Accretionary and post-accretionary cooling, exhumation and tectonic history of the central and western Andes of Colombia

The project consists of a thermochronological (40Ar/39Ar, fission-track and (U-Th)/He)) study of various mineral phases extracted from crystalline and sedimentary rocks from several traverses across the Central Cordillera (Tahami Terrane), the Western Cordillera (Calima Terrane), the Inter-Andean Depression in Colombia, as well as the coastal ranges that tectonically lie above the Choco Terrane (Serrania de Baudo). We try to combine the thermochronological information with petrological studies to constrain the thermal, shearing, faulting and exhumation history of distinct fault blocks within the cordilleras. This work will be combined with geochemical and geochronological analyses of fractionated mafic lavas that are exposed on the eastern and western flanks of the Inter-Andean Depression in Colombia and Ecuador to assess their origin (arc lavas or plateau material?), timing of crystallisation, their cooling and exhumation histories and the nature of the basement of the Interandean Depression.

The acquired data and interpretations will be used to develop hypotheses for the accretionary and post-accretionary history of the oceanic province, the ocean-continent suture and the Central Cordillera of Colombia. The hypotheses will be tested via comparisons with the composition and kinematics of the present day and relic subducting and approaching oceanic plate to check if signficant upper-plate tectonic episodes such as terrane accretion or sudden increases in exhumation rate correspond to tectonic rearrangements or subducted heterogeneities in the Nazca and Farallon plates. The final aim is to propose a coherent geological model for the North Andean Segment and to further assess the influence of the Caribbean Plate on this region.