A Neoproterozoic hyper-extended margin associated with Rodinia's demise and Gondwana's build-up: The Araguaia Belt, central Brazil

Magnetic Properties of Ferritchromite and Cr‐Magnetite and Monitoring of Cr‐Spinels Alteration in Ultramafic and Mafic Rocks

“… Ternary plot of trivalent cation concentrations (Al 3+ , Cr 3+ , and Fe 3+ ) in spinel alteration rims from (a) the four studied serpentinite units (data for North Aït Ahmane serpentinites are from Hodel et al., 2017; core compositions are from Hodel et al., 2017, 2019) and (b) from the Grochowiec serpentinites (Poland) in which Kądziałko‐Hofmokl et al. (2010) detected a spinel alteration phase with a T c ca.…”

“…This study is based on extensive sampling of ultramafic units from Neoproterozoic ophiolites in Brazil (the Araguaia Belt, Hodel et al, 2019) and Morocco (Bou Azzer and Khzama, Hodel et al, 2017Hodel et al, , 2018Hodel et al, , 2020. All samples investigated are fully serpentinized peridotite (hydrated mantle) that have been differently affected by obduction-related metamorphism and, for some of them, by intense hydrothermal alteration (Hodel et al, 2017(Hodel et al, , 2018.…”

“…Serpentinites from Araguaia Belt ultramafic units are located between the Amazonian Craton and the Paranaïba basin in central Brazil (see the detailed petrographic and petrological study in Hodel et al., 2019). They display a classical pseudomorphic mesh texture mainly constituted of lizardite/chrysotile assemblages (low‐temperature serpentine varieties), attesting to a static oceanic‐like serpentinization and a regional metamorphism that involved temperatures below 350°C (e.g., Evans, 2004; Hodel et al., 2019; Mével, 2003; Schwartz et al., 2013). Spinels of these serpentinites are generally well‐preserved and weakly altered (Figures 2a and 2b).…”

“…Indeed, the chemistry of spinel core reflects partial melting and refertilization processes while spinel alteration rims (when present) testify the metamorphic conditions endured by their host rock (e.g., Barnes, 2000;Barnes & Roeder, 2001;Dick & Bullen, 1984). Spinels are commonly the only pristine mineral preserved in fully serpentinized peridotites, making them one of the most investigated minerals in these rocks (e.g., Ahmed & Surour, 2016;Arai, 1994;Barnes, 2000;Barra et al, 2014;Dick & Bullen, 1984;González-Jiménez et al, 2009;Hodel et al, 2017Hodel et al, , 2019Hodel et al, , 2020Ishii et al, 1992;Marques et al, 2007;Mellini et al, 2005;Pearce et al, 2000;Saumur & Hattori, 2013).…”

A suture related accretionary wedge in the Gondwana assembly: Insights from serpentinites in the Hoggar shield, Algeria

“…Moreover, the ocean closure developed southward in the Panafrican-Brasiliano belt also implies eastern vergence of intra-oceanic subduction interpreted in the Kabye massif (i.e., Togo; Guillot et al, 2019), and allowed the exhumation of rare remnants of serpentinized mantle along the Araguaia hyper-extended margin, accreted on the Amazonian craton (Hodel et al, 2019).…”