Terrane Accretion and Transpression Created New Exploration Frontiers in Northwestern South America

Abstract

Abstract A new concept for the origin of the Colombian Caribbean region is proposed. The separation of the North American plate (NAP), South American plate (SAP), and African plate (AP) initiated from a triple junction made up of two oceanic ridges and one transform fault (R-R-TF). Separation created an oceanic basin associated with a convergent, transform margin, where the oceanic plate was consumed while the northwestern portion of South America was expanded through terrane accretion. Oblique terrane accretion occurred along a margin under transpressive and dextral wrenching. Previous models of the Colombia Caribbean were based on the separation of NAP, SAP, and AP by three oceanic ridges (R-R-R). We see no evidences for an oceanic ridge in the Caribbean. Previous models proposed a convergent margin with the Caribbean plate (CP) being subducted under the SAP or the Colombian Caribbean Margin corresponding to a passive margin. However, the CP was originally part of the Pacific plate and was displaced eastwardly and northeastwardly in between two major transform faults as North and South America separated. Hydrocarbon prospectivity of the Caribbean Colombian Margin is higher using our model than that of a subduction model. Understanding the distribution of the reservoir, seal, and source rocks in our model is critical for prospecting the area. Structural traps of different styles, including basement blocks and positive flower structures resulting from the transpressive settings associated with terrane accretion, are common. We identify numerous untested plays along the Caribbean Margin.