Abstract:Located in the western part of Inner Mongolia, the Yabulai Mountain possesses extensively exposed intermediate-felsic plutons and some felsic volcanic rocks. Zircon U-Pb dating indicates that the granitic rocks from the Yabulai Mountain were formed in the Early to Middle Permian, as evidenced by the data from granodiorite (280±1 Ma), K-feldspar granite (286±1 Ma), tonalite (272±1 Ma), and dacite (275±2 Ma). In the K-feldspar granite, only a few zircon grains show positive εHf(t), and εHf(t) of most zircons is below 0, implying that some juvenile crustal materials or depleted mantle materials were involved in the generation of the rocks. In granodiorite, tonalite and dacite, zircons are all characterized by εHf(t) lower than 0. Zircon Hf isotope indicates that the sources of these igneous rocks were mainly old crustal materials, and this feature is similar to that of felsic igneous rocks from cratons. The Early Permian granodiorite and the Early Permian K-feldspar granite share similar major and trace element compositions, and REE patterns of granodiorite and K-feldspar granite are high in LREEs and low in HREEs, with weak to moderate Eu negative anomalies. The Middle Permian tonalite exhibits positive Eu anomaly and higher Sr/Y ratios (>300) than the granodiorite and the K-feldspar granite. The high Sr/Y ratio feature of the tonalite suggests that the tonalite might have been generated in the lower crust, with no assimilation/contamination of country rocks or fractionation of felsic magma in the upper crust. Because the presence of plagioclase, amphibole and biotite cannot significantly affect the Sr/Y ratio of the equilibrium melt, the differences of geochemistry between the granodiorite, K-feldspar granite and the tonalite may be attributed to the fact that the source of the tonalite was deeper and the garnet was present in the source. Combined with previous studies, the authors hold that the Permian magmatism probably formed a nearly EW-trending magmatic rock belt along the whole northern margin of North China Craton (NCC) and Alxa Block, and the Permian igneous rocks in the Yabulai Mountain might have been formed in a collision or post-collision setting during the convergence of the Zongnaishan-Shalazhashan and Yabulai-Nuoergong-Honggueryulin belts.

Abstract:Located in the east segment of Harlik, the Omoertage alkaline intrusion (OMTG) was emplaced in Xiaopudong calc-alkaline granitic pluton during the Late Paleozoic. The purplish red OMTG alkaline granites exhibit uniform micrographic texture and contain typical alkaline ferromagnesian minerals such as arfvedsonite and aegirine and accessory minerals like zircon, ilmenite and fluorite. Geochemically, the alkaline granites are rich in silicon, alkalis, iron, and poor in calcium and magnesium, and show enrichment of Rb, Cs, Th, U and Zr and depletion of Ba, Sr, P and Ti. They also have relatively high concentrations of Nb, Ta, Hf, Ga, and display high (10⁴ Ga/Al) values (3.41~3.65) and strong Eu depletions (δEu=0.30~0.33). Zircon saturation temperatures of OMTG alkaline granites vary from 940 to 952℃, which is in agreement with the characteristics of typical A-type granite. Zircon LA-ICP-MS U-Pb dating yielded a mean age of 288.9±1.6 Ma, indicating that the alkaline intrusion was formed during the Early Permian. The OMTG granites have high εHf(t) values (+8.7~+12.5) and young one-stage Hf model ages (600~430 Ma). The alkaline granites also show higher Y/Nb ratios (2.92~3.17), suggesting that they belong to the A2 type granite. An integrated study of the tectonic setting and geochemical characteristics show that the OMTG A2-type granite experienced fractional crystallization by the alkaline magma which was produced by the partial melting of Neoproterozoic-Early Paleozoic juvenile crust induced by slab break-off after post-collision events.

Abstract:This paper reports the characteristics of the Changjie olivine pyroxenolite from the Tongdao area in western Hunan Province, western segment of Jiangnan orogenic belt. Laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) U-Pb zircon dating of the Changjie olivine pyroxenolite yielded an age of 701±11 Ma. The Changjie olivine pyroxenolite contains clinopyroxene, olivine and plagioclase together with a small amount of Fe-Ti oxide minerals, probably suggesting that clinopyroxene, olivine and plagioclase fractionated within the magma chamber. Geochemically, the Changjie olivine pyroxenolite is characterized by relatively low SiO₂ (44.01%~47.72%), Al₂O₃ (6.77%~9.10%), TiO₂ (0.49%~0.75%), and total alkali (Na₂O+K₂O=0.07%~2.04%), and high MgO (23.97%~30.70%) content, and these rocks are of tholeiitic series and belong to sub-alkali series. These rocks display ocean island basalt (OIB)_like signatures, characterized by the enrichment of light rare earth elements and large ion lithophile elements (LILE) relative to high rare earth elements (HREE). Moreover, they also display typical arc magma features, such as significant Nb-Ta troughs, relatively high Th/Nb ratios (0.52~0.81) and low Nb/La (0.25~0.44) ratios, and typical low Nb content (1.11×10^-6~3.91×10^-6). These rocks show relatively high initial (⁸⁷Sr/⁸⁶Sr)_i ratios (0.707 206~0.708 561) and positive εNd(t) values (0.25~0.41). Furthermore, the geochemical signature also suggests that the Changjie olivine pyroxenolite was produced by low degree of partial melting (4%~7%) of the spinel-facies, asthenospheric mantle peridotite which had been matasomatized by slab-derived fruits/melts. In combination with the regional geology, the authors infer that the deep dynamic mechanism for the formation of the Changjie olivine pyroxenolite was related to the partial melting of upwelling asthenosphere mantle due to the rifting at about 700 Ma in the western segment of Jiangnan orogenic belt.

