The origin of EM1 (Enriched Mantle 1) reservoir, initially defined by the ocean island basalts (OIBs) with extremely low 143Nd/144Nd and 206Pb/204Pb, has been long debated, because melting of the ambient refractory peridotite along with the EM1 component will dilute the “EM1 fingerprints” recorded in these rocks. Comparing to the OIBs, Cenozoic potassic basalts from northeast China, the typical EM1‐type basalts in continental region, are formed at a lower‐degree melting, and therefore have the chance to preserve more information of the EM1 component. Here high‐precision Fe isotopes of these potassic basalts are reported to constrain the source lithology. Their δ57Fe (0.15–0.28‰) are positively correlated with the K2O, SiO2, K/U, and Rb/Y, and negatively correlated with the εNd and δ26Mg, forming binary mixing arrays. One endmember is the inferred EM1 reservoir, whereas the other is the local lithospheric mantle. Major elemental compositions of the melts released from the EM1 component resemble those sediment‐derived experimental melts. Combining with their heavier Fe isotopes and higher Zn/Fe ratios relative to those mid‐ocean ridge basalts (MORBs), an eclogitic source of these potassic basalts is therefore proposed to account for these features. Differing from the most conventional thinking of the metasomatized, phlogopite‐bearing lithospheric mantle, we argue that the EM1 component in the source of continental potassic basalts are composed of ancient subducted crustal materials (i.e., recycled sediment ± oceanic crust). This deep EM1 component will transform into eclogite and release high‐SiO2 potassic melts when ascending to the shallow asthenosphere.

Quantitative in situ electron probe microanalysis (EPMA) was applied to determine the F, Cl, Nb and P contents of glass materials. Using reference glasses with low FeO T (< 10% m/m) mass fractions to construct a F calibration line to correct the Fe interference on the F peaks, is unsuitable for analysing natural Fe-rich melt inclusions with up to 21% m/m FeO T , which commonly occur in picritic, nephelinitic and basanitic samples. For this reason, this study presents a series of seven F-free glasses, which show a wider range of FeO T (1-20% m/m) that were synthesised to improve the overlap correction of Fe on F. Using this improved method, reference glasses of USGS and glasses synthesised from powders of other rock RMs were analysed to evaluate well-known reference materials (RMs) as quality control materials for EPMA measurement of F, Cl, Nb and P mass fractions. The results show that amongst the tested RMs, USGS BHVO-2G is the most appropriate RM for F-Cl determination because different pieces of this glass RM analysed by different laboratories yielded results that agree within uncertainty.

Abstract1,2‐Diphenyl‐1,2‐dimethyldisilanylene‐bridged bis‐cyclopentadienyl complex [η5,η5‐C5H4PhMeSiSiMePh‐C5H4]Fe2(CO)2(μ‐CO)2 (1) was synthesized by a modified procedure, from which the trans‐isomer 1b that was previously difficult to obtain has been isolated for the first time. More interestingly, two new regio‐isomers [η5,η5‐C5H4SiMe(SiMePh2)C5H4]Fe2(CO)2(μ‐CO)2 (2) and [η5,η5‐C5H4Me2SiSiPh2C5H4]Fe2(CO)2(μ‐CO)2 (3) were occasionally obtained during above process, the novel structures of which opened up new options for further study of this type of Si–Si bond‐containing transition metal complexes. The molecular structure of 2 has been determined by the X‐ray diffraction method.