‘Diffuse faulting’ in the Machu Picchu granitoid pluton, Eastern Cordillera, Peru

Mazzoli, Stefano; Vitale, Stefano; Delmonaco, Giuseppe; Guerriero, Vincenzo; Margottini, Claudio; Spizzichino, Daniele

doi:10.1016/j.jsg.2009.08.010

Cited by 24 publications

(9 citation statements)

References 28 publications

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“…En rocas cristalinas, tales como granitoides, rocas volcánicas y rocas metamórficas foliadas, la arquitectura de la roca, su composición, el enfriamiento y la exhumación influyen en el enlace de dichas estructuras para la iniciación de las fallas (Žák et al, 2006;Crider, 2015). La reactivación de las debilidades o estructuras precursoras es común a diversas escalas y por lo general requiere mucha menos energía que la generación de nuevas estructuras (Flodin y Aydin, 2004;Mazzoli et al, 2009). La ruptura de la roca y la reactivación de fallas preexistentes obedecen a múltiples parámetros como las orientaciones (rumbo e inclinación) de estructuras previas, la razón de esfuerzos y un régimen tectónico favorable, así como la profundidad, la cohesión, el coeficiente de fricción y la presión de poros (Alaniz-Álvarez et al, 1998).…”

Section: Introductionunclassified

“…Las heterogeneidades mecánicas (planos de debilidad preexistentes) tienen una fuerte influencia sobre la nucleación y la propagación de fallas, tal y como se ha documentado en estudios experimentales, así como, de campo (Martel, 1990;Peacock y Sanderson, 1992;Gross et al, 1997;Kattenhorn et al, 2000;Wilkins et al, 2001;Wilkins y Gross, 2002;Flodin y Aydin, 2004;Soliva y Benedicto, 2004;Mazzoli et al, 2009). Por ejemplo, se ha demostrado que tales heterogeneidades pueden evolucionar a fallas mayores, generando rampas de relevo y superficies de fallas corrugadas (Gupta y Scholz, 2000;Kattenhorn y Pollard, 2001;Mansfield y Cartwright, 2001;Marchal et al, 2003).…”

Section: Introductionunclassified

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Efecto de las fracturas de enfriamiento en la formación de fallas normales: El ejemplo de Santa María del Río, San Luis Potosí, México

Botero-Santa¹,

Xu²,

Nieto-Samaniego³

et al. 2020

BOL. SOC. GEOL. MEX.

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The reactivation of pre-existing fractures is an important issue in the study of nucleation, union, growth, and evolution of fault systems. Pre-existing zones of weakness, such as cooling fractures, can determine the configuration of important fault systems. In particular, it is important to study the role of cooling fractures in the reactivation of faults for three reasons: first, there are many cooling fractures in volcanic rocks; second, the vertical fractures have a low tendency to slip; and third, there are many strikes and striae in several directions, making it difficult to interpret their mecha nical origin. This paper presents an example of a fault system that overprinted on a volcanic field in

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Section: Introductionunclassified

Efecto de las fracturas de enfriamiento en la formación de fallas normales: El ejemplo de Santa María del Río, San Luis Potosí, México

Botero-Santa¹,

Xu²,

Nieto-Samaniego³

et al. 2020

BOL. SOC. GEOL. MEX.

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“…Sericitization of feldspars triggers both an 62 increase of the rock ductility and a decrease of its strength. The deformation of mica-rich 63 et al, 2002; Butler and Mazzoli, 2006;Carminati, 2009, Mazzoli et al, 2009 mainly because 78 markers are usually lacking and polyphased tectonic history complicates strain analysis. In the 79 basement units of the Axial Zone in the Pyrenees (Fig.…”

