Water Content In The Emeishan Large Igneous Province

The large igneous provinces(LIPs)represent consequences of the melting of the Earth.The recent investigation of water content of the primary magma in the global LIPs shows that the source hydration had played important role in their genesis.The Emeishan LIP is one of the Permian LIPs in the world.The previous work on the Dali picrites,within the initial stage of eruption,indicates that water largely promoted the partial melting of mantle.However,whether the water played significant role in the other stages of eruption is not clear now,which is critical to understand the genesis model of LIPs.Here,we report the water content of picrites and basalts from Binchuan,within the upper part of eruption sequences of ELIP.The result shows that the primary magma of picrites could have water as high as 2.8 ± 1.1 wt.%.slightly lower than that of Dali picrites,but still considerably higher than that of MORB and OIB.The basalts have similar water contents.The olivine-Al thermometer shows that the liquids temperature of olivine is 1430±40?,and the calculated mantle potential temperature is 1476±40?.The percentage of pyroxenite-drived melts in the primary magma of Binchuan picrites,recovered by the high precision Fe/Mn ratios,is around 63%.The basalts contacted with Binchuan picrites have comparable water contents than picrites,but the mantle potential temperature is slightly lower.These data shows that the mantle hydration,recycled crutal materials,and high temperature played significant role not only for the initial stage,but also for the lage stage of eruption of ELIPs.