Structure of the andean palaeozoic basement in the chilean coast at 31° 30' S: geodynamic evolution of a subduction margin
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2014
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Facultad/escuela
Idioma
en
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Universidad Complutense de Madrid
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Licencia CC
Atribution 4.0 International (CC BY 4.0)
Licencia CC
https://creativecommons.org/licenses/by/4.0/deed.es
Resumen
The Palaeozoic basement outcropping to the north of Los Vilos is formed by (i) the Choapa Metamorphic Complex (ChMC) made of
metabasites (amphibolites and retrogressed eclogites), fine-grained gneisses, schists and quartz-schists, and (ii) the meta-sedimentary and
sedimentary rocks of the Arrayán and Huentelauquén formations respectively. Near Huentelauquén (31º 30’ S), the ChMC has been af fected by three deformation episodes related with the Gondwanan orogenic episode. The first episode (D1) is represented by a foliation
(S1) formed under HP-LT metamorphic conditions and preserved in syn-D2 garnet and albite porphyroblasts. A generalised crenulation
cleavage (S2) was developed under pressure decreasing conditions during the second deformation episode (D2). This episode is responsible
for the exhumation of the ChMC, which took place through an east-directed reverse fault system that thrusts the ChMC over the Arrayán
Formation, producing more than 20 km shortening. The third deformation episode (D3) is represented by a west-verging kilometre-scale
anticline, with a thrust in its reverse limb (Las Caldas thrust). Minor folds and crenulations are also associated with D3. D3 structures af fect the ChMC and the Arrayán Formation and are responsible for the overturning of the D2 thrusts. The Huentelauquén Formation, late
Carboniferous – Permian in age, is the latest unit deformed by Gondwanan structures. The characterisation of the structure and its relation
to metamorphism in the study area, lead to propose a geodynamic model related with an Andean type non-collisional orogenic process, for
the Gondwanan orogenic episode of the Andes at this latitude.
Notas
Indexación Scopus.
Palabras clave
Gondwanan Structure, Tectono-Metamorphic Evolution, Choapa Metamorphic Complex, Chile, System Thrust
Citación
Journal of Iberian Geology. Volume 40, Issue 2, Pages 293 - 308. 2014
DOI
10.5209/rev_JIGE.2014.v40.n2.45300