Tectonic Development of the North Chilean Andes in Relation to Plate Convergence and Magmatism Since the Jurassic

Scheuber, Ekkehard; Bogdanic, T.; Jensen, Arturo; Reutter, Klaus-J.

doi:10.1007/978-3-642-77353-2_9

Cited by 108 publications

(104 citation statements)

References 27 publications

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“…The WF is usually described as a sub-vertical strike-slip fault system integrating the Precordilleran Fault System (e.g. Scheuber and Reutter, 1992;Scheuber et al, 1994;Reutter et al, 1996;Victor et al, 2004). The change in relative velocities west and east of the WF indicates variations in the composition of the rocks and thermal state of the materials across these faults.…”

Section: Discussionmentioning

confidence: 99%

More constraints to determine the seismic structure beneath the Central Andes at 21°S using teleseismic tomography analysis

Heit¹,

Koulakov²,

Asch³

et al. 2008

Journal of South American Earth Sciences

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A set of seismological stations was deployed in the Central Andes region along a ~600 km long profile at 21°S between Chile and Bolivia and operated for a period of almost two years, from March 2002 to January 2004. Here we present the results of the tomographic inversion for P-wave velocity anomalies, based on teleseismic data recorded at the stations. The reliability of the results has been checked by a series of synthetic tests. The tomographic images show high-velocities on the west of the profile that are indicative of cold material from the fore-arc. A low-velocity anomaly is detected at the border between the fore-and the volcanic arc where the Quebrada Blanca seismic anomaly was previously described. This anomaly might be related to the presence of fluids that originate at the cluster of earthquakes at a depth of ~100 km in the subducted plate. A strong low-velocity anomaly is detected beneath the entire Altiplano plateau and part of the Eastern Cordillera, in agreement with previous receiver function results. The Brazilian Shield is thought to be responsible for the strong high-velocity anomaly underneath the Interandean and Subandean regions.

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Section: Discussionmentioning

confidence: 99%

More constraints to determine the seismic structure beneath the Central Andes at 21°S using teleseismic tomography analysis

Heit¹,

Koulakov²,

Asch³

et al. 2008

Journal of South American Earth Sciences

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“…The magmatic arc was dominated by tholeiitic basaltic rocks, gabbros and mafic dykes associated with calcalkaline andesites and basaltic andesite flows with almost no contribution from the underlying crust (Mpodozis and Ramos 1990;Scheuber et al 1994;Oliveros et al 2006). These basic rocks were dominant in the present Cordillera de La Costa and are very near to the present-day trench.…”

Section: Tarapacá Segment (218-278s Lat)mentioning

confidence: 99%

“…Periods of increased convergence have been linked with uplift and deformation, whereas slow convergence rates have been associated with extensional tectonics (Sébrier et al 1988;Scheuber et al 1994). However, the variations in convergence rates as depicted by Pardo Casas and Molnar (1987) and Somoza (1998) have a significant role in increasing or decreasing the deformation, but subordinated to the absolute plate motion.…”

Section: Strike-slip Regimesmentioning

confidence: 99%

The tectonic regime along the Andes: Present‐day and Mesozoic regimes

Ramos¹

2009

Geological Journal

227

139

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The analyses of the main parameters controlling the present Chile-type and Marianas-type tectonic settings developed along the eastern Pacific region show four different tectonic regimes: (1) a nearly neutral regime in the Oregon subduction zone; (2) major extensional regimes as the Nicaragua subduction zone developed in continental crust; (3) a Marianas setting in the Sandwich subduction zone with ocean floored back-arc basin with a unique west-dipping subduction zone and (4) the classic and dominant Chile-type under compression. The magmatic, structural and sedimentary behaviours of these four settings are discussed to understand the past tectonic regimes in the Mesozoic Andes based on their present geological and tectonic characteristics. The evaluation of the different parameters that governed the past and present tectonic regimes indicates that absolute motion of the upper plate relative to the hotspot frame and the consequent trench roll-back velocity are the first order parameters that control the deformation. Locally, the influences of the trench fill, linked to the dominant climate in the forearc, and the age of the subducted oceanic crust, have secondary roles. Ridge collisions of seismic and seismic oceanic ridges as well as fracture zone collisions have also a local outcome, and may produce an increase in coupling that reinforces compressional deformation. Local strain variations in the past and present Andes are not related with changes in the relative convergence rate, which is less important than the absolute motion relative to the Pacific hotspot frame, or changes in the thermal state of the upper plate. Changes in the slab dip, mainly those linked to steepening subduction zones, produce significant variations in the thermal state, that are important to generate extreme deformation in the foreland.

