Geochemical and tectonic evolution of Late Cretaceous to early Paleocene magmatism along the Southern Central Andes (35-36°S)

Cretaceous-Cenozoic growth of the Patagonian broken foreland basin, Argentina: Chronostratigraphic framework and provenance variations during transitions in Andean subduction dynamics

“…Contrasting phases of shortening and extension are likely linked to differences in coupling of the downgoing and overriding plates during shallowing and resteepening of the subducting slab Horton, 2018b), as expressed in the irregular Late Cretaceous inboard advance, Paleocene-middle Eocene cessation, and middle-Eocene-Miocene trenchward retreat and broadening of arc magmatism (Folguera and Ramos, 2011;Gianni et al, 2018). Episodes of Paleocene-Eocene intraplate volcanism may be related to slab window genesis or lithospheric removal (Muñoz et al, 2000;de Ignacio et al, 2001;Aragón et al, 2011b;2013;Kay et al, 2007;Zaffarana et al, 2012;Iannelli et al, 2018).…”

A geodynamic model linking Cretaceous orogeny, arc migration, foreland dynamic subsidence and marine ingression in southern South America

“…These datasets were complemented with ages fromSuárez et al (1986);Lara and Moreno (2004),Moreno and Lara (2008) and IIG/MMAJ/JICA(1978). b) Spatio-temporal analysis of arc magmatism showing an arc migration stage since around 100-90 Myr and its relation to synorogenic deposition.Through a geochemical study in volcanic rocks at 35°30'S and a comparison with equivalents rocks between 35°-41°S,Iannelli et al (2018) concluded that the expanded Late Cretaceous-Paleocene arc had a weaker arc-like signature and less slab-fluid influence in its northernmost extreme. This contrasting behavior along with the documentation of localized extensionallycontrolled magma ascent in the hinterland of the Cretaceous orogen(Tapia, 2015; Fennell et al., 2017) has been explained by the development of an incipient slab window at 35º30′S around 70 Ma.…”

Southward-Directed Subduction of the Farallon–Aluk Spreading Ridge and Its Impact on Subduction Mechanics and Andean Arc Magmatism: Insights From Geochemical and Seismic Tomographic Data

“…This is further complicated in settings where mid-ocean ridge subduction took place obliquely to the subduction zone producing a time-space migration of the slab window process along the active margin. The latter tectonic configuration has been suggested in plate kinematic reconstructions in the southeast Pacific Ocean indicating that the Farallon-Aluk mid-ocean ridge should have subducted obliquely beneath the Andes sometime during Late Cretaceous to Paleogene times (Cande and Leslie, 1986;Ramos and Kay, 1992;Aragón et al, 2011;Somoza and Ghidella, 2012;Eagles and Scott, 2014;Iannelli et al, 2018;Fennell et al, 2019).…”

“…Recent plate kinematic reconstructions suggest that the Farallon-Aluk mid-ocean ridge collided against the Andean margin at ∼30 • S during the Late Cretaceous (∼80 Ma) and started migrating southwards reaching Patagonian latitudes (∼42 • S) by Eocene times (Cande and Leslie, 1986;Somoza and Ghidella, 2005;Aragón et al, 2011;Eagles and Scott, 2014;Müller et al, 2016;Wright et al, 2016). Along these latitudes, the emplacement of scattered magmatic sequences with contrasting geochemical signatures and the development of magmatic lulls between Late Cretaceous to Eocene times have been associated with the development of slab windows directly linked to the progressive southward sweeping of this oceanic ridge (Ramos and Kay, 1992;Muñoz et al, 2000;Aragón et al, 2011;De La Fuente, 2014;Jalowitzki et al, 2017;Gianni et al, 2018a;Iannelli et al, 2017Iannelli et al, , 2018. Contrastingly, late Eocene-Oligocene magmatism show arc-related signature with no influence from the slab window (Iannelli et al, 2017;Fernández Paz et al, 2019).…”

“…In this study, we provide new isotopic data from three arcrelated magmatic units located in key segments along the Andes between 35 • and 42 • S and integrate it with its previous field and geochemical data to test the potential influence of the southward migration of the Farallon-Aluk ridge over Andean magmatism between the Late Cretaceous to early Miocene times. These arcrelated units include Los Ángeles Unit magmatism (67 Ma) at the Southern Central Andes (35 • 30 S); the Eocene Huitrera Formation (44 Ma) at the North Patagonian Andes (40 • S) and the Auca Pan Formation (29 Ma) located in the transitional area between Southern Central and North Patagonian Andes (39 • S) (Iannelli et al, 2017(Iannelli et al, , 2018. To better evaluate the regional influence of the spreading ridge on Andean magmatism, we integrate geochemical evolution of these arc-related units with available geochemical data from coeval magmatic sequences from the whole arc region between the studied latitudes (35-42 • S) (e.g., Kay et al, 2006;Zamora Valcarce et al, 2006).…”