f Assessing the Regional Effects of the Miocene-to-Recent Panama Arc Collision and its Influence on the Maturation and Distribution of Hydrocarbons in Northwestern South America and Southern Central America

The northwestern margin of South America has undergone different phases of deformation since the late Paleozoic related to continental and arc collisions, strike-slip events, and subduction of oceanic plateaus. The purpose of this talk is to isolate the effects of the most recent of these superimposed tectonic events - the collision of the Panama arc with the northwestern margin of South America - and to assess its impact on the regional distribution and maturation of hydrocarbons. The precise age of the Panama collision has remained a topic of continuing research. Geologic work that includes onland-based structural mapping, radiometric dating, and paleomagnetism has shown that the Panama area formed as a semi-emergent island chain from the Oligocene (30 Ma) - but the emergent isthmus and barrier separating the Caribbean and Pacific Oceans was not fully established until the Late Pliocene (2.8 Ma). To improve constraints on the timing of the actual collision of the island arc basement rocks of Panama with the previous orogenic belts of northwestern Colombia, we have compiled: 1) previous thermochronological work on the arc and continental basement of both northwestern South America and Panama; 2) thickness and ages of the clastic wedges eroded from this basement areas and summarized this information into burial curves from induvial basins; 3) the ages of known angular unconformities within the deformed sedimentary basins; and 4) compiled and restored the measured lengths of now subducted slabs beneath both northwestern South America and Panama. These data show that: 1) the timing of the collision occurred at least since the late Miocene - about 13 Ma - which resulted in the uplift of the northern Andes, clastic flooding including the Magdalena submarine fan that has accelerated to the present-day and unleashed hydrocarbon generation and expulsion in offshore Caribbean depocenters ; 2) a large basement arch extends eastward from Panama beneath northwestern South America and forms a hydrocarbon-poor zone as few deep basins are present in this area of uplifted basement; and 3) deformational effects have propagated eastward into the Cordillera Oriental and Llanos basins and triggered a pulse of deep burial and maturation of hydrocarbons.