Influence of Structural Styles on the Architecture, Stacking Patterns, and Evolution of Deepwater Systems: Insights From the Colombian-Caribbean Margin

Abstract

Continental margin configuration affects the distribution of offshore depositional environments. Thus, several authors postulate models that relate the tectonic nature of continental margins to the morphology of submarine fans. In the Colombian-Caribbean active tectonic margin, however, the Caribbean Plate collides obliquely with the South American Plate resulting in structural styles that vary along strike and are associated to different depositional environments. This study integrates seafloor bathymetry, 2D and 3D seismic interpretation and well data from offshore Colombia to understand the processes that operate in the different structural domains and improve our ability to predict reservoir presence and quality.

Towards the SW, the margin is characterized by orthogonal compression, imbricate thrust anticlines and mud diapirism. Plio-Pleistocene deepwater sedimentation is mainly sourced from the fold belt and consists of turbidites and MTCs that progressively filled piggy-back basins, eventually reaching the basin floor. Further N, a gap in the fold belt coincides with the apex of the Magdalena Fan. This gap is interpreted to form by oblique subduction and strain partitioning with right-lateral deformation causing the break-up and lateral displacement of the fold belt. The Magdalena Fan, a mud-rich system fed by the Magdalena River, developed on a relatively undeformed slope, dominated by high-relief channel-levee complexes and MTCs. Well penetrations encountered stacked high-quality sandstones deposited on the lower slope and basin floor; channel-levee systems thus effectively filtered out mud and delivered clean sand to the basin floor. To the NE of the Magdalena Fan, oblique subduction yielded a transpressional structural style with imbricate thrust anticlines and deep, fault-bounded sub-basins at the rear of the fold belt. The Santa Marta Massif, composed mainly of igneous and metamorphic rocks, created a steep slope with a hard substrate that together with the presence of regional strike-slip fault systems, favored the creation of submarine canyons that delivered coarse-grained sands to the basin floor.

This study shows that structural styles and sedimentation patterns may vary considerably in a single continental margin, and that although assumptions on the architecture of deepwater depositional systems based on the type of tectonic margin are useful, lateral variations may significantly affect the presence and quality of deepwater reservoirs.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018