Rodingites from the Xigaze ophiolite, southern Tibet – new insights into the processes of rodingitization

High‐P metamorphism of rodingites during serpentinite dehydration (Cerro del Almirez, Southern Spain): Implications for the redox state in subduction zones

“…In some of these investigations, mineralogical variations between different metarodingite types have been attributed to different degrees of oceanic metasomatism that were preserved during subsequent metamorphism (e.g., Ferrando, Frezzotti, Orione, Conte, & Compagnoni, 2010;Li et al, 2004). However, only a few studies have precisely determined the metamorphic evolution of metarodingites by detailed thermodynamic modelling (e.g., Li, Rahn, & Bucher, 2008;Li et al, 2017;Zanoni et al, 2016).…”

Garnet-Vesuvianite Equilibrium in Rodingites from Dobšiná (Western Carpathians)

“…Recently, the reaction Grt → Ves was also documented by Micro-Raman mapping performed on rodingites from the Northern Apennines [45]. The physicochemical conditions of this reaction were investigated using multiple thermodynamic modeling approaches [5,[44][45][46]; rather low silica activity and high Ca activity are typically accepted, which is consistent with the composition of rodingitization fluid. The CO2 fugacity in the fluid was commonly suggested to be rather low [47,48], but the study by Salvioli-Mariani et al [45] shows that the formation of vesuvianite can occur at higher CO2 fugacity values as well.…”

“…The chemical signature of diopside relics dominated by very high Ca and Mg contents is in agreement with diopside compositions from rodingites around the world, e.g., [38][39][40] and confirms its metasomatic origin. As the diopside (possibly with older grossular cores) is considered to be the oldest mineral phase, there are no indications allowing us to discuss the protolith of the rock, although the most often reported protoliths around the world are various mafic magmatic rocks commonly associated with serpentinized bodies, e.g., [3,5,41]. No primary (magmatic) minerals were identified, and contrary to the mineralogy described by Putiš et al [32], we did not observe Fe-Ti oxides.…”

“…The CO2 fugacity in the fluid was commonly suggested to be rather low [47,48], but the study by Salvioli-Mariani et al [45] shows that the formation of vesuvianite can occur at higher CO2 fugacity values as well. In any case, the vesuvianite tends to form at later stages of the rodingitization process and thus represents a higher extent of metasomatic transformation [4,5,12,42,46]. This mineral is abundant in rodingites affected by intense metamorphism [41,42,44,49], but numerous descriptions of rodingites lacking vesuvianite are equally frequent [6,10,39,[50][51][52][53][54][55].…”

“…Rodingite represents a particular calcium-rich metasomatic rock. Its formation is closely related to the serpentinization process of ultramafic rocks since the origin of the metasomatic fluid is generally regarded as a product of serpentinization [1][2][3][4][5][6]. These rocks are characterized by a heterogeneous and quite complex mineralogy, mostly dominated by Ca-rich often hydrated silicate minerals: garnet, vesuvianite, diopside, chlorite, epidote, zoisite, tremolite, prehnite and others [7][8][9][10][11].…”