Slab flattening and the rise of the Eastern Cordillera, Colombia

Siravo, Gaia; Faccenna, Claudio; Gérault, Mélanie; Becker, T. W.; Fellin, Maria Giuditta; Herman, Frédéric; Molin, Paola

doi:10.1016/j.epsl.2019.02.002

Cited by 39 publications

(34 citation statements)

References 59 publications

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“…Magmatic additions have also played a role in crustal thickening; magmas have been emplaced at the bottom of the crust and have ascended through crustal faults. Slab shallowing and flattening in the late Miocene‐Pliocene could have triggered exhumation and uplift (Siravo et al, ), as well as the magmatic processes.…”

Section: Discussion and Tectonic Implicationsmentioning

confidence: 99%

Deep Crustal Faults, Shear Zones, and Magmatism in the Eastern Cordillera of Colombia: Growth of a Plateau From Teleseismic Receiver Function and Geochemical Mio‐Pliocene Volcanism Constraints

et al. 2019

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The Eastern Cordillera of Colombia, in the northern Andes, is an example of an orogen in which Mesozoic basins were compressed during the Cenozoic, forming a ~2,500‐m‐high plateau in its northern portion. Significant shortening and crustal thickening have contributed to the construction of the present topography and elevation. In this contribution, we combine the use of teleseismic receiver functions, Hf isotopes, whole‐rock geochemistry, and U‐Pb dating to help elucidate the main mechanisms that played a role in the crustal thickening and uplift of the cordillera. Receiver functions calculated for three stations on top of the plateau are consistent with the presence of thrusts that converge into major crustal interfaces at upper‐middle crustal depths; they also suggest the existence of two crustal anisotropic layers beneath the western flank of the cordillera, which we interpret to have formed as a result of shearing. In the northern portion of the plateau, in the area where two Mio‐Pliocene volcanic domes and their related deposits outcrop, a lower crustal high seismic velocity layer is suggested by the receiver functions; we propose magmatic underplating for the origin of this layer. The geochemical characteristics of the volcanic rocks in the area are consistent with partial melt in a mantle influenced by slab‐related fluids; this magma could have been added to the crust and portions of it ascended and reached the surface, experiencing assimilation and differentiation during the process. We hypothesize that this Mio‐Pliocene volcanism was related to flattening of the Nazca subducting slab.

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Section: Discussion and Tectonic Implicationsmentioning

confidence: 99%

Deep Crustal Faults, Shear Zones, and Magmatism in the Eastern Cordillera of Colombia: Growth of a Plateau From Teleseismic Receiver Function and Geochemical Mio‐Pliocene Volcanism Constraints

et al. 2019

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“…The results of numerical models presented in Figure 6 illustrate this effect. We use a 2-D, cylindrical finite-element code adapted from MILAMIN (Dabrowski et al, 2008;Gérault et al, 2012), which has been used previously to study regional flat slab dynamics (Gérault et al, 2015;Siravo et al, 2019). The computation solves for the velocity and pressure fields using an infinite Prandtl number and incompressible Stokes flow formulation with Newtonian rheology.…”

Section: Stresses In the Overriding Plate: Insights From Numerical Momentioning

confidence: 99%

Widening of the Andes: An interplay between subduction dynamics and crustal wedge tectonics

Martinod

Gérault

Husson

et al. 2020

Earth-Science Reviews

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Shortening of the continental lithosphere is generally accommodated by the growth of crustal wedges building above megathrusts in the mantle lithosphere. We show that the locus of shortening in the western margin of South America has largely been controlled by the geometry of the slab. Numerical models confirm that horizontal subduction favors compression far from the trench, above the asthenospheric wedge and steeply dipping segment of the subducting slab. As a result, a second crustal wedge grows in the hinterland of the continent, and widens the Andes. In the Bolivian orocline, this wedge corresponds to the Eastern Cordillera, whose growth was triggered by a major episode of horizontal subduction. When the slab returned to a steeper dip angle, shortening and uplift pursued, facilitated by the structural and thermo-chemical alteration of the continental lithosphere. We review the successive episodes of horizontal subduction that have occurred beneath South America at different latitudes and show that they explain the diachronic widening of the Andes. We infer that the present-day segmented physiography of the Andes results from the latitudinally variable, transient interplay between slab dynamics and upper plate tectonics over the Cenozoic. We emphasize that slab flattening, or absence thereof, is a major driving mechanism that sets the width of the Andes, at any latitude.

