INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
What is the structure of the forearc region in the Central Andes of northern Chile? An approach from field data and 2-D reflection seismic data
LÓPEZ, CRISTOPHER; GIAMBIAGI, LAURA; MAKSYMOWICZ, ANDREI; MARTÍNEZ, FERNANDO; RIQUELME, RODRIGO
ELSEVIER SCIENCE BV
Lugar: Amsterdam; Año: 2019 vol. 769
The tectonic evolution of the Andean forearc in the Central Andes is understood by the superimposition ofdeformational events associated with different tectonic regimes, which control the main morpho-tectonic unitsof northern Chile. Varied interpretations have opened a great discussion about the deep structure of the Andeanforearc and its implications in the evolution of the Central Andes. These ideas are commonly accompanied by thelack of regional tectonic models that explain the geometry and kinematics of first-order structures. The mainlimitations are due to the unknown origin of the structural styles in the substrate and their relationships withthose exposed in the field. In order to solve this problem, we present a new structural model of the forearc regionof northern Chile, specifically along the Central Depression (22°-23°S) supported by field observations and thestructural interpretations of 2D seismic data. Four major tectono-sequences have been recognized related to (a) aPaleozoic-Triassic basement rocks, (b) a Jurassic-Lower Cretaceous synrift deposits, (c) Upper CretaceousPaleocene volcano synorogenic deposits and (d) a Late Cenozoic covered gravel. The first-order structural stylesidentified correspond to inverted half-graben basement structures related to the Jurassic Tarapacá Basin. Thehanging wall blocks of the master faults are usually composed of large inversion anticlines along which, Jurassicand Lower Cretaceous siliciclastic deposits were expelled. Other basement contractional structures consist ofshort-cut and by-pass faults that modified the previous geometry of extensional systems. The second-order thinskinned fold and thrust exposed in the region accommodated the shortening experienced by the Mesozoic synriftdeposits during the basin inversion. The Upper Cretaceous-Paleocene deposits usually unconformably overlie thefolded Mesozoic synrift deposits. This structural feature is first-order evidence of the positive reactivation of theMesozoic rift basins and therefore is a regional marker of the onset of the Andean uplift in the region.