Abstract:The Dahutang tungsten polymetallic deposit is located in the western segment of the Jiuling-zhanggongshan uplift in the Jiangnan orogen. The zircon U-Pb geochronologic, geochemical and Nd-Hf isotopic stud_ies of the Yanshanian Dahutang ore-forming granite-porphyry were carried out in this paper. The LA-ICP-MS zircon U-Pb age of the Dahutang granite-porphyry is 146.01±0.78 Ma. The granite-porphyry is characterized by high content of silicon and alkalis and high differentiation index, which, along with the characteristics of the major and trace element, suggests that the granite might be highly differentiated S-type granite. The Rb/Sr and Rb/Nb ratios of the granites are significantly higher than those of the upper crust and eastern China's upper crust, indicating that the granite-porphyry originated from melting of high-maturity crustal components. The ratios of Nb/Ta and Zr/Hf are much lower than those of normal granite, and there is REE tetrad effect, suggesting a strong melt-fluid interaction at the late stage of magma evolution. Heterogeneous Hf isotopic composition [εHf(t) =-19.9～-5.3;t_DM2=1.54～2.46 Ga] demonstrates that the granite-porphyry was derived dominantly from a Precambrian crustal source of 1.9～1.6 Ga and part of basic rocks, with the involvement of small amounts of late Archean basement rocks of Yangtze craton (2.5 Ga). The A/CNK ratios of the granite-porphyry are all higher than 1.15, suggesting that the granite-porphyry is a syn-collisional (syn-orogenic) granite rather than a volcanic arc granite; the young granite-porphyry has the post-collisional (post-orogenic) characteristics in the tectonic environment discrimination diagrams. The tectonic setting evolution of the old granite-porphyry and the young granite-porphyry indicates that "the extrusion-extension cycle" lasted about 11Ma with the transition from extrusion to extension in this area. This extrusion-extension cycl of 11Ma provided sufficient required dynamic duration for the multiple rock-forming and ore-forming activities in this area, and also served as an important geological prerequisite for extensive mineralization.

Abstract:Located in the Eren Nur area of China-Mongolia border region, the Qagan Dele amphibole_ and biotite-bearing monzogranitic pluton and the Weijing biotite monzogranitic pluton have zircon U-Pb ages of 276±2 Ma and 279±1 Ma, respectively. They are both Early Permian plutons. Geochemical data show that these two granite bodies have high SiO₂ (67.63%～74.75%), K₂O (2.94%～6.13%) values and weak Eu negative anomalies with A/CNK ratios less than 1.1, thus belonging to weakly peraluminous high potassium calc-alkaline series and exhibiting I-type granitoids features. Qagan Dele granites have zircon εHf(t) values between -18.65 to -10.95 and older model ages (t_DM2) in the range of 2470～1989 Ma, suggesting the probable existence of older crustral materials in the source. Weijing granites have zircon εHf(t) values between +1.71 and +5.44 and younger model ages (t_DM2) in the range of 1193～954 Ma, implying juvenile source at depth and crustal growth. Combined with regional tectonic evolution, it is held that these granitoids might have been formed in a syn-collisional to post-collisional setting. The fact that the two different plutons in the same area have different zircon Hf isotopes indicates completely different sources, which implies that recycling of old crust and crustal growth could occured in the same region.

Abstract:The Taoziwo tin deposit located in the west of Lianhuashan faulted belt is a typical volcanic-subvolcanic tin deposit. With the ore-bearing volcanic-subvolcanic rock and granite in the Taoziwo tin deposit as the study objects, the authors performed in situ zircon U-Pb dating and Hf isotopic analyses for the first time. Two samples of volcanic-subvolcanic rocks yielded weighted average ²⁰⁶Pb/²³⁸U ages of 172.1±1.1 Ma and 171.8±0.9 Ma respectively. A granite sample yielded the weighted average ²⁰⁶Pb/²³⁸U age of 168.9±1.5 Ma. These data indicate that they were formed at different stages of the same Middle-Jurassic magmatic event. Most of εHf(t) values are negative, except for three εHf(t) values which vary from -13.96 to 9.53 with the mean value being -7.92. In the εHf(t)-t diagram, εHf(t) values are mostly beneath the chondrite evolution line with three points between the chondrite evolution line and the depleted mantle evolution line. All the two-stage model ages are between 1 450.8 Ma and 2 102.5 Ma except for three points which lie in the range of 609.6～795.5 Ma, indicating that rock-forming materials were mainly derived from the partial melting of ancient early-middle Proterozoic crust with the addition of some juvenile Neoproterozoic crustal materials. In combination with the previous research results, the authors consider that the Taoziwo tin deposit and the related volcanic-subvolcanic rocks were genetically associated with the subduction of the Pacific plate to the Eurasian continent.

