The geobarometric significance of plagioclase in mantle peridotites: A link between nature and experiments

Publication year: 2011
Source: Lithos, In Press, Accepted Manuscript, Available online 13 June 2011

Giulio, Borghini , Patrizia, Fumagalli , Elisabetta, Rampone

Few previous studies on orogenic plagioclase peridotites, and recent low-P subsolidus experiments on lherzolites (Borghini et al., 2010; J.Petrology 51, 229–254) have revealed that the composition of plagioclase is a marker of varying P conditions in mantle peridotites. Here we confirm this inference, by comparing microstructural-chemical features observed in natural plagioclase-facies recrystallized lherzolites from the External Liguride ophiolitic Unit (EL, Northern Apennine, Italy) with the results of previous (Borghini et al., 2010) and new (this study) experiments on fertile lherzolite with the same bulk composition. Detailed microanalytical work and textural observations on the EL lherzolites revealed systematic chemical zoning in…

 Highlights: ► We document that the plagioclase composition is a marker of P conditions in mantle peridotites. ► A detailed micro-analytical work on ophiolitic plagioclase-bearing lherzolites is reported. ► We implement an experimental dataset on a mantle peridotite composition. ► We compare experimental and natural data to trace the shallow P-T evolution of the mantle. ► We discuss the applicability of our approach in the context of other plagioclase peridotites.