Pervasive Listwaenitization: The Role of Subducted Sediments within Mantle Wedge, W. Chalkidiki Ophiolites, N. Greece

Listwaenitization processes have significantly altered the mantle section of West Chalkidiki ophiolites, generating second largest magnesite deposit in Greece. Although research studies been conducted region, post-magmatic processes, and especially geotectonic settings under which listwaenitization took place, remain unclear. In this study, minerals rocks were studied applying XRD, clay fraction, SEM, EMPA, ICP-MS, INAA, LA-ICP-MS, thermodynamic modeling. The results revealed that alteration affected wedge peridotite protoliths leading to following chemical changes (a) SiO2 increase with decreasing MgO, (b) Cs, Pb, As, V enrichments, (c) limited magnesiochromite hosted within listwaenitized chromitites (d) enrichment PPGE Au desulfurized laurite. Alteration was induced by fluids deriving from subducted Mesozoic sediments, represented Prinochori Formation or chemically similar formations. final product completely silicified (silica listwaenite) is thermodynamically stable Earth-surface conditions, dolomite phyllosilicates transforming into minerals. Based on detailed petrographical observations, peridotites subjected serpentinization, subsequently, serpentine interacted CO2, silica calcium-bearing fluids, its transformation amorphous rusty-silica mass and/or tremolite.