Electromagnetic study of the active continental margin in northern Chile

Echternacht, F.; Tauber, Sebastian; Eisel, Markus; Brasse, Heinrich; Schwarz, Gerhard; Haak, V.

doi:10.1016/s0031-9201(96)03261-x

Cited by 56 publications

(24 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…We used phase error floors of 5%, 15% for TM and TE modes and apparent resistivity error floors of 15% and 30% for TM and TE modes. In this way special emphasis was put on fitting the TM data over TE data, since TM data are usually less sensitive to threedimensional effects (see Wannamaker et al, 1984Wannamaker et al, , 1987Wannamaker et al, , 1989Echternacht et al, 1997). Also more emphasis is given to phase data over apparent resistivity data as phase is not affected by static shift effects as suggested by several authors (e.g., Brasse et al, 2009).…”

Section: Analysis and Modellingmentioning

confidence: 99%

Crustal architecture beneath Madurai Block, southern India deduced from magnetotelluric studies: Implications for subduction–accretion tectonics associated with Gondwana assembly

Naganjaneyulu

Santosh

2011

Journal of Asian Earth Sciences

View full text Add to dashboard Cite

Section: Analysis and Modellingmentioning

confidence: 99%

Crustal architecture beneath Madurai Block, southern India deduced from magnetotelluric studies: Implications for subduction–accretion tectonics associated with Gondwana assembly

Naganjaneyulu

Santosh

2011

Journal of Asian Earth Sciences

View full text Add to dashboard Cite

“…Its main branch is the West fault (WF; also: West Fissure/Falla Oeste), which can be traced for 170 km almost continuously from Calama to Quebrada Blanca [Dilles et al, 1997] ( Figure 1a). Regional magnetotelluric surveys (PICA and ANCORP profiles, Figure 1a) have identified the PFS as a first-order feature that most likely transects the entire forearc lithosphere [Brasse et al, 2002;Echternacht et al, 1997].…”

Section: Geological Settingmentioning

confidence: 99%

Correlation of electrical conductivity and structural damage at a major strike‐slip fault in northern Chile

2004

View full text Add to dashboard Cite

[1] Large-scale strike-slip fault zones are often imaged as electrically conductive structures in the brittle crust. However, the relationship of conductivity and internal architecture of the fault zone remains largely unclear. This paper presents results of a study designed to compare the record of structural deformation across a fault zone with its electrical conductivity image. Two high-resolution magnetotelluric profiles trend perpendicularly across the West fault, a branch of the Precordilleran fault system in northern Chile. The magnetotelluric and geomagnetic response functions in the frequency range from 1000 Hz to 0.1 Hz clearly image a fault zone conductor (FZC) about 350 m wide and 1500 m deep, trending along the surface trace of the fault. The position of the FZC and its geometric properties (width, dip) correlate with a region of intense fluid alteration and the orientation of fault-related damage elements (minor faults, fractures). According to estimates of fluid salinity and rock porosity, the conductivity anomaly results from meteoric water penetrating into a permeable zone. This suggests that the increase in electrical conductivity is causally related to a mesh of minor faults and fractures, acting as a pathway for fluids. The FZC reflects the central and most fractured part of the damage zone. In view of similar published magnetotelluric studies, we infer a dependency of a fault's state of activity and the characteristics of the FZC such as its conductance, width, and depth extent. Ongoing deformation is the controlling factor for maintaining a permeable and electrically conductive fracture network.

show abstract

“…The aim was to infer the electrical conductivity distribution in the subsurface and its relation to subduction processes at the South American continental margin. Most of the data show typically a 2-D behavior, and consequently, they were interpreted in previous studies based on 2-D models (Brasse et al 2002;Brasse 2011;Echternacht et al 1997;Schwalenberg et al 2002). Nevertheless, some questionable 3-D effects remained which were not taken into account, in particular near the coast and on the Eastern Altiplano.…”

Section: Introductionmentioning

confidence: 96%

“…The principal results were a vast zone of partial melts beneath the Altiplano at latitude 21°S at mid and lower crustal depths, and the highly conductive West Fissure Zone beneath the Precordillera, explained by rising saline fluids from the deeper crust or even the downgoing slab (Echternacht et al 1997). …”

Section: Introductionmentioning

confidence: 98%

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

2014

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Electromagnetic study of the active continental margin in northern Chile

Cited by 56 publications

References 18 publications

Crustal architecture beneath Madurai Block, southern India deduced from magnetotelluric studies: Implications for subduction–accretion tectonics associated with Gondwana assembly

Crustal architecture beneath Madurai Block, southern India deduced from magnetotelluric studies: Implications for subduction–accretion tectonics associated with Gondwana assembly

Correlation of electrical conductivity and structural damage at a major strike‐slip fault in northern Chile

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

Contact Info

Product

Resources

About