Spatial-temporal migration of granitoid magmatism and the phanerozoic tectono-magmatic evolution of the Colombian Andes

Abstract

Plutonic and hypabyssal porphyritic granitoids (and their volcanic equivalents) are important constituents of the composite geological record of the Colombian Andes, not only from a volumetric standpoint but more so as products of the complex Phanerozoic tectono-magmatic evolution of the region. Based upon U-Pb (zircon) age data circa 1995–2017, six principle periods of Phanerozoic granitoid magmatism have been identified, including early Paleozoic (ca. 485–439 Ma), Carboniferous (ca. 333–310 Ma), Permo-Triassic (ca. 289–225 Ma), latest Triassic-Jurassic (ca. 210–146 Ma), late Cretaceous to Eocene (ca. 100–42 Ma) and latest Oligocene to Mio-Pliocene (ca. 23–1.2 Ma). Mio-Pliocene granitoids of this last period, located within the physiographic Central Cordillera, are essentially coaxial with the Pleistocene to Recent Colombian (Northern Andean) volcanic arc. Major, trace and REE lithogeochemical data for Colombian granitoids are interpreted to reflect mantle vs. crustal magma source regions and variations in petrogenetic processes, including magmatic differentiation, partial melting, crustal anatexis/assimilation and magma mixing. Supported by Sr-Nd, Pb and Hf isotope analyses and regional geological and geophysical constraints, the lithogeochemical and isotopic compositions of Colombian granitoids are interpreted within the wide range of settings which characterize Phanerozoic tectonic evolution of the Northern Andean region. Mantle- and crustal-derived granitoids associated with subduction-related arcs, collision-type orogeny and post-orogenic collapse, regional taphrogenesis, back-arc extension, oceanic rifting and crustal anatexis related to slab delamination, asthenospheric upwelling and crustal underplating are all potentially represented. The analytical resolution of combined U-Pb (zircon), lithogeochemical and isotope data permits a detailed analysis of the temporal vs. spatial migration and petrogenetic variation of granitoid magmatism during the Phanerozoic. Major granitoid suites have herein been integrated into pre-Northern Andean, proto-Northern Andean and Northern Andean orogenic phases of Colombian tectonic evolution.