Crustal-scale electrical conductivity anomaly beneath inflating Lazufre volcanic complex, Central Andes

Budach, Ingmar; Brasse, Heinrich; Díaz, Daniel

doi:10.1016/j.jsames.2012.11.002

Cited by 21 publications

(21 citation statements)

References 29 publications

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“…On the one hand, there is no clear evidence of a wide partially melted zone, similar to APMB beneath the Lazufre area and, on the other hand, all the models support a source located at a shallower level in the upper crust Simons, 2002, 2004;Froger et al, 2007;Ruch et al, 2008;Anderssohn et al, 2009;Henderson and Pritchard, 2013;Pearse and Lundgren, 2013]. Instead of a wide partially melted zone, Budach et al [2013], on the base of magnetotelluric data, proposed than melts ascent from the upper mantle through a narrower structure (some tens of km wide) and fed a potential magma reservoir within the upper crust, beneath Lazufre volcanic center.…”

Section: Discussionmentioning

confidence: 82%

“…Instead of a wide partially melted zone, Budach et al . [], on the base of magnetotelluric data, proposed than melts ascent from the upper mantle through a narrower structure (some tens of km wide) and fed a potential magma reservoir within the upper crust, beneath Lazufre volcanic center.…”

Section: Discussionmentioning

confidence: 99%

“…The presence of a crustal‐scale electrical conductivity anomaly beneath Lazufre has been revealed by Budach et al . [], interpreted by them as imaging partial melt rising from the upper mantle and feeding an intracrustal magma reservoir.…”

Section: Introductionmentioning

confidence: 99%

“…Chemical and isotopic analysis of hot fluids emitted from four fumarolic areas located at the Lastarria cone suggests that the fluids originate mainly from a large, actively degassing magmatic source, with relatively recent emplacement of magmatic fluids [Aguilera et al, 2012]. The presence of a crustal-scale electrical conductivity anomaly beneath Lazufre has been revealed by Budach et al [2013], interpreted by them as imaging partial melt rising from the upper mantle and feeding an intracrustal magma reservoir.…”

Section: Introductionmentioning

confidence: 99%

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Persistent uplift of the Lazufre volcanic complex (Central Andes): New insights from PCAIM inversion of InSAR time series and GPS data

Rémy

Froger

Perfettini

et al. 2014

Geochem. Geophys. Geosyst.

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We reanalyzed the surface displacements observed at the Lazufre volcanic complex in the Southern Andean Central Volcanic Zone using GPS measurements made between 2006 and 2008 and a large InSAR data set. We performed a detailed spatiotemporal analysis of the displacements using a principal component analysis inversion method (PCAIM). The PCAIM reveals a source with no significant changes in shape and dimension and with a remarkably linear strength increase over the whole period of observation (i.e., [2003][2004][2005][2006][2007][2008][2009][2010]. Then we used a three-dimensional mixed boundary element method (MBEM) to invert the first component of surface displacement as obtained from PCAIM. We explored a continuum of geometries from a shallow elliptic crack to a deep massive truncated elliptical cone that could represent a sill or a large magma chamber, respectively. The best models indicate a large flat-topped source with a roof area between 40 and 670 km 2 and a depth of between 2 and 14 km below ground surface. Lastly, on the basis of the limited data available for the thermomechanical structure of the crust in the Southern Andean Central Volcanic Zone, we consider some possible scenarios to explain the spatial and temporal pattern of displacements at Lazufre.

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Section: Discussionmentioning

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Persistent uplift of the Lazufre volcanic complex (Central Andes): New insights from PCAIM inversion of InSAR time series and GPS data

Rémy

Froger

Perfettini

et al. 2014

Geochem. Geophys. Geosyst.

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“…This even holds for potentially very active volcanoes like Lascar (Díaz et al 2012). The only exception has been the Lazufre complex where rising partial melts lead to an uplift of 3 cm/year over a large area (Budach et al 2013).…”

Section: Volcanic Arcmentioning

confidence: 99%

Three-dimensional inversion of magnetotelluric data from the Central Andean continental margin

2014

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Magnetotelluric data were collected in the late 1990s in the Central Andes of Chile and Bolivia, with the aim to delineate the electrical conductivity distribution in the subsurface and its relations to subduction processes. In previous studies, these data were interpreted based on 2-D models. The principal result was a vast conductivity zone beneath the Altiplano high plateau at mid and lower crustal depths and a much smaller, though significant conductor associated with the Precordillera Fault System. However, there are some significant 3-D effects in the investigation area, in particular near the coast and on the eastern Altiplano. The aim of this work is to give a reinterpretation based on new 3-D inversion of these data. The 3-D inversion not only provides a better fit to the data compared to 2-D results but furthermore allows to include sites with strong telluric distortion which were ignored in previous studies. We are now able to explain anomalous phases above 90°and induction arrows pointing subparallel to the coast as observed at several sites in the Coastal Cordillera. These strongly distorted data are caused by highly conductive near-surface structures that are partly connected to the Pacific Ocean, forcing currents to flow around the sites. The lower crust beneath the Coastal Cordillera resembles a poorly conductive, nearly homogeneous half-space and is electrically unremarkable. Besides, we can now image the Precordillera conductor as a continuous, elongated feature. The volcanic arc of the Western Cordillera is highly resistive with the exception of a few conductive spots which may be associated with certain individual volcanoes or geothermal resources, respectively. The Altiplano conductor is again the dominant electrical feature in the Central Andes, indicating widespread melting of the middle and lower back-arc crust.

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Three‐dimensional resistivity image of the magmatic system beneath Lastarria volcano and evidence for magmatic intrusion in the back arc (northern Chile)

Díaz

Heise

Zamudio

2015

Geophysical Research Letters

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Lazufre volcanic center, located in the central Andes, is recently undergoing an episode of uplift, conforming one of the most extensive deforming volcanic systems worldwide, but its magmatic system and its connection with the observed uplift are still poorly studied. Here we image the electrical resistivity structure using the magnetotelluric method in the surroundings of the Lastarria volcano, one of the most important features in the Lazufre area, to understand the nature of the magmatic plumbing, the associated fumarolic activity, and the large‐scale surface deformation. Results from 3‐D modeling show a conductive zone at 6 km depth south of the Lastarria volcano interpreted as the magmatic heat source which is connected to a shallower conductor beneath the volcano, showing the pathways of volcanic gasses and heated fluid. A large‐scale conductive area coinciding with the area of uplift points at a magma intrusion at midcrustal depth.

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Crustal-scale electrical conductivity anomaly beneath inflating Lazufre volcanic complex, Central Andes

Cited by 21 publications

References 29 publications

Persistent uplift of the Lazufre volcanic complex (Central Andes): New insights from PCAIM inversion of InSAR time series and GPS data

Persistent uplift of the Lazufre volcanic complex (Central Andes): New insights from PCAIM inversion of InSAR time series and GPS data

Three-dimensional inversion of magnetotelluric data from the Central Andean continental margin

Three‐dimensional resistivity image of the magmatic system beneath Lastarria volcano and evidence for magmatic intrusion in the back arc (northern Chile)

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