Active deformation in the Bolivian Andes, South America

Lamb, Simon

doi:10.1029/2000jb900187

Cited by 83 publications

(130 citation statements)

References 51 publications

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“…Anticlockwise rotations are prevalent in the northern limb of the orocline, while clockwise rotation dominates the southern limb [e.g., Beck, 1987;Roperch and Carlier, 1992;Randall, 1998;Somoza et al, 1996;Lamb, 2001]. Observed gradients in shortening within the Andean orogenic belt (i.e., decreased shortening away from the center of the orocline) are consistent with tectonic rotation of the Andean margin as large fore-arc blocks [e.g., Isacks, 1988;Kley, 1999;Macedo-Sanchez et al, 1992], and there is some indication that these rotations may continue to the present day [Lamb, 2000].…”

Section: A316 Tyrrhenian Basinmentioning

confidence: 62%

Collisional model for rapid fore‐arc block rotations, arc curvature, and episodic back‐arc rifting in subduction settings

Wallace

Ellis

Mann

2009

Geochem Geophys Geosyst

102

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[1] We review geophysical and geological data from 23 active and ancient plate boundaries to document a compelling spatial and temporal relationship between collision, plate boundary curvature, rapid tectonic rotations, and the occurrence of back-arc rifting. Our observations support a conceptual model where the change from subduction to collision causes rapid fore-arc rotation (when viewed in a reference frame relative to the bounding tectonic plates), leading to marked plate boundary curvature. Our global compilation reveals that most active back-arc rifts are associated with rapidly rotating fore arcs and nearby collisions. Thus, we propose that collision and rapid fore-arc rotations play a major role in the evolution and kinematics of back-arc basins. We conduct numerical modeling to better understand the physical processes behind these observed rapid tectonic rotations at convergent margins. Our results suggest that the presence of an indentor or choke point in the subduction system (e.g., collision) can generate rapid rotation of the fore arc about a nearby pole and lead to back-arc rifting. The rate of fore-arc rotation and back-arc rifting depends on the incoming indentor velocity and can be greatly enhanced by slab rollback and the presence of a low-viscosity back arc. Where viscosity of the back arc is low, fore-arc rotation dominates; where back-arc viscosity is high, the formation of strike-slip faults and tectonic escape dominates. Our observational and model-derived results illustrate that shallow crustal forces produced by the entry of buoyant features into subduction zones are a fundamental mechanism for the generation of fore-arc block rotations, plate boundary curvature, back-arc rift evolution, and tectonic escape in subduction systems. Rollback of the subducting slab within the mantle will certainly enhance the processes we describe but it is not the only driving force. Wallace, L. M., S. Ellis, and P. Mann (2009), Collisional model for rapid fore-arc block rotations, arc curvature, and episodic back-arc rifting in subduction settings, Geochem. Geophys. Geosyst., 10, Q05001,

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Section: A316 Tyrrhenian Basinmentioning

confidence: 62%

Collisional model for rapid fore‐arc block rotations, arc curvature, and episodic back‐arc rifting in subduction settings

Wallace

Ellis

Mann

2009

Geochem Geophys Geosyst

102

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“…The strain rates are typical of wide active plate boundary zones, with 7-15 mm/yr across 150-200 km, or ϳ5 × 10 −8 /yr, (Lamb and Vella 1987;Lamb 2000Lamb , 2015Flesch et al 2007). At this strain rate, the rate of surface uplift through crustal thickening, for a final crustal thickness of ϳ60 km, would be ϳ0.5 mm/yr or ϳ0.5 km/Myr.…”

Section: Rate Of Upliftmentioning

confidence: 99%

“…4, San Juan del Oro surfaces). Their existence shows that internal folding and thrusting within the Eastern Cordillera had ceased ϳ12 Ma, although conjugate strike-slip faulting continued and is active today (Lamb 2000;Funning et al 2005). …”

Section: Eastern Cordilleramentioning

confidence: 99%

“…The latter may be described by a simple "piston" model, in which the lower crust is squeezed and thickened by the rigid "piston" of the underthrust lithosphere ( Fig. 2; Isacks 1988; Gubbels et al 1993;Allmendinger and Gubbels 1996;Lamb 2000Lamb , 2011Hindle et al 2005;Barke and Lamb 2006;Sobolev et al 2006). In this case, for a piston of thickness C p , underthrust a distance S, lower crustal shortening and thickening across a final width (W f ) will result in surface uplift (U s ):…”

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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“…Many investigations of retroarc deformation, crustal thickening, plateau uplift, and foreland basin generation have emphasized the importance of horizontal shortening in driving Andean orogenesis [Isacks, 1988;Roeder, 1988;Sheffels, 1990;Schmitz, 1994;Wigger et al, 1994;Beck et al, 1996;Allmendinger et al, 1997;Lamb and Hoke, 1997]. Recently, GPS studies have provided an opportunity to compare modern displacements to geologic rates of shortening [Norabuena et al, 1998;Horton, 1999;Liu et al, 2000;Lamb, 2000;Bevis et al, 2001;Hindle et al, 2002;Khazaradze and Klotz, 2003]. These comparisons, however, arrive at conflicting conclusions about whether shortening rates have increased, decreased, or remained steady during Cenozoic deformation.…”

Section: Introductionmentioning

confidence: 99%

Revised deformation history of the central Andes: Inferences from Cenozoic foredeep and intermontane basins of the Eastern Cordillera, Bolivia

2005

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Investigation of Cenozoic deformation, sediment accumulation, and provenance in the Eastern Cordillera of Bolivia at 17–21°S indicates major shortening (60–140 km) and foredeep development followed by limited internal shortening and intermontane basin development. Contrasting histories of shortening, deposition, sediment dispersal, and detrital composition distinguish a formerly extensive Paleogene foredeep exposed along an eastern belt of synclines from a zone of principally Neogene intermontane basins in the central Eastern Cordillera. New 40Ar/39Ar ages of 25–17 Ma for interbedded tuffs reveal latest Oligocene–early Miocene accumulation in intermontane basins at rates <80 m/Myr, several times lower than Andean foredeeps. Although poorly dated, foredeep evolution probably coincided with middle Eocene–Oligocene deformation and denudation in adjoining regions to the west. A mid‐Cenozoic transition from foredeep to intermontane conditions may be attributable to emplacement of a basement‐involved tectonic wedge beneath the Eastern Cordillera. In this interpretation, wedge emplacement drove flexural foredeep subsidence from roughly 40 to 25 Ma, whereas subsequent accumulation occurred in localized internally drained basins in elevated intermontane areas. Regardless of the regional subsurface structural geometry, 40Ar/39Ar ages define a 25–21 Ma onset of intermontane sedimentation that signifies the termination of major upper crustal shortening over large parts of the Eastern Cordillera and possibly the age of initial shortening in the Interandean and Subandean zones to the east. In contrast to several popular models, the revised tectonic history presented here suggests significant pre‐Neogene shortening in the Eastern Cordillera and underscores the large uncertainties in estimates of long‐term shortening rates in the Andes.

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Active deformation in the Bolivian Andes, South America

Cited by 83 publications

References 51 publications

Collisional model for rapid fore‐arc block rotations, arc curvature, and episodic back‐arc rifting in subduction settings

Collisional model for rapid fore‐arc block rotations, arc curvature, and episodic back‐arc rifting in subduction settings

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

Revised deformation history of the central Andes: Inferences from Cenozoic foredeep and intermontane basins of the Eastern Cordillera, Bolivia

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