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A flare‐up of granitoids occurred at 465–445 Ma in the South Altyn Tagh, synchronously with the exhumation of subducted continental crust. Nevertheless, it remains enigmatic whether a petrogenetic connection exists between them. Here, we report a 454–451 Ma monzogranite pluton, which is characterized by abundant inherited zircons, located in the northern margin of the South Altyn Tagh high‐pressure (HP)—ultrahigh‐pressure (UHP) metamorphic terrane. U–Pb ages and Hf–O isotopic compositions of inherited and synmagmatic zircons are investigated to trace the source rocks and petrogenesis of this pluton. The inherited zircons (zircons that predate the magmatism) exhibit a wide range of ages from 2618 to 484 Ma, displaying three major peaks at 1800–1100 Ma, 1000–800 Ma and 500 Ma. By comparing these inheritance age patterns with zircon spectra of main (meta‐)sedimentary sequences and the widespread Early Neoproterozoic granites (presently as granitic gneisses) in South Altyn Tagh, along with zircon εHf(t) and whole‐rock Nd isotopic composition, we argue that the main source rocks of the studied monzogranite are Early Neoproterozoic granitic gneisses and Late Mesoproterozoic paragneisses from the South Altyn Tagh HP–UHP metamorphic terrane. The ca. 500 Ma inherited zircons have a metamorphic origin, which is simultaneous with the peak metamorphic ages of HP–UHP metamorphic rocks in the Altyn Tagh Complex. These observations indicate that the source rocks of the monzogranite pluton are the subducted continental crust, which underwent metamorphism at ca. 500 Ma and followed by partial melting at 454–451 Ma. In addition, synmagmatic zircons exhibit variable δ18O and εHf(t) values ranging from 5.4 to 11.7‰ and from −19 to +10.3, respectively, indicating a minor contribution of mantle‐derived melts in the formation of the monzogranite. Given the studied pluton and contemporaneous extensive granitoids (465–445 Ma), characterized by similar geochemistry and source rocks, are synchronous with the final exhumation of subducted South Altyn Tagh continental crust, we propose that the reworking of exhumed continental crust at middle to lower crustal depths is their main petrogenesis. [ABSTRACT FROM AUTHOR]

The mineral chemistry of thirteen trioctahedral chlorite samples from four regions in northwestern China, having a wide range of Fe and Mg contents and relatively constant Al and Si contents, were studied via raman spectroscopy, near infrared (NIR) spectroscopy, X-ray diffraction (XRD) analysis and electron - probe microanalysis. Five absorption features of the twenty samples near 4525, 4440, 4350, 4270 and 4180 cm−1 were observed, and two diagnostic features at 4440 and 4270 cm−1 were recognized. Assignments of the two diagnostic features were made for two combination bands ((ν+δ)(AlAl)O−OH and (ν+δ)(SiAl)O−OH) by regression with Raman fundamental absorptions. Furthermore, the determinant factors of the NIR band position were found by comparing the band positions with relative components. The results showed that Fe2+/(Fe2++Mg) values are negatively correlated with the two NIR combination bands. The findings provide an interpretation of the NIR band formation and demonstrate a simple way to use NIR spectroscopy to discriminate between chlorites with different components. More importantly, a simple example of mapping Fe-rich and Mg-rich chlorites were executed using remote sensing data based on this theory. The spectroscopic detection of mineral chemical variations in chlorites provides geologists with a tool with which to collect information on hydrothermal alteration zones from hyperspectral-resolution remote sensing data.

The article discusses about a study that is initially performed on chemical dating of the uranium mineral in WMOB for better understanding of its ore-forming mechanism. Electron probe microanalyses (EPMA) is used for the study. The study reports that in-situ ages of the brannerite in WMOB with EPMA chemical dating.