Sinu Basin Tectonostratigraphy Between Two Fold Belts and Timing of the Panama Arc-South America Collision

Abstract

Rapid uplift of the Eastern Cordillera and formation of the Sinu Fold Belt in offshore Colombia have been widely attributed to an oblique collision between Panama Arc and South America Plate. Timing of the collision ranges from late Middle Miocene to Late Miocene according to onshore and offshore seismic and well data. However, interpretation of our large 3D seismic data and recent deepwater exploration wells in/near the Sinu Basin in offshore Colombia seems to show a more constrained collision timing. In addition, sedimentary and structural records in the Sinu Basin between the Panama Fold Belt and Sinu Fold Belt provide a direct insight into the collisional process and its impact on basin evolutionary history. It is also a unique case with a basin deformed and controlled by two fold belts at an intersecting position of three plates: the Caribbean, South America, and Nazca plates. Three stages of basin evolution are recognized in the Sinu Basin. Before the collision, the Sinu Basin was an open basin receiving sediments in amalgamated channel complexes and basin floor fans from large drainage systems during Miocene. At latest Miocene to earliest Pliocene collision of the Panama Arc with South America Plate formed the Panama Fold Belt and the Sinu Fold Belt, deformed the Sinu Basin as a closed foredeep basin with NNE-striking normal faults with accompanied grabens, half grabens, and slumps, en echelon wrench faults, and thrust faults, which fit into a classical strain ellipse nicely. The foredeep basin was filled, eroded, refilled, and leveled off at the end of the foredeep basin stage with sediments thinning towards a basement high to the north. In the early stage of the foredeep basin development, a series of south-dipping normal faults evolved due to forebulge flexural bending of the Sinu Basin. During late Early Pliocene to Pleistocene, the Sinu Basin, still a closed basin, turned into a different depositional phase with sections thickening to the Panama Fold Belt to the south and thinning towards north. This change may have resulted from the NNE obduction of the Panama Arc over the Caribbean Plate and NNE propagation of the Panama Fold Belt. The basin received fast deposition with mixed processes dominated by MTCs originating from the Sinu Fold Belt. A rapid thrusting of the frontal Sinu Fold Belt during Pleistocene with tightly imbricated thrust faults and folds further enhanced the high depositional rates and MTC occurrences.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017