Abstract:There exist two different viewpoints concerning the bottom age of Nanhua System. i.e., early age (780 Ma or 760 Ma) and late age (725 Ma or 720 Ma). Zircon LA-ICP-MS U-Pb dating of a tuff sample from the upper part of Yanmenzhai Formation in Dongqiao, Pingxiang, was carried out, and 28 analyses of zircons show five main age groups. Then the authors probed into the geological settings of the five age groups and reached the following conclusions. The first and the second age groups with weighted mean age of 805.5±10.6 Ma and 767.6±7.7 Ma respectively came from inherited magmatic zircons, and were related to the island-arc magmatism on the southeastern margin of Yangtz Block during 810～800 Ma and the magmatism of 760 Ma in middle Banxi Period respectively. The fourth and the fifth age groups with weighted mean age of 390.8±2.8 Ma and 211.2±1.5 Ma respectively came from metamorphic zircons, and were related to the late Caledonia tectonic-hydrothermalism and the late Indonian tectonic-hydrothermalism respectively. The third age group with weighted mean age of 717.2±8.9 Ma came from 11 magmatic zircons and represents the formation age of the tuff. The age of 717.2±8.9 Ma provides a constraint for the bottom age of 720 Ma of Nanhua System. In addition, the authors studied the zircon U-Pb ages of around 760 Ma which came from the lower part of Chang'an Formaion in Bixi, center Hunan; it is pointed out that the ages came from inherited zircons, and that the upper limit age of 720 Ma held by 50 percent of the zircons suggests that the rock-forming age is 720 Ma rather then 760 Ma.

Abstract:Two kinds of carbonate hosted Pb-Zn deposits, namely carbonate-rich Pb-Zn deposits and fluorite-rich Pb-Zn deposits, extensively exist in the same Pb-Zn metallogenic belt in the world according to the classification based on gangue mineral assemblages. The relationship between the two kinds of deposits remains unclear. In the middle part of the 'Sanjiang' metallogenic belt in the Tibetan Plateau, the Dongmozhazhua carbonate-rich Pb-Zn deposit and the Mohailaheng fluorite-rich Pb-Zn deposit occur in the same carbonate-hosted Pb-Zn ore concentration area. In the two deposits, the carbonate strata are host rocks, the thrust faults are the main ore-controlling structures, the main orebody attitudes are of stratabound type, and sphalerite and galena are the main ore minerals. However, calcite and dolomite are the main gangue minerals in the Dongmozhazhua deposit while calcite and fluorite are the main gangue minerals in the Mohailaheng deposit. The geochemical features of rare earth elements (REE) in calcium-bearing minerals are different in the two deposits. The REE values of calcite in the Dongmozhazhua deposit are mainly characterized by obvious fractionation of LREE and HREE, enrichment of LREE, negative Eu anomalies and 'V'_shaped curves of chondrite-normalized REE patterns with right deviation. In contrast, the REE values of calcite and fluorite in the Mohailaheng deposit are chiefly characterized by no obvious fractionation between LREE and HREE, negative Eu anomalies and 'M'_shaped curves of chondrite-normalized REE patterns with right deviation. The total concentrations of REE (∑REE) of calcite (0.46×10^-6～10.79×10^-6) in the Dongmozhazhua deposit are higher than those in the Mohailaheng deposit (0.25×10^-6～5.88×10^-6). The geochemistry of the REE indicates that calcium-bearing minerals in the two deposits were all precipitated from a kind of hydrothermal fluids which had nothing to do with igneous activities. The salinity and reducibility of the fluids decreased with the sulfide precipitation. The two kinds of deposits had similar hydrothermal fluids; nevertheless, there existed another kind of fluid for the Mohailaheng deposit, which was a kind of fluorine-rich fluid from deep metamorphic basement. This fluorine-rich fluid controlled the location of the fluorite-rich carbonate hosted Pb-Zn deposits and could be used to explain the phenomenon why this kind of Pb-Zn deposits were more easily precipitated near the main thrust faults and the lowest carbonate strata in the region. The result achieved by the authors could answer the question why the carbonate-rich Pb-Zn deposit and the fluorite-rich Pb-Zn deposit can occur in the same region and same time in the world.

