Geochronology, geochemistry and tectonic evolution of the Western and Central cordilleras of Colombia

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Autochthonous rocks of the pre-Cretaceous continental margin of NW South America (the Tahami Terrane) are juxtaposed against a series of para-autochthonous rock units that assembled during the Early Cretaceous. Allochthonous, oceanic crust of the Caribbean Large Igneous Province collided with and accreted onto the margin during the Late Cretaceous. We present the first regional-scale dataset of zircon U–Pb LA–ICP–MS ages for intrusive and metamorphic rocks of the autochthonous Tahami Terrane, Early Cretaceous igneous para-autochthonous rocks and accreted oceanic crust. The U–Pb zircon data are complemented by multiphase 40Ar/ 39Ar crystallization and cooling ages. The geochronological data are combined with whole rock major oxide, trace element and REE data acquired from the same units to constrain the tectonic origin of the rock units and terranes exposed in the Western Cordillera, Cauca–Patía Valley and the Central Cordillera of Colombia. The Tahami Terrane includes lower Paleozoic orthogneisses (~ 440 Ma) that may have erupted during the active margin stage of the Rheic Ocean. Basement gneisses were intruded by Permian, continental arc granites during the final assembly of Pangea. Triassic sedimentary rocks were subsequently deposited in rift basins and partially melted during high-T metamorphism associated with rifting of western Pangea during 240–220 Ma. Continental arc magmatism during 180–145 Ma is preserved along the whole length of the Central Cordillera and was followed by an Early Cretaceous out-board step of the arc axis and the inception of the Quebradagrande Arc that fringed the continental margin. Back-stepping of the arc axis may have been caused by the collision of buoyant seamounts, which were coeval with plateau rocks exposed in the Nicoya Peninsular of Costa Rica. Rapid westward drift of South America closed the Quebradagrande basin in the late Aptian and caused medium-high P–T metamorphic rocks of the Arquía Complex to exhume and obduct onto the continental margin. Subduction beneath hot-spot derived rocks of the Caribbean Plateau (~ 100–92 Ma) formed an intra-oceanic arc (~ 92–75 Ma), which collectively comprise the Late Cretaceous Caribbean Large Igneous Province. The remnant ocean basin located between South America and the Caribbean Large Igneous Province was partly consumed via continental subduction, forming the large Antioquia Batholith. The Caribbean Large Igneous Province collided and accreted to South America during ~ 75–70 Ma along the Cauca–Almaguer Fault, resulting in the cessation of both arcs and the Paleocene onset of subduction beneath the accreted oceanic crust.