Fault-Related Thermal Springs: Water Origin and Hydrogeochemical Processes at Liquiñe Area (Southern Volcanic Zone, Chile)

2019 ◽  
Author(s):  
Linda Daniele ◽  
Matías Taucare ◽  
Tomas Roquer ◽  
Benoît Viguier ◽  
Josefa Sepúlveda ◽  
...  
2019 ◽  
Author(s):  
Linda Daniele ◽  
Matías Taucare ◽  
Tomas Roquer ◽  
Benoît Viguier ◽  
Josefa Sepúlveda ◽  
...  

2020 ◽  
Vol 218 ◽  
pp. 106611
Author(s):  
Linda Daniele ◽  
Matías Taucare ◽  
Benoît Viguier ◽  
Gloria Arancibia ◽  
Diego Aravena ◽  
...  

2019 ◽  
Vol 60 (5) ◽  
pp. 907-944 ◽  
Author(s):  
Jacqueline Vander Auwera ◽  
Olivier Namur ◽  
Adeline Dutrieux ◽  
Camilla Maya Wilkinson ◽  
Morgan Ganerød ◽  
...  

Abstract Where and how arc magmas are generated and differentiated are still debated and these questions are investigated in the context of part of the Andean arc (Chilean Southern Volcanic Zone) where the continental crust is thin. Results are presented for the La Picada stratovolcano (41°S) that belongs to the Central Southern Volcanic Zone (CSVZ) (38°S–41·5°S, Chile) which results from the subduction of the Nazca plate beneath the western margin of the South American continent. Forty-seven representative samples collected from different units of the volcano define a differentiation trend from basalt to basaltic andesite and dacite (50·9 to 65·6 wt % SiO2). This trend straddles the tholeiitic and calc-alkaline fields and displays a conspicuous compositional Daly Gap between 57·0 and 62·7 wt % SiO2. Interstitial, mostly dacitic, glass pockets extend the trend to 76·0 wt % SiO2. Mineral compositions and geochemical data indicate that differentiation from the basaltic parent magmas to the dacites occurred in the upper crust (∼0·2 GPa) with no sign of an intermediate fractionation stage in the lower crust. However, we have currently no precise constraint on the depth of differentiation from the primary magmas to the basaltic parent magmas. Stalling of the basaltic parent magmas in the upper crust could have been controlled by the occurrence of a major crustal discontinuity, by vapor saturation that induced volatile exsolution resulting in an increase of melt viscosity, or by both processes acting concomitantly. The observed Daly Gap thus results from upper crustal magmatic processes. Samples from both sides of the Daly Gap show contrasting textures: basalts and basaltic andesites, found as lavas, are rich in macrocrysts, whereas dacites, only observed in crosscutting dykes, are very poor in macrocrysts. Moreover, modelling of the fractional crystallization process indicates a total fractionation of 43% to reach the most evolved basaltic andesites. The Daly Gap is thus interpreted as resulting from critical crystallinity that was reached in the basaltic andesites within the main storage region, precluding eruption of more evolved lavas. Some interstitial dacitic melt was extracted from the crystal mush and emplaced as dykes, possibly connected to small dacitic domes, now eroded away. In addition to the overall differentiation trend, the basalts to basaltic andesites display variable MgO, Cr and Ni contents at a given SiO2. Crystal accumulation and high pressure fractionation fail to predict this geochemical variability which is interpreted as resulting from variable extents of fractional crystallization. Geothermobarometry using recalculated primary magmas indicates last equilibration at about 1·3–1·5 GPa and at a temperature higher than the anhydrous peridotite solidus, pointing to a potential role of decompression melting. However, because the basalts are enriched in slab components and H2O compared to N-MORB, wet melting is highly likely.


2021 ◽  
Author(s):  
Francisca Mallea-Lillo ◽  
Miguel Ángel Parada ◽  
Eduardo Morgado ◽  
Darío Hübner ◽  
Claudio Contreras

2018 ◽  
Vol 353 ◽  
pp. 83-94 ◽  
Author(s):  
Carlos Cardona ◽  
Andrés Tassara ◽  
Fernando Gil-Cruz ◽  
Luis Lara ◽  
Sergio Morales ◽  
...  

2007 ◽  
Vol 255 (1-2) ◽  
pp. 229-242 ◽  
Author(s):  
Brian R. Jicha ◽  
Brad S. Singer ◽  
Brian L. Beard ◽  
Clark M. Johnson ◽  
Hugo Moreno-Roa ◽  
...  

1992 ◽  
Vol 29 (10) ◽  
pp. 2211-2225 ◽  
Author(s):  
E. H. Chown ◽  
Réal Daigneault ◽  
Wulf Mueller ◽  
J. K. Mortensen

The Archean Abitibi Subprovince has been divided formally into a Northern Volcanic Zone (NVZ), including the entire northern part of the subprovince, and a Southern Volcanic Zone (SVZ) on the basis of distinct volcano-sedimentary successions, related plutonic suites, and precise U–Pb age determinations. The NVZ has been further formally subdivided into (i) a Monocyclic Volcanic Segment (MVS) composed of an extensive subaqueous basalt plain with scattered felsic volcanic complexes (2730–2725 Ma), interstratified with or overlain by linear volcaniclastic sedimentary basins; and (ii) a Polycyclic Volcanic Segment (PVS) comprising a second mafic–felsic volcanic cycle (2722–2711 Ma) and a sedimentary assemblage with local shoshonitic volcanic rocks.A sequence of deformational events (D1–D6) over a period of 25 Ma in the NVZ is consistent with a major compressional event. North–south shortening was first accommodated by near-vertical east-trending folds and, with continued deformation, was concentrated along major east-trending fault zones and contact-strain aureoles around synvolcanic intrusions, both with a downdip movement. Subsequent dextral strike-slip movement occurred on southeast-trending faults and major east-trending faults which controlled the emplacement of syntectonic plutons (2703–2690 Ma).This study suggests that the NVZ, which is a coherent geotectonic unit, initially formed as a diffuse volcanic arc, represented by the MVZ, in which the northern part, represented by the PVS, evolved into a mature arc as documented by a second volcanic and sedimentary cycle associated with major plutonic accretion. Volcano-sedimentary evolution and associated plutonism, as well as structural evolution, are best explained by a plate-tectonic model involving oblique convergence.


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