Section: Introduction 43mentioning

confidence: 99%

Shortening of the axial zone, pyrenees: Shortening sequence, upper crustal mylonites and crustal strength

et al. 2019

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The strength of the lithosphere may be constrained qualitatively by field observations on 19 localized vs distributed modes of deformation and by the mineral assemblages formed during 20 deformation. The internal deformation of the Bielsa basement unit of the Pyrenean Axial zone 21 is investigated through structural, microstructural and thermometric data. In this area, 22 shortening is widely distributed as attested by the folded attitude of the interface between the 23 basement and its sedimentary Triassic cover. Shortening is estimated around 1.7 km (13%) 24 from a regional balanced cross-section and should be considered in pre-Pyrenean 25 reconstructions. Shortening probably occurred before strain localization on crustal ramps as 26 suggested by zircon fission-track analysis. Distributed shortening is characterized at small-27 scale by low-temperature mylonites and cataclasites. In thin-section, feldspar originally 28 present in magmatic rocks is partially to totally sericitized. This transformation led to 29 significant weakening of the rock and took place in the 250-350°C temperature range. 30 Sericitization is ubiquitous, even in un-deformed granodiorites. This shows that the 31 weakening effect of sericitization not only occurs in ultra-mylonites, ultra-cataclasites and 32 2 phyllonites but also more generally in the upper crust early during the shortening history, with 33 implications for the shortening style. Estimates of the geothermal gradient suggest that 34 inherited thermicity may also have influenced the style of shortening. We propose that the 35 upper crust was very weak before or at the onset of its shortening due to high-thermal gradient 36 and fluid circulation that induced large-scale sericitization in greenschist facies conditions. 37 This has strong implications on the rheological evolution of the upper crust submitted to 38 metamorphic alteration in the greenschist facies and below.

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“…This is interpreted to be due to the fact that the continental lithosphere of the foreland plate is generally cooler and stronger with respect to that of the orogen, which is characterized by a warmer lithosphere and therefore a weaker rheology [ Butler and Mazzoli , ]. In the Andes, basement shortening associated with strong inversion and uplift of the axial zone of the Permo‐Triassic rift in the Eastern Cordillera of Peru, although being accommodated by localized shear involving widespread reactivation (at lower greenschist facies conditions) of inherited mesoscopic fractures, has been documented to represent a process of distributed strain at the orogen scale [ Mazzoli et al ., ]. This process has been invoked to explain internal straining of basement blocks in order to accommodate thick‐skinned Andean shortening (e.g., in the Malargüe fold and thrust belt of Argentina, at latitudes 34–36°S) [ Mescua et al ., ].…”

Section: Introductionmentioning

confidence: 99%

(Un)Coupled thrust belt‐foreland deformation in the northern Patagonian Andes: New insights from the Esquel‐Gastre sector (41°30′–43°S)

et al. 2016

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The Patagonian Andes represents a unique natural laboratory to study surface deformation in relation to deep slab dynamics. In the sector comprised between latitudes 41°30′ and 43°S, new apatite (U‐Th)/He ages indicate a markedly different unroofing pattern between the “broken foreland” area (characterized by Late Cretaceous to Paleogene exhumation) and the adjacent Andean sector to the west, which is dominated by Miocene‐Pliocene exhumation. These unroofing stages can be confidently ascribed to inversion tectonics involving reverse fault‐related uplift and concomitant erosion. Late Cretaceous‐Paleogene shortening and exhumation are well known to have affected also the thrust belt sector of the study area during a prolonged stage of flat‐slab subduction. Therefore, the different ages of near‐surface unroofing documented in this study suggest coupling of the deformation between the thrust belt and its foreland during periods of flat‐slab subduction (e.g., during Late Cretaceous‐Paleogene times) and dominant uncoupling during periods of steep‐slab subduction and rollback, even when these are associated with high convergence rates (i.e., > 4 cm/yr), as those documented in Miocene times for the Patagonian Andes.

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‘Diffuse faulting’ in the Machu Picchu granitoid pluton, Eastern Cordillera, Peru

Cited by 24 publications

References 28 publications

Efecto de las fracturas de enfriamiento en la formación de fallas normales: El ejemplo de Santa María del Río, San Luis Potosí, México

Efecto de las fracturas de enfriamiento en la formación de fallas normales: El ejemplo de Santa María del Río, San Luis Potosí, México

Shortening of the axial zone, pyrenees: Shortening sequence, upper crustal mylonites and crustal strength

(Un)Coupled thrust belt‐foreland deformation in the northern Patagonian Andes: New insights from the Esquel‐Gastre sector (41°30′–43°S)

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