Abstract:The Mogou alkalic pluton, located in the southern margin of the North China Block, is mainly composed of aegirine-augite syenite, with minor syenite and porphyritic (aegirine-augite) syenite as well as mafic magma enclaves. LA-ICP-MS U-Pb dating of the aegirine-augite syenite yielded two ages of 237.6±2.9 Ma (MSWD=0.95) and 210.4±2.0 Ma (MSWD=0.39), suggesting the middle and late Triassic epoch, as also shown by previous studies. The aegirine-augite syenite is of peralkaline series and belongs to potassic alkaline rock with σ being 8.93～11.08, K₂O 10.70%～13.76%, and K₂O/Na₂O 3.87～10.35. The REE and trace elements are enriched in LREE and large ion lithophile elements, and depleted in high-field strength elements, with slightly negative to no obvious anomalies of Eu. The aegirine-augite syenite shows high (⁸⁷Sr/⁸⁶Sr)_i values with a large variation and significantly negative εNd(t) values. The zircon Hf isotopic compositions are characterized by εHf(t) values of -21.6 to -4.5, and the two-stage model ages of 1 555 to 2 629 Ma. The formation of the Mogou pluton could be interpreted as mixing/mingling of crustal-melted magma and mantle-derived magma which originated from phlogopite-bearing enriched mantle by low degree partial melting. The early stage magmatic activity of the Mogou pluton occurred in a local extension setting during a great regional collision period, while the late stage magmatism took place in the post-collision environment.

Abstract:A black rock series occurs in Xiamaling Formation, eastern Yanshan area, North China. Major and trace element compositions of the representative rocks were analyzed in this paper. Five samples have varying major element oxides (e.g., SiO₂=53.00%～78.83%, A1₂O₃=1.20%～17.57%). Their PAAS-normalized REE patterns are HREE-enriched with positive negative Ce anomalies, which is the typical feature of modern seawater. These samples show high A1₂O₃ and TiO₂ values (1.31%～18.48%); their U concentrations (averaging 3.95×10^-6), Th/Sc ratios (0.97～1.26), Th/U ratios (averaging 3.50), and chondrite-normalized REE and continental crust-normalized trace element patterns indicate that terrigenous detrital materials significantly contributed to the deposition. The Ba/Sr ratios (9.28～22.79), Co/Zn ratios (0.01～0.29) and related diagrams show that the black rock series was evidently influenced by marine hydrothermal activities during its precipitation. However, the proportion of hydrothermal fluid in original solution was less than 0.1%. The major and trace element ratios, Ce/Ce^* ratios (0.82～0.93) and tectonic discrimination diagrams also indicate that this black rock series was probably deposited in the deep-water anoxic environment of a continental arc setting.

Abstract:The Dashantounan basic-ultrabasic intrusion hosting Ni-Cu sulfide deposit is located in the eastern part of the Beishan fold belt on the southern margin of the Central Asian Orogenic Belt (CAOB). Detailed field geological survey indicates that only Gudongjing Group of Changcheng System occurs in the south of the intrusion. The complex is composed mainly of granodiorite, diorite, gabbro, norite bronzitite, olivine norite-gabbro, olivine websterite, lherzolite, othopyroxenite peridotite, and dunite. Among them, lherzolite, othopyroxenite peridotite and dunite are closely related to the Cu-Ni mineralization. The major element, trace element and REE geochemistry indicates that the values of K₂O, Na₂O and TiO₂ are low; the values of Mg^# are between 0.74 and 0.85, and MgO/FeO^T ratios are between 1.6 and 3.1, suggesting mafic and ultramafic rocks. The values of REE are low, varying between 6.37×10^-6 and 37.51×10^-6. The chondrite normalized REE partition curve exhibits right-inclined REE patterns, implying that the intrusion is enriched in LREE. The ratios of LREE/HREE vary between 3.03 and 4.11, and the AFM diagram shows a trend of tholeiitic magmafic differentiation. Through the zircon SHRIMP U-Pb dating of gabbro, the authors obtained the intrusion age of 374.3±3 Ma, similar to ages of Dashantou and Heishan intrusion, which suggests the emplacement took place in middle-late Devonian. The age has important practical significance for Cu-Ni mineral exploration in this area.

Abstract:The characteristics of elements content can be somewhat reflected by remote sensing. The remote sensing geochemistry can provide a parameter in many areas, especially in low geological exploration regions or in areas abroad where the acquisition of geological data are difficult. In this paper, according to the relationship between the element content and the spectra, four indicators of the remote sensing geochemical model were established, i.e., correlation slope of bands, slope index of bands, absorption depth of index of bands, and polynomial related index of bands. With the Duolong ore concentration area in Tibet as the study area, Cu element remote sensing geochemistry based on regression algorithm is in accordance with the measured Cu geochemistry, and F test confirmed the credibility of the inversion results. The remote sensing Cu geochemical results are good and can be considered to be an independent remote sensing parameter, as demonstrated by the comparison between the measured Cu element geochemistry and the remote sensing alteration anomalies.

