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Apatite, an important mineral widely distributed in various geological environments, can be used for in situ U–Pb dating and Sr–Nd isotope analyses. The LA-ICPMS U–Pb dating and Sr–Nd isotopic determinations require suitable matrix-matched reference materials. Current apatite standards are rare and have some defects. Most natural apatite references display high and variable common Pb, which may be the most difficult issue in microbeam determination. We provided a gem-quality apatite MAP-3, subjected to detailed major- and trace element composition, U–Pb dating, and Sr–Nd isotopic analyses to assess its homogeneity of chemical composition and suitability as a reference material for microbeam U–Pb dating and Nd isotope analyses. Through comprehensive analyses, we show that the MAP-3 apatite is free of mineral inclusions and is uniform at the level of analytical precision of major- and trace element, U–Pb isotopic, and Nd isotopic ratios despite compositional zones from CL images. The MAP-3 apatite has ID-TIMS determined mean isotopic ratio values of 0.13222 ± 0.00016 for 206Pb/238U, 1.2084 ± 0.0030 for 207Pb/235U, and 0.0663 ± 0.0001 for 207Pb/206Pb and the weighted mean 206Pb/238U ages of 800.5 ± 0.9 Ma (2 s, MSWD = 1.5, n = 11). The 143Nd/144Nd isotopic results determined by (ID)-TIMS are 0.511248 ± 0.000006 (2 s, MSWD = 4.2, n = 11) with moderate Nd contents of ∼1532 ppm. U–Pb age and Nd isotopic compositions obtained by LA-(Q, SF-SC, MC)-ICPMS analysis are reproducible and agree with the values of TIMS, which indicates that MAP-3 apatite has the potential to be a primary reference material for microbeam determination of U–Pb ages and Nd isotope analyses. To validate the effectiveness of the potential, we dated some apatite reference materials of known age and two geological apatites. The results demonstrated the high-quality U–Pb dating reference materials used with MAP-3 apatite. [ABSTRACT FROM AUTHOR]

JingFenCui is a type of rhodonite jade from the Changping district of Beijing, China, which is a manganese skarn deposit formed through the metasomatism of the granite aplite and Cambrian limestone. The pink color of JingFenCui is richer and brighter than that of rhodonite jade from other deposits. The surface of JingFenCui exhibits dendritic iron and manganese oxides, which is the outstanding advantage of rhodonite jade for carving works. The zoning pattern of mineralogy between the contact zone with the wallrock is obvious. The main skarn minerals consist mainly of spessartine, diopside, augite, manganotremolite, clino-suenoite, rhodonite, galena, etc. Compared with rhodonite jade from the Makeng in Fujian and the Luziyuan in western Yunnan, vittinkiite (MnSiO3) is more concentrated in the rhodonite of the JingFenCui Deposit as a Mn-Ag-Pb-Zn-Fe polymetallic deposit. There is a good agreement among the rhodonite, amphibole, and galena in the spider diagrams of the trace elements. The results of trace elements and REE analysis show that the metallogenic fluids of the JingFenCui deposit are mainly from magma related to the Heixiongshan granite. It is suggested that the JingFenCui deposit is a manganese skarn deposit formed through the metasomatism of the manganese-bearing limestone and fine-grained granite of the Heixiongshan. [ABSTRACT FROM AUTHOR]

Subduction zone fluids are critical for transporting materials from subducted slabs to the mantle wedge. Jadeitites from Myanmar record fluid compositions and reactions in the forearc subduction channel. Here we present high‐precision Mg isotope data of the Myanmar jadeitites and associated rocks to understand the Mg isotope composition of subduction zone fluids at forearc depths. Two types of jadeitites (white and green) exhibit distinct Mg isotope compositions. The white jadeitites precipitated from Na‐Al‐Si‐rich fluids and have low δ26Mg values, varying from −1.55‰ to −0.92‰, whereas the green jadeitites have higher δ26Mg values (−0.91‰ to −0.74‰) due to metasomatic reactions between fluids and Cr spinel. The amphibole‐rich blackwall in the contact boundaries between jadeitites and serpentinites also exhibits low δ26Mg values (−1.17‰ to −0.72‰). Therefore, the jadeite‐forming fluids have not only high concentrations of Na‐Al‐Si but also low δ26Mg values. The low δ26Mg signature of the fluids is explained by the dissolution of Ca‐rich carbonate in subducted sediments or altered oceanic crust, which is supported by the negative correlation of δ26Mg with CaO/TiO2, CaO/Al2O3, and Sr in the white jadeitites. Given the common occurrence of Ca‐rich carbonates in the subduction channel, the Mg isotope composition of low‐Mg aqueous fluids would be significantly modified by dissolved carbonates. Metasomatism by such fluids along conduits has the potential to generate centimeter‐scale Mg isotope heterogeneity in the forearc mantle wedge. Therefore, Mg isotopes could be a powerful tracer for recycled carbonates not only in the deep mantle but also in the shallow regions of subduction zones. Key Points: The Myanmar jadeitites have δ26Mg values lower than normal mantleJadeite‐forming fluids have high contents of Na‐Al‐Si and low Mg contents and δ26Mg valuesSubduction zone fluids at forearc depths may have low δ26Mg values due to carbonate dissolution [ABSTRACT FROM AUTHOR]