Abstract:There were multiple episodes of magmatism in the Southern Da Hinggan Mountains during the Late Jurassic to Early Cretaceous, and an in-depth study of the petrogenesis and evolutionary process is of great geological significance to reveal the Mesozoic geodynamic background and mineralization. In this paper, LA-ICP-MS zircon U-Pb dating and whole-rock geochemistry for medium-grained adamellite, fine-grained adamellite and granite pegmatite in Hailiute area were carried out. The zircon ²⁰⁶Pb/²³⁸U weighted average ages of the medium-grained adamellite, fine-grained adamellite and granite pegmatite are 142.0±0.7 Ma, 141.2±1.1 Ma and 139.7±2.4 Ma respectively, belonging to the Early Cretaceous. They have high SiO₂ and total alkali contents, and their A/CNK value is 1.01~1.18, with an average value of 1.09, which is weak peraluminous. They are characterized by enrichment of large ion lithophile elements such as Rb, Th and K and depletion of high field strength elements including Ba, Sr, P and Ti, with extremely negative Eu anomalies (δEu=0.012~0.040). The Zr+Nb+Ce+Y value of them is between 38.25×10^-6 and 258.2×10^-6, less than 350×10^-6. The zircon saturation temperature of them is 723℃ to 778℃. The primary muscovite and alkaline-mafic minerals are not found among them. The magma experienced the fractional crystallization of plagioclase and K-feldspar during its evolution. The Zr/Hf, La/Ta and La/Nb of them are lower than the range of normal granite, however Nb/Ta and Y/Ho of them are in the area of normal granite. The parameters of tetrad effect of rare earth element (TE_1,3) of them is between 1.18 and 1.34, greater than 1.1. In conclusion, the Hailiute granite belongs to early Cretaceous highly differentiated I-type granite. It has weak interaction between melt and fluid in the process of crystallization differentiation, which can promote the formation of tungsten, tin and rare metals minerals.

Abstract:Jigongshan granite is an important batholith in Tongbai-Dabie orogenic belt. In order to discuss the petrogenesis and dynamic background of the Jigongshan granite and guide regional prospecting, this paper has carried out zircon U-Pb dating, rock geochemistry and Sr-Nd-Hf isotope studies on the Jigongshan granite. The results show that the pluton is a paraaluminous-weak peraluminous granite, belonging to the high-potassium calc-alkaline series and fractionated I-type granite, accessory mineral includes minor hornblende. Zircon U-Pb dating shows that the age of the Jigongshan pluton is 141.8 ±0.8 Ma (n=26, MSWD=1.15), indicating that the Jigongshan pluton was formed in the Early Cretaceous. The (⁸⁷Sr/⁸⁶Sr)_i, εNd (t) values and the two stage model age of whole rock are 0.707 75～0.708 18, -19.21～-17.63 and 2.49～2.36 Ga, respectively. The ¹⁷⁶Hf/¹⁷⁷Hf, εHf (t) values and the two stage model age of zircon are 0.281 845～0.282 083, -29.67～-21.31 and 3.07～2.54 Ga, respectively. Sr-Nd-Hf isotopic characteristics suggest that the Jigongshan pluton may be formed by the remelting of Neoarchean middle-lower crust of the Yangtze plate. The granite has high (La/Yb)_N, Sr/Y values, and inapparent Eu negative anomalies, similar to the adakite-type granite in the Dabie Mountains. The granite formed in extensional structure, as the product of partial melting of the thickened lower crust that has not yet been delaminated. Jigongshan pluton may be the parent granite of pegmatite vein in the pluton.

Abstract:Timing of the collision between India and Eurasian plate is still debated. In this paper, zircon U-Pb geochronology, whole rock geochemistry and zircon Hf isotope analysis have been carried out for the Tuolong intrusion exposed in the middle of Linzhou County, Tibet, in order to further constrain the collision time of the India-Eurasian plate. The quartz monzonite porphyry outcropped in Tuolong pluton intruded into the Pana Formation as stock. Zircon U-Pb dating results show that the quartz monzonite porphyry was formed in Eocene (50.5±0.6 Ma) with εHf (t) value of -0.6 to -0.5. Quartz monzonite porphyries display metaluminous and shoshonitic characteristics with low A/CNK and high K₂O/Na₂O value and high K₂O contents. They are generally depleted in high field strength elements (Nb, Ta, Ti and P) and enriched in large ion lithophile elements (Th, U and Pb). Chondrite- normalized REE patterns are characterized by high (La/Yb)_N values (15.3~16.3) with weak negative Eu anomalies(0.56~0.69), the differentiation of light and heavy rare earth elements is obvious. The low A/CNK value, the negative correlation between P₂O₅ and SiO₂, and the positive correlation between Y content and Rb content indicate that the quartz monzonite porphyry is I-type granite. Combined with results of previous studies, it is considered that the Tuolong quartz monzonite porphyry may be the product of partial melting of the relatively ancient metamorphic intermediate-basic rock, and was formed as the consequences of subduction and break-off caused by the India-Eurasian plate collision, indicating that the India-Asia continent collision should have occurred before 50 Ma.

