An early Jurassic graben caldera of Chon Aike silicic LIP at the southernmost massif of the world: The Deseado caldera, Patagonia, Argentina. (August 2020)

• Record Type: Journal Article
• Authors: Navarrete, C.; Butler, K.L.; Hurley, M.; Márquez, M.
• Is Part Of: Journal of South American earth sciences. Volume 101(2020)
• Publication Date: 2020-08
• Subjects: Chon aike silicic LIP -- Jurassic -- Patagonia -- Graben caldera; 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.2020.102626
• Languages: English
• ISSNs: 0895-9811

Abstract

Abstract: Detailed geological mapping of 900 km 2, newly defined volcanic and volcaniclastic lithofacies, multiple stratigraphic profiles, and a new zircon U/Pb eruption age (178.7 ± 1.9 Ma) describe an early Jurassic extensional-related piece-meal collapsed graben caldera in the eastern sector of Deseado Massif, at southern Patagonia. This volcano-tectonic structure, here referred to as The Deseado Caldera, collapsed at least twice controlled by two major NW-striking normal faults, during which a large acidic ignimbrite (predominantly moderate to extremely high-grade) and co-ignimbrite lag breccias were extruded through multiple NW-fissure vents. During the two post-collapse periods, alluvial fans, lagoons and laharic sedimentary environments re-worked the intra-caldera volcaniclastic deposits. Finally, numerous elongated and aligned rhyolitic lava domes and dykes were emplaced during the final magmatic resurgence stage. This caldera represents the first clear evidence of the extensional tectonic regime influence, associated with the inception of Gondwana breakup, on the eruptive mechanisms of the Jurassic Chon Aike Silicic LIP in the Deseado Massif. Highlights: A new NW Jurassic graben caldera of the Deseado Massif, directly related to the extensional regime ascribed to the inception of the Gondwana breakup. A new detailed geological map of 900 km2 of the eastern sector of the Deseado Massif. New U-Pb zircon age data of the Chon Aike Formation (Chon Aike Silicic LIP).