Fault-controlled development of shallow hydrothermal systems: Structural and mineralogical insights from the Southern Andes

Roquer, Tomás; Arancibia, Gloria; Rowland, J. V.; Iturrieta, Pablo; Morata, Diego; Cembrano, José

doi:10.1016/j.geothermics.2016.12.003

Cited by 32 publications

(19 citation statements)

References 60 publications

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“…ATFs also have been thought to control the Neogene forearc basin architecture and megathrust rupture segmentation associated with the seismic subduction cycle (Glodny et al, ; Melnick et al, ). Furthermore, deformation of the ATFs might be activated from megathrust earthquakes (Aron et al, ; Arriagada et al, ; Farías et al, ; Stanton‐Yonge et al, ), and may control crustal fluid migration within the intra‐arc region (Cembrano & Lara, ; Katz, ; Pérez‐Flores et al, ; Rivera & Cembrano, ; Roquer et al, ; Sánchez‐Alfaro et al, ; Sielfeld et al, ; Wrage et al, ).…”

Section: Tectonic Setting Of Southern Andesmentioning

confidence: 99%

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: 99%

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

2019

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“…This causes the maximum flow direction to orient parallel to the fault plane (Caine et al, 1996;Faulkner et al, 2010). Simultaneously, the migration and accumulation of fluids within these fault systems play a key role in the nucleation of earthquakes, as increased pore fluid pressures reduce the effective normal stress projected on a fault plane, consequently increasing its probability of failure (Cox, 2010(Cox, , 2016Roquer et al, 2017;Sibson, 1985). These interdependent processes result in episodic and anisotropic migration of fluids within fault zones, along with the heterogeneous distribution of hydromechanical properties therein (Cox, 2010;Rowland & Sibson, 2004;Sibson, 1996Sibson, , 2004.…”

Section: Introductionmentioning

confidence: 99%

Reactivation of Fault Systems by Compartmentalized Hydrothermal Fluids in the Southern Andes Revealed by Magnetotelluric and Seismic Data

et al. 2020

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 In the Andean volcanic arc, margin-parallel and blind oblique fault systems control volcanic, hydrothermal and ore-porphyry processes  Subsurface conductivity structure and seismicity show a WNW-trending active fault in the Andean Southern Volcanic Zone  Results show magmatic/hydrothermal fluids are compartmentalised by local faults, and elevated fluid pressures promote fault reactivation

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“…These sites are located in the very active SVZ, where prior studies have shown absence 59 or minor amount 60 of quartz in ashes. The predominant minerals detected in fault-controlled hydrothermal systems in the southern Andes are Ca and Ca (-Na) zeolites, minor quartz was also locally found 61 . The relatively low quartz concentration at sites 15–21 suggests a reduction of amorphous silica by carbon monoxide during the frequent explosive eruptions in the zone.…”

Section: Discussionmentioning

confidence: 98%

Elemental and Mineralogical Composition of the Western Andean Snow (18°S–41°S)

Alfonso

Cordero

Rowe

et al. 2019

Sci Rep

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The snowpack is an important source of water for many Andean communities. Because of its importance, elemental and mineralogical composition analysis of the Andean snow is a worthwhile effort. In this study, we conducted a chemical composition analysis (major and trace elements, mineralogy, and chemical enrichment) of surface snow sampled at 21 sites across a transect of about 2,500 km in the Chilean Andes (18–41°S). Our results enabled us to identify five depositional environments: (i) sites 1–3 (in the Atacama Desert, 18–26°S) with relatively high concentrations of metals, high abundance of quartz and low presence of arsenates, (ii) sites 4–8 (in northern Chile, 29–32°S) with relatively high abundance of quartz and low presence of metals and arsenates, (iii) sites 9–12 (in central Chile, 33–35°S) with anthropogenic enrichment of metals, relatively high values of quartz and low abundance of arsenates, (iv) sites 13–14 (also in central Chile, 35–37°S) with relatively high values of quartz and low presence of metals and arsenates, and v) sites 15–21 (in southern Chile, 37–41°S) with relatively high abundance of arsenates and low presence of metals and quartz. We found significant anthropogenic enrichment at sites close to Santiago (a major city of 6 million inhabitants) and in the Atacama Desert (that hosts several major copper mines).

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Fault-controlled development of shallow hydrothermal systems: Structural and mineralogical insights from the Southern Andes

Cited by 32 publications

References 60 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

Reactivation of Fault Systems by Compartmentalized Hydrothermal Fluids in the Southern Andes Revealed by Magnetotelluric and Seismic Data

Elemental and Mineralogical Composition of the Western Andean Snow (18°S–41°S)

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