This thesis investigates the tectonic histories of igneous and metamorphic rocks exposed in the Mérida Andes, Venezuela, and Santander Massif, Colombia from the Late Cambrian to the present day. Zircon U-Pb ages from 52 igneous and metamorphic rocks constrain the main periods of arc magmatism on the north-western corner of Gondwana from ~500 to ~413 Ma and from ~294 Ma to ~196 Ma. Peak Barrovian metamorphic conditions are recorded by anatexis at ~477 Ma and the intrusion of synkinematic granitoids until ~472 Ma. Back-arc extension is recorded at ~453 Ma. High exhumation rates constrained by 40Ar/39Ar and apatite U-Pb data suggest a second orogenic phase at ~250 Ma. Combined isotopic data show that the basement rocks of the studied regions are autochthonous to north-western Gondwana, and that arc magmatism sampled more juvenile sources during extension than during orogenesis. Low temperature thermochronology suggests that the Santander Massif started exhuming at ~40 Ma.