A review of Devonian–Carboniferous magmatism in the central region of Argentina, pre-Andean margin of SW Gondwana

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Dahlquist, Juan A. and Morales Cámera, Matías M. and Alasino, Pablo H. and Pankhurst, R.J. and Basei, Miguel A.S. and Rapela, Carlos W.. and Moreno Moreno, Juan Antonio (2021) A review of Devonian–Carboniferous magmatism in the central region of Argentina, pre-Andean margin of SW Gondwana. Earth-Science Reviews, 221 (103781). ISSN 0012-8252, ESSN: 1872-6828

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Official URL: https://doi.org/10.1016/j.earscirev.2021.103781



Abstract

We review a widespread project database for Devonian–Carboniferous magmatism in the Sierras Pampeanas and Frontal Cordillera between 27° and 35°S, including petrological, geochemical, geochronological, and isotope data, with compiled data from the literature and some new results. We distinguish four main magmatic domains: 1) Devonian Arc, 2) Devonian Foreland, 3) Carboniferous Arc, and 4) Carboniferous Retro-Arc. Devonian segmented subduction led to two oceanic slab configurations: 1) flat-slab subduction in the outboard region and resubduction >800 km inland from the trench, including lithosphere delamination of the upper plate and break-off of the subducted oceanic slab, along with asthenospheric mantle upwelling (31°–33° 30′S), and 2) normal subduction (34° - 35°S). In the first configuration the arc magmatism was absent, but voluminous foreland magmatism was developed, including small-scale high silica adakite. The second geodynamic setting took place during the latest Devonian and Carboniferous when the oceanic slab roll-back occurred. Arc and retro-arc magmatism were developed coetaneously between 27° and 31°S, with northwest migration that could be explained by movement relative to hot asthenospheric mantle. The arc is represented by calc-alkaline granitoids, whereas retro-arc magmatism consisted of (a) metaluminous to weakly peraluminous A-type granites, and (b) strongly peraluminous A-type granites, these latter with sometimes incomplete isotopic homogenization of the parental magma. Devonian–Carboniferous magmatic evolution here is explained by segmented tectonic subduction and a switch-off and switch-on geodynamic model. Magmatic activity was mainly continuous from ca. 390 to 320 Ma, although compositional variations occurred through time and space (foreland, arc, and retro-arc). Major involvement of mantle sources in the genesis of the Carboniferous arc granites at 28°–30°S contrast with a dominant continental signature in the granites of the Devonian arc at 34°–35°S. These differences are explained by two different configurations in the subduction system related to advance (28°–30°S) or retreat (34°–35°S) of the subducted ocean slab. The main conclusion of this work is that the complex interaction of oceanic and continental plates can produce different types of magmatism (or its absence): subduction processes do not consist only of an oceanic plate sinking under a continental plate.


Item Type:Article
Uncontrolled Keywords:Devonian and Carboniferous magmatism, Pre-Andean margin SW Gondwana, Magmatic domains, Calc-alkaline and A-type magmatism, Adakites, Frontal Cordillera and Sierras Pampeanas, Segmented tectonic subduction, Switching geodynamic model, Geochronological, Geochemical, and isotopic data
Subjects:Sciences > Geology > Geochemistry
Sciences > Geology > Petrology
ID Code:69356
Deposited On:21 Dec 2021 17:24
Last Modified:22 Dec 2021 08:17

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