Introduction to Journal of South American Earth Sciences special issue on “Magmatism of southernmost South America”

Abstract

The southernmost region of South America has an extremely rich and complex magmatic history due to the occurrence of multiple large-scale geological processes that include mantle plumes impingements, slab windows opening, collisional episodes, normal and flat subduction events, mantle transition zone-derived melts ascent, slab break-off events, etc. (e.g., Mpodozis and Kay, 1992; Gorring et al., 1997; Riley et al., 2001; Pankhurst et al., 2006; Kay et al., 2007; Ramos, 2008; Breitsprecher and Thorkerlson, 2009; Aragón et al., 2013; Gianni et al., 2018; Navarrete et al., 2019; 2020; Iannelli et al., 2020). Although this magmatic history began during the Neoproterozoic, the igneous activity of the last 300 Myr has been remarkably intense and voluminous, constituting one of the most distinctive geological features of this region. So much so that three Phanerozoic Large Igneous Provinces (LIPs) have been proposed (Kay et al., 1989; Pankhurst et al., 1998; Kay et al., 2007; Bastías-Mercado et al. 2020 – this special issue). The first of them linked to the Permian-Triassic Journal Pre-proof subduction events (Choiyoi SLIP - Bastías-Mercado et al. this especial issue, and references therein; Oliveros et al., 2019), although there are also proposals that have suggested an origin related to slab-breakoff episodes (e.g., Mpodozis and Kay, 1992; Pankhurst et al., 2006). The second would have been generated by the Jurassic Karoo mantle plume impingement added to the paleo-pacific subduction during the beginning of the Gondwana breakup (Chon Aike SLIP - e.g., Kay et al., 1989; Pankhurst et al., 1998), whereas the origin of the Oligocene-Miocene third province (Somuncura LIP – Kay et al., 2007) is still under discussion. There are proposals that invoke a mantle plume impingement (Kay et al., 2007), a lithospheric delamination event (Remesal et al., 2012), as well as the mantle transition zone-derived melts ascent due to the Farallon slab stagnation (Navarrete et al., 2020), between others. In this special issue, most of the articles are linked to these Permian-Triassic, Jurassic and mid-Cenozoic LIPs (Fig. 1), although multiple subduction-related magmatic events are also included, such as the formation of the Patagonian Batholith (e.g., Pankhurst et al., 1999) and the eruption of the volcanic products linked to the magmatism of the Andean subduction zone (e.g., Rapela et al., 1984; 1988).