The upper Oligocene San Rafael intrusive complex (Eastern Cordillera, southeast Peru), host of the largest-known high-grade tin deposit

Depositing >1.5 Mt of Tin Within <1 m.y. of Initial Granitic Intrusion in the San Rafael Tin (-Copper) Deposit, Southeastern Peru

“…The surface exposure of the San Rafael intrusive complex (SRIC) is dominated by a peraluminous S-type megacrystic biotite-cordierite monzogranite characterized by pluricentimetric phenocrysts of K-feldspar (Figs. 2A and 3A) with lesser comagmatic enclaves of varied granitoids and subordinate lamprophyres (Kontak and Clark, 2002;Harlaux et al, 2021b). Other petrologic aspects of the SRIC which are relevant in the context of this study include: 1) whereas the bulk of the main intrusion constituting the SRIC is the aforementioned megacrystic facies, there are textural variants of this, namely a fine-grained granite that shows progressive gradual contacts toward the granitic cupola; 2) in the upper part of the intrusion, granophyric to graphic textures are noted; and 3) a variety of granitic phases and lamprophyres are observed deeper in the SRIC, such as comagmatic enclaves and dikes, demonstrating commingling and mixing of felsic and mafic magma batches (Kontak and Clark, 2002;Harlaux et al, 2021b).…”

“…Other petrologic aspects of the SRIC which are relevant in the context of this study include: 1) whereas the bulk of the main intrusion constituting the SRIC is the aforementioned megacrystic facies, there are textural variants of this, namely a fine-grained granite that shows progressive gradual contacts toward the granitic cupola; 2) in the upper part of the intrusion, granophyric to graphic textures are noted; and 3) a variety of granitic phases and lamprophyres are observed deeper in the SRIC, such as comagmatic enclaves and dikes, demonstrating commingling and mixing of felsic and mafic magma batches (Kontak and Clark, 2002;Harlaux et al, 2021b). Selected samples illustrating these features are provided in Appendix Figure A1 and the reader is referred to Harlaux et al (2021b) for details. The SRIC has two major components, i.e., the San Rafael granite exposed in the southwestern part of the district and the Quenamari granite occurring in its northeastern part.…”

“…1B). This area is transitional to the megacrystic granite and consists of a quartz-muscovite greisen with minor tourmaline and dumortierite (Gialli et al, 2019;Harlaux et al, 2021b).…”

“…The regional and metallogenic settings of mineralization were documented by Kontak (1985), Clark et al (1983Clark et al ( , 1990, Kontak et al (1990a,b), and Sandeman et al (1997), while the geodynamic evolution was outlined by Sandeman et al (1995) and Mlynarczyk and Williams-Jones (2005). Major contributions to the petrology and geochemistry of the granitic host rocks and the alteration and mineralization processes at San Rafael were brought by Kontak and Clark (2002), Mlynarczyk et al (2003), Mlynarczyk (2005), Mlynarczyk and Williams-Jones (2006), Wagner et al (2009), Corthay (2014), Prado Flores (2015, Gialli et al (2019), Harlaux et al (2020Harlaux et al ( , 2021bHarlaux et al ( , 2021c, and Cazorla Martínez (2022). Building on a revised paragenetic sequence for the San Rafael deposit, we present the results of 40 Ar/ 39 Ar and U-Pb chronometers for magmatic (biotite, K-feldspar) and hydrothermal (muscovite, adularia, cassiterite) minerals to constrain the lifetime of the magmatic-hydrothermal ore system.…”

Copper-rich tin deposits

“…Cu-bearing deposits and prospects of porphyry type and all deposits with well-preserved advanced argillic lithocaps are highlighted. Age assignments are from compilations by Sillitoe and Perelló (2005) for Cu deposits and Gemmrich et al (2021) for Sn deposits, supplemented by data in Redwood and McIntyre (1989) and Simón et al (2021) spatially and temporally related to some Sn granites, including most of those that gave rise to Sn-Cu deposits (e.g., Štemprok and Seifert 2011; Table 1), and (2) petrogenetic evidence for direct mafic magma contributions to ore-related granites in the Central Andean, western Tasmania, South China, Cornubian, Inner Mongolia, and other Sn provinces as well as at Neves Corvo (Lehmann et al 2000;Black et al 2010;Cheng et al 2013b;Simons et al 2016;Wan et al 2019;Marques et al 2020), and including deposits in which lamprophyres are the only observed mafic component (e.g., San Rafael; Harlaux et al 2021a). At least in the case of late-to post-collisional Sn provinces, and certainly some of those in back-arc settings, in situ or actively delaminating subcontinental lithospheric mantle, metasomatized during prior subduction, is the likely source of the mafic and lamprophyric magmas (e.g., Murphy 2020) and any contributed Cu as it also is in the case of porphyry Cu deposits generated in comparable post-collisional settings (Richards 2011).…”