Abstract:There are two composite plutons, Fucheng and Zhulanbu, emplaced in the Huichang region of the northern Nanling Mountains. Nevertheless, very insufficient researches have been conducted on the Zhulanbu composite pluton, and its age and petrogenesis remain problems of much controversy. The Zhulanbu composite pluton consists of early intrusive coarse-grained biotite mozonite and late intrusive fine-grained mozonite, and LA-ICP-MS zircon dating suggests that they were formed in Indosinian (228 Ma) and Late Yanshanian (135~133 Ma), respectively; however, the Fucheng composite pluton was emplaced in Indosinian. Chemical analyses of major and trace elements indicate that both the early and late granitic intrusive bodies of the Zhulanbu composite pluton are characterized by intermediate-strong peraluminous nature, high content of Si, Al, K, low content of Ca, Mg, enrichment of Rb, Th, U, and depletion of Sr, Ba, P, Ti, Eu. They also have lower ΣREE (<165×10^-6 on average) and Zr + Nb + Ce + Y content (<350×10^-6). These geochemical characteristics suggest S-type granites. The whole rock Sr-Nd isotopic analysis results show that the early intrusive granite exhibits higher (⁸⁷Sr/⁸⁶Sr)_i than the late counterparts (0.715 6~0.726 0 and 0.710 5~0.716 4, respectively), but they exhibit the same variation of εNd(t) values (ranging from -10.0 to -7.0). Zircon in-situ Lu-Hf isotopic analysis indicates their similarities of εHf(t) values (-12.9~-7.7 and -15.1~-10.5, respectively) and t_DM^C (2.0~1.7 Ga and 2.1~1.8 Ga, respectively). The elemental and isotopic results suggest that the Zhulanbu composite pluton probably originated from the partial melting of a mixed crustal source involving the Paleoproterozoic metapelite and minor metagreywacke. The Fucheng composite pluton and the early intrusive granite of Zhulanbu composite pluton were formed in a compressive background of the Tethys tectonic domain during the Indosinian; in contrast, the late intrusive granite of Zhulanbu composite pluton was formed in the intraplate extensional environment of the paleo-Pacific tectonic domain during the Yanshanian period.

Abstract:The syenogranite in Qinghai Province is located on the east periphery of the Kendekeke deposit in the Qimantag area, East Kunlun Mountains. It consists of alkali feldspar (50%~60%), quartz (20%~30%), plagioclase (10%~20%), and biotite and hornblende (1%~5%). The results of LA-ICP-MS zircon U-Pb isotope dating reveal that the syenogranite was formed at 217.9±1.7 Ma (MSWD=0.74, n=20), suggesting the Late Triassic and the same time as the metallogenic age of the iron-polymetallic deposit in Qimantag area. The syenogranite is characterized by high silicon (SiO₂=74.62%~75.28%), high alkali (K₂O + Na₂O=8.81%~8.95%), and fairly high ratio of FeO^T/MgO (18.02~31.48). The trace element and REE compositions show the features of significant negative Eu anomalies (δEu=0.04~0.05), enrichment of Rb, Th, U, K, Ga, and depletion of Sr, Ba, Ta, P, Ti. The geochemical characteristics indicate that the syenogranite belongs to metaluminous-weakly peraluminous A-type granite. The εHf(t) values of syenogranite vary from 2.0 to 12.4 with the two-stage model ages being t_DM2 of 1 126~458 Ma. It is held that the source region of syenogranite probably had a mixture with the mantle and ancient crust, which provided abundant materials for the iron-polymetallic mineralization in this area. In the discrimination diagrams of A-type granite, the syenogranite falls into A2-type granites, which suggests that it was formed in an extensional tectonic regime after the orogenic process. All these characteristics display a transition of the Late Variscan-Indosinian orogenic cycle from the epi-orogenic stage to the extensional tectonic regime in Qimantag area in the late Triassic.

Abstract:The South Qinling microcontinent is one of the important tectonic units of the Qinling orogenic belt. In order to study the provenance of sediments in Mesozoic graben basin in South Qinling, the authors conducted LA-ICP-MS zircon U-Pb isotopic dating on polymictic conglomerate of Tianjiaba Formation and tuff sandstone of Zhoujiawan Formation of Lower Cretaceous in Fengtai area. Two groups of dating data were obtained, which have 40 effective ages respectively. The results show that the zircon ages have five age peaks with ranges of 2 595~2 771 Ma, 1 215~1 916 Ma, 749~1 142 Ma, 424~576 Ma and 218~306 Ma, which correspond respectively to Kenor, Columbia, Rodinia, Gondwana and Pangaea supercontinent events. Based on zircon dating analyses and combined with the regional geological data, it is concluded that the North Qinling accretion-type orogen and the North China plate provided the dominant clastic materials for the Mesozoic basin in South Qinling, followed by the Yangtze plate. The North Qilian orogenic belt and the northern margin of West Qinling orogenic belt also contributed to the provenance of sediments in the Mesozoic basin of South Qinling.

