Tectonic segmentation of the North Andean margin: impact of the Carnegie Ridge collision

Gutscher, Marc‐André; Malavieille, Jacques; Lallemand, Serge; Collot, Jean‐Yves

doi:10.1016/s0012-821x(99)00060-6

Cited by 351 publications

(344 citation statements)

References 44 publications

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“…The intersecting basement ridges to the foothills of the Himalaya apparently inhibit the occurrence of great earthquakes. Similar inferences were also drawn elsewhere along subduction margins [56][57][58] . The bending portion of the lithosphere was probably the high-strained zone of stress accumulation 59 , and deformed severely before the mainshock.…”

Section: Discussionsupporting

confidence: 78%

Insights into the Great <i>Mw</i> 7.9 Nepal Earthquake of 25 April 2015

2017

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The 2015 Mw 7.9 earthquake occurred in the Nepal Himalaya between the Indian and Asian plates. The gravity modelling has been carried out along a 2D trench-orthogonal profile passing through the epicentre of this earthquake. The projections of mainshocks and aftershocks show their major confinement around the bending segment of the Indian upper crust (IUC). The operative shallowly plunging maximum compressive stress led to the accumulation of strain energy around the bending zone of the IUC, and triggered thrust-dominated southward movement of the Indian crustal block along a shallowly, dipping shear plane in the anisotropic layer. This can be broadly explained by three-stage rupture processes: the first one was associated with slow nucleation and rupture growth for early ~15 sec, the second one migrated upward, rupturing the uppermost part of the IUC for the next ~10 sec, and the third one propagated very fast during deformation for the remaining ~25 sec till the fracture-tip reached the overlying brittle Asian crust.

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Section: Discussionsupporting

confidence: 78%

Insights into the Great <i>Mw</i> 7.9 Nepal Earthquake of 25 April 2015

2017

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“…These values, however, may be larger when besides young subduction also older slabs subduct at the same subduction zone in a 3-D con¢guration, in which case the pulling force of slab roll-back may contribute considerably. This may for example be the case at the west coast of South America [13]. These estimates show that the power, introduced by the velocity boundary conditions, is probably of the correct order of magnitude.…”

Section: Discussionmentioning

confidence: 71%

“…Furthermore, the trench roll-back is a result of the pulling force which is generated by an old and heavy slab and not by young and gravitationally stable slabs. Buoyant plateaus may give an explanation for shallow £attening of the subducting plates [13], but do not form a driving mechanism for this type of subduction. With adherence to the overriding plate by a non-hydrostatic pressure force [17] or a slab suction force [18,19], a de£ection of the subducting slab towards the horizontal can be explained.…”

Section: Introductionmentioning

confidence: 99%

A thermo-mechanical model of horizontal subduction below an overriding plate

Hunen

Berg

Vlaar

2000

Earth and Planetary Science Letters

112

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Subduction of young oceanic lithosphere cannot be explained by the gravitational driving mechanisms of slab pull and ridge push. This deficiency of driving forces can be overcome by obduction of an actively overriding plate, which forces the young plate either to subduct or to collide. This mechanism leads to shallow flattening of the slab as observed today under parts of the west coast of North and South America. Here this process is examined by means of numerical modeling. The convergence velocity between oceanic and continental lithospheric plates is computed from the modeling results, and the ratio of the subduction velocity over the overriding velocity is used as a diagnostic of the efficiency of the ongoing subduction process. We have investigated several factors influencing the mechanical resistance working against the subduction process. In particular, we have studied the effect of a preexisting lithospheric fault with a depth dependent shear resistance, partly decoupling the oceanic lithosphere from the overriding continent. We also investigated the lubricating effect of a 7 km thick basaltic crustal layer on the efficiency of the subduction process and found a log^linear relation between convergence rate and viscosity prefactor characterizing the strength of the oceanic crust, for a range of parameter values including values for basaltic rocks, derived from empirical data. A strong mantle fixes the subducting slab while being overridden and prevents the slab from further subduction in a Benioff style. Viscous heating lowers the coupling strength of the crustal interface between the converging plates with about half an order of magnitude and therefore contributes significantly to the subduction process. Finally, when varying the overriding velocity from 2.5 to 10 cm yr 31 , we found a non-linear increase of the subduction velocity due to the presence of non-linear mantle rheology. These results indicate that active obduction of oceanic lithosphere by an overriding continental lithosphere is a viable mechanism for shallow flat subduction over a wide range of model parameters. ß

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“…[85] Several aseismic ridges have been subducting at this margin for at least the last 20 Ma, and previous workers have discussed the role that ridge subduction may play in the fore-arc tectonics [e.g., Yañez et al, 2001;Gutscher et al, 1999], curvature, and rotation of the Andean margin [e.g., Rousse et al, 2003]. For example the Juan Fernandez ridge was being subducted at the bend of the Bolivian Orocline at $25 Ma ago [Yañez et al, 2001], coinciding with the onset of deformation and rotations associated with formation of the orocline at 25 Ma ago [e.g., Rousse et al, 2003;Roperch et al, 2000].…”

Section: A316 Tyrrhenian Basinmentioning

confidence: 99%

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

104

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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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Tectonic segmentation of the North Andean margin: impact of the Carnegie Ridge collision

Cited by 351 publications

References 44 publications

Insights into the Great <i>Mw</i> 7.9 Nepal Earthquake of 25 April 2015

Insights into the Great <i>Mw</i> 7.9 Nepal Earthquake of 25 April 2015

A thermo-mechanical model of horizontal subduction below an overriding plate

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

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