Tectonics, magmatism and paleo-fluid distribution in a strike-slip setting: Insights from the northern termination of the Liquiñe–Ofqui fault System, Chile

Pérez-Flores, Pamela; Cembrano, José; Sánchez-Alfaro, Pablo; Veloso, Eugenio E.; Arancibia, Gloria; Roquer, Tomás

doi:10.1016/j.tecto.2016.05.016

Cited by 81 publications

(74 citation statements)

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“…The convergence vector direction has been relatively constant over the last 10 Ma (Pardo‐Casas & Molnar, ). Late Miocene‐Pliocene transpressional deformation is well documented by field structural geology combined with geochronological data (Arancibia et al, ; Cembrano et al, , ; Lavenu & Cembrano, ; Pérez‐Flores et al, ; Rosenau et al, ), as well as by geodetic and seismological studies (e.g., Agurto et al, ; Haberland et al, ; Lange et al, ; Legrand et al, ; Moreno et al, ; Wang et al, ).…”

Section: Tectonic Setting Of Southern Andesmentioning

confidence: 91%

“…The Southern Andes are characterized by long‐term partial partitioning of an overall transpressional deformation regime arising during interseismic phases of the subduction earthquake cycle (e.g., Arancibia et al, ; Cembrano et al, ; Lavenu & Cembrano, ; Pérez‐Flores et al, ). Dextral‐oblique convergence between the Nazca and South American plates trends N80°, with an average velocity of ca.…”

Section: Tectonic Setting Of Southern Andesmentioning

confidence: 99%

“…In the Andean Southern Volcanic Zone (SVZ), in particular along the margin‐parallel Liquiñe‐Ofqui Fault System (LOFS), stratovolcanoes, minor eruptive centers, and geothermal features, are spatially related to the geometry and kinematics of long‐lived faults (Cembrano & Lara, ; Sánchez‐Alfaro et al, ). Additionally, for the long‐term geological record, margin‐parallel faults (i.e., LOFS) coexist with second order transverse‐to‐the‐arc oriented faults (Andean Transverse Faults, ATF; Aron et al, ; Kaizuka, ; Katz, ; Melnick et al, ; Yáñez et al, ; among others), developing a causal relationship with crustal fluid‐flow (Cembrano & Lara, ; Pérez‐Flores et al, , ; Sánchez‐Alfaro et al, ; Tardani et al, ; Wrage et al, ). Based on kinematic and dynamic analysis of fault‐slip data, Pérez‐Flores et al () suggest that bulk transpressional deformation is partially partitioned into variable orientations and scales within the Southern Volcanic Zone (SVZ) of the Andean magmatic arc.…”

Section: Introductionmentioning

confidence: 99%

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Intra‐Arc Crustal Seismicity: Seismotectonic Implications for the Southern Andes Volcanic Zone, Chile

2019

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We examine the intra-arc crustal seismicity of the Andean Southern Volcanic Zone. Our aim is to resolve interseismic deformation in an active magmatic arc dominated by both margin-parallel (Liquiñe-Ofqui fault system, LOFS) and Andean transverse faults. Crustal seismicity provides information about the schizosphere tectonic state, delineating the geometry and kinematics of high strain domains driven by oblique-subduction. Here, we present local seismicity based on 16-month data collected from 34 seismometers monitoring a~200-km-long section of the Southern Volcanic Zone, including the Lonquimay and Villarrica volcanoes. We located 356 crustal events with magnitudes between M w 0.6 and M w 3.6. Local seismicity occurs at depths down to 40 km in the forearc and consistently shallower than 12 km beneath the volcanic chain, suggesting a convex shape of the crustal seismogenic layer bottom. Focal mechanisms indicate strike-slip faulting consistent with ENE-WSW shortening in line with the long-term deformation history revealed by structural geology studies. However, we find regional to local-scale variations in the shortening axes orientation as revealed by the nature and spatial distribution of microseismicity, within three distinctive latitudinal domains. In the northernmost domain, seismicity is consistent with splay faulting at the northern termination of the LOFS; in the central domain, seismicity distributes along ENE-and WNW-striking discrete faults, spatially associated with, hitherto seismic Andean transverse faults. The southernmost domain, in turn, is characterized by activity focused along a N15°E striking master branch of the LOFS. These observations indicate a complex strain compartmentalization pattern within the intra-arc crust, where variable strike-slip faulting dominates over dip-slip movements.Plain Language Summary In active volcanic chains, there is a strong interplay between deformation and volcanism. In this research, we take the "pulse" of active tectonics in a volcanic arc setting by measuring natural seismicity. We installed a network of 34 seismometers over 200 km along the volcanic arc in Southcentral Chile. Our results indicate active faulting in coherence with long-lived faults and the overall regional-scale stress regime. In fact, crustal regions in which faults are more active are spatially associated with inherited faults and with higher temperature gradient domains, as inferred from volcanic and geothermal activity. The maximum depth of seismicity is shallow (<12 km) in the central part of the volcanic arc, whereas is much deeper (~40 km) toward the forearc and back-arc regions. This observation suggests that elevated geothermal gradients lead to a thinner brittle portion of crust, which is then mechanically easier to (re-)break up. Our results can be used for understanding the way by which faulting interacts with crustal fluids, which in turn may help improving geothermal exploration strategies and seismic hazard assessment. Furthermore, seismicity reveals detailed information on how...