Abstract:The Xiangyangping uranium ore deposit is a new-found deposit in Miaoershan ore field for the past few years. Chloritization is one of the most important alteration types and prospecting indicators in the Xiangyangping uranium deposit. Based on the detailed field and interior petrographic observation for the ore samples in the Xiang-yangping uranium deposit, electron probe microanalyzer (EPMA) is employed to study paragenetic association characteristics and morphological features of chlorites. Chemical compositions of chlorites could help to confirm the chemical types of chlorites and formation condition of chlorites, and finally to discuss their formation mechanism and the relationship with uranium mineralization. The chlorites in the Xiangyangping uranium ore deposit could be divided into four types, including biotite-alteration type, fracture-filling type, uranium-associated types and clay minerals transformed types. The Fe-Si diagram has revealed that the chlorites are mainly brunsvigite area, partly ripidolite and few pycnochlorite, respectively. The formation temperature range of chlorite is 190~265℃ (averagely 239℃), which belong to the mesothermal epithermal alteration. The formation mechanism is dissolution-crystallization and dissolution-migration-crystallization. The chloritization provided the environment for uranium mineralization, and promoted the activation, migration and deposition of uranium.

Abstract:The Kulagangri Dome is located at the eastern part of the Himalayan metallogenic belt. Based on the 1∶50 000 mineral geological mapping and sparse surface engineering, the Gabo pegmatite-type lithium deposit was firstly found at the eastern part of the Kulagangri Dome. Ore-bearing spodumene pegmatite dikes are generally hosted by the marble in the middle unit of the dome, with length ranging from 1 m to 1 200 m, and width ranging from 0.8 m to 40 m. The main lithium containing minerals in the spodumene pegmatite are spodumene, elbaite and lepidolite. At present, two main Li mineralization zones are controlled by 5 surface engineering. The mineralization zone I is about 2 km long, and includes 2 main orebodies (K₁ and K₂). The mineralization zone Ⅱ is about 700 m long, and include one main orebody (K₃). The K₁ orebody is about 1 200 m long and 5~40 m thick, with an average thickness of about 20 m. The K₂ and K₃ orebodies occur as the large lenticular shape, with strike extension >100~600 m and thickness 15~50 m. The total thickness of K₂ orebody is 45.3 m. The average grade of Li₂O, Rb₂O and BeO is 1.11%, 0.064% and 0.047%, respectively. The newly discovered Gabo lithium deposit is dominated by Li, Be and Rb, associated with Nb, Ta, Cs, W and Sn. Based on the geological survey results, the Gabo lithium deposit is large in scale, and showing considerable potential for further prospecting in the area. The discovery of Gabo lithium deposit is another breakthrough in the exploration of rare metals in the Himalayan metallogenic belt, which is of great significant role in further understanding of the tectono-magmatic evolution and rare metal mineralization in the Cenozoic Himalaya, and further enriching the theory of collisional orogenesis and mineralization in the southern Qinghai-Tibet Plateau.