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“…Most likely this represents the southernmost occurrence of similar phenomena widespread in northern Chile during Jurassic times. Left-lateral strike-slip during Jurassic times, causing stretching of the outermost continental margin, becomes prominent in northern Chile known as the Atacama fault system (e.g., Scheuber et al, 1994;Scheuber and González, 1999). On the other hand, the strike-slip system may have commenced during late Triassic times and thus could be related to the marked tectonic change throughout central Chile, which involved basin formation in the former accretionary wedge and granitoid intrusion into the Western Series.…”

Section: The Jurassic Post-accretion Developmentmentioning

confidence: 99%

“…Particularly, the traverse east of Constitución (35°30'S) was shown to represent a complete and coherent architecture of the accretionary system (Willner, 2005;Richter et al, 2007). Particularly in northern Chile, episodic destruction of the continental margin by shortening-related subduction erosion during Mesozoic times is supposed to have affected the metamorphic basement (e.g., Scheuber et al, 1994;Scheuber and González, 1999). Kay et al (2005) proposed that subduction erosion affected the margin at 34°S during late Tertiary times.…”

Section: Introductionmentioning

confidence: 99%

Structural overprint of a late Paleozoic accretionary system in north-central Chile (34°-35°S) during post-accretional deformation

Willner

Richter

Ring

2009

AndGeo

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ABSTRACT. In the Coastal Cordillera of central Chile a coherently preserved architecture of a late Paleozoic accretionary prism is exposed at 36°-35°S in close spatial association with a neighbouring area at 34°-35°S, where it is strongly modifi ed by post-accretional processes. Syn-and post-accretional structures can be distinguished relatively easily in this region studying the deviations from the original architecture. South of 35°S a transitional contact between two major units is observed, which refl ects a continuous change of the mode of accretion in the accretionary wedge before ~305 Ma: the structurally overlying metagreywacke of the Eastern Series exhibits structures typical of frontal accretion, i.e., subvertical chevron folds of bedding planes with an axial-plane foliation S 1 . With increasing fi nite strain structurally downwards, open F 2 folds develop associated with a S 2 -foliation which becomes gradually fl attened as it rotates into a subhorizontal orientation. S 2 is the penetrative transposition foliation in the structurally underlying Western Series. It affects the continent-derived metagreywacke series as well as metabasite intercalations of oceanic origin and was formed during basal accretion. This principal evolution of the accretionary system places fi rm constraints on the original architecture also in regions where it was destructed after accretion. Accretion ceased at ~225 Ma, when a major tectonic change from a convergent to an extensional/strike-slip regime occurred. Although the development of the margin in central Chile is largely characterized by extension during Mesozoic and Cenozoic times, two pronounced episodes involving shortening of the forearc particularly affected the Western Series north of 35°S: 1. Expressions of strike-slip activity during Jurassic times involve local steepening of the originally fl at S 2 -foliation planes, local rotation of the stretching lineation L 2 into the N-S direction, tight upright folding of the S 2 foliation and refolding about steep axes with associated vertical cataclastic left-lateral shear zones. 2. The left-lateral reverse Pichilemu-Vichuquén fault at the boundary between both units is a prominent brittle structure that formed at ~100 Ma concomitant with basin closure and acceleration of exhumation rates in the forearc. Similar contractional structures occur along the coast further north, where both units partly disappeared by subduction erosion most likely during these deformation episodes. The transition between nearly unaffected accretion systems in the south and disrupted and partly subducted ones in the north occurs at 35°S. (34°-35°S)... (34°-35°S), durante deformación posacrecional. En la Cordillera de la Costa de Chile, de 36° a 35°S, se encuentra expuesta la arquitectura coherentemente preservada de un prisma de acreción del Paleozoico tardío, en cercana vecindad a un área entre los 34° y 35°S, donde el mismo está fuertemente modifi cado por procesos postacrecionales. Estudiando las desviaciones de la arquitectura original,...

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Tectonic Development of the North Chilean Andes in Relation to Plate Convergence and Magmatism Since the Jurassic

Cited by 108 publications

References 27 publications

More constraints to determine the seismic structure beneath the Central Andes at 21°S using teleseismic tomography analysis

More constraints to determine the seismic structure beneath the Central Andes at 21°S using teleseismic tomography analysis

The tectonic regime along the Andes: Present‐day and Mesozoic regimes

Structural overprint of a late Paleozoic accretionary system in north-central Chile (34°-35°S) during post-accretional deformation

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