. In the case of fault-related 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. Thus, it is of critical importance to understand and predict the contractional fault-related fold kinematics in passive margins in order to understand the regional distribution of potential clastic reservoirs for petroleum exploration in these settings. We used seismic amplitudes extracted from a 3D seismic volume across multiple pre-growth and growth horizons from a fault-related fold in the deep-water Niger Delta to constraint the 3D structural sequential restoration of this structure. Combined mechanisms of kink-band migration and limb rotation are invoked to explain the three dimensional kinematics of this fault-related fold in the deep-water Niger Delta.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005