Abstract:The Galinge skarn iron deposit, one of the large skarn deposits in the west of China, is located in the middle of the contact zone between the Qimantag orogen and the Qaidam basin, and possesses abundant potential values. This paper aimed to make specific research on the mineralogy of the Cl-rich amphiboles from the Galinge deposit so as to investigate the association of melt, fluid and minerals. The Cl-rich amphibole belongs to the magnesian hastingsitic subgroup, and its geochemical characteristics are 0.3< Mg/(Mg+Fe²⁺) <0.69; Si <6.25 apfu; and 0.681% < Cl <3.161%. The content of X_Cl shows the positive linear relation with the X_Mg, and the X_K and X_Fe²⁺ show the strong inverse relation with the X_Cl. The linear relation between the cation and the chlorine can be interpreted by the crystal structure consideration of Cl-rich amphiboles. In respect of the substitution between the Cl^- and OH^-, the Cl incorporation is expressed empirically by the function of ln (X_Cl/X_OH)_amp=ln (f_Cl/f_OH)_fluid +A·^[4]Al·Fe²⁺/RT+B/RT, where A and B are constant. Therefore, if all Cl-rich amphiboles are in equilibrium with the coexisting fluid at the same temperature and if each amphibole is in equilibrium with a fluid of relatively constant f_Cl/f_OH, the ln(X_Cl/X_OH)amp versus ^[4]Al·Fe²⁺ should show a linear correlation, and the effect of the cation substitution is contributed by the structure constraints for ^[4]Al and by a chemical constraints for Fe²⁺. The existence of amphibole zones implies that the X_Cl values decrease first and then increase from the core to the edge, since OH is preferentially incorporated relative to Cl. Therefore, when the free fluid phase is gradually consumed as a consequence of continued hydration/chloridisation reactions, the Cl^- content of the fluid should be increased. The crystal/liquid partitioning behavior of the trace elements is controlled by the framework of the lattice, and the volatile concentration in the fluid is also a key factor. The decrease of the Cl concentration in the fluid is attributed to the increase of the REE partition coefficients. Generally, the high saline hydrothermal fluid exsolved from the magma in the early crystallization stage is the dominated reservoir of metals because of the high Cl^- content and low pH value. The Cl^- plays an important role in the transportation of metals. When the ore fluid is reacted with an alkaline carbonate wall rocks, or mixed with meteoric water, the chlorine complex of iron would decompose and precipitate. Meanwhile, the increased pH value makes the f_OH of fluid ascend, which is beneficial for the incorporation of OH into the amphibole.

Abstract:The intermediate-acid magmatic hydrothermal activity in the late Jurassic led to the formation of a Mo-W(Fe)_Pb-Zn-Ag polymetallic metallogenic series in Luanchuan area, western Henan. The Luotuoshan sulfur-zinc polymetallic deposit is located in the contact zone between the rock mass and the strata in the Nannihu orefield. The characteristics of trace elements were studied by using ICP-MS analysis of sphalerite and pyrite based on field geological investigation. Trace element data confirm that the sphalerite from the Luotuoshan deposit is characterized by enrichment of Cd, In and Cu and depletion of Ga and Tl. The dispersed elements such as Cd, In, Ga mainly occur in sphalerite, while Co and Ni mainly occur in pyrite. The values of rare earth elements (∑REE) in sphalerite and pyrite are obviously lower than those in wall rocks. REE of the early stage sphalerite shows a fairly pronounced fractionation and has right-inclined patterns. The REE fractionation is not pronounced, with lower ∑LREE, and the patterns are relatively flat, which shows a opposite trend in the pyrite when it came to the late stage. Some kinds of trace elements like Ga, Ge, Cd, In and Tl can be indicators for metallogenic temperature, ore-forming fluid and genesis. The features of trace elements in sphalerite are closely related to the magmatic hydrothermal activity and suggest that this is a relatively medium-high temperature deposit which is similar to the Zhongyuku deposit in Luanchuan. Ore-forming conditions such as metallogenic temperature exhibit regular variation, as shown by the comparative analysis of the deposits from the proximal part to the periphery of the metallogenic series.

