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The No. 5 pegmatite vein is the most evolved and well mineralized vein in the Renli deposit, with beryl being the most important beryllium mineral. The vein represents one of the most important gem-quality aquamarine mines at Renli. In this study, beryl crystals from the No. 5 pegmatite vein were examined by EMPA (electron microprobe analysis), ICP-MS (inductively coupled plasma-mass spectrometry), XRD (diffraction of X-rays), FTIR (fourier transform infrared spectrometer), and Raman analyses. Field and petrographic observations showed that most beryl crystals are euhedral to subhedral with light to medium blue color. EMPA analyses indicated that the main chemical compositions of beryl are close to the ideal values, with relatively low Fe (0.222–0.690 wt%) and alkali metal (0.280–0.820 wt%) contents. Geochemical and spectroscopic analyses indicated that cations replacement in beryl is relatively simple. The substituting cations of beryl in the octahedral Al site include mainly: Mg2+, Fe2+, Fe3+, Mn2+, Cr3+, Ti4+, and the excess Si. The tetrahedral Be site is mainly replaced by Li. Alkali metals in channel (esp. Na) serve as a charge compensator. According to the Fe-Mg-alkali and Li-Cs contents, the beryls from No. 5 pegmatite belong to the low Li-Cs and low Fe-Mg-medium alkali beryl groups. Field and geochemical data indicated that the No. 5 pegmatite vein formed by the multistage Mufushan granitic pluton emplacement and the magma source was less evolved.

The Jiajika rare-metal deposit located in western Sichuan Province (China) is renowned as the largest lithium deposit in Asia, and the No. 134 pegmatite dike is the largest lithium pegmatite under mining conditions in the area. On the basis of a detailed characterization of textures and minerals in the Jiajika No. 134 pegmatite, two zones (the barren Zone I and the spodumene Zone II) and three subzones (Zone II was subdivided into microcrystalline, medium-fine grained and coarse-grained spodumene zones) have been identified. The detailed mineralogical characteristics of lithium minerals and other indicator minerals from each zone were evaluated by EPMA for illustrating the magmatic–hydrothermal evolution and the cooling path of the Jiajika No. 134 pegmatite. From the outer zone inwards, grain size gradually increased, the typical graphic pegmatite zone was absent, and spodumene randomly crystallized throughout nearly the whole pegmatite body. This evidence indicated a Li-saturated melt prior to pegmatite crystallization, which could be the main cause of the super-large-scale Li mineralization of the Jiajika No. 134 pegmatite. A comparison of the Cs content between primary beryl in the Jiajika No. 134 pegmatite and other important Li-Cs-Ta pegmatites in the world indicates that No. 134 pegmatite shows a high degree of fractional crystallization. The evolution of mica species from muscovite to Li-micas from Zone I to Zone II marks the transition from the magmatic to the hydrothermal stage in pegmatite evolution. The absence of individual lepidolite and the relatively limited scale of alteration of spodumene (

Granitic pegmatite deposits, which are usually products of orogenic processes during plate convergence, can be used to demonstrate regional tectonic evolution processes. In the eastern Tibetan Plateau in China, the Jiajika, Dahongliutan, Xuebaoding, Zhawulong, and Ke’eryin rare metal pegmatite deposits are located in the southern, western, northern, midwestern, and central areas of the Songpan−Ganzê orogenic belt, respectively. In this study, we dated two muscovite Ar−Ar ages of 189.4 ± 1.1 Ma and 187.0 ± 1.1 Ma from spodumene pegmatites of the Dahongliutan deposit. We also dated one zircon U-Pb age of 211.6 ± 5.2 Ma from muscovite granite, two muscovite Ar−Ar ages of 179.6 ± 1.0 Ma and 174.3 ± 0.9 Ma, and one columbite−tantalite U-Pb age of 204.5 ± 1.8 Ma from spodumene pegmatites of the Zhawulong deposit. In addition, we dated one muscovite Ar−Ar age of 159.0 ± 1.4 Ma from spodumene pegmatite of the Ke’eryin deposit. Combining these ages and previous studies in chronology, we concluded that the granitic magma in the Jiajika, Xuebaoding, Dahongliutan, Zhawulong, and Ke’eryin deposits intruded into Triassic metaturbidites at approximately 223, 221, 220−217, 212, and 207−205 Ma, respectively, and that the crystallization of the corresponding pegmatite ceased at approximately 199−196, 195−190, 189−187, 180−174, and 159 Ma, respectively. In this study, we demonstrated that the peak in magmatic activity and the final crystallization age of the pegmatite lagged behind one another from the outer areas of the orogeny belt to the inner areas. The pegmatite−parented granitic magmas were sourced from Triassic metaturbidites that were melted by shear heating along the large-scale decollement resulting from Indosinian collisions along the North China block, Qiangtang−Changdu block, and Yangtze block. As a result, the above temporal and spatial regularities indicated that the tectonic−thermal stress resulting from the collisions of three blocks was transferred from the outer areas of the orogenic belt to the inner areas. A large amount of heat and a slow cooling rate at the convergent center of thermal stress in two directions will lead to crystallization and differentiation of magma in the Songpan−Ganzê orogenic belt, forming additional rare metal deposits.

Wavelet transformation has been widely used in geophysical and geochemical exploration, and the fractal feature of wavelet coefficients has recently stood out from many wavelet threshold methods. We introduced the wavelet–fractal method to analyze the polarizability and resistivity of graphite deposits. Due to the unique nature of graphite-bearing gneiss, characterized by high polarizability and low resistivity, we concluded that the polarizability background mode is better suited to depict the morphology of the graphite-bearing formation, with the resistivity background mode serving as complementary information for verification. Symlets5 is regarded as the optimal mother wavelet to indicate the characteristics of graphite ore by means of comparison and analysis. The polarizability anomalies showed two different linear forms: the direction of the measuring line and the strike of the ore bodies. According to the data of drill holes on the profile, we inferred that the high values of the anomaly mode can be used to delineate the target area where the graphite is enriched. Combining the application of both modes, we used the wavelet–fractal method for the quantitative prediction and effective selection of a potential area with a high grade. The approach used in this current study can be extended to the prospecting of other graphite deposits or sedimentary–metamorphic deposits containing conductive minerals, where geochemical and geophysical data are available.