Abstract:The Diyanqin'amu Mo deposit is located in Dong Ujimqin Banner, Inner Mongolia. The barely exposed intrusive rocks in this deposit are mainly composed of fine-grained syenite and mafic dikes. The Mo mineralization predominantly occurs in Jurassic volcanic rocks with minor in fine-grained syenite veins, mainly including veinlet, vein and disseminated mineralization types. Ore-bearing quartz-potassium feldspar-fluorite miarolitic cavities or hydrothermal veins with these minerals in the center are identified in the fine-grained syenite, which are direct evidence for exsolution of magmatic fluids. In this study, based on detailed petrographic observation, we conducted cathodoluminescence imaging for main minerals in the quartz-potassium feldspar-fluorite miarolitic cavities, microthermometry for fluid inclusions in quartz and fluorite, and compositional analysis for fluid inclusions using SEM/EDS, LRM and LA-ICP-MS. On the basis of above analyses we discussed the process of fluid exsolution, features of initial ore-forming fluids and precipitation mechanism of ore minerals. Our results show that the Mo mineralization was genetically related to the magmatic fluids derived from fluid exsolution of the fine-grained syenite. Enriched fluorine and other volatiles decreased the solidus and viscosity of the ore-related magma, which enabled rapid upwelling of this melt to the shallow upper crust via faults. Rapid decompression during ascent was probably the major mechanism for fluid exsolution of magma. The initial magmatic fluids were F- and CO₂-riched fluids with medium-high temperature (227~457℃) and medium-low salinity [0.3%~8.6%, w(NaCl_eq)]. The initial magmatic fluids separated into a CO₂-riched gas phase with low salinity and a liquid phase with high salinity owing to boiling caused by rapid decompression. Therefore, the escape of CO₂ caused by boiling was probably the main reason for molybdenite precipitation.

Abstract:Minerals are the most important component of the lithosphere, whose deformation behavior, properties and physical/chemical processes directly affect the mechanical strength and rheological property of the continental lithosphere. Quartz is one of the main minerals in the crust. Dauphiné twinning in quartz consists of a 60° rotation around the c-axis. Previous studies have shown that Dauphiné twinning is only formed in the transformation between the α-quartz and β-quartz, however, furthermore evidences reveal that mechanical Dauphiné twinning is related to the influence of temperature and stress. Combined with the previous studies, we present structure and EBSD analysis of the deformed quartzites in the Gaoligong shear zone and find that the presence of Dauphiné twins has a great influence in the deformation process in quartz. The compliance of positive rhomb <r> is greater than the compliance of negative rhomb <z> in α-quartz. Thus, the positive rhomb <r> direction is more compliant for the stress. Dauphiné twinning is driven by the anisotropy in the elastic compliance of quartz and results in a little-described quartz crystallographic preferred orientation, characterized by the alignment of the poles of the planes of the more compliant positive rhomb <r> nearly parallel to the compression direction. Dauphiné twinning also plays an important role in the distribution of the intracrystalline plastic deformation and the activation of different sets of slip systems in the plastic deformation of quartz. Dauphiné twinning is a specific weakening mechanism and has a great contribution to the processes of intracrystalline strain localization, which not only results in the recoverable structu- ral weakening, but control the grain size reduction by dynamic recrystallization and grain boundary sliding mechanism. In addition, Dauphiné twinning could be a potential palaeopiezometer in quartz-bearing rocks.

Abstract:There are abundant vein quartz mineral resources in the phyllite of the Silurian Meiziya Formation in the Ankang area of the South Qinling Mountains, but the research degree of the vein quartz as the raw material of high-purity quartz is low, especially the lack of systematic understanding of the content of trace impurity elements and their occurrence that affect the purification of quartz state, which greatly restricts the quality evaluation of the high-purity quartz raw material in this area and further exploration breakthrough. On the basis of determining the geological development characteristics of vein quartz, this paper has carried out sample impurity element detection on three vein quartz samples (AK200, AK201, AK202) produced in three regions, studied the mineralogical characteristics, impurity occurrence and purification performance of the samples, and then conducted purification experiments. The results show that the SiO₂ content of the three samples after purification is 99.993 11%, 99.997 66% and 99.998 58%, respectively, all of which reaches the quality of high-purity quartz products, in which the AK202 sample reaches 4N8 level after purification. The results show that after purification, Al, Ti, Na, K are the main impurity elements, and Al may exist in two ways: impurity minerals and lattice impurities; Ti may exist in the form of lattice impurities; Na and K mostly exist in fluid inclusions. Impurity mineral, fluid inclusion and lattice impurity all have varying degrees of influence on the quality of the vein quartz in this area, among which fluid inclusion is the main influencing factor, lattice impurity is the second, and impurity mineral has the least effect. This conclusion has an important reference significance for evaluating the quality of vein quartz mineral resources in this area and defining the prospecting target in the future.

