Characterization of Counter-Regional Normal Faulting in the South Gabon Basin from 2D Seismic Interpretation

Abstract

The modern equatorial West African offshore slope and deep South Atlantic basins from southern Angola to Equatorial Guinea are comprised of laterally extensive, and discontinuous passive margin fold and thrust belts. These gravity-driven systems are the result of overburdern and subsequent deformation inducing gravity sliding on the underlying Aptian-Albian evaporate deposits. Interpretion of 2D seismic data courtesy of Spectrum Geo Inc. gives insight to the characterization of the offshore region of the South Gabon Basin as well as the structural styles of this particular fold belt including landward-dipping growth faults, antiforms and synforms, and toe thrusts with folding as well as salt deformation and evacuation of diapirs, walls, and stocks which formed these tectonic structures. The landward dipping growth faults, also known as counter-regional normal faults (CRNFs), are uncharacteristic for typical passive margin fold and thrust belts. Their formation is likely initiated by a significant and concentrated sediment input. Interpreting regionally adjacent 2D seismic and using Midland valley move to backstrip, decompact, and reconstruct the horizons indicates salt mobility in the early phases of overlaid strata. With difficulty in salt imaging and recent significant pre-salt discoveries in the area this sedimentary input can be indicative of pre-salt reservoir potential.

AAPG Datapages/Search and Discovery Article #90350 © 2019 AAPG Annual Convention and Exhibition, San Antonio, Texas, May 19-22, 2019