Metamorphic Facies and Deformation Fabrics Diagnostic of Subduction: Insights From 2D Numerical Models

Abstract

Following the pioneering works carried out in the seventies (e.g., England & Richardson, 1977;Oxburgh & Turcotte, 1970, 1971Toksöz & Bird, 1977) several key advances have been made in numerical modeling methods that have improved the understanding of the thermo-mechanical evolution of the oceanic and continental lithosphere during oceanic subduction and continental collision (e.g.

Cld-St-And-Bearing Assemblages in the Central Southalpine Basement: Markers of an Evolving Thermal Regime during Variscan Convergence

“…In the Southalpine domain, andalusite mostly occurs in high-temperature basement rocks that include sillimanite, cordierite, and/or spinel that reflect Permian-Triassic Buchan/Abukuma-type metamorphism. In the upper Val Camonica, andalusite is instead found in chloritoid-staurolite-garnet-bearing metapelites, which suggest higher P/T conditions as characteristic of Barrovian/Dalradian metamorphism [1,2]. This case study thus represents an excellent opportunity to improve our understanding of the Variscan basement exhumation path, from the Variscan convergence to the Permian-Triassic lithospheric thinning.…”

“…Andalusite is an indicator of high thermal regimes, such as those characterizing contact metamorphism or regional Buchan/Abukuma-type metamorphism in the metapelites of the continental crust [1,2]. High T/P ratios accountable for andalusite development are envisaged in various convergent and divergent settings, including late-orogenic thinning and lithospheric delamination in the mature stages of continental collision, as well as lithospheric thinning announcing continental rifting in post-orogenic settings [3,4].…”

Quantitative X-ray Maps Analaysis of Composition and Microstructure of Permian High-Temperature Relicts in Acidic Rocks from the Sesia-Lanzo Zone Eclogitic Continental Crust, Western Alps

“…Metagranitoids (Apgr1) and metagabbros (Apg1) emplacement conditions are also reported (Table 1). Metamorphic facies modified after [111][112][113][114]. Black arrows represent geothermal gradients traditionally associated to arc regions (A) and plate interior (Pi), warm subduction complexes (WS), and cold subduction complexes (CS), as presented by [115].…”

Metamorphic Facies Distribution in the Western Alps Predicted by Petrological‐Thermomechanical Models of Syn‐Convergent Exhumation

“…Such numerical models have been applied to investigate the mechanisms of exhumation of (U)HP rocks within Alpine‐type collisional belts (e.g., Burov et al., 2001; Butler et al., 2014; Gerya et al., 2002; Ruh et al., 2015; Stöckhert & Gerya, 2005; Warren et al., 2008; Yamato et al., 2008, 2007). Several of these studies trace individual numerical markers (e.g., Gerya & Yuen, 2003) in order to assess P ‐ T ‐ t trajectories during syn‐convergent exhumation (e.g., Butler et al., 2014; Gerya et al., 2002; Regorda et al., 2021; Ruh et al., 2015; Stöckhert & Gerya, 2005; Warren et al., 2008; Yamato et al., 2008, 2007). Although such numerical models successfully reproduce individual exhumation P ‐ T ‐ t trajectories that are comparable to the Alps (e.g., Butler et al., 2014; Gerya & Yuen, 2003; Ruh et al., 2015; Warren et al., 2008; Yamato et al., 2008, 2007), only few numerical modeling studies (e.g., Butler et al., 2014; Regorda et al., 2021) attempted to reproduce the spatially continuous distributions of metamorphic facies and the entire, regional‐scale metamorphic architecture of the Western Alps (Figure 2).…”

“…Such numerical models have been applied to investigate the mechanisms of exhumation of (U)HP rocks within Alpine-type collisional belts (e.g., Burov et al, 2001;Butler et al, 2014;Gerya et al, 2002;Ruh et al, 2015;Stöckhert & Gerya, 2005;Warren et al, 2008;Yamato et al, 2008Yamato et al, , 2007. Several of these studies trace individual numerical markers (e.g., Gerya & Yuen, 2003) in order to assess P-T-t trajectories during syn-convergent exhumation (e.g., Butler et al, 2014;Gerya et al, 2002;Regorda et al, 2021;Ruh et al, 2015;Stöckhert & Gerya, 2005;Warren et al, 2008;Yamato et al, 2008Yamato et al, , 2007. Although such numerical models successfully reproduce individual exhumation P-T-t trajectories that are comparable to the Alps (e.g., Butler et al, 2014;Gerya & Yuen, 2003;Ruh et al, 2015;Warren et al, 2008;Yamato et al, 2008Yamato et al, , 2007, (b) Approximate pressure-temperature metamorphic facies grid (modified after Philpotts & Ague, 2009) with representative P-T estimates for Western Alpine units (dashed and solid lines are used for clearer visualization), BIU = (Rubatto & Hermann, 2001), MR = (Luisier et al, 2019;Vaughan-Hammon et al, 2021b), SE = (Lardeaux et al, 1982;Vuichard & Ballevre, 1988), VA = (Bousquet et al, 2002;Goffé & Bousquet, 1997;Wiederkehr et al, 2007), GP = (Bousquet et al, 2008;Manzotti et al, 2018), LU = (Wiederkehr et al, 2008), DB = (Cortiana et al, 1998...…”