Abstract:Based on analyses of the sampled shales of field outcrops and well cuttings, the authors studied the geochemical characteristics of the shales of Mesoproterozoic Xiamaling Formation in Beijing. Al₂O₃, Na₂O and K₂O are depleted whereas SiO₂, TiO₂ and Fe₂O₃^T are relatively enriched. The shales show homogeneous REE content, relatively enrichment of LREE and depletion of HREE,obvious negative Eu anomaly, and slightly negative Ce anomaly. The REE distribution patterns from different shale samples showing an affinity reveal that they have the same source rocks including granitic, dioritoid and mafic rocks from the upper continental crust of Inner Mongolia uplift, and the ratios of trace elements show these features too. They were deposited in a reducing environment with relatively deep water. The tectonic setting of the source area seems to have been a continental island arc.

Abstract:The Pusangguo lead-zinc polymetallic deposit is located in the volcanic-magma arc of the southern Gangdise metallogenic belt, Tibet. The skarn type orebodies mainly occur in nearly bedded and lenticular shapes in nearly east-west direction and are hosted in the skarnized marble of the Cretaceous Takena Formation, with lots of skarn minerals developed in this deposit. In order to further identify the species of skarn minerals and types of the skarn and analyze the formation environment of the skarn and its relationship with mineralization types, the authors analyzed the chemical composition of the skarn minerals by using the electron microprobe technology and on the basis of the systematic microscope observation. According to the results obtained, the garnet is mainly composed of discontinuous isomorphism of andradite and grossular (And_47.39~98.17Gro_0.59~50.22Ura + Pyr + Spe_0~3.53), the clinopyroxene is mainly composed of hedenbergite-johannsinite-diopside (Hd_37.91~74.16Jo_0.91~61.66Di_0.43~46.07), the pyroxenoid is mainly wollastonite, and the endmember compositions are Wo_99.09~99.26En_0.50~0.56Fs_0.13~0.24. In addition, the hornblendes are mainly magnesium hornblendes and have the features of calcium hornblende, the epidote is relatively enriched in aluminum and calcium but poor in iron and magnesium, and the chlorite belongs to the type of pycnochlorite. The skarn mineral assemblage characteristics indicate that the skarns in the Pusangguo deposit have the features of both calcium-skarn and manganese-skarn. At the early stage of skarn mineralization, the skarns were mainly formed under the conditions of high temperature, pH, oxygen fugacity, and the ore-forming fluid had high oxygen fugacity. Manganese skarn mineral characteristics and the single silver minerals show that this deposit has the silver ore prospecting potential, which can serve as the next step prospecting direction in the future exploration.

Abstract:The Xianglushan copper deposit in Weining of northwest Guizhou is located in the copper bed between the top of the third unit of Emeishan basalt Formation and the bottom of Xuanwei Formation, and belongs to basalt type copper deposit. In order to study the geological characteristics of copper-hosting strata and mineralogical and petrological characteristics of copper-hosting rocks, the authors carried out rock-mineral determination, scanning electron microscope and electron microprobe analysis systematically in combination with field geological survey. The results show that the ore minerals of lithic siltstone are mainly composed of chalcocite, etrahedrite, bornite and malachite, and gangue minerals are mainly feldspar, quartz, chlorite and carbonaceous materials; the ore minerals of volcanic breccia are mainly composed of pyrite, bornite, chalcopyrite, chalcocite, tetrahedrite and malachite, and gangue minerals are mainly quartz, chlorite, dolomite and clay minerals. According to main mineral content, primary ores can be divided into three natural types, i.e., natural copper + chalcocite + hematite ore, natural copper + chalcopyrite + tetrahedrite ore and chalcopyrite + bornite + hematite ore. On the basis of mineral assemblages and intercalation relationship, mineralization can be divided into hydrothermal stage and supergene stage. The sequence of ore minerals at the hydrothermal stage is bornite→chalcopyrite→tetrahedrite→natural copper→chalcocite. At the supergene stage, malachite, hematite, hematite, ilmenite and limonite have been formed.

