Transpresión dextral y partición de la deformación en la Zona de Falla Liquiñe-Ofqui, Aisén, Chile (44-45&amp;ordm;S)

Arancibia, Gloria; Cembrano, José; Lavenu, Alain

doi:10.4067/s0716-02081999000100001

Cited by 43 publications

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“…Cembrano and Hervé [1993] interpreted en échelon lineaments in the southern segment of the LOFZ (44°S-46°S) as part of a dextral, crustal-scale duplex structure. Combined structural and geochronological [Arancibia et al, 1999;Lavenu and Cembrano, 1999;Cembrano et al, 2002;Lagabrielle et al, 2004] and thermochronological [Thomson, 2002;Adriasola et al, 2006] studies demonstrated the Neogene dextral transpressional kinematics of this duplex structure. To the south (46°S-47.5°S), the LOFZ bends seaward into the Golfo de Penas, which has been interpreted as an actively spreading, LOFZ-related, pull-apart basin at the trailing edge of the Chiloé block Murdie et al, 1993].…”

Section: Plate Tectonic Setting and Regional Geologymentioning

confidence: 99%

Kinematic constraints on intra‐arc shear and strain partitioning in the southern Andes between 38°S and 42°S latitude

2006

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[1] On the basis of structural field work, fault kinematic analysis, and the analysis of digital imagery, we describe the northern part of the southern Andean intra-arc Liquiñe-Ofqui Fault Zone (LOFZ) as an SC-like fault zone system accommodating part of the Nazca-South American plate convergence obliquity. Kinematic modeling suggests that the LOFZ accommodated 124 (+24/À21) km of dextral displacement between 40°S and 42°S and 67 (+13/À11) km between 38°S and 40°S since the Pliocene. Associated vertical axis rotations are 31 ± 4°c lockwise and 9 ± 1°counterclockwise along synthetic and antithetic faults, respectively. Mean Pliocene to recent shear rates along the LOFZ decrease northward from 32 ± 6 mm/yr to 13 ± 3 mm/yr compatible with partitioning of half of the convergence obliquity into the intra-arc zone north of 40°S and complete partitioning to the south. The displacement gradient along the intra-arc zone results in margin-parallel shortening of the fore arc.

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Section: Plate Tectonic Setting and Regional Geologymentioning

confidence: 99%

Kinematic constraints on intra‐arc shear and strain partitioning in the southern Andes between 38°S and 42°S latitude

2006

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“…1). The right lateral strike-slip, oblique slip, reverse slip ductile to brittle deformation characterizing a transpressional regime along this system has been active during the late Cenozoic (Cembrano et al, 1996(Cembrano et al, , 2002Lavenu and Cembrano, 1999;Arancibia et al, 1999;Thomson, 2002;Rosenau et al, 2006;Adriasola et al, 2006), associated to the oblique northeasterly (N77ºE) subduction of the Nazca plate beneath the South American plate, with an average of 66 mm/yr at present (Angermann et al, 1999). South of 46-47ºS, the convergence margin is characterized by orthogonal subduction of the Antarctic plate beneath the South American plate at an average rate of 20 mm/yr (DeMets et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

“…Regional tectonic context at the triple junction of the Nazca, Antarctic and SouthAmerican plates, and location of the 2007 seismic swarm that occurred in the Patagonian Andes. Left top: Regional tectonic plate's context of the Patagonian Andes, indicating the main regional trace of the intra-arc Liquiñe-Ofqui Fault Zone and Late Pleistocene-Holocene large volcanoes (LOFZ; Forsythe and Nelson, 1985;Hervé, 1994;Cembrano et al, 1996Cembrano et al, , 2002Arancibia et al, 1999;Thomson, 2002;Adriasola et al, 2006;Rosenau et al, 2006;Stern et al, 2007;Melnick et al, 2009). Black lines to the left show the latitudinal rupture of the 1960 Valdivia earthquake (Plafker and Savage, 1970;Kanamori, 1977;Cifuentes, 1989), and the 2010 Maule earthquake (Farías et al, 2010;Vargas et al, 2011;Vigny et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Submarine earthquake rupture, active faulting and volcanism along the major Liquiñe-Ofqui Fault Zone and implications for seismic hazard assessment in the Patagonian Andes

