The origins of high-Ti and low-Ti magmas in large igneous provinces, insights from melt inclusion trace elements and Sr-Pb isotopes in the Emeishan large Igneous Province

Zinc Isotope Constraints on Recycled Oceanic Crust in the Mantle Sources of the Emeishan Large Igneous Province

“…Our results are also consistent with observations in recent studies (e.g., Ren et al, ; Yu et al, ; Zhang et al, ). For example, Yu et al () found that olivine phenocrysts in the Emeishan picrites have slightly heavier oxygen isotope compositions than that of the mantle, indicating that the Emeishan picrites were from a hybridized and metasomatized mantle source containing recycled components.…”

“…Modeling suggests that addition of~15% recycled basaltic oceanic crust into the mantle source, along with a small Zn isotope fractionation induced by mantle melting, can reasonably account for the heavier zinc isotope composition of the Emeishan picrites relative to other large-degree partial melts of the mantle. This provides independent evidence in supportive of the important role of recycled oceanic crust in the source and generation of the Emeishan picrites (e.g., Ren et al, 2017;Yu et al, 2017;Zhang et al, 2019). Our data show no evidence for recycling of marine carbonates into source of the Emeishan LIP and thus possibly into the Earth's deep mantle (>660 km).…”

Nature of the Mantle Plume Under the Emeishan Large Igneous Province: Constraints From Olivine‐Hosted Melt Inclusions of the Lijiang Picrites

“…The Lijiang melt inclusions have mantle-like to lower Nb/U (16.0-55.5, average = 32.7) and Ce/Pb (7.0-24.3, average = 14.8 ratios compared with typical OIBs (Nb/U = 47 ± 10, Ce/Pb = 25 ± 10; Hofmann et al, 1986), and have higher Th/U ratios (3.2-6.0, (Danyushevsky & Plechov, 2011) and the olivine-melt model of Ford et al (1983). The blue squares are the compositions of Dali picrites and melt inclusions (data from Ren et al, 2017 andL. Zhang et al, 2019); average Ti/Y of melt inclusions is 396).…”

“…(a) The patterns of the picrites (red lines) and the average melt inclusion compositions (yellow line). The light-blue field is the compositional field of melt inclusions in Dali picrites (L Zhang et al, 2019)…”

“…Hou et al (2011) argued that the different Ti/Y ratios of magmatic rocks are not a reflection of different sources but rather of differential fractional crystallization of Fe-Ti oxides magmas of the Emeishan LIP. Ren et al (2017) and L. Zhang et al (2019) proposed that the Emeishan LIP was derived from a relatively homogeneous pyroxenite source and that the mixing of melts from different depths and melting degrees of the mantle plume may explain the compositional variability of magmas. R. Xu et al (2020) argued that a relatively homogeneous peridotitic mantle plume source can explain the compositional ranges of olivines and picrites in the Emeishan LIP.…”