Abstract:The disseminated and banded chromites in the serpentinized ultrabasic rocks of the Dacaotan area, East Tianshan Mountains, are helpful to clarifying the characteristics and evolutionary process of the rocks. Some chromites have zoned texture,with rich Al but poor Fe in the core. The geochemical characteristics of the core of chromites, with the data Cr₂O₃ 39.27%~42.65%,Al₂O₃ 24.58%~26.21%,TiO₂ less than 0.20%,FeO 12.18%~18.14%,Fe₂O₃ 0.33%~7.30%, Cr^# 50.6~53.5, Mg^# 53.3~68.2, and Fe^{2 + #} 31.8~46.7, are in accord with the features of ophiolites serpentinite and may be a member of ophiolites. Moreover, the crystallization temperature and pressure of the chromite are estimated to be 1 385℃ and 2.77 GPa on average, respectively, with a formation depth of about 86 km, which is similar to features of the asthenosphere. The oxygen fugacity relative to FMQ buffer is FMQ -4.38~FMQ + 0.63 log units, FMQ -1.15 log units on average. Furthermore,the degree of partial melting of the mantle is estimated to be in the range of 21.04%~21.28%,21.18% on average, in the light of its relationship with Cr^#. These parameters provide some clues to the physicochemical conditions:these peridotites were derived from garnet lherzolites located in the asthenosphere of the upper mantle, and Dacaotan serpentinite was formed in the depleted island-arc setting of supra-subduction zone. The compositional zoning suggests that the peridotites have undergone a thermal path of decreasing temperature and increasing oxygen fugacity.It can be inferred that the mantle peridotites experienced the process from the stage of high temperature and high pressure mantle with lower oxygen fugacity to the thrusting slice stage to reach the crustal surface, where they were subjected to regional metamorphism with higher oxygen fugacity.

Abstract:The Taihexian Pb-Zn deposit is located in southeastern Hunan Province. In order to understand its fluid properties and evolution and discuss its metallogenic mechanism, the authors conducted field investigation and analyzed the ores of different metallogenic phases by such means as fluid inclusion petrography, microthermometry and laser Raman microprobe. The results reveal the existence of three ore-forming stages in the Taihexian Pb-Zn deposit, characterized by vein cutting relation and mineral assemblages of quartz-pyrite-arsenopyrite (the early stage), quartz-Pb-Zn polymetallic sulfides (the middle stage) and quartz-calcite-pyrite. Four main types of fluid inclusions were distinguished in the hydrothermal quartz, i.e., liquid-rich inclusions (type Ia), vapor-rich inclusions (type Ib), carbon-aqueous two-phase inclusions (type Ⅱ), and carbon-aqueous three-phase inclusions (type Ⅲ). Microthermometic data show that the homogenization temperatures of the fluid inclusions from the early stage to the late stage are gradually decreased, from 235~349℃, through 159~272℃ to 128~205℃, with the corresponding salinities being 2.03%~7.44%, 1.39%~10.86%, and 1.39%~7.58%. Raman microspectroscopic studies of the fluid inclusions show that the main component of aqueous inclusions in quartz-pyrite-arsenopyrite, quartz-Pb-Zn polymetallic sulfides and quartz-calcite-pyrite is H₂O, followed by CO₂, with a little reducing gas CH₄ and N₂. The metals precipitation resulted from fluid immiscibility caused by CO₂ escaping at the early stage, fluid mixing caused by meteoric water and interlayer water at the middle stage and natural cooling of fluid system at the late stage.

Abstract:Infrared (IR) spectroscopy, X-ray powder diffractometry (XRD), scanning electron microscope (SEM), laser Raman spectroscopy and LA-CP-MS were used to study the mineral composition, inclusions and trace element characteristics of Shuikeng Stone from Shoushan, Fujian Province. The results of IR spectroscopy and XRD indicate that the main mineral of Shuikeng Stone is dickite, with nacrite, pyrophillite and illite also detected in Shuikeng Stone as accessory minerals. The crystal particle size of the turnip vein is smaller than the particle size of dickite matrix, and the crystal particles are arranged non-directionally. The dark granular minerals with metallic luster exist in two different forms, i.e., euhedral and anhedral, and are embedded in the dickite matrix. The result of Raman spectroscopy analysis indicates that the turnip vein consists of svanbergite, and the mineral composition of dark granular minerals is pyrite. A comparison of the trace element characteristics between Shuikeng Stone, Gaoshan Stone and Tianhuang Stone shows some differences between them. The discriminant criteria of Gaoshan Stone, Shuikeng Stone and Tianhuang Stone are established by SPSS, and the three kinds of samples can be separated by these criteria. The estimated value of discriminant accuracy for a new sample is 90.8%. The difference between LREE and HREE in Shuikeng Stone is not very obvious, and the content of LREE in Shuikeng Stone is not rich. The primary ore-forming environment of Shuikeng Stone was a reducing environment. The turnip vein and the pyrite are both primary inclusions. Secondary environment caused the difference of trace elements between Gaoshan Stone, Shuikeng Stone and Tianhuang Stone. Groundwater environment caused the migration of LREE. These differences can be used to identify the three kinds of Shoushan Stone.

