Upper Triassic to Middle Jurassic magmatic evolution of northern Patagonia: Insights from the tectonic and crustal evolution of the Los Menucos area, North Patagonian Massif, Argentina. (January 2022)

• Record Type: Journal Article
• Authors: Falco, Juan Ignacio; Hauser, Natalia; Scivetti, Nicolás; Reimold, Wolf Uwe; Schmitt, Ralf Thomas; Folguera, Andres
• Is Part Of: Journal of South American earth sciences. Volume 113(2022)
• Publication Date: 2022-01
• Subjects: U-Pb/Hf isotopes on zircon -- Upper triassic flat-slab -- Jurassic magmatism -- Pre-Cuyano -- Los Menucos -- Patagonia; Geology -- Latin America -- Periodicals; Earth sciences -- Latin America -- Periodicals; Geology -- Antarctica -- Periodicals; Earth sciences -- Antarctica -- Periodicals; Geology -- Caribbean Area -- Periodicals; Earth sciences -- Caribbean Area -- Periodicals; Géologie -- Amérique latine -- Périodiques; Sciences de la terre -- Amérique latine -- Périodiques; Géologie -- Antarctique -- Périodiques; Sciences de la terre -- Antarctique -- Périodiques; Géologie -- Caraïbes (Région) -- Périodiques; Sciences de la terre -- Caraïbes (Région) -- Périodiques; Earth sciences; Geology; Antarctica; Caribbean Area; Latin America; Periodicals; 550.5
• DOI: 10.1016/j.jsames.2021.103631
• Languages: English
• ISSNs: 0895-9811

Abstract

Abstract: The Upper Triassic magmatic and tectonic evolution of the central North Patagonian Massif is evaluated on the basis of the zircon U–Pb-Hf record and whole-rock geochemistry for volcanic rocks of the Los Menucos area. The sample analyzed in this study yields a 210 ± 3 Ma U–Pb zircon age, and the geochemical data for the Upper Triassic rocks are indicative of a high-K calk-alkaline arc-type magmatism, which also has adakitic signature related to melting of the subducted oceanic slab. The Hf isotope data for zircon from this sample, with ƐHf(T) values between −6.1 and −8.7, support a mixed source that may have involved melted slab and crustal reworking. A comprehensive evaluation of the Upper Triassic – Lower Jurassic magmatic and tectonic evolution of northern Patagonia is in agreement with the hypothesis of an Upper Triassic South Gondwanian flat-slab, which shifted the magmatic arc towards the continental interior at a time of crustal shortening and with arc-type adakitic magmatism. The Lower Jurassic magmatic record is consistent with slab detachment and later roll-back, which would have promoted crustal extension and intraplate magmatism, and also shifted the arc magmatism to the paleo-trench. As a consequence of this stage, the Subcordilleran and North Patagonian batholiths were emplaced. The progressively – with time - less negative Hf isotope signatures for magmatic zircon are consistent with less evolved magmas generated throughout the Jurassic. The Upper Triassic-Middle Jurassic magmatism in northern Patagonia was part of a complex tectonic evolution, which involved crustal shortening and extension during plate reorganization during the critical period of Gondwana supercontinent break-up. Highlights: An Upper Triassic succession was studied in the Los Menucos area, Central North Patagonian Massif. Geochemistry, Hf-isotopes, and cooling ages are consistent with the Upper Triassic flat-slab model. Lower to Middle Jurassic Hf-isotopes on zircon data are consistent with a period of sustained extension.