某钽铌钨铍矿化花岗岩岩石化学特征

During the magmatie evolution from biotite granite through two-mlca granite to mineralized muscovite granite it has been noted that Na^ , Mm^2 , Si^4 increase while K^ , Ca^2 , Mg^2 , Fe^2 , Fe^3 , Ti^4 , and P^5 decrease systematically in this district. Oreforming metals occur in higher abundance in biotite granite which is thought to be the representative of primary magma, and have been enriched rapidly with magmatic evolution R^ /R^2 Na^ /K^ , Rb/K, Mn/Fe and other petrochemical parameters increase whereas Ti^4 /Si^4 decreases in a sympathetic way with the enrichment of niobium and tantalum, providing good indicators of the degree of differentiation and metasematism of the magma ,Within the mineralized granite, there is a same trend of variation upward whioh is found closely related to the enrichment of tantalum. Fluorine is strongly concentrated in wall rocks above blind mineralized granite, and the eontente of tantalum and niobium in wolframite from quartz veins genetically related to the granite increase towards buried mineralization. The latter two phenomena are suggested by the author as clues to buried ore bodies.     

广西中生代花岗岩石成因及其成矿专属性的初步探讨

Granites are widespread in Ouangxi Province, and distributed in four tectonicmagmatic belts. Geochemical characteristics of these Mesozoic granites can be outlined as: (1) petroebemically being rich in silica, alkali and volatiles; (2) low oxidation ratio ond relatively high A1 index and K2O/Na2O ratio. As indicated by their geochemical,petroiogieal and mineralogical features, many granites in Guangxi belong to S type,frequently associated with mineralizations of rare-earth, tin, tungsten, niobium and tantalum.     

Geological and Geochemical Constraints on the Newly Discovered Yangchongli Gold Deposit in Tongling Region, Lower Yangtze Metallogenic Belt

The newly discovered Yangchongli gold deposit is a unique independent gold deposit in the Tongling ore-cluster region controlled by the tectonic alteration firstly discovered in the Lower Yangtze Metallogenic Belt(LYMB). The host magmatic rocks mainly consist of monzodiorite and K-feldspar granite. The LA-ICP-MS U-Pb zircons dating yielded weighted mean ~(206)Pb/~(238)U ages of 140.7 ± 1.8 Ma and 126.4 ± 1.2 Ma for the monzodiorite and K-feldspar granite, respectively. Monzodiorites are enriched in Sr, Ba, Rb, and depleted in Y, Yb with high Sr/Y and La/Yb ratios, similar to the geochemical features of adakite, considered as products of differentiation of mafic magmas originating from lithospheric mantle melt/fluids caused by metasomatism during paleo-Pacific Plate subduction in the Mesozic. In contrast, the compositions of K-feldspar granites are A-type granites, indicating an extensional tectonic background. Gold ores hosted in the fracture zone occurred as quartz vein within cataclastic rock. Sulfur and lead isotopes from pyrites show crust-mantle mixing characteristics. Metal components from strata also took part in the gold mineralization, and resulted from two episodes of magmatism that were probably related to tectonic transition from a compressive to an extensional setting between 140–126 Ma, which led to the Mesozoic large-scale polymetallic mineralization events in eastern China.     

Volatile Constituents in Magmatic Inclusions

Laser Raman microprobe has been applied to the analysis of volatile components in shrinkage gas bubbles of individual magmatic inclusions in quartz crystal fragments and phenocrystals from the Mesozoic volcanic complexes of Tonglu and Shouchang,Zhejiang Province.Quantitative analyses are given for CO2,CH4,H2O,CO,H2 N2,H2S, and SO2.In conjunction with the microthermometry and microbarometry data and the chemical composition of magmatic inclusions,the results permit one to calculate the physico-chemical parameters Ptotal,?O2,?CO2,?CH4,?H2O,?CO,and ?H2 at the time individual magmatic inclusions were trapped.Based on the data obtained,some physico-chemical conditions for the Mesozoic volcanic magma evolution in the Tonglu and Shouchang areas are discussed.This work shows that this type of studies has become an indispensable new and rising domain in modern magmatic petrology,especially modern volcanic petrology.It can help us to reconstruct the physico-chemistry of the crystallization-evolution of a natural magma.     

