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Olivine‐hosted melt inclusions have the potential to provide direct evidence about the nature of the mantle sources of magmas. In this study, we report the major and trace element and Sr–Nd–Pb–Hf isotope compositions of the Lijiang picrites from the Emeishan large igneous province, as well as major and trace element and Pb isotopic compositions of olivine‐hosted melt inclusions in the picrites. Using these data, we infer the nature of the mantle sources for the Lijiang high‐Ti picrites (Ti/Y = 645–654), and compare them with the Dali low‐Ti picrites (Ti/Y = 351–408). Lijiang melt inclusions have highly heterogeneous Pb isotope compositions (208Pb/206Pb = 2.015–2.201, 207Pb/206Pb = 0.812–0.882, 260 Ma age‐corrected) that overlap the majority of the fields from FOZO to enriched mantle 1 (EM1). The primitive mantle‐normalized trace element patterns of these melt inclusions reveal an enriched composition with depletions in Ba, Nb, Ta, Zr, and Hf. We suggest that an old recycled GLOSS II‐like sediment was probably the main component that imparted the EM1 signature into the sources of the Lijiang picrites. Furthermore, we reverse calculated the mantle potential temperature (Tp) beneath Lijiang and Dali using the Al‐in‐ol temperature. The estimated mantle Tp beneath Lijiang is lower than Dali. We infer that the Lijiang picrites might have originated from the mantle plume with lower thermal energy, corresponding to the waning stage of the axis of the Emeishan mantle plume. Our study suggest that high‐Ti magmas of the Emeishan large igneous province were derived from those parts or stages of the mantle plume with lower thermal energy. Key Points: Highly heterogeneous Pb isotope compositions of olivine‐hosted melt inclusions are found in the Lijiang picritesGLOSS II‐like subduction sediments are responsible for the enriched mantle 1‐like component in the source of the Emeishan large igneous province (LIP)Thermal variation of the mantle plume controlled the types and distribution of basaltic magmas in the Emeishan LIP [ABSTRACT FROM AUTHOR]

Melt inclusions provide unique insights into magmatic sources and processes. This study presents a method for simultaneously measuring Pb isotopes and trace elements in melt inclusions using a 193 nm excimer laser ablation system coupled to a multiple‐collector inductively coupled plasma‐mass spectrometer (MC‐ICP‐MS) and a sector‐field ICP‐MS (SF‐ICP‐MS). The ablated aerosol was split with a Y‐shaped connector into two gas streams, which were simultaneously transported into two mass spectrometers. Lead isotopes were measured on the MC‐ICP‐MS, while trace element concentrations were determined on the SF‐ICP‐MS. Little analytical bias was observed when the aerosol is divided into variable proportions (5:5, 6:4, 7:3, 8:2–9:1) to the two instruments. The precision and accuracy of this method were evaluated by analyzing five geological reference glasses with two laser spot diameters (33, and 45 μm). All the 33 measured trace element concentrations are consistent with the reference values (±10%) and have precisions less than 15% (2RSD). The precisions of the 208Pb/206Pb, and 207Pb/206Pb ratios correlate with Pb concentrations. From BHVO‐2G (Pb = 1.6 ppm) to TB‐1G (Pb = 16.1 ppm), the precision on these ratios improve from about 0.4%–0.2% with a 33 μm laser spot diameter. The mean Pb isotope ratios for the five reference glasses are within 0.15% of the reference values. Using our new method, Pb isotope ratios and trace element contents of plagioclase‐hosted melt inclusions in a mid‐ocean ridge basalt from the Indian Ocean were measured. Key Points: Accurate Pb isotopic ratios and trace elements in five geological reference glasses were simultaneously measured by laser ablation split stream‐inductively coupled plasma‐mass spectrometer (LASS‐ICP‐MS)The proposed method was applied to plagioclase‐hosted melt inclusions in an Indian mid‐ocean ridge basalt sampleThe compositional variation of melt inclusions can be explained by the simple two‐component mixing of Depleted MORB Mantle and EM1 [ABSTRACT FROM AUTHOR]

