Structure and Hydrocarbon Prospectivity of the North Panama Deformed Belt: Insights from latest seismic reflection imaging

Abstract

The latest 2D seismic reflection data provides unprecedented insights into the structure and potential petroleum system(s) of the North Panama Deformed Belt (NPDB) and its vicinity. The NPDB is an arcuate accretionary wedge situated north of the Panamanian isthmus in the Caribbean Sea. It is flanked by the San Blas [piggy-back] Basin to the south and the underthrusting Colombian Basin to the north. The complex faulting within the accretionary wedge shows changes in thrust vergence, reflective of mechanical variations in the detachment horizon. Sediments in the trench basinward of the wedge show onlap onto Colombian Basin strata, consistent with foreland flexure and obduction (backthrusting) of the Panama Orocline onto the Colombian Basin. The depth-imaged data suggest a complex internal structure in the prism, with multiple thrust fronts and nappe belts. Structural mapping demonstrates that shortening within the prism is driven by a rising thrust from under the island arc (oroclinal basement wedge) to the south. The rising thrust model implies the uplift of the arc ridge itself, which leads to erosion and addition of sediment to the prism section to the north. The oroclinal thrust is observed at two different levels in the eastern part of the NPDB, compared to a single thrust in the western part. Options for possible source rocks correlated with known hydrocarbon occurrences in southern Costa Rica, the Atrato-Uraba area and the Sinú-San Jacinto basin are discussed. Turonian-Coniacian source rock equivalent shales found in Costa Rica may also be present in the deeper section of the prism throughout the foldbelt. Sediment thickness (8 km) above the Cretaceous coupled with a rising thrust model increases the likelihood of thermal maturation, along with hot geothermal fluids escaping from beneath the oroclinal thrust(s). Multiple trap types including basin floor fans, MTDs, channel fills, pinchouts, reef-like features are seen in addition to the numerous fault-controlled structures within the main body and toe of the prism. These observations present all the elements of a functional petroleum system in the frontier region of offshore Panama.

AAPG Datapages/Search and Discovery Article #90330©2018 AAPG Hedberg: Geology of Middle America – the Gulf of Mexico, Yucatan, Caribbean, Grenada and Tobago Basins and Their Margins “Integration of the geology of the area from the southern onshore of North America to the northern onshore of South America”, Siguenza, Guadalajara, Spain, July 2-5, 2018