Abstract:The Wanbaogou Group is located on the southern margin of the Qaidam block and along the middle segment of the East Kunlun orogenic belt. It consists of effusive basaltic lavas, terrigenous and volcaniclastic rocks, and limestones. The Wanbaogou basalts can be divided into two groups:high-Ti (HT) alkaline and low-Ti (LT) tholeiitic basalts. The former shows high Ti/Y ratios (502~660), Nb/Y ratios (0.8~1.6) and TiO₂ values (2.76%~4.97%), similar to features of OIB. The latter has relatively low Ti/Y ratios (383~439), Nb/Y ratios (0.3~0.4) and TiO₂ values (1.80%~2.49%), which resembles E-MORB. Zircon SIMS analyses indicate that the Wanbaogou basalts were formed in the Neoproterozoic (762±2 Ma). The field occurrence and geochemical characteristics suggest that the Wanbaogou basalts were formed in a continental rift or an initial oceanic basin environment, and represented the peak stage of the Rodinia breakup.

Abstract:On the basis of core observation and high density slice identification, the authors consider that Es₃^x-Es₄^s mudstone in Jiyang depression is mainly controlled by sedimentation and diagenesis. The composition and structure types are mainly controlled by sedimentation, whereas crystal texture characteristics are mainly controlled by diagenesis. According to the genesis and degree of recrystallization of calcite, combined with the mineral composition and structure characteristics, the Paleogene mudstone in Jiyang depression can be divided into three types, i.e., sedimentation-controlled type, sedimentation and diagenesis-controlled type and diagenesis-controlled type. The sedimentation-controlled type is the most widely distributed type which includes various types of lithofaces and whose structural characteristics reflect the formation environment. Sedimentation and diagenesis-controlled type mainly appears as laminated rock facies consisting of interlayered laminae of the argillaceous and granular crystallized calcite. Diagenesis-controlled type is characterized by column or fiber-column calcite crystals in the veined or lenticular forms perpendicular to the bedding plane. The diagenesis-controlled type and sedimentation and diagenesis-controlled type are closely related to Oil and gas in shale, and they are the most favorable genetic lithofacies.

Abstract:There exists a suite of complex porphyries in the Yao'an Pb-Ag deposit, such as syenite porphyry, trachyte, pseudoleucite porphyry, and phenocryst-bearing syenite aplite, with the syenite porphyry being the host rock. Through an integrated study of the spatial distribution and petrological and mineralogical characteristics of pseudoleucite porphyry through field geological survey, microscopic identification, electron microprobe analysis and X ray diffraction analysis, the following results have been obtained:① Pseudoleucite porphyry is outcropped in the periphery of syenite porphyritic volcanic breccia in the forms of veins, breccia or small apophyses and is mainly distributed in the southwest of breccia-type orebodies and the northeast of F₄ fault. Pseudoleucite porphyry is associated with breccia pipe and peripheral fault in space; ② Pseudoleucite has two generations. The early pseudoleucite phenocryst is in the grayish green round form rich in Al, whereas the late pseudoleucite phenocryst, which exhibits high Si and Na, is grayish white tetragonal trisoctahedron phenocryst. Both of them have been replaced by altered minerals such as potash feldspar, kaolinite, and quartz; ③ Pseudoleucite porphyry was formed in an intraplate extensional environment after the collision between India continent and Eurasia continent; ④ Pseudoleucite porphyry was formed later than trachyte, syenite porphyry and earlier than phenocryst-bearing syenite aplite. It had no direct genetic connection with galena mineralization.