Abstract:⁴⁰K could be an important heat source during the evolution of the earth in that it may serve as a substantial heat source in the cores of the earth,sodium (Na) should be an important element in deep subducted slab,and subducted slab could transfer materials from the earth's crust to deep mantle of the earth. Moreover,garnet and clinopyroxene are common minerals in subducted slab. This paper presents a review of the progress in natural discovery and experimental study of K and Na behavior between garnet and clinopyroxene in the past five decades: ① the discovery of Na/K bearing garnet and its forming mechanism and significance; ② the discovery of K bearing clinopyroxene and its forming mechanism and significance; ③ experimental petrology study of K-bearing mafic-rock system. K,as a large ion lithophile element,could be incorporated into garnet and clinopyroxene under high pressure by substitution mechanisms of K^X+Si^Y=(Ca,Mg)^X+Al^Y and Mg^M1+Ca^M2=Al^M1+K^M2 respectively. It is significant for the K recycling from the crust to the deep earth. In subducting slab, Na could still be transferred into deeper mantle when clibopyroxene is not stable any more by the substitution of Na^X+Si^Y=(Ca,Mg)^X+Al^Y and the subsequent incorporation into garnet. K₂O content in clinopyroxene and Na₂O content in garnet present positive correlation with pressure according to previous high pressure-temperature experiments in K-bearing basalt/clinopyroxene systems under the mantle p-T conditions, while K and Na behavior in K-bearing basic rock system under the p-T condition of subducting slab remains rarely studied.

Abstract:In this paper, through the summary of research results of China's typical rare metal granites in the aspects of basic characteristics, research progress, petrogenesis, mineralization and ecological environment influence, the authors have reviewed and described the characteristics of rare metal granite and its mineralization with the purpose of helping researchers to understand the latest achievements of the research on the mineralization and the exploration of the rare metal granite and to find and identify the rare metal granite. In addition, the natural pollution of rare metal granite to the ecological environment and its health damage to the residents are discussed, and the authors appeal to the society and the public to pay adequate attention to these problems.

Abstract:It is known that Fe is essential for life. Moreover, that the biosphere interacts with the lithosphere, hydrosphere and atmosphere, and biological action plays critical roles in the evolution of the Earth. Therefore, it is of significance to understand Fe isotope behavior during biological processes. In this paper, the authors summarize the Fe isotope compositions of various types of organism, and Fe isotope fractionation during biological activities. It is shown that organism takes up light isotopes preferentially, and the isotope fractionation occurs stepwise along the biological pathways. During the biologically induced processes (including Dissimilatory Iron Reduction and bacterial Fe oxidation), Fe actually does not enter the cell. The values of Fe isotope fractionation of these processes are consistent with those for non-biological reduction-oxidation. During biologically controlled processes (including microorganism, plants, animals and human beings), Fe does enter the cell. The Fe isotope fractionation during these processes is mainly controlled by the redox state of Fe. Fe isotopes have great potential applications in biology and medical science, and are likely to be a new tracer in these research fields.

Abstract:In this paper, the fractionation of Pb isotope during the purification procedure is assessed,and the purification methods for isotope determination by MC-ICPMS are described. Purification procedure indeed leads to the mass fractionation of Pb isotope through AG1-X8 anion exchange resin. Though the fractionation is very small (0.43‰ amu^-1), it is beyond the instrument error apparently (0.23‰ amu^-1). The very low recovery of Pb during the purification procedure would cause Pb isotope value to deviate from the real value. With AG1-X8 as exchange resin,0.2 mL 1 mol/L HBr solution as loading solution, 5 mL 1 mol/L HBr and 0.5 mL 2 mol/L HCl solution as eluent for cleaning up the impurities,and 1.5 mL 6 mol/L HCl solution as eluent for desorption of the Pb adsorbed by the resin, the value determined after the purification of sample by using the separation procedure would be close to the true value within error. Under such a condition,the early fractions of the eluate are systematically enriched in the light isotopes (δ²⁰⁸Pb >0),whereas the late fractions of the eluate are systematically enriched in the heavy isotopes (δ²⁰⁸Pb >0),which indicates that the heavy Pb isotopes partition is absorbed more strongly into the resin than the lighter isotopes,and the distribution coefficient of Pb absorbed into the resin ²⁰⁸D/²⁰⁴D >1. Pb isotope fractionation may happen with the exchange of Pb in different types of complex compound in the desorption process, which implies that Pb isotope fractionation would occur in the reaction including inorganic compound or organic macromolecules. The results achieved by the authors not only enrich the knowledge of Pb isotope fractionationbut also provide more information for the analysis and application of Pb isotopes.