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.