Minor elements in olivine inspect the petrogenesis of orogenic peridotites

A large dataset of minor elements (Ni, Mn, Co, Zn, Ca, Ti, Al, Cr and Na) in divines from orogenic peridotites is reported to investigate the application of these elements as sensitive tracers of mantle processes in subduction zones. Orogenic mantle peridotites can be distinguished from crustal peridotites by overall higher Ni and lower Co and Zn contents in olivine. In particular, the Ni/Co ratio of olivine can successfully discriminate between the two types of peridotites. When mantle peridotites underwent transfer from hot lithospheric mantle to cool subduction zones, olivine Ca, Al and Cr contents dramatically decreased, and Ca in olivine can be a useful geothermometer for orogenic peridotites. The Na contents of olivines from garnet-facies mantle peridotites (mostly >20 ppm) are typically higher than those from spinel-facies mantle peridotites (mostly <11 ppm), indicating that Na in olivine is a potential pressure indicator for orogenic peridotites. The high Ti contents of olivine may be caused by subducted crustal metasomatism, producing the wide occurrence of Ti-clinohumite and rutile in strongly metasomatized garnet Iherzolites. Olivines from these high-Ti garnet lherzolites also have Mn contents deviating from the normal mantle olivine range, implying high sensitivity of Mn in olivine to crust-mantle interaction in subduction zones. Our data highlight the broad prospects for olivine geochemistry in the realm of subduction zone geodynamics. (C) 2019 Elsevier B.V. All rights reserved.