Abstract:Meta_sedimentary rocks comprising sillimanite_garnet_biotite gneisses and mica schist are cropped out in the middle_north segment of Ailao Mountain me tamorphic complex belt. Petrographic observation reveals that the sillimanite_ga rnet_biotite gneisses experienced amphibolite_granulite facies metamorphism and subsequent retrogressive superimposition. Traditional thermobarometry (GB_GASP) was applied to constraining p_T conditions of the mineral assemblage at each metamorphic stage. The mineral assemblage of the peak stage (M₁) is character ized by Grt+Sil₁+Bt₁+Kfs+Pl+Qtz+Ilm, recording p_T conditions of 690~7 50℃ and 690~810 MPa. The near_isothermal decompressional stage (M₂) is disti nguished by the directional alignment of all metamorphic minerals, with typical dehydration reaction being 2 Bt→Sil+6 (Mg, Fe)O+K₂O+5 Qtz+2 H₂O, and minera l assemblage is characterized by Grt+Sil₂+Bt₂+Kfs+Pl+Qtz+Ilm, formed un der p_T conditions of 650~720℃ and 450~630 MPa. The mineral assemblage of the retrograde stage (M₃) is composed of Bt+Ms+Qtz+Pl, suggesting p_T con ditions of 580~640℃ and 400~500 MPa. The metamorphic evolution is characteriz ed by an isothermal decompressional clockwise p_T path, revealing a subducti on and continent_continent collision process between Indian and Yangtze blocks, following a tectonic exhumation accompanied by high temperature strike_slip shea ring and biotite dehydration_melting.

Abstract:The Xicheng (Xihe-Chengxian) ore concentration area in Gansu Province is one of the most important polymetallic ore concentration areas in the West Qinling orogen. There are mainly lead-zinc deposits and subordinately gold, copper and molybdenite deposits (ore spots). The Changba biotite monzo-granite is located in the mid-east of the Xicheng ore concentration area, and the molybdenum-bearing coarse-grained quartz veins occur on its southern margin. The subhedral molybdenite occurs within the quartz veins in lumpy form. The Re-Os isotopic dating of 7 molybdenum samples yielded model ages ranging from 207.7±3.0 to 209.8±2.8 Ma, with the average model age of 208.9±1.1 Ma and the isochron age of 209±15 Ma, indicating that the Mo mineralization on the southern margin of the Changba pluton took place in the Late Triassic, slightly later than the formation of the Changba pluton. The low content of Re (18.82×10^-6~21.97×10^-6) shows that the material was mainly derived from the crust, with the mixture of a little mantle material. In combination with the ages (200~225 Ma) of the regional magmatism, it is held that gold, lead-zinc deposits and molybdenite mineralization on the south margin of the Changba pluton resulted from the tectonism, magmatism and fluid metallogenic event in the late Triassic period. The Re-Os dating of the molybdenite provides a new thinking for exploration of the Indosinian quartz vein type Mo deposits in the contact zone of the late Triassic granitoid plutons in the West Qinling orogen.

Abstract:The Katebaasu gold deposit is one of the superlarge gold deposits recently discovered in the Nalati-Hongliuhe gold-copper-nickel-lead and zinc-jade-muscovite ore-forming belt. Based on field geological survey and indoor integrated study, the authors investigated the modes of occurrence of gold in the gold ore by such means as microscope identification, scanning electron microscopy and X-ray energy spectrum analysis. The results show that gold minerals in the Katebaasu gold deposit mainly occur as native gold and silver-bearing native gold, with the fineness of the native gold being 764.5‰~1 000‰. The main gold-carrying mineral is pyrite, with a small amount of chalcopyrite and gangue minerals. The main gold mosaic forms include crack gold, intercrystalline gold and minor enclave gold. In the ore, native gold exclusively exhibits microscopic grained gold with the grain size less than 40 μm.

Abstract:The Lunlang skarn-type lead-zinc deposit is located in the lead-zinc-silver metallogenic belt on the north side of the Gangdise porphyry copper ore belt. Based on the ore-forming geological conditions, the authors systematically studied the S, Pb isotopic composition characteristics of sphalerite, galena, pyrrhotite and pyrite in the ore, and investigated the sources of the ore-forming materials in comparison with the characteristics of regional mineral resources. It is shown that the δ³⁴S values of the minerals vary in the range of -2.3‰~4.1‰ with an average of -1.46‰, and the δ³⁴S histogram is distributed approximately in a tower shape, which indicates a mantle source. The ²⁰⁸Pb/²⁰⁴Pb ratios are between 38.532 and 39.305 (38.900 on average), the ²⁰⁷Pb/²⁰⁴Pb ratios are between 15.588 and 15.802 (15.687 on average), the ²⁰⁶Pb/²⁰⁴Pb ratios are between 18.179 and 18.692 (18.543 on average), and the μ values are between 9.44 and 9.83, suggesting that Pb was derived from a orogenic belt whose source was composed of the upper crust and the mantle. S, Pb isotopic characteristics of the Lunlang deposit are identical with those of other skarn deposits in northern subbelt of the Gangdise metallogenic belt. The ore-forming materials of the Lunlang deposit was mainly derived from materials of Nyainqentanglha basement gneiss, and partly from the mantle.

