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We describe and model a potential re-equili-\udbration process that can affect compositions of melt\udinclusions in magnesian olivine phenocrysts. This pro-\udcess, referred to as ``Fe-loss'', can operate during natural pre-eruptive cooling of host magma and results in lower\udFeOt and higher MgO contents within the initially\udtrapped volume of inclusion. The extent of Fe-loss is\udenhanced by large temperature intervals of magma\udcooling before eruption. The compositions of homoge-\udnised melt inclusions in olivine phenocrysts from several\udsubduction-related suites demonstrate that (1) Fe-loss is\uda common process, (2) the maximum observed degree of\udre-equilibration varies between suites, and (3) within a\udsingle sample, variable degrees of re-equilibration can be\udrecorded by melt inclusions trapped in olivine pheno-\udcrysts of identical composition. Our modelling also\uddemonstrates that the re-equilibration process is fast\udgoing to completion, in the largest inclusions in the most\udmagnesian phenocrysts it is completed within 2 years.\udThe results we obtained indicate that the possibility of\udFe-loss must be considered when estimating composi-\udtions of parental subduction-related magmas from nat-\udurally quenched glassy melt inclusions in magnesian\udolivine phenocrysts. Compositions calculated from\udglassy inclusions affected by Fe-loss will inherit not only\uderroneously low FeOt contents, but also low MgO due to\udthe inherited higher Mg# of the residual melt in re-\udequilibrated inclusions. We also demonstrate that due to\udthe higher MgO contents of homogenised melt inclu-\udsions affected by Fe-loss, homogenisation temperatures\udachieved in heating experiments will be higher than\udoriginal trapping temperatures. The extent of overheat-\uding will increase depending on the degree of re-equili-\udbration, and can reach up to 50 degrees C in cases where\udcomplete re-equilibration occurs over a cooling interval\udof 200 degrees C

Re-equilibration of melt inclusions trapped by magnesian olivine phenocrysts from subduction-related magmas: petrological implications