Abstract:Extracellular polymeric substances (EPS) extracted from iron bacteria can promote the iron aggregation and then form iron minerals by stabilization and deposition actions of ferric ions. In this paper, based on the key regulation or influence on ferric bio-mineralization by iron bacteria or their EPS, the authors introduced the bio-mineralization formation of iron oxyhydroxides in soluble EPS-containing solutions from Acidithiobacillus ferrooxidans cultures without/with Fe(Ⅱ) or Fe(Ⅲ) at various molar rates of Cl^-/SO₄^2-. It mainly described the change of solution pH values and the phases and structures of the formed iron minerals characterized by XRD, FTIR and FESEM. The decrease of solution pH values and the characterization results suggested that the micro-sphere schwertmannite covered by "pincushion" or nano-spheroid schwertmannite and micro-prism jarosite particles could form in all reaction solutions. The resulting iron precipitates uld be regulated by bacterial EPS, which, however, hardly had impact on ferrous oxidation, and addition of iron salts could promote the transformation of initial schwertmannite into jarosite phase. It was also demonstrated that phase transformation and particle agglomeration could be prevented with the increase of Cl^-/SO₄^2- molar ratios (i.e. increase of Cl^- content). This might be related to the higher SO₄^2- content occurring in the reaction solutions, which facilitated phase transformation of iron minerals and presence of the tightly assembled spheroid particle morphology.

Abstract:In this study, the authors investigated the role of reactive oxygen species (ROS) in inducing A549 apoptosis by activated mitochondria apoptosis pathway in chrysotile asbestos. Human lung epithelial cell (A549) cells were exposed to different concentrations of chrysotile asbestos dust and, on such a basis, the authors conducted detection of cell viability by MTT assay and detection of cell apoptosis rate, intracellular ROS level and mitochondrial membrane potential by flow cytometry before and after pretreatment of N-acetyl-l-cysteine (NAC) of ROS inhibitor, and then performed determination of caspase-3 and p53 protein expression level by Western blot. The experimental results show that chrysotile asbestos dust can reduce the survival rate of A549 cells and present the effectiveness relationship between the time and the dose. NAC could significantly reduce intracellular ROS level, prevent mitochondrial membrane potential declining, lower the expression level of caspase-3, p53 protein, and inhibit the occurrence of some cell apoptosis. The results indicate that ROS could activate mitochondrial apoptotic pathway by raising p53 protein expression and thus induce apoptosis of A549 cells.

Abstract:p-T conditions and p-T paths of (ultra)high-pressure metapelites are important aspects in the study of (ultra)high-pressure metamorphism. This paper introduces several kinds of geothermobarometers applicable to (ultra)high-pressure metapelites, which include the garnet-phengite Fe^{2 +} -Mg exchange geothermometer, garnet-chlorite Fe^{2 +} -Mg exchange geothermometer, chloritoid-chlorite Fe^{2 +} -Mg exchange geothermometer, Si-in-phengite geobarometer, Zr-in-rutile geothermometer, Zr-in-titanite geothermobarometer, Ti-in-zircon geothermobarometer, Ti-in-quartz geothermobarometer and oxygen isotope geothermometer. In addition, a review is given concerning the applicable conditions and points for attention in use of the above geothermobarometers.

Abstract:This paper has predominantly discussed four aspects in the study of very low-grade metamorphism:① The major features of very low-grade metamorphism and research contents; ② The significance and necessity to strengthen the study of very low-grade metamorphism; ③ Current research status and existing problems both in China and abroad; ④ Main problems in strengthening the study of very low-grade metamorphism:the first is seting up projects, the second is continuous projects funds, the third is talent training, the fourth is providing advanced instruments and equipment.