Peculiarities of some mafic―ultramafic-hosted massive sulfide deposits from southern Urals ― A likely forearc occurrence

摘要

Mafic-ultramafic-hosted massive sulfide deposits from southern Urals show several analogies with counterparts in modern oceanic environments characterized by highly permeable substrates, especially near-rift off-axis sites and sediment-covered spreading centers. However, the occurrence of high-Cr, low-Ti detrital chromite, often carrying inclusions of low-Ti, low-K melts, within the ore and surrounding rocks excludes a mid-ocean ridge origin for the mineralizations. It is proposed that the studied deposits formed in a forearc environment characterized by tectonic and/or sedimentary melanges carrying disrupted mafic-ultramafic rocks of crustal and mantle derivation.