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Section: Tectonic Setting Of Southern Andesmentioning

confidence: 91%

Section: Tectonic Setting Of Southern Andesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Intra‐Arc Crustal Seismicity: Seismotectonic Implications for the Southern Andes Volcanic Zone, Chile

2019

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“…Ofqui Fault System (LOFS) and the NW-trending Arc-Oblique Fault System (ALFS) (Cembrano and Lara, 2009;Sánchez et al, 2013;Tardani et al, 2016: Perez-Flores et al, 2016. Within this setting, the active Tolhuaca geothermal field in the northern termination of the LOFS hosts a high enthalpy system that has been drilled to ~3 km depth but is not yet affected by geothermal production or re-injection (Melosh et al, 2012:Sanchez-Alfaro et al, 2016 Geological mapping, drillcore logging studies and kinematic analysis of fault-slip data have revealed that the Tolhuaca geothermal system is characterized by a structural and mineralogical compartmentalization in a transtensional stress regime (Sanchez-Alfaro et al, 2016).…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…In the vicinities of Tolhuaca volcano, detailed structural studies of fault systems revealed that dilatational jogs are formed at linking zones between NNE-and NE-striking faults. Syntaxial bladed-like calcite crystals of about 1 cm in size fill these dilatational jogs which indicate transient pressure drop likely related to fault activity in the LOFS (Perez-Flores et al, 2016).Therefore, the Tolhuaca geothermal system is a good analogue to evaluate the impacts of internal and external triggers on fluid evolution and mineralization in a hydrothermal reservoir.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

The optimal windows for seismically-enhanced gold precipitation in the epithermal environment

Sánchez-Alfaro

Reich

Driesner

et al. 2016

Ore Geology Reviews

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Epithermal gold (Au) deposits result from the combination of a sustained flux of metalrich fluids and an efficient precipitation mechanism. Earthquakes may trigger gold precipitation A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTby rapid loss of fluid pressure but their efficiency and time-integrated contribution to gold endowment are poorly constrained. In order to quantify the feedbacks between earthquake-driven fracturing and gold precipitation in the shallow crust, we studied the gold-rich fluids in the active Tolhuaca geothermal system, located in the highly seismic Southern Andes of Chile. We conditions -may significantly enhance gold precipitation rates in the shallow crust and lead to overall increases in metal endowment over time.

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Tectonic role of margin-parallel and margin-transverse faults during oblique subduction in the Southern Volcanic Zone of the Andes: Insights from Boundary Element Modeling

et al. 2016

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Obliquely convergent subduction margins develop trench‐parallel faults shaping the regional architecture of orogenic belts and partitioning intraplate deformation. However, transverse faults also are common along most orogenic belts and have been largely neglected in slip partitioning analysis. Here we constrain the sense of slip and slip rates of differently oriented faults to assess whether and how transverse faults accommodate plate‐margin slip arising from oblique subduction. We implement a forward 3‐D boundary element method model of subduction at the Chilean margin evaluating the elastic response of intra‐arc faults during different stages of the Andean subduction seismic cycle (SSC). Our model results show that the margin‐parallel, NNE striking Liquiñe‐Ofqui Fault System accommodates dextral‐reverse slip during the interseismic period of the SSC, with oblique slip rates ranging between 1 and 7 mm/yr. NW striking faults exhibit sinistral‐reverse slip during the interseismic phase of the SSC, displaying a maximum oblique slip of 1.4 mm/yr. ENE striking faults display dextral strike slip, with a slip rate of 0.85 mm/yr. During the SSC coseismic phase, all modeled faults switch their kinematics: NE striking fault become sinistral, whereas NW striking faults are normal dextral. Because coseismic tensile stress changes on NW faults reach 0.6 MPa at 10–15 km depth, it is likely that they can serve as transient magma pathways during this phase of the SSC. Our model challenges the existing paradigm wherein only margin‐parallel faults account for slip partitioning: transverse faults are also capable of accommodating a significant amount of plate‐boundary slip arising from oblique convergence.

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Tectonics, magmatism and paleo-fluid distribution in a strike-slip setting: Insights from the northern termination of the Liquiñe–Ofqui fault System, Chile

Cited by 81 publications

References 81 publications

Intra‐Arc Crustal Seismicity: Seismotectonic Implications for the Southern Andes Volcanic Zone, Chile

Intra‐Arc Crustal Seismicity: Seismotectonic Implications for the Southern Andes Volcanic Zone, Chile

The optimal windows for seismically-enhanced gold precipitation in the epithermal environment

Tectonic role of margin-parallel and margin-transverse faults during oblique subduction in the Southern Volcanic Zone of the Andes: Insights from Boundary Element Modeling

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