Late Paleozoic geodynamic evolution of the western North Patagonian Massif and its tectonic context along the southwestern Gondwana margin

Abstract

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

The origin of Patagonia: insights from Permian to Middle Triassic magmatism of the North Patagonian Massif

“…To the south and west, the NPM is limited by the Patagonian Precordillera that exposes Upper Triassic to Lower Jurassic rocks, and the Jurassic-Cretaceous Cañadón Asfalto Basin, respectively (Figs 1 and 2). The pre-Permian stratigraphy of the NPM comprises Cambrian plutonic and metasedimentary rocks, as well as Ordovician S-and I-type granitoids, all of which are covered by a Late Silurian to Carboniferous sedimentary succession (Pankhurst et al 2006;Rapalini et al 2010Rapalini et al , 2013Marcos et al 2020). Parts of these sequences have been included in the Colohuincul and Mina Gonzalito complexes, and the Cushamen, Mamil Choique, Nahuel Niyeu and El Jagüelito formations (Fig.…”

“…This resetting has been related to geodynamic processes associated with subduction along the proto-Pacific margin of Gondwana (e.g. Oriolo et al 2019;Marcos et al 2020).…”

“…In the western NPM, along the Andean foothills, at least three episodes of Palaeozoic crustal shortening have been recognized, which produced folding and thrusting of the country rocks (Marcos et al 2020, for a synthesis). The oldest phase was dated to the Carboniferous-Permian transition (c. 300 Ma), the second was linked to the late Cisuralian (c. 272 Ma), and the third to the late Guadalupian (c. 265 Ma).…”

“…The conundrum of whether Patagonia was an allochthonous, autochthonous or even paraautochthonous terrane has been responsible for a considerable increase in geological knowledge about the North Patagonian Massif (NPM); however, interpretations of its tectonic evolution and origin still vary widely (e.g. Ramos & Naipauer, 2014;Castillo et al 2017;Vizán et al 2017;Luppo et al 2019;López de Luchi et al 2020;Marcos et al 2020;Ramos et al 2020). Over the past three decades, the hypothesis that northern Patagonia could have been an exotic terrane during most of the Palaeozoic, which would have been accreted to the SW margin of Gondwana in the early Permian, has been strongly debated (e.g.…”

“…1; Lock, 1980;Dalziel et al 2000). Marcos et al (2020) proposed the existence of shallow eastward-directed subduction along the NPM during the transition from the Carboniferous to the early Permian, based on prograde to retrograde metamorphism of basement rocks in the western NPM. López de pointed out that a possible cause for the middle to late Permian deformation in the NPM might have been eastward-directed flat-slab subduction.…”