Ore Genesis of the Kalatongke Cu-Ni Sulfide Deposits, Western China: Constraints from Volatile Chemical and Carbon Isotopic Compositions

The Kalatongke Cu-Ni sulfide deposits located in the East Junggar terrane, northern Xinjiang, western China are the largest magmatic sulfide deposits in the Central Asian Orogenic Belt （CAOB）. The chemical and carbon isotopic compositions of the volatiles trapped in olivine, pyroxene and sulfide mineral separates were analyzed by vacuum stepwise-heating mass spectrometry. The results show that the released volatiles are concentrated at three temperature intervals of 200-400°C, 400-900°C and 900-1200°C. The released volatiles from silicate mineral separates at 400-900°C and 900-1200°C have similar chemical and carbon isotopic compositions, which are mainly composed of H2O （av. ~92 mol%） with minor H2, CO2, H2S and SO2, and they are likely associated with the ore-forming magmatic volatiles. Light δ13CCO2 values （from -20.86‰ to -12.85‰） of pyroxene indicate crustal contamination occurred prior to or synchronous with pyroxene crystallization of mantlederived ore-forming magma. The elevated contents of H2 and H2O in the olivine and pyroxene suggest a deep mantle-originated ore-forming volatile mixed with aqueous volatiles from recycled subducted slab. High contents of CO2 in the ore-forming magma volatiles led to an increase in oxygen fugacity, and thereby reduced the solubility of sulfur in the magma, then triggered sulfur saturation followed by sulfide melt segregation; CO2 contents correlated with Cu contents in the whole rocks suggest that a supercritical state of CO2 in the ore-forming magma system under high temperature and pressure conditions might play a key role in the assemblage of huge Cu and Ni elements. The volatiles released from constituent minerals of intrusion 1# have more CO2 and SO2 oxidized gases, higher CO2/CH4 and SO2/H2S ratios and lighter δ13CCO2 than those of intrusions 2# and 3#. This combination suggests that the higher oxidation state of the volatiles in intrusion 1# than intrusions 2# and 3#, which could be one of key ore-forming factors for large amounts of ores and high contents of Cu and Ni in intrusion 1#. The volatiles released at 200-400°C are dominated by H2O with minor CO2, N2＋CO and SO2, with δ13CCO2 values （-25.66‰ to -22.98‰） within the crustal ranges, and are considered to be related to secondary tectonic-hydrothermal activities.

The Mechanism of Structural Control of Ore Formation and Geochemical Characteristics in the Massive Sulfide Deposits of the Wushan Copper Ore Field,Jiangxi

The ore-controlling mechanism of the bedding fault system in the massive sulfide deposits of the Wushancopper orefield may be generalized as the control of ore deposition by optimum surface in an ore-formingstructural trap. The mechanism has three major features: (1) timing of mineralization; (2) positioning of hostformation; and (3) dependence of ore-controlling structure on properties of rocks. The 'optimum surface' is adivisional structural plane which marks obvious difference in physical, chemical and mechanical properties andis favorable for mineralization. It is also a unity of structures. lithofacies and orebodies. The structural and geochemical characteristics of the ore deposits indicate the migration trend of the ma-jor characteristic clements in the ore-controlling fault belt: elements with a small radius (Si, Fe, Mg and Al)moved towards and concentrated at the center of the belt while large-radius ones (Ca, K and Na) were remotefrom the center.

A new interpretation for the origin of the Norilsk type PGE-Cu-Ni sulfide deposits

The origin of PGE—Cu—Ni sulfide deposits of Norilsk and Talnakh located in the northwest flank of the Triassic basalt trap formation of Siberia is considered.It is shown that ore elements of these deposits（probably,except Fe） are derived from the crust rather than from the mantle.They entered the basalts owing to a remobilization（recycling） of ore elements from the Paleoproterozoic sediments and from the rocks of the Siberian platform＇s basement.Prospecting criteria for similar deposits are as follows：（1） a presence of a large Paleoproterozoic aulacogen and a related magmatic sulfide Cu—Ni mineralization;（2） a confinement of perspective areas to troughs associated with long-lived deep fault zones：（3） association with mobile orogenic belts,island-arc systems and tectonomagmatic activation zones;（4） temporal association with boundaries of global periods characterized by active processes of continental breakup and large-scale trap magmatism.A combination of several factors（the first one is obligatory） is favorable for the discovery of a large ore body.