The Source System of Mesozoic Magmatism in Middle and Lower Yangtze Valleys and Adjacent Areas—A Geochemical Tracer Study

The mechanism that controls regional mineralization must be governed by a series of geochemical reactions in relation to the source system of magmatism.In this respect,the geological bodies must have been overprinted by various kinds of tracers in terms of either chemical elements or isotopes.For this reason,the problem may be better approached by treating the lithosphere as a whole with due considerations given to the various tracer elements and isotopes and the various media of the magmatism(magmatic as well as sedimentary rocks).Presented in this paper are the results of this attempt based on a great wealth of available data concerning the source system of Mesozoic magmatism in the Middle and Lower Yangtze Valleys and adjacent areas.     

GEOCHEMICAL CHARACTERISTICS OF GRANITES AND ITS STRUCTURAL GENETIC ENVIRONMENT IN THE NANDAN-HECHI METALLOGENETIC BELT, NORTHWEST GUANGXI

The Nandan-Hechi metallogenetic belt is the most important tin-polymetallic producing district in China, and is the location of the Dachang super-large tin deposit. Based on the detailed field investigation and isotopic data, the stages of magmatic activity in the Nandan-Hechi metallogenetic belt have been lined out in this paper. Through the study about the geochemical characteristics of different granites, and by using ω(Al2O3)-ω(SiO2), ω(TFeO)/[ω(TFeO) ω(MgO)]-ω(SiO2), AFM, ACF and Rb-Yb Ta, Rb-Y Nb,Ta-Yb, Nb-Y discrimination diagrams in combination with regional geological setting analysis, the authors carried out analyses about the structural environment for the formation of the granites, and discussed the structural environment and dynamic setting for the large scale mineralization in this area. Our study indicates that the majority of the granites in Nandan-Hechi metallogenetic belt belong to the POG type,while the later stage alaskite belongs to the RRG CEUG type. The granites were formed at the stage of structural transformation from postorogenic phase to intraplate setting. But the major structural environment is characterized by steady regional extension. The formation age for the granites coincides with the time for this transformation, and this translation environment is favored for large-scale metallogenesis.     

中国有色金属工业总公司矿产地质研究院

The Changpo tin-polymetallic deposit occurs in the Upper Devonian marine carbonate rocks and silicious rocks and is controlled jointly by three factors, i.e., strata (D3), structures and magmatic rocks, bearing dual characteristics of the syndepositional deposit and hydrothermal one. According to modes of occurrence and mineral assemblages, it can be divided into two types of mineralizations: stratiform stanniferous sulfides and veinlike cassiterite-sulfides. The former has such characteristics of sedimentary deposits as being controlled by the strata, and possessing typical syndepositional structure, e. g., striped and laminated structure, as well as less developed wall rock alterations. In contrast, veinlike mineralizations are characterized by features of hydrothermal deposits, such as being governed by fracture systems and affected by tectonic activities, showing polystage pulsation and having typical hydrothermal wall rock alterations including sericitization, tourmalinization and fluoritization. The two types display distinct differences not only in geological characteristics, but also in mineral assemblages, metallogenic physical-chemical conditions and temperatures as well as ore-forming time. Nevertheless, there exist close relations between the two mineralizations: (1) they occur in the same spatial position; (2) they have similar vertical mineral zoning: pyrite in the upper part of the orebody and pyrrhatite in the lower; (3) δ34S values of pyrite and sphalerite are similar in the two types, being -4.5‰ - +1.3‰ in the pyrite and -7.1‰ - +0.2‰ in the sphalerite respectively. All this implies that these two mineralizations have intimate relationships and also obvious differences. On the one hand, they were formed in different ore-forming stages and diverse geological conditions; on the other hand, the stratiform mineralization was- superimposed and remolded by the late ore-forming hydrothermal fluids, i. e., veinlike mineralization, whose material sources in turn had something to do with the stratiform mineralization. Studies show that the stratiform mineralization is of sea-floor syndepositional type formed in Late Devonian whose formation was probably related to the eruptive sedimentation of the volcanic hot spring ascending along the deep-seated fractures. The metallogenic elements such as S, Sn, Pb and Zn were derived from the depth of the crust, and the veinlike mineralization resulted from the hydrothermal liquid of Yanshanian granitic magma. Under the action of the magmatic solution and the heat of the magma, the metallogen materials in the stratiform mineralization were activated and transported, and thus provided some ore-forming materials for veinlike mineralization, such as S, Sn, Pb and Zn. It is therefore concluded that the Changpo ore deposit is a composite-origin type formed both by syndeposition, i.e., eruptive deposition from volcanic hot spring at seafloor, and by superimposition-reformation of the magmatic hydrothermal fluids, and that this deposit must have evolved from the stratiform stanniferous sulfide mineralization.     