Abstract:The Tawuerbieke gold deposit is one of the important Au deposits in Tulasa fault basin of the West Tianshan Mountains. The rock types in the study area mainly consist of andesite, andesitic pyroclastic rocks of the Dahalajunshan Formation and monzonite porphyry rocks, by which the gold mineralization is hosted. The orebodies are controlled by faults, and alterations are strongly developed in the wall rocks. The metallic minerals mainly include pyrite, native gold, hematite and chalcopyrite, whereas non-metallic minerals comprise quartz, plagioclase and calcite. The mineralization can be divided into three stages, i.e., quartz and pyrite stage, quartz and sulfide vein stage, quartz and carbonate stage. The type of fluid inclusions in quartz and calcite is simple, mainly comprising vapor-liquid two-phase inclusions and pure liquid inclusions. The homogenization temperatures of inclusions vary from 100℃ to 196℃. The salinities are 0.0%~7.3% NaCl_eq. The densities range from 0.9 g/cm³ to 1.0 g/cm³. The estimated pressures of the ore-forming fluids range from 5.2 MPa to 81.9 MPa, corresponding to the depth of ore-forming range from 0.5 km to 7.4 km. The features of the inclusions demonstrate low temperatures, salinities and densities with small pressures and low depth. In combination with the characteristics of the ore geology, fluid inclusion and the previous results, the authors have reached the conclusion that the Tawuerbieke gold deposit is an epithermal gold deposit.

Abstract:Zeolite P was synthesized via in-situ hydrothermal method with metakaolin-based geopolymer (SiO₂/Al₂O₃=3.2) as a staring material. The major factors influencing the crystallization and morphology of Zeolite P were investigated in the aspects of hydrothermal temperature,concentration of sodium hydroxide solution and hydrothermal time.The results showed that zeolite P was successfully transformed from metakaolin-based geopolymer at 100℃ curing for 24 h in the sodium hydroxide solution of 2.0 mol/L.Being simple, environment-friendly and controllable,the in-situ hydrothermal method is expected to be used to synthesize other zeolites by changing the raw material compositions and reaction conditions.

Abstract:In this paper, modified goethite samples doped with different cations were prepared and characterized. XRD showed that doping cations Mn²⁺, Cr³⁺ and Al³⁺ didn't significantly change the types of crystal structure for α-FeOOH, indicating that the cations were doped into the α-FeOOH lattice, and solid solutions were respectively formed when Fe³⁺ was partially replaced by Mn²⁺, Cr³⁺ and Al³⁺. The infrared analysis also showed a similar result. The results of TGA-DTA and TEM exhibited that these metal cations had entered the goethite lattice. By UV-vis diffuse reflection spectrum analysis, it was found that the band gaps of goethite doped with Mn²⁺ and Cr³⁺ were 2.18 and 2.24 eV, respectively, lower than the band gap of pure goethite (2.28 eV); in contrast, the band gap of goethite doped with Al³⁺ was increased to 2.34 eV. In addition, the reductive effects of different complex systems of Fe(Ⅱ) combined with pure goethite and its counterparts doped with above three different cations on 2-NP reduction were investigated, and it was found that the 2-nitrophenol (2-NP) reductive transformation followed the pseudo-first-order kinetics under the condition pH=6 and temperature 25℃. The system Fe(Ⅱ)/goethite doped with Al³⁺ showed the best degradation of 2-NP with a removal efficiency of 100% within 120 min. However, the reductive rate of 2-NP transformation was clearly reduced with the initial concentrations of 2-NP increasing to a certain extent. Moreover, the rate constant (k) of the system doped with Al³⁺ was increased with the increment of the solution pH value.

Abstract:The supported adsorbent was prepared by loading Fe-Mn binary oxide onto the surface of palygorskite clay with the oxidation reduction coprecipitation techniques. The adsorption properties and mechanism of adsorbing phosphate were investigated by static adsorption experiments with a discussion on the adsorption kinetics and thermodynamic characteristics. The results demonstrate that the initial pH value, adsorption time and temperature of the solution can influence adsorption capability, and adsorption equilibrium can be reached after about 90 min under neutral conditions. It is found that the adsorption processes follow pseudo-second-order equation most effectively, with the adsorption apparent activation energy being 11.76 kJ/mol. The fitting of the adsorption isotherms with Freundlich equation is slightly better than that with Langmuir equation, and the maximum adsorption capacity is 26~31mg/g. Adsorption enthalpy is 9.29 kJ/mol, adsorption entropy is positive and adsorption Gibbs free energy changes are in the range of -4.3~-5.8 kJ/mol. The adsorption is multilayered and heterogeneous, with the coexistence of physical and chemical effects, without strong chemical bond function.