New constraints on the chronology, magnitude, and distribution of deformation within the central Andean orocline

Eichelberger, Nathan W.; McQuarrie, Nadine; Ehlers, Todd A.; Enkelmann, Eva; Barnes, J. B.; Lease, Richard O.

doi:10.1002/tect.20073

Cited by 39 publications

(82 citation statements)

References 117 publications

(291 reference statements)

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“…The structural style in the Interandean zone is similar to that in the Subandean zone, and together they were the main locus of shortening on the eastern margin of the Andes since ϳ25 Ma, with deformation focused in the Subandean zone since ϳ10 Ma, accommodating underthrusting of the Brazilian Shield (Fig. 1b;Kley 1996;Eichelberger et al 2013).…”

Section: Interandean and Subandean Zonesmentioning

confidence: 87%

“…2a, 3a; Table 1 ;Roeder 1988;Hérail et al 1990;Baby et al 1992Baby et al , 1993Baby et al , 1995Wigger et al 1993;Dunn et al 1995;Kley and Monaldi 1998;Kley 1996Kley , 1999McQuarrie 2002;Uba et al 2006;Barke and Lamb 2006;Eichelberger et al 2013). The Brazilian Shield is overlain to the northeast by a Cenozoic foreland basin up to 5 km thick, which thins towards the outcrop of the Brazilian shield (data held by oil companies, 1995).…”

Section: Interandean and Subandean Zonesmentioning

confidence: 99%

“…These have been deformed in a Paleogene fold and thrust belt since ϳ40 Ma, with a westward vergence in the west, on the margins of the Altiplano, and eastward vergence in the east, towards the foreland with a total Paleogene shortening of 65-100 km, decreasing away from the axis of the Bolivian oroclene ( Fig. 2; Table 1; GEOBOL and YFPB 1978;McBride et al 1987;Farrar et al 1988;Kley 1996Kley , 1999Kley and Monaldi 1998;Müller et al 2002;McQuarrie 2002;Eichelberger et al 2013). Along the northern profile, the tightly folded and thrusted Oligocene Luribay Conglomerate, together with underlying Maastrichtian and older sequences, are overlain with angular unconformity by the 28-22 Ma Lower Salla Formation (Fig.…”

Section: Eastern Cordilleramentioning

confidence: 99%

“…Folding and reverse faulting of these sequences indicate that the Eastern Cordillera has undergone more-or-less continual contractional deformation during the early to mid Miocene, accommodating 30 ± 10 km of shortening, possibly with a component of dextral strike-slip, although the precise timing of shortening varies from basin to basin ( Fig. 3b; Kennan et al 1995;Hérail et al 1996;Müller et al 2002;Horton 2005;Eichelberger et al 2013). …”

Section: Eastern Cordilleramentioning

confidence: 99%

“…Calculated and observed crustal thickening and resultant surface uplift (U s ) in 2-D shortening models (see text) for Central Andes between 18°S and 21°S, using value of focusing factor ␥ that gives a good fit to observed paleo-elevations (see Table 2 and Fig. 8 Müller et al 2002;Elger et al 2005;Barke and Lamb 2006;McQuarrie 2002;Lamb 2011;Eichelberger et al 2013).…”

Section: Underthrusting and Lower Crustal Shorteningmentioning

confidence: 99%

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Cenozoic uplift of the Central Andes in northern Chile and Bolivia—reconciling paleoaltimetry with the geological evolution

Lamb

2016

Can. J. Earth Sci.

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Abstract:The Cenozoic geological evolution of the Central Andes, along two transects between ϳ17.5°S and 21°S, is compared with paleo-topography, determined from published paleo-altimetry studies. Surface and rock uplift are quantified using simple 2-D models of crustal shortening and thickening, together with estimates of sedimentation, erosion, and magmatic addition. Prior to ϳ25 Ma, during a phase of amagmatic flat-slab subduction, thick-skinned crustal shortening and thickening (nominal age of initiation ϳ40 Ma) was focused in the Eastern and Western Cordilleras, separated by a broad basin up to 300 km wide and close to sea level, which today comprises the high Altiplano. Surface topography at this time in the Altiplano and the western margin of the Eastern Cordillera appears to be ϳ1 km lower than anticipated from crustal thickening, which may be due to the pull-down effect of the subducted slab, coupled to the overlying lithosphere by a cold mantle wedge. Oligocene steepening of the subducted slab is indicated by the initiation of the volcanic arc at ϳ27-25 Ma, and widespread mafic volcanism in the Altiplano between 25 and 20 Ma. This may have resulted in detachment of mantle lithosphere and possibly dense lower crust, triggering 1-1.5 km of rapid uplift (over Ͻ Ͻ5 Myrs) of the Altiplano and western margin of the Eastern Cordillera and establishing the present day lithospheric structure beneath the high Andes. Since ϳ25 Ma, surface uplift has been the direct result of crustal shortening and thickening, locally modified by the effects of erosion, sedimentation, and magmatic addition from the mantle. The rate of crustal shortening and thickening varies with location and time, with two episodes of rapid shortening in the Altiplano, lasting <5 Myrs, that are superimposed on a long-term history of ductile shortening in the lower crust, driven by underthrusting of the Brazilian Shield on the eastern margin.