A Preliminary Review on the Metallogeny of Pb-Zn Deposits in China

Lead and zinc resources are abundant in China, with the reserves of 100 million tons ranking only second in the world. There are more than 3000 lead-zinc mine areas nationwide. The classification of lead-zinc (Pb-Zn) deposits has been a highly controversial issue. From the standpoint of evaluating the potential of mineral resources, we construct a Pb-Zn deposit predictive type of classification scheme, and propose a Pb-Zn deposit comprehensive classification scheme (including 5 classes and 13 sub-types) that regards mineralization as the primary factor and the ore rock as secondary. According to the temporal and spatial distribution of Pb-Zn deposits, we conclude that a multi-period, multi-cycle orogenic environment is the most favorable for lead-zinc deposit growth, that the Proterozoic is the major eon for the growth of igneous-type deposits, the Paleozoic is an important development era for sedimentary Pb-Zn deposits, and the Mesozoic and Cenozoic are the heyday eras of magmatic type lead-zinc deposits. On this basis, we analyse the relationship between tectonic evolution and Pb-Zn metallogenic, and propose that the key factors determining geological mineralization are the metallogenic epoch of mineralization and tectonic environment, which determine the temporal and spatial distribution.     

Migration of Some Elements and Radionuclides across aGranite-Granite Contact Zone: A Natural Analoguefor Safe Disposal of High-Level Radwastes

Elements and natural radionuclides in the contact zone of two granites with different ages would migrate from one to the other because of the difference in their chemical contents and later water-rock interactions. This migration could serve as an analogue for the near-field process of radwastes in a high-level radwaste deep geological disposal repository.In the contact between the Indosinian granite (whole-rock Rb-Sr isochron age at 214@3 Ma) and Hercynian granite (zircon U-Pb isochron age at 296@31 Ma) located in Ziyuan County, Guangxi, the O and Pb isotope characteristics and the activity ratios of 234U/238U, 230Th/238U, 230Th/234U and 226Ra/230Th show that, based on the whole-rock chemical contents, both of the two granites have maintained a relatively open chemical system in their evolution processes. However, as there is no obvious open fault, the migration of major elements, trace elements and natural U-series nu-clides takes place within only 1-2 m in the contact zone, and water-rock interaction     

Review……………………………………………………A Preliminary Review on the Metallogeny of Pb-Zn Deposits in China

Lead and zinc resources are abundant in China, with the reserves of 100 million tons ranking only second in the world. There are more than 3000 lead-zinc mine areas nationwide. The classification of lead-zinc (Pb-Zn) deposits has been a highly controversial issue. From the standpoint of evaluating the potential of mineral resources, we construct a Pb-Zn deposit predictive type of classification scheme, and propose a Pb-Zn deposit comprehensive classification scheme (including 5 classes and 13 sub-types) that regards mineralization as the primary factor and the ore rock as secondary. According to the temporal and spatial distribution of Pb-Zn deposits, we conclude that a multi-period, multi-cycle orogenic environment is the most favorable for lead-zinc deposit growth, that the Proterozoic is the major eon for the growth of igneous-type deposits, the Paleozoic is an important development era for sedimentary Pb-Zn deposits, and the Mesozoic and Cenozoic are the heyday eras of magmatic type lead-zinc deposits. On this basis, we analyse the relationship between tectonic evolution and Pb-Zn metallogenic, and propose that the key factors determining geological mineralization are the metallogenic epoch of mineralization and tectonic environment, which determine the temporal and spatial distribution.     