Vargas

Rebolledo

Sepúlveda

et al. 2013

andgeo

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ABSTRACT. The Liquiñe-Ofqui fault zone (LOFZ) in the Patagonian Andes is an active major transpressional intra-arc fault system along which Quaternary faulting and volcanism develop. Subaerial and submarine geomorphologic and structural characterization of latest Pleistocene-Holocene faults and monogenetic volcanoes allows us to assess geological cartography of active faults and the kinematic model for recent tectonics during postglacial times, since 12,000 cal. years BP. This allows increasing the basic geological knowledge necessary for determining the seismic hazard associated with cortical structures in the Aysén region in southern Chile. Fault cartography and field observations suggest dominant dextral-reverse strike slip along north-south and locally NNW-striking faults, dextral-normal strike slip along NE to NNE-striking faults, and sinistral strike slip along east-west faults. This kinematics is consistent with regional SW-NE shortening in the context of a major transpressional fault zone. Holocene and even historic monogenetic and sub-aquatic volcanism occurred in this tectonic setting in a close spatial relationship and probably favored by the activity and local architecture of faults. Submarine fault scarps and deformed sediments observed at the bottom of the Aysén Fjord were associated with the destructive April 2007 Mw6.2 earthquake located along the LOFZ. Our observations show that this earthquake occurred along dextral 15-20 km long N-S structure named Punta Cola Fault (PCF). This fault system is located some kilometres to the east of the main N-S Río Cuervo Fault (RCF). Most of the epicentres of the seismic swarm during 2007 were located along or in between both structures. The study area is a transference zone between N-S regional branches of the LOFZ. The cartography of fault segments proposed here together with geophysical and geologic data suggest that large earthquakes Mw6.2-6.5 can be typically expected along most of the active faults. Besides, seismic hazard assessment should also consider the possibility of earthquake magnitude in the order of 7.1 along the main fault systems like the RCF. RESUMEN.Ruptura sísmica submarina, tectónica y volcanismo activo a lo largo de la Falla Liquiñe-Ofqui e implicancias para el peligro sísmico en los Andes patagónicos. La Zona de Falla Liquiñe-Ofqui es un sistema de intraarco activo y paralelo al contacto entre las placas tectónicas de Nazca y Sudamérica, a lo largo del cual el fallamiento y el volcanismo cuaternarios están estrechamente asociados. A partir de observaciones geomorfológicas y estructurales subaéreas, la prospección subacuática de fallas con evidencia de actividad pleistocena tardía-holocena y la caracterización de volcanes monogenéticos, se propone una cartografía y un modelo cinemático para la tectónica reciente, con énfasis en los últimos 12.000 años, asociada a fallas activas en el área del Fiordo Aysén. Esto permite incrementar sustancialmente el conocimiento geológico básico necesario para la determinación del peligro sísmico asocia...

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“…To the north of the CTJ, the most obvious structure is the long-lived intra-arc Liquiñe-Ofqui fault zone (LOFZ, Hervé, 1976;Cembrano et al, 1996Cembrano et al, , 2000, which has accommodated an arc-parallel component of plate motion and controlled the emplacement of intrusions of the NPB (Hervé et al, 1993Pankhurst et al, 1992Pankhurst et al, , 1999Cembrano et al, 2002). Shaded relief digital elevation modeling (Rosenau et al, 2006), regional and structural fi eld mapping (Thiele et al, 1986;SERNAGEOMIN-BRGM, 1995 1 ;Diriason et al, 1998;Arancibia et al, 1999;Lavenu and Cembrano, 1999), microstructural analyses (Cembrano et al, 1996(Cembrano et al, , 2002Arancibia et al, 1999), and Ar/Ar laser-total fusion and step-heating geochronology of synkinematic minerals (Cembrano et al, , 2002López, 2001) in deformed plutonic rocks consistently demonstrate right-lateral transpression along the LOFZ in Late Miocene to Pliocene times. This interpretation is supported by apatite and zircon fi ssion track thermochronometric data collected along the southern Andes between 41° and 47°S, indicating an episode of enhanced cooling and denudation along the LOFZ in the Late Miocene to Pliocene (Thomson et al, 2001;Thomson, 2002;Adriasola et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Cooling histories and deformation of plutonic rocks along the Liquiñe-Ofqui Fault Zone, Southern Chile (41°-42°15'S)

Adriasola

Stöckhert

2008

Rev. geol. Chile

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ABSTRACT. Structural and microstructural observations combined with apatite and zircon fi ssion-track thermochronology within two sectors of the Main Andean Range in the Los Lagos Region of Chile reveal an episodic history of intrusion and deformation in the North Patagonian Batholith (NPB). A dextral displacement of ~30 km along the Liquiñe-Ofqui fault zone (LOFZ) is inferred from the correlation of corresponding Cretaceous intrusions of the NPB across the fault zone at Reloncaví. Relative uplift of the western block in the late Miocene is indicated by apatite and zircon fi ssiontrack cooling histories. Microstructures in samples from Miocene and Cretaceous plutons along the fault zone generally indicate deformation at temperatures below ~300°C, with the exception of some samples from Cretaceous intrusions showing deformation at higher temperatures. In the Hornopirén area, signifi cant relative uplift of the eastern block is indicated by 1. the different styles of deformation observed across the fault zone, 2. kinematic analysis of a shear zone in tonalite and 3. geobarometry of contact metamorphic mineral assemblages. For the plutonic rocks in the Hornopirén area, extremely rapid cooling is indicated by thermochronometry, suggesting the activity of hydrothermal systems or thermal effects of late shallow intrusions.

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Transpresión dextral y partición de la deformación en la Zona de Falla Liquiñe-Ofqui, Aisén, Chile (44-45ºS)

Cited by 43 publications

References 0 publications

Kinematic constraints on intra‐arc shear and strain partitioning in the southern Andes between 38°S and 42°S latitude

Kinematic constraints on intra‐arc shear and strain partitioning in the southern Andes between 38°S and 42°S latitude

Submarine earthquake rupture, active faulting and volcanism along the major Liquiñe-Ofqui Fault Zone and implications for seismic hazard assessment in the Patagonian Andes

Cooling histories and deformation of plutonic rocks along the Liquiñe-Ofqui Fault Zone, Southern Chile (41°-42°15'S)

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