Abstract
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 affected 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 affect 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.
Highlights
In the Chilean coast, the existence of rock suites that formed part of a Palaeozoic accretionary prism during subduction of the palaeo-Pacific plate is accepted since the works of Hervé (1988), Hervé et al (1988) and Irwin et al (1988)
The Palaeozoic basement outcropping to the north of Los Vilos is formed by (i) the Choapa Metamorphic Complex (ChMC) made of metabasites, 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 affected by three deformation episodes related with the Gondwanan orogenic episode
Summary
In the Chilean coast, the existence of rock suites that formed part of a Palaeozoic accretionary prism during subduction of the palaeo-Pacific plate is accepted since the works of Hervé (1988), Hervé et al (1988) and Irwin et al (1988). These rocks are exposed in several discontinuous outcrops from the Península de Mejillones (23o S latitude, see Fig. 1b), in northern Chile, to the Los Vilos area, located at 32o S latitude (Fig. 1a). This study led to fit the study area in a new proposal of geodynamic evolution model for the Gondwanan orogenic episode at this latitude
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