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“…Erosion, magmatism, and tectonic shortening set the crustal thickness that in turn controls elevation (e.g., Allmendinger et al, 1997;Kley and Monaldi, 1998;Giese et al, 1999). Additionally, mantle dynamics especially above subduction zones or crustal flow also influence topography, exhumation, and the shape of a mountain belt (e.g., Jordan et al, 1983;Braun, 2010;Martinod et al, 2010;Dávila and Lithgow-Bertelloni, 2015;Flament et al, 2015;Siravo et al, 2019). In particular, and as for instance observed for the modern Pampean flat slab segment (28 -32°S), flattening of the subducting slab may generate dynamic uplift (Dávila and Lithgow-Bertelloni, 2015;Flament et al, 2015) and induce shortening in the upper plate's interior far away from the trench, which leads to the widening of the mountain belt (Martinod et al, 2010).…”

Section: Crustal Thickening Magmatism and The Geothermal Field Of Thmentioning

confidence: 99%

The relationships between tectonics, climate and exhumation in the Central Andes (18–36°S): Evidence from low-temperature thermochronology

Stalder

Herman

Fellin

et al. 2020

Earth-Science Reviews

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The Central Andes between 18°S and 36°S latitude strike north-south for 2000 km along the Chilean subduction margin, cross several climate zones from hyperarid to humid and exhibit mean elevations in excess of 4000 m.a.s.l. Here, we investigate the relationships between tectonics, climate and exhumation by inverting low-temperature thermochronological data compiled from the literature (824 ages from 549 samples) and new data (238 ages from 146 samples) to quantify the exhumation rate history of the Central Andes since 80 Ma. Our inferred exhumation rates west of the drainage divide and between 18 and 32°S did not exceed 0.25 km/Ma. Such low exhumation rates are consistent with low shortening rates and arid conditions in this region. Local pulses of exhumation occurred only during the Eocene as 2 response to active deformation and during the Miocene, probably as response to uplift of the western Andean slope. East of the drainage divide between 18 and 28°S, the observed exhumation pattern reflects the onset and eastward propagation of deformation. Here, exhumation occurred locally since the middle-to-late Eocene in the Eastern Cordillera and the Altiplano-Puna and subsequently affected larger parts of these regions and the northwestern Sierra Pampeanas during the Oligocene. In the early Miocene (~20 Ma), the Interandean zone started exhuming and at 12-10 Ma exhumation propagated into the Subandean zone. Enhanced shortening rates and intensified precipitation along the eastern deformation front associated with the onset of the South American Monsoon led to increased exhumation rates in the eastern Interandean and the Subandean zones in the Plio-Pleistocene (0.6 km/Ma). Higher Pleistocene exhumation rates are also observed in the northern Sierra Pampeanas (1.5 km/Ma) that can be related to rock uplift along steep reverse faults coupled with high precipitation. South of 32°S on the western side, exhumation rates in the Principal Cordillera increased from ca. 0.25 km/Ma in the Miocene to rates locally exceeding 2 km/Ma in the Pleistocene. Whereas the tectonic regime in the southern Principal Cordillera remained unchanged since the late Miocene, these higher rates are likely associated with enhanced erosion resulting from intensified Pleistocene precipitation and glacial growth in this region, reinforced by isostatic rock uplift and active tectonics. Our study shows that the onset of exhumation correlates mainly with the initiation of horizontal shortening and crustal thickening, whereas the magnitude of exhumation is largely set by the amount of precipitation and glacial erosion and by the style of deformation, which is controlled by inherited structures and the amount of sediments in the foreland. In the following, we present new low-temperature thermochronological data (238 ages) that we complement with literature data (824 ages) to constrain the exhumation rate history of the Andean mountain belt at large temporal (Ma) and spatial scales (18 to 36°S). We focus on apatite and zircon fission track (AFT and ZFT, respe...

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Slab flattening and the rise of the Eastern Cordillera, Colombia

Cited by 39 publications

References 59 publications

Deep Crustal Faults, Shear Zones, and Magmatism in the Eastern Cordillera of Colombia: Growth of a Plateau From Teleseismic Receiver Function and Geochemical Mio‐Pliocene Volcanism Constraints

Deep Crustal Faults, Shear Zones, and Magmatism in the Eastern Cordillera of Colombia: Growth of a Plateau From Teleseismic Receiver Function and Geochemical Mio‐Pliocene Volcanism Constraints

Widening of the Andes: An interplay between subduction dynamics and crustal wedge tectonics

The relationships between tectonics, climate and exhumation in the Central Andes (18–36°S): Evidence from low-temperature thermochronology

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