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Section: Interandean and Subandean Zonesmentioning

confidence: 87%

Section: Interandean and Subandean Zonesmentioning

confidence: 99%

Section: Eastern Cordilleramentioning

confidence: 99%

Section: Eastern Cordilleramentioning

confidence: 99%

Section: Underthrusting and Lower Crustal Shorteningmentioning

confidence: 99%

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Cenozoic uplift of the Central Andes in northern Chile and Bolivia—reconciling paleoaltimetry with the geological evolution

Lamb

2016

Can. J. Earth Sci.

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Crustal-scale block tilting during Andean trench-parallel extension: Structural and geo-thermochronological insights

et al. 2016

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Despite a long history of plate convergence at the western margin of the South American plate that has been ongoing since at least the Early Paleozoic, the southern Peruvian fore‐arc displays little to no evidence of shortening. In the light of this observation, we assess the deformation history of the southern Peruvian fore‐arc and its geodynamic implications. To accomplish this, we present a new structural and geo‐thermochronological data set (zircon U‐Pb, mica 40Ar/39Ar, apatite and zircon fission‐track and zircon (U‐Th)/He analyses) for samples collected along a 400 km long transect parallel to the trench. Our results show that the Mesoproterozoic gneissic basement was mainly at temperatures ≤350°C since the Neoproterozoic and was later intruded by Jurassic volcanic arc plutons. Along the coast, a peculiar apatite fission‐track age pattern, coupled with field observations and a synthesis of available geological maps, allows us to identify crustal‐scale tilted blocks that span the coastal Peruvian fore‐arc. These blocks, bounded by normal faults that are orthogonal to the trench, suggest post‐60 Ma trench‐parallel extension that potentially accommodated oroclinal bending in this region. Block tilting is consistent with the observed and previously described switch in the location of sedimentary sources in the fore‐arc basin. Our data set allows us to estimate the cumulative slip on these faults to be less than 2 km and questions the large amount of trench‐parallel extension suggested to have accommodated this bending.

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Kinematics, Exhumation, and Sedimentation of the North Central Andes (Bolivia): An Integrated Thermochronometer and Thermokinematic Modeling Approach

2017

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Quantifying mountain building processes in convergent orogens requires determination of the timing and rate of deformation in the overriding plate. In the central Andes, large discrepancies in both timing and rate of deformation prevent evaluating the shortening history in light of internal or external forcing factors. Geologic map patterns, age and location of reset thermochronometer systems, and synorogenic sediment distribution are all a function of the geometry, kinematics, and rate of deformation in a fold‐thrust‐belt‐foreland basin (FTB‐FB) system. To determine the timing and rate of deformation in the northern Bolivian Andes, we link thermokinematic modeling to a sequentially forward modeled, balanced cross section isostatically accounting for thrust loads and erosion. Displacement vectors, in 10 km increments, are assigned variable ages to create velocity fields in a thermokinematic model for predicting thermochronometer ages. We match both the pattern of predicted cooling ages with the across strike pattern of measured zircon fission track, apatite fission track, and apatite (U‐Th)/He cooling ages as well as the modeled age of FB formations to published sedimentary sections. Results indicate that northern Bolivian FTB deformation started at 50 Ma and may have begun as early as 55 Ma. Acceptable rates of shortening permit either a constant rate of shortening (~4–5 mm/yr) or varying shortening rates with faster rates (7–10 mm/yr) at 45–50 Ma and 12–8 Ma, significantly slower rates (2–4 mm/yr) from 35 to 15 Ma and indicate the northern Bolivian Subandes started deforming between 19 and 14 Ma.

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New constraints on the chronology, magnitude, and distribution of deformation within the central Andean orocline

Cited by 39 publications

References 117 publications

Cenozoic uplift of the Central Andes in northern Chile and Bolivia—reconciling paleoaltimetry with the geological evolution

Cenozoic uplift of the Central Andes in northern Chile and Bolivia—reconciling paleoaltimetry with the geological evolution

Crustal-scale block tilting during Andean trench-parallel extension: Structural and geo-thermochronological insights

Kinematics, Exhumation, and Sedimentation of the North Central Andes (Bolivia): An Integrated Thermochronometer and Thermokinematic Modeling Approach

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