Abstract We present the results of 59 new apatite fission tracks (AFT), 24 new vitrinite reflectance analysis, and 154 new He thermocronometric analysis from the eastern flank of the Colombian eastern Cordillera at lat7° N to constrain the roles of plate tectonics, tectonic inheritance, and surface processes in building the Cocuy syntaxis. The Cocuy syntaxis is the region with the highest structural and topographic relief in the eastern Cordillera. The primary factor controlling that is faster tectonism, apparently related to the most important Panama collision at 4 Ma. This push from behind is focused between two resistant plates and escapes toward a weak foreland plate, which is able to flex. However, we document new Pliocene and younger AFT ages in the eastern side of the eastern Cordillera, which are related with focused and faster exhumation in the eastern flank. We suggest that this episode is responsible for the limited advance of the deformation front as basement-involved blocks. In addition, faster denudation causes faster sedimentation rates in the weak foreland plate east of the Cocuy syntaxis. In this case, the thick pile of Neogene synkinematic sediments would have limited thin skin deformation migration.

Abstract A combination of new surface and subsurface structural data, new stratigraphic data on conventional provenance, facies and palaeocurrents, low-temperature thermochronology and detrital zircon U–Pb provenance data provides a comprehensive account of the timing of deformation in the intermountane Middle Magdalena basin of the Central Colombian Andes, and allows evaluation of the style of foreland basin deformation associated with tectonic inversion. This robust dataset enabled documentation of focused tectonic activity in two competing low-relief basement structures to the east and west of the present Middle Magdalena Valley during the Palaeogene, earlier than previously recognized. Cenozoic sediment accumulation of a sedimentary pile up to 7 km thick in the Middle Magdalena Basin created a large original taper angle in this part of the north Andes. At that time, when the detachment rocks were deeply buried, the original larger taper angle facilitated the forelandward advance of deformation instead of promoting its stagnation. Supplementary material: Raw data results from geochronometrial analyses are available at: http://www.geolsoc.org.uk/SUP18627

Abstract The initial stages of tectonic inversion and the mechanisms of selective reactivation and abandonment of pre-existing normal faults during contractional orogenesis are explored in a partially buried Cenozoic thrust belt in the Andes of Colombia. A multidisciplinary approach that includes subsurface structural mapping, multimethod thermochronometry and detrital zircon U–Pb geochronology reveals the extent of a Palaeogene thrust belt buried underneath the Cenozoic strata of the Middle Magdalena Valley Basin. A less oblique orientation with respect to compressive stress and shorter traces in faults of the Middle Magdalena Valley Basin with respect to faults in the western part of the Eastern Cordillera, apparently acted as deformation inhibitors of the Magdalena faults in advanced Neogene stages of inversion. Protracted Cenozoic eastwards tilting of the Central Cordillera and the tectonic load from the uplifting Eastern Cordillera favoured the accumulation of a thick Cenozoic sedimentary sequence in an, at least episodically, closed basin. All the above-mentioned conditions helped to block deformation in the Magdalena Basin, favouring deformation to be taken up by structures in the western Eastern Cordillera. These relationships underscore the importance of buried structural records in elevated hinterland basins, in which the low-relief stratigraphic cover overlies a complex subsurface record, potentially including large magnitudes of deformation during early orogenesis. Supplementary material: Tables and figures on the laboratory methods for the thermochronometrical and geochronometrical analyses are available at http://www.geolsoc.org.uk/SUP18601 .

Abstract The Northern Andes of Colombia is a key locality for understanding tectonic inversion of symmetric rifts. A review of available data on structural geometry and deformation timing, and new thermochronology and provenance data from selected localities, enable the construction of balanced cross-sections and shortening budgets. During early deformation in the Palaeocene, most shortening was focused in the western sector of the orogen, in the Central Cordillera and the Magdallena Valley, although widely spaced and mild inversion occur in areas as far to the east as the Llanos Basin. After a period of tectonic quiescence in the Middle Eocene, deformation resumed across a former early Mesozoic graben in the Eastern Cordillera. Peak shortening rates and out-of-sequence reactivation of the main inversion faults were in place in latest Miocene time, during a phase of topographical growth. Our results indicate that coeval activation of basement highs and adjacent slower-slip shortcuts appear to be characteristic of inverted symmetric grabens. However, before reactivation and brittle faulting occur, strain hardening is required. Deformation rates in the Eastern Cordillera correlate with the westwards velocity of the South American Plate. A threshold convergence rate of approximately 2 cm year −1 seems to be necessary to activate shortening in the upper plate.