Isotope Geochemistry of Erentaolegai Silver Deposit, Inner Mongolia, China

Detailed studies have been conducted on the geology and geochemistry of the deposit and granite in the mining district in the last two decades, and by comparing this deposit with other typical epithermal deposits in the world, it is clear that the Erentaolegai silver deposit is a lower-sulfidation, adularia-sericite-type epithermal silver deposit and the bulk mineralogy of this deposit is consistent with low-sulfidation epithermal mineralization. Determined by the Rb-Sr isochron method, the age of magmatic intrusives in the mining district is 120 Ma. So, it can be concluded that the local areas were marginally subjected to the movement in Late Yanshanian and produced granitic magma, and about 29% mantle material, as is calculated, was involved in magmatism. The magma experienced crystallization-differentiation, resulting in the formation of granite and quartz porphyry; the latter was the product of violent granitic magma crystallization-differentiation, so silver was enriched in later petrogenetic stages and post-petrogenetic ore fluids from which Ag was derived dominantly. Oxygen and hydrogen isotopic characteristics indicate that meteoric waters on the Earth‘ s surface played an important role in the formation of granitic magma and the deposit: ( 1 ) contributing a lot to the fundamental complex partial melting;(2) contributing a lot to magma crystallization-differentiation, and bringing silver into the magma which is eventually responsible for the formation of quartz porphyry; and (3) contributing a lot to the formation of great amounts of ore fluid. The lead isotopic characteristics show that the silver and lead have an affinity for each other.     

作为赋存于花岗岩中钨锡矿化勘探指南的流体包裹体异常——前景展望

Studies of the distribution and abundance of fluid inclusions in granitic quartz associated with granite-hosted Sn-W mineralization of the British Isles reveal local and regional scale anomalies.At a sampling interval of c.5～50m,inclusion abundances increase towards zones of vein and stockwork mineralization exemplified by case history examples from exploration prospects in the Mourne Mountains of Northern Ireland and the Carrock Fell mining district of northwestern England.These steam aureoles provide a greater exploration target than the zone of visible alteration and mineralization and the lithogeochemical halo.But it is important to link them to geochemical data on fluid inclusion compositions,such as the semi-quantitative data from decrepitation-linked,ICP-AES (D-ICP)analysis,to optimize their exploration potential.Regional scale fluid inclusion anomalies,based on sampling intervals of c. 2km from the Sn-W mineralized granites of southwest England also broadly correlate with zones of intense mineralization in some areas. Regional-scale D-ICP analyses of quartz from SW England granites did not provide any convincing regional scale anomalies linked to mineralization except for positive boron anomalies around the centrally-mineralized Birch Tor area of the Dartmoor granite.Follow-up D-ICP analysis of quartz from stream sediments from this area,however,could be used to discriminate between samples related to mineralization from those draining unmineralized areas,using multivariate statistical analysis.At the present stage of development, the main contribution of fluid inclusion studies to mineral exploration is mostly limited to the conceptual stage where they continue to contribute to ore genetic theory and models.Costs and lack of knowledge transfer between research scientists and mineral explorationists limit their direct use during regional and target selection stages of exploration.Analysis of steam sediment quartz,using the more sensitive ICP-MS technique as a variant of the D-ICP method,appears to offer the greatest potential for future development as an exploration tool.     

Element Geochemistry and Petrogenesis of High—K Potassic Dike Rocks in Two Types of Gold Ore Fields in Northwest Jiaodong,Shandong,China

This paper deals with the high-K,potassic dike rocks in two types of gold ore fields at Linglong and Dayigezhuang,Northwest Jiaodong.The rocks can be divided into three types.i.e.,(1) lamprophyre,(2) andesite porphyrite,and (3) dacite porphyrite,based on their geological occurrence and space-time relationship with gold mineralization.These rocks were the products of early,synchronous and late mineralization.respectively,Element geochemistry shows that variations in chemical composition of major oxides follow the general rules of magmatic fractional crystallization.The fractional crystallization of mineral phases of augite in the early stage(namely in the lamprophyre stage)and hornblende and plagioclase in the late stge(namely from the andesite-porphyrite to dacite porphyrite stage)controlled the magma evolution.The rocks are enriched in alkili and have higher K2O and lower TiO2 contents,as well as strongly enriched in large ion lithophile elements such as Ba,Sr and Rb,and LREE but strongly depleted in transition elements such as Cr and Ni,Rb is depleted relative to Sr and Ba,and Rb/Sr ratios are low.Volatile constituents are abundant.These characteristics indicate that the initial magma originated from the metamorphic subduction ocean-crust that had been intensively contaminated by crustal materials,and retrogressive metamorphism is characterized by low-degree partial melting during back-arc spreading,Varying degrees of partial melting and different emplacement enviornments may be the main causes for the evolution of the rocks and mineralization in different degrees in the two gold ore fields at Linglong and Dayigezhuang,Shandong.     

