Kinematic Model Linking Basin Subsidence and Fault Evolution Along the Obliquely Convergent South America-Caribbean Plate Boundary Zone

Escalona, Alejandro¹, Paul Mann¹, Luc Lavier² (1) Jackson School of Geosciences, The University of Texas at Austin, Austin, TX (2) The Unviersity of Texas at Austin, Ausitn, TX

We integrate one-dimensional well data subsidence, GPS, and subsurface mapping using 2D seismic data along the Caribbean-northern South America plate boundary to constrain a three-stage kinematic model: Stage One: oblique arc collision generates a narrow fold-thrust belt and a foreland basin above the former passive margin; wells record rapid subsidence in the proximal foreland. Stage Two: As convergence ends and shifts eastward, gravitational pull of the north-dipping South American slab induces intra-arc rifting within the former fold-thrust belt. Eventual detachment of the dangling slab into the mantle produces isostatic rebound and erosion in the overlying fold-thrust belt. Wells record rapid subsidence in newly formed basins. Stage Three: Oblique convergent plate motion is accommodated by a broad zone of right-lateral shear and backthrusting along the northern edge of the deformed belt. The broad shear zone is characterized by segmentation of previously linear belts along northwest-striking normal faults. The backthrust zone accommodates hundreds of kms of shortening in the older convergent zones in the west but dies to zero displacement to the east. Wells record pulses of subsidence in localized basins. The three stage model provides a framework for the generation, trapping and migration of hydrocarbons along the margin.