Abstract:As one of the strategic mineral material, high-purity quartz has been widely used in integrated circuits, semiconductor chips, solar energy and other high-tech industries. However, raw material deposits that can be used to produce high-purity quartz are extremely scarce, especially in China. Southeastern Hubei is the main distribution area of vein quartz deposits in Hubei Province. In this paper, the gangue mineral types and inclusion characteristics of vein quartz from the Fujiashan quartz deposit in southeastern Hubei are observed by optical microscope and scanning electron microscope. The trace element concentrations of the raw quartz material are analyzed by inductively coupled plasma atomic emission spectrometry (ICP-OES) to obtain the impurity element characteristics of Fujiashan quartz deposit and evaluate the potential of the deposit as a raw material for high-purity quartz. The results show that the average content of SiO₂ of the raw quartz is more than 99.95%, and the impurity elements(Al, K, Fe, Ti, Ca, etc.)mainly occur in gangue minerals such as muscovite, potassium feldspar and iron oxide, lattice-bound form and fluid inclusions. The results show that the quality of Fujiashan quartz raw ore reaches the standard of low-end high-purity quartz, and it may have the potential to produce middle-to-high end high-purity quartz after traditional purification.

Abstract:Since hemimorphite shows the properties of high pyroelectric coefficient and low dielectric constant, it is a potential sensor material in temperature measurement, infrared spectroscopy measurement, and catalysis fields. However, due to the isomorphism substitution in hemimorphite, the complex composition of hemimorphite limits the research on pyroelectric mechanism and the following application. Hence, researchers focus on the synthetic methods of hemimorphite with high purity. In this paper, the physical properties, synthesis methods, and remaining problems in the study of hemimorphite are reviewed based on the current research progress. The results will provide an important reference on the synthesis, the pyroelectricity mechanism, and the performance regulation of hemimorphite in the future.

Abstract:High-silica granitic magmatism is not only considered as one of the key indexes to measure the maturity of continental crust, but also can provide essential information for understanding the growth of continental crust and the rare-mental mineralization. However, the origin, evolution, and geodynamic environment of the high-silica granitic magmatism remains highly controversial. This paper presents a comprehensive study of zircon U-Pb ages, bulk-rock geochemistry, and Sr-Nd isotopes for the Duocai high-silica granites in the central Tibetan Plateau. Zircon U-Pb dating of the studied rocks yields ages of 219±2 Ma, indicating those rocks represent the products of the Late Triassic magmatism. The Duocai granites have I_Sr ratios of 0.708 4, εNd(t) values from -8.12~-7.36, and t_2DM ages of 1.65~1.59 Ga, similar to the Triassic turbidites in the Hohxil-Bayan Har-Songpan-Garzê (HBSG) terrane. Geochemical and isotopic signatures indicate that the Duocai high-silica granites might be derived from partial melting of meta-greywackes, and they had experienced a relatively high degree of fractional crystallization. Combining with the other regional studies, the Late Triassic magmatism in the north margin of the North Qiangtang (NQ) terrane was induced by slab rollback of the Garzê-Litang Palaeo-Tethyan ocean.

Abstract:The provenance study of ancient jade artifacts is of great significance to reveal the exploitation and utilization of jade resources, cross-regional material and cultural exchanges in the prehistoric age. Due to the constraints of the test methods and the disquisitive samples, tracing the origin of ancient jade artifacts is still a bottleneck restricting the research of jade archaeology. In recent years, with the deepening of archaeological research and the advancement of scientific testing methods, the geological, archaeological and museological communities have carried out closer interdisciplinary cooperation, and made many new explorations on the origin tracing techno- logy of ancient jade artifacts, and some important results have been achieved. Based on the results of predecessors and our team, this paper summarizes the research of the application of multiple modern major and trace elements testing techniques, such as proton induced X-ray emission(PIXE),X-ray fluorescence spectrometer(XRF),laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS),electron probe microanalysis (EPMA), as well as radioisotope and stable isotope geochemistry in the origin traceability of ancient jade artifacts. The progress of different geochemical testing techniques in tracing the origin of ancient jade artifacts is comprehensively analyzed, and the problems in the current researches are discussed. Overall, petrogeochemical testing techniques have contributed significantly to the provenance study of prehistoric jade artifacts. The key topics of the future researches should include: systematic geological research of known jade resources, the construction of geochemical (main and trace elements, isotopes) database of jade materials from different geographic origins, the development of nondestructive sample-size-unlimited petrogeochemical analysis techniques and their large-scale applications in the testing of ancient jade samples.