Accretion and subduction mass transfer processes: Zircon SHRIMP and geochemical insights from the Carboniferous Western Series, Central Chile

Seamount Subduction Dynamics and Long‐Term Evolution of the Franciscan Active Margin

“…Deformation above the seamount is expected during subduction of the seamount, and is visible in the top thrust above the SMVC (interface 1, Figures 10b and 11b). While deformation might be localized along a thin plate interface when a smooth ocean plate subducts (e.g., Agard et al., 2018; Bebout & Penniston‐Dorland, 2016), seamount subduction is likely associated to transient thickening of the subduction interface (Lallemand et al., 1994; Munoz‐Montecinos et al., 2023; Noda et al., 2020) together with diffuse deformation of the upper plate (Dominguez et al., 1998; Ranero & von Huene, 2000; Wang & Bilek, 2011). The mylonitic sedimentary sliver located above Snow Mountain on Saint John Mountain eastern slopes (Figures 5b and 5c), with P ‐ T conditions in agreement with that of the SMVC (Figure 8a), hints to such upper plate deformation, as it possibly corresponds to a formerly accreted unit that was tectonically eroded and bulldozed down during subduction of the SMVC.…”

“…Seamounts in exhumed units from fossil subduction zones are generally dismembered and difficult to identify by other means than pillow basalts, bulk-rock geochemistry, and/or intercalation with carbonate sedimentary rocks (Barbero et al, 2021;Munoz-Montecinos et al, 2023;Tan et al, 2017). Among the best field examples of exhumed subducted seamounts with multi-kilometer-scale continuity, only a few have been extensively…”

“…Seamounts in exhumed units from fossil subduction zones are generally dismembered and difficult to identify by other means than pillow basalts, bulk‐rock geochemistry, and/or intercalation with carbonate sedimentary rocks (Barbero et al., 2021; Munoz‐Montecinos et al., 2023; Tan et al., 2017). Among the best field examples of exhumed subducted seamounts with multi‐kilometer‐scale continuity, only a few have been extensively documented, among which: (a) the Snow Mountain Volcanic Complex (SMVC) in the Franciscan Complex of California (MacPherson, 1983), (b) the Anarak unit in Central Iran (Bagheri & Stampfli, 2008), and (c) the Siah Kuh unit in southeastern Iran (Bonnet et al., 2020; Bonnet, Agard, Angiboust, Fournier, & Omrani, 2019; Bonnet, Agard, Angiboust, Monié, et al., 2019).…”