Mesozoic fault systems, deformation and fault block rotation in the Andean forearc: a crustal scale strike-slip duplex in the Coastal Cordillera of northern Chile

Taylor, Graeme K.; Grocott, John; Pope, A.; Randall, Darren E.

doi:10.1016/s0040-1951(98)00200-5

Cited by 80 publications

(44 citation statements)

References 36 publications

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“…In the other hand, the Paleogene deformation is more widely distributed across the Andes of northern Chile (Arriagada et al, 2000(Arriagada et al, , 2003(Arriagada et al, , 2006bTaylor et al, 2007). Eocene-Oligocene deformation was accompanied by tectonic shortening, mountain uplift and significant clockwise block rota tions (e.g., Hartley et al, 1992;Riley et al, 1993;Forsythe and Chisholm, 1994;Randall et al, 1996;Taylor et al, 1998;Arriagada et al, 2000;Somoza and Tomlinson, 2002;Arriagada et al, 2003Arriagada et al, , 2006bArriagada et al, , 2008. Fission track thermochronology indicates that tectonic uplift and erosion were mainly active during the EoceneEarly Oligocene 'Incaic Orogeny', when at least 4-5 km of rocks were eroded during exhumation of tectonic blocks of the Cordillera de Domeyko between ca.…”

Section: Introductionmentioning

confidence: 99%

The Lautaro Basin: A record of inversion tectonics in northern Chile

Martínez

Arriagada

Mpodozis

et al. 2012

andgeo

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ABsTrACT. The Triassic and Jurassic tectonic history of northern Chile has been dominated by extension, although clear evidence about the nature and geometry of the extensional basins and subsequent inversion structures has been adequately illustrated in only a few cases. In this contribution we present a structural study of the Lautaro Basin located at the western edge of the Frontal Cordillera in the Atacama region of northern Chile. The Lautaro Basin is a Jurassic half-graben, filled by at least 2,600 m of marine deposits of the Lautaro Formation and developed on top of, at least 2,000 m of Triassic volcanic successions of the La Ternera Formation, also accumulated during an earlier period of extensional deformation. Detailed field mapping and construction of a regional balanced cross-section, supported by good exposures along the Copiapó River valley, allow reconstruction of the structural style of both the Jurassic and Triassic extensional depocenters. New structural data have shown that the Lautaro Basin has a complex structural framework reflected in two major Mesozoic extensional periods, overprinted by Cenozoic inversion involving thin-and thick-skinned tectonics. Shortening was accommodated by a combination of inversion of pre-existing normal faults, buttresses, development of footwall short-cuts, and both thin and thick-skinned thrusting. New estimates of shortening are up to 13.1 km (30%), while Mesozoic extension is estimated to be 3 km (7%). resuMen. La Cuenca Lautaro: un registro de inversión tectónica en el norte de Chile. Durante el Triásico y Jurá-sico la evolución tectónica del norte de Chile fue dominada por extensión cortical. No obstante, evidencias claras acerca del estilo estructural y subsecuente inversión de las cuencas asociadas con el evento extensional, han sido ilustradas en pocos casos. En este trabajo, se presenta un estudio estructural de la Cuenca Lautaro, localizada en el borde occidental de la Cordillera Frontal, en la región de Atacama del norte de Chile. La Cuenca Lautaro, es un hemigraben que aloja al menos 2.600 m de depósitos marinos de la Formación Lautaro, acumulados sobre al menos 2.000 m de sucesiones volcánicas triásicas de la Formación La Ternera. Los excelentes afloramientos de la región permitieron construir una sección balanceada y restaurar el estilo estructural de los depocentros extensionales triásicos y jurásicos. Los resultados obtenidos muestran que la Cuenca Lautaro tiene una arquitectura estructural compleja, reflejada en dos episodios extensionales mayores. Posteriormente, se sobreimpone al menos un evento de inversión tectónica que desarrolla una tectónica mixta de piel fina y piel gruesa. El acortamiento se acomoda por una combinación de inversión de fallas preexistentes, desarrollo de fallas de atajo y corrimientos de piel fina y piel gruesa, que involucran bloques rígidos o 'buttresses'. Las estimaciones de acortamiento son de 13,1 km (30%), mientras que la extensión mesozoica es de 3 km (7%).

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Section: Introductionmentioning

confidence: 99%

The Lautaro Basin: A record of inversion tectonics in northern Chile

Martínez

Arriagada

Mpodozis

et al. 2012

andgeo

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“…[7] The rocks of the Coastal Cordillera record some of the largest paleomagnetic rotations in the Andes [Forsythe and Chisholm, 1994;Forsythe et al, 1987;Randall et al, 1996;Taylor et al, 1998]. The study area lies at the southern limit of the Central Valley between 26.5 and 27.5°S and east of the city of Copiapó (Figures 2 and 3).…”

Section: Geological and Tectonic Settingmentioning

confidence: 99%

Implications for crustal rotation and tectonic evolution in the central Andes fore arc: New paleomagnetic results from the Copiapó region of northern Chile, 26°–28°S

et al. 2007

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New paleomagnetic data from the Coastal Cordillera‐Precordillera boundary area of northern Chile, east of Copiapó, between 26°00′S and 28°00′S are reported. Early Cretaceous to earliest Paleocene volcanics and sediments are nearly completely remagnetized, the remagnetization typically being carried by both magnetite and hematite. In a small minority of sites a pretilting remanence is retained, however, both pretilting and posttilting remanences yield similar directions. These remanences plus primary remanences from Paleocene intrusions indicate a significant >35° rotation of the whole area, in agreement with previous results from the region. The data suggest that the whole of this part of the Andean fore arc has undergone a substantial, regionally coherent, clockwise rotation. This rotation, it is argued, is in response to rapid and highly oblique Nazca–South American plate convergence in the period ∼60–45 Ma prior to later Incaic deformation in the east of the study area. In the east, heterogeneous rotations associated with the Domeyko Fault System are interpreted as being superimposed on this regional rotation resulting in a highly variable and localized pattern of rotations in the vicinity of the main structures comprising the fault system itself.

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“…The magnitude of vertical axis rotations determined palaeomagnetically is frequently much larger than can be reconciled with observed fault slip displacements. For example, in the Coastal Cordillera of northern Chile, clockwise vertical axis rotations typically approach 45 ~ although it is difficult to identify displacements on faults at an appropriate scale and magnitude to account for these as simply localised in situ block rotations (Randall et aL 1996;Taylor et al 1998). This dilemma may be resolved in one of two ways: either a pattern of faults exists in space and time and at a range of scales, so that each fault set accounts for only an increment of the vertical axis rotation (Grocott & Taylor 2002); or rotation is achieved by distributed strain during (oroclinal) bending as described in this volume for the Japan arc by Fabbri, Iwamura, Matsunaga, Coromina & Kanaori.…”

Section: Vertical Axis Rotationsmentioning

confidence: 99%