Geochemistry of Granitoid Rocks from Zhejiang Province and Crustal Evolution—Ⅰ.Phanerozoic Granitoid Rocks

The Phanerozoic granitoid rocks include the Caledonian,Indosinian and Yenshanian granitoid rocks.The existence of Caledonian and Indosinian granites was evidenced by zircon U-Pb ages,The study of the characteristics of major,trace and rare-earth elements,isotopic composition and petrogenesis for the granitoid rocks has been made,The Caledonian and Indosinian granites were derived from partial melting of the Proterozoic basement rocks and the two tectonic activities were weak,The Yenshanian grantoid rocks were derived from mixing of mantle and crustal materials,It implies that the crustal accretion took place in Mesozoic time.     

Radioactivity and mineralogy of the altered granites of the Wadi Ghadir shear zone, South Eastern Desert, Egypt

Quartz-diorite, gneissose granodiorites, two-mica granite and perthite leucogranie are the main rock units cropping out in the Wadi Ghadir area, South Eastern Desert of Egypt. Along the NNE-SSW mega-faults, a broad brittle shear zone is developed in the Ghadir two-mica granite. Brittle deformation is manifested by severe myloniti-zation and alteration of these granites. These sheared altered granites are characterized by the presence of radioactive mineralization, associated with alteration features such as silicification, hematization and kaolinitization. Radioelement measurements revealed that the unaltered and altered two-mica granites are considered as uraniferous granites. The average uranium and thorium contents in the unaltered two-mica granites are 12.29×10-6 and 19.81×10-6, respectively, and the average Th/U ratio is 1.62. The altered granites exhibit higher concentrations of U (averaging 97.949), but have lower Th and Th/U ratios (13.83 and 0.16, respectively), which indicates uranium enrichment in the granites. Binary relations of eTh/eU against either eU or eTh and eU with eTh in the studied gran-ites suggest that the distribution of radioactive elements not only magmatic (positive correlation between eU and eTh), but also due to hydrothermal redistribution of radioelements (weak correlation between eU and eTh/eU). The magmatic U and Th are indicated by the presence of uraninite, thorite, zircon and monazite whereas the evidence of hydrothermal mineralization is the alteration of rock-forming minerals such as feldspar and the forma-tion of secondary minerals such as uranophane and pyrite. Microscopic, XRD and scanning electron microscopic studies revealed the presence of uraninite, uranophane, thorite, Ce-monazite and zircon, in addition to phlogopite-fluor mica in the studied altered granites of the Wadi Ghadir shear zone.     

A Novel Approach in Hydrogeochemical Exploration for Uranium Mineralization: an Example from West Central Sinai, Egypt

Groundwater in contact with ore deposits may acquire a chemical composition that could be used as a guide for exploration. Eight well-water samples are collected from a known uranium-mineralized area near Abu Zenima, west central Sinai to examine the applicability of using the hydrogeochemical technique in the search for uranium mineralization in similar arid areas. The analytical chemical data of the ground water is compared with ground radiometric measurements. The obtained results indicate that groundwater affected by uranium mineralization has a specific relativity of major anions expressed essentially as SO4>Cl>HCO3 and to a lesser extent as Cl>SO4>HCO3, associated as a rule with low magnesium content. This association constitutes a signature of uranium mineralization on the composition of groundwater in west central Sinai and could be used as an important exploration guide in the search for uranium deposits in similar areas. Anomalies in Ni, Fe, Zn and Cr and other pathfinder elements in groundwater can furnish geochemical guides to uranium ores. The immobile trace element anomalies, including Zn, Ni and Fe are strongly distributed near the orebody; whereas the relatively mobile trace elements, including Co, U, V and Cr, constitute the dispersion haloes away from the orebody. A new hydrogeochemical discrimination diagram is constructed to be used as a quick and cost effective exploration tool in the search for uranium occurrences in environmentally similar arid areas. Based on the obtained results, a new site for uranium occurrence, west of W. Baba, is delineated and recommended for future detailed geological and geochemical surveying.     

