Deep deformation pattern from electrical anisotropy in an arched orogen (Betic Cordillera, western Mediterranean)

Long-period magnetotelluric data acquired in the Iberian Massif and the Betic Cordillera arched orogen provide the first evidence of electrical anisotropy in the upper mantle of the Mediterranean region. Strike analysis at different periods reveals preferred structure orientation related to olivine...

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Bibliographic Details
Published in:Geology (Boulder) 2010-08, Vol.38 (8), p.731-734
Main Authors: Ruiz-Constán, Ana, Galindo-Zaldívar, Jesús, Pedrera, Antonio, Arzate, Jorge A, Pous, Jaume, Anahnah, Farida, Heise, Wiebke, Monteiro Santos, Fernando A, Marín-Lechado, Carlos
Format: Article
Language:English
Subjects:
African Plate
Alpine Orogeny
Anisotropy
applied (geophysical surveys & methods)
Betic Cordillera
body waves
Continental dynamics
deformation
delamination
elastic waves
electrical properties
Electromagnetism
Eurasian Plate
Europe
geodynamics
Geomorphology
geophysical methods
geophysical surveys
Geophysics
Iberian Peninsula
kinematics
magnetotelluric methods
mantle
Mediterranean region
Mediterranean Sea
orogenic belts
orogeny
plate boundaries
Plate tectonics
preferred orientation
seismic waves
SKS-waves
solid Earth (tectonophysics)
Southern Europe
Spain
strike
structural analysis
subduction
surveys
tectonics
transpression
upper mantle
West Mediterranean
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Summary:Long-period magnetotelluric data acquired in the Iberian Massif and the Betic Cordillera arched orogen provide the first evidence of electrical anisotropy in the upper mantle of the Mediterranean region. Strike analysis at different periods reveals preferred structure orientation related to olivine elongation in the mantle, and points to a heterogeneous anisotropy pattern. At deep levels (periods ≥104 s), all the sites show a common north-south geoelectrical strike (∼N170°E), which may represent a low-intensity deformation, possibly related to "frozen" prealpine plate tectonics. For periods between 10 and 103 s, a north-south constant strike (∼N180°E) at the Betic Cordillera sites contrasts with the east-west strike (∼N85°E) in the Iberian Massif. An increase in the magnitude of the induction arrows from the Iberian Massif to the inner part of the Betic Cordillera probably reflects higher deformation toward the axis of the Eurasian-African plate boundary. The integration of electrical anisotropy data with seismic anisotropy allows us to discuss mantle deformation patterns produced by delamination and subduction, suggesting that the latter mechanism may be more suitable for the alpine evolution of the western Gibraltar Arc.
ISSN:0091-7613
1943-2682
DOI:10.1130/G31144.1