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Deformation and uplift of the Burica Peninsula along the Panama-Costa Rica border results from eastward migration of the Panama Triple Junction (PTJ); the boundary between three tectonic plates. As the triple junction migrates to the southeast at ~55 mm/yr along the Middle America Trench (MAT), the Panama Fracture Zone (PFZ), separating the Cocos and Nazca plates, subducts under the Panama microplate. Differences in the thickness of the plates across the PFZ, as well as the rate and angle of subduction between the Cocos and Nazca plates, cause the Panama microplate to step up and over the Cocos plate. A flight of up to seven marine terraces are recognized on Burica, the highest of which does not exceed ~80 m. Terraces grade from thin, sediment-starved strata deposits to ~10 m thick bay-filled shelf sediments. Radiocarbon and Optical Stimulated Luminescence (OSL) ages indicate these deposits range in age from Marine Isotope Stage (MIS) 3 (45,800 ± 7,100 YBP) to latest Holocene (90 ± 50 YBP). Uplift rates calculated from terrace ages and high-precision DGPS surveys range between 2.2 mm/yr and 3.2 mm/yr. The consistent elevation of inner edges (paleo-high tide line) indicates that uplift of the Burica Peninsula is spatially uniform. The Panama microplate is being uplifted at a constant and uniform uplift rate along a north striking and eastward dipping thrust fault in response to subduction of the Cocos Ridge.
Davidson, Daniel, "Recent Uplift of the Burica Peninsula, Panama and Costa Rica, Recorded by Marine Terraces" (2010). Geosciences Student Honors Theses. 4.
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