The Earth's mantle shows large‐scale geochemical heterogeneities bounded by several identifiable end‐member compositions. However, the origin of extreme mantle reservoirs, for example, high 238U/204Pb (HIMU), and their location in the Earth's interior remains poorly constrained. Clinopyroxenes from late Cenozoic Wudi lavas in eastern China have heterogeneous Pb isotopic compositions, even though the erupted lavas are isotopically homogeneous. Our new results provide, to our knowledge, the first evidence for the existence of a HIMU‐like component in the sources of late Cenozoic lavas. Analyses of olivines and their host lavas indicate that the basaltic melts are derived from partial melting of carbonated peridotite. The HIMU source is likely to be younger than 700 Ma old and related to subduction events of the Paleo‐Asian ocean. In addition to deep and ancient recycling, storage of a metasomatically produced mantle reservoir in the mantle transition zone may be an important mechanism for developing extreme isotopic signatures. Key Points: We provide the first evidence for the presence of HIMU component in the magma sourceSubduction‐related, carbonatite‐metasomatized mantle is a likely candidate for the HIMU reservoirThe transition zone may be an important reservoir in the development of mantle heterogeneities [ABSTRACT FROM AUTHOR]

Picrites are potentially near‐primary melts that offer rare insights into the earliest stages of magmatic evolution. However, without detailed investigation of magmatic processes, robust records of early melt evolution and mantle melting behavior cannot be acquired. Here petrological and geochemical interrogations of the Dali picrites were conducted to investigate the magmatic processes. Compositional variation observed in the Dali picrites is dominated by variable accumulation of a wehrlitic assemblage, transported by a low MgO carrier melt. Groundmass clinopyroxenes were produced by direct crystallization of the carrier melt. In contrast, compositions of olivine‐hosted melt inclusions and clinopyroxene macrocrysts indicate that olivine and clinopyroxene macrocrysts crystallized from diverse melt batches that are genetically related to the carrier melt, which formed as a consequence of magma mixing. The compositional range of melts in equilibrium with clinopyroxene macrocrysts with Mg# < 88 (> 88) is similar to (notably smaller than) the range of melt inclusions hosted in olivine macrocrysts with equivalent forsterite values. This observation can be explained by coupling between major and trace elements during partial melting in the mantle. Overall, a process involving periodic magma replenishment, tapping, and fractional crystallization in deep magma chamber(s) can explain the compositional variations recorded in the Dali macrocryst assemblage. Close genetic relationships between macrocrysts and carrier melts appear to be common to many primitive mafic rocks, which may reflect common deep magma chamber processes whereby diverse mantle‐derived melts are injected and evolved, and the primitive macrocrysts thus formed are subsequently transported by mixed liquids, producing macrocryst‐bearing primitive mafic rocks. Key Points: Compositional variation in the Dali picrites is dominated by variable accumulation of olivine and clinopyroxene macrocrystsThe macrocrysts crystallized from multiple parental magmas and are genetically related to the carrier meltPeriodic RTX processes in the magma chamber(s) dominate the compositional evolution of the diverse parental melts [ABSTRACT FROM AUTHOR]

New petrological and geochemical data for Early Cretaceous volcanic rocks in the North China Craton (NCC) combined with published data of cotemporaneous volcanic rocks in the NCC and eastern Central Asian Orogenic Belt (ECAOB) are used to understand their petrogenesis and crustal growth and evolution. Early Cretaceous volcanic rocks in the NCC show characteristics typical of continental crust, with negative Nb and Ta anomalies, and enrichment of K and Pb. The εNd of Early Cretaceous volcanic rocks in the NCC correlate with indices of differentiation (e.g., Mg#), implying that mantle‐derived magmas were modified by open‐system processes. The high‐Mg clinopyroxene and melt inclusions hosted by high‐Fo olivine in Early Cretaceous volcanic rocks in the NCC have lower 207Pb/206Pb and 208Pb/206Pb ratios than low‐Mg clinopyroxene and melt inclusions hosted by low‐Fo olivine, which can be explained by the interaction between lower crust and basaltic magmas (magma mixing or assimilation). Unlike contemporaneous counterparts in the NCC, Early Cretaceous volcanic rocks in the ECAOB have high εNd values. Such features can also be produced by crustal assimilation and/or magma mixing, given the juvenile lower crust beneath the ECAOB. The "adakitic" signature of Early Cretaceous volcanic rocks is most likely inherited from the lower continental crust. Large‐scale partial melting of the lower crust may have been related to continuous magmatic underplating in an extensional environment. This work suggests that Early Cretaceous volcanic rocks in the Central‐East Asia represent a nonnegligible contribution to crustal growth, despite having "crust‐like" trace element and isotopic characteristics. Key Points: Adakitic‐like signatures of most Early Cretaceous volcanic rocks are likely inherited from lower continental crust with normal thicknessIntermediate to felsic volcanic rocks formed through complex processes involving AFC, magma mixing, and lower crust partial meltingEarly Cretaceous magmatism in the Central‐East Asia contributes to crustal growth [ABSTRACT FROM AUTHOR]