Emplacement of the Triassic Pueblito Pluton, NW Colombia: Implications for the Evolution of the Western Margin of Pangea

We present the first structural geology focused study of a Triassic pluton in the Northern Andes, which provides new insights into the understanding of the tectonically complex northwestern corner of South America. Based on a combination of field structural data (377 stations) and a detailed magnetic susceptibility survey, 159 sites, we studied the structure of the Pueblito Pluton (PP), an original suprasubduction mafic cumulate structure emplaced in the northern part of the Arquia Terrane (western margin of Central Cordillera of Colombia). Even though the PP has resided along an active margin for over 230 million years ago, geochronology suggests no postcrystallization Ar‐loss and, probably, no major reset of the original emplacement fabric. The PP magnetic fabric is dominatly parallel to the measured field foliation and formed under submagmatic to high‐temperature conditions, at the final stages of cooling. The pluton internal contacts, mylonitic structures along the western margin, shape of the pluton, scalar parameters of the magnetic fabric, the directional field/magnetic data, and the geochronological data are compatible with a sinistral transpressional tectonic regime of emplacement by ca 233 Ma. This regime was regionally extended in the Arquia and Tahami Terranes (western margin of Pangea). Key Points We present the first structural study based on field and magnetic fabric data of a Triassic pluton in NW South America External shape and fabric of the Pueblito Pluton suggest emplacement in a transpressional shear zone Plutons with similar structural position, age, and shape define a Triassic regional sinistral shear zone along the western margin of Pangea