Discovery of the Archean Magmatic Cu-Ni Sulfide Deposit in China—Taoke Deposit,Shandong Province

The formation ages of global magmatic sulfide Ni-Cu deposits are from Archean to Mesozoic,the Neoarchean and Neoproterozoic are the two peaks.In China,the formation ages of magmatic sulfide deposits are from Proterozoic to Mesozoic,and the Neoproterozoic and late Paleozoic are the two peaks,.Compared with the global magmatic deposits,there is no case study of the Archean magmatic Ni-Cu sulfide deposits in China before.The nickel deposits formed in Neoproterozoic are located on the margin of the North China Block and Yangtze Block(e.g.Jinchuan,Dapoling),and those formed in the late Paleozoic are mainly distributed in the Central Asian Orogenic Belt(CAOB).Emeishan and Tarim Large Igneous Provinces(LIPs).such as Kalatongke,Yangliuping,and Pobei.     

Rb—Sr Isotopic Chronology of the Au—Bearing Quartz Veins in Gold Depostits in the Eastern Part of North China Platform

In the eastern part of Chian there had occurred large-scale gold mineralization during the Mesozoic,resulting in a large number of inprotant gold ore-concentrated areas.In this paper we have selected some isotope data(including four gold deposits previously studied and two gold deposis in this work)of Au-bearing quartz veins of the representative gold deposits in six impor-tant gold ore-concentrated areas in the periphery of the North China Platform and calculated their metallogenic ages using the method of Ludwig(2.90 version).The results show that the repre-sentative gold deposits in the six gold ore-concentrated areas were formed during the Mesozoic.     

Chemical origin of acid mine drainage and its computer simulation with Phreeqc——-A case study of Zibo coal mining district

Research on the origin of acid mine drainage （AMD） is helpful to find a way to avoid and remediate AMD and its pollution. AMD is mainly from pyrite （FeS2）-containing minerals （such as coal and ore） during mining process and reproduction, and is common and dangerous to water environment in the world. The results of research showed that ions of calcium and magnesium in AMD came mainly from calcite and dolomite. To my knowledge, other sources （such as chlorite） for the ions and their chemical origin were not studied. In this paper, the AMD in the Zibo coal-mining district as a case, its chemical characteristics and its origin were determined. And based on the analysis of the regional geological conditions, Phreeqc was used to stimulate the AMD＇s chemical origin. The results showed that acidification and neutralization are two processes, and the characteristics depended upon chemical reactions that occurred in the two processes. In the AMD, sulfate ion came from FeS2 and is an indicator of acid process, and ions of calcium and magnesium originated from calcite and chlorite and were indicators of neutral process.     

Typomorpic Characteristics of the Major Minerals in the Puziwan Gold Deposit, Datong, Shanxi, China

Utilizing theories of minerageny and prospecting mineralogy, the authors studied the attitude, morphotype and chemical composition of metallic minerals of pyrite, gold, chalcopyrite, galena and sphalerite, non-metallic minerals of quartz, carbonate, dolomite and rutile in the Puziwan gold deposit. The study shows the following results. （1） The mineral assemblage is complex and the species of sulfide are abundant with occurrences of sulfosalt minerals. （2） The composition in the minerals is complex and there rich micro elements, including As, Sb, Bi, Se, Te, Au, Ag, Cu, Pb, Zn, and Cr, Ni, V. The typomorphic characteristics of the association of the elements and their specific value suggest that gold mineralization is associated with shallow magmatic hydrothermal activity, the oreforming fluid is the mixture of abundant rising alkali magmatic water originating from the mantle or the lower crust and the descending acid atmospheric water. （3） Ankerite, Fe-rich sphalerite, granular Ti-rich rutile are widely distributed, which indicate great denudation depths, high mineralization temperature. The deposit is found in the middle and shallow positions of the porphyry series. The deep layers are not favorable for gold mineralization. （4） Copper minerals are rich in the ores and sulfides have high content of copper, suggesting possible porphyry-type Cu （Au） mineralization in deep positions and the surrounding areas.