The Dakalasu No.1 pegmatitic rare-element deposit is a representative of Be-Nb-Ta pegmatites in Altai, Xinjiang, China. Beryl is the most important beryllium-carrying mineral in Dakalasu No.1 pegmatite. To constrain the concentration mechanism of Be, we conducted a study of the textural relationships and chemical compositions (major and trace elements) of beryl, along with microthermometry and Raman spectroscopy on beryl-hosted fluid inclusions. Two generations of beryl were recognized. The early beryl I was formed in the magmatic stage, whereas the late beryl IIa and IIb were formed in the magmatic-hydrothermal stage. Lithium and Cs contents increased from beryl I, beryl IIa, to beryl IIb, whereas Mg and Rb contents decreased. Scandium, V, and Ga contents of beryl IIa are similar to beryl IIb, but different in beryl I. Titanium is enriched in beryl IIa. The high FeO contents and Na/Cs ratios of beryl (I, IIa, and IIb) reveal the low degree of differentiation evolution of the Dakalasu No.1 pegmatite. Two types of melt inclusions and four types of fluid inclusions were identified in beryl IIa, IIb, and associated quartz. The microthermometry results indicated that beryl II is formed at 500 °C–700 °C, and 200 MPa–300 MPa. The Dakalasu No.1 pegmatite melt is enriched in volatiles, such as B, F, and CO₂, evidenced by a large amount of tourmaline in the wall zone, the occurrence of a variety of tiny cryolite (Na₃AlF₆) inclusions, and CO₂-rich fluid inclusions in beryl IIa. The enrichment mechanism of Be may be related to the crystallization of beryl at highly undercooled states of melt, and melt–melt–fluid immiscibility during the evolution and differentiation of the melt.

The West Junggar region, located in the Central Asian Orogenic Belt (CAOB), is characterized by extensive Carboniferous magmatism and porphyry Cu (-Au) deposits. The Shiwu porphyry Cu-Au deposit, located in the east of the Barluk Mountains, the West Junggar region, is not only a newly discovered deposit but also a representative porphyry Cu-Au deposit in this area. The volcanic rocks (including andesite and tuff) and intrusive rocks (including diorite, quartz diorite, quartz diorite porphyry, and tonalite porphyry) occurred in the Shiwu area and the mineralization associated with the quartz diorite porphyry. The secondary ion mass spectrometry (SIMS) zircon U–Pb ages of quartz diorite porphyry and tonalite porphyry are 310.4 ± 2.3 Ma and 310.1 ± 2.4 Ma, respectively, indicating that the Shiwu deposit is related to the Late Carboniferous magmatism. Intrusive rocks, which were characterized by the enrichment of large ion lithophile elements (LILEs) and pronounced negative high field strength elements (HFSEs), belong to the calc-alkaline or tholeiitic series. Their (⁸⁷Sr/⁸⁶Sr)_i, (¹⁴³Nd/¹⁴⁴Nd)_I, and εNd(t) values range from 0.703569 to 0.704311, 0.512488 to 0.512512, and 4.9 to 5.3, respectively. Volcanic rocks, which belong to the calc-alkaline series, have similar geochemical features as the intrusive rocks, and their (⁸⁷Sr/⁸⁶Sr)_i, (¹⁴³Nd/¹⁴⁴Nd)_i, and εNd(t) values, respectively, are 0.703704–0.704071, 0.512520–0.512542, and 5.49–5.92. These characters indicate that the igneous rocks in the Shiwu area derived dominantly from the mantle and formed in an island arc setting. These characters also further confirmed that the Barluk Mountains is still in an island arc setting in the Late Carboniferous and the accretionary orogenesis can exist until 310 Ma at least.