GEOCHEMICAL CHARACTERISTICS OF PLATINUM GROUP ELEMENTS IN JINCHUAN SUPER-LARGE SULFIDE COPPER-NICKEL DEPOSIT, JINCHANG CITY, GANSU PROVINCE, CHINA

The platinum-group element geochemistry of rocks and ores from Jinchuan super-large copper-nickel sulfide deposit is systemically studied in this paper. The Cu/Pd mean ratio of Jinchuan intrusion is lower than that of original mantle magma, which indicates that these ultrabasic rocks were crystallized from magma that lost Pd in the form of melting segregation of sulfides. The PGE of the rocks show trend of partial melting, similar to that of mantle peridotite, which shows that magma formation occurs during rock-forming and ore-forming processes. The chondrite normalized PGE patterns of the rocks and ores are well related to each other, which signifies the signatures of multi-episode magmatic intrusion, melting and differentiation in the formation processes of rocks and ores. In addition, analyses about the relation between PGE and S, and study on Re-Os isotopes indicate that few contamination of the crustal substances occurred during the magmatic intrusion and the formation of deposit. However, contamination by crustal substances helps to supply part of the S for the enrichment of PGE. Meanwhile, the hydrothermal process is also advantageous for the enrichment of PGE, especially lbr Pt and Pd, due to deep melting segregation. The characteristic parameters （such as Pt/（Pt＋Pd）, （Pt＋Pd）/（Ru＋Ir＋Os）, Pd/Ir, Cu/（Ni＋Cu）, and so on.） for platinum-group elements for Jinchuan sulfide copper-nickel deposit show the same features as those for sulfide copper-nickel deposit related to basic magma, which also illustrates its original magma property representative of Mg-high tholeiite. Therefore, it is the marie （not ultramafic） magma that resulted in the formation of the superlarge sulfide copper-nickel deposit enriched in Cu and PGE. To sum up, the geochemical characteristics of platinum-group elements in rocks and ores from Jinchuan copper-nickel sulfide deposit are constrained by the continental rift tectonic environment, the parent magma features, the enriched mantel magma source, the complex metallogenesis and PGE geochemical signatures, and this would be rather significant for the study about the genetic mechanism of copper-nickel sulfide deposits.

A Genetic Model for Ore Magma of the Chibaisong Copper-Nickel Sulphide Deposit, Jilin

In the early 1980's, the author proposed his view that copper-nickel sulphide deposts are of ore magma origin. For more than ten years, this view has aroused attention of his colleagues at home and abroad. In this paper an attempt is made to deal with the genetic model for ore magma of copper-nickel sulphide deposits in more details on the basis of geological, geochemical, petrophysico - chemical and thermodynamic studies of the Chibaisong copper-nickel sulphide deposit in the Changbai Mountains, Jilin province.

The Massive Sulfide Deposit of Siirt Madenkoy,South-Eastern Turkey--Geology,Geochemistry and Mineral Raw Material Potential

The Siirt Madenköy massive sulfide ore deposit has been in operation since 2005. With its approx. 39 Mt reserves (2.40% Cu), it represents the largest Cu deposit and the largest mining operation in the country (1.5 Mt ore/year). The thickness of the adjacent rocks is composed of olivine-pyroxenite basalts pillow lava, which is spilite, interchangeable ore lenses of chalcopyrite and pyrite is about 170 m and reaches a depth of 350 m. The mid-Eocene aged porphyritic, strongly altered spilites are locally interspersed with diabase and covered by conglomerates. The ores appear massive, stock work and disseminated. Main ore minerals are idiomorphic pyrite, cataclastic chalcopyrite and fine-grained magnetite. The geochemical composition of the Cu ores of the Siirt-Madenköy deposit shows in places high levels of Cu, Fe and S, as important trace elements, As, Ba, Co and Ti are listed. In relation to Clarke values, Se, Bi, Cu, Mo and Co are strongly enriched, while Na, K and Ca as well as their coherent trace elements Rb, Sr and Cd are depleted due to hydrothermal alteration. The elemental distribution is characterized by log-normal distribution, proportionality effect, high Cu/Ni ratio and significantly positive correlation between the element pairs MgO-Ni, Cr-Ni and Co/FeO-Co. The dependence of Cu and SO3 contents and Cu/FeO, SO3/FeO ratios are to be interpreted as an indication of the common origin of Cu, Fe and S. In general, Cu, Zn, Pb and S content decrease with depth, whereas those of Fe3O4 increase. The variograms of the ore distributions are characterized by hole effect, trend and zonal anisotropy, which reflect alternation of ores with host rocks and changes in elemental contents. The Siirt Madenköy deposit is attributable to Cu and Zn ratios of the Cu class of ophiolitic massive sulfide deposits. Due to the very high Cu/Pb and Cu/Zn ratios, it can be described as an analogous deposit of the mid oceanic ridge, for example comparable to ores of Galapagos Ridge. The Siirt Madenköy deposit is considered to be a syngenetic volcanogenic-exhalative massive sulfide ore deposit based on the results of the study. It belongs to the “Cyprus deposit type”. Similar deposits are Küre and Ergani-Maden in Turkey, Ermioni in Greece and Outukumpu in Finland.

Geochemical Characteristics,Genesis of Concealed Cu-rich Ore Body in the Jinchuan Deposit,Northwestern China,and Its Prospecting

The Jinchuan deposit is hosted by the olivine-rich ultramafic rock body, which is the thirdlargest magmatic sulfide Ni-Cu deposit in the world currently being exploited. Seeking new relaying resources in the deep and the border of the deposit becomes more and more important. The ore body, ore and geochemistry characteristics of the concealed Cu-rich ore body are researched. Through spatial analysis and comparison with the neighboring II1 main ore body, the mineralization rule of the concealed Cu-rich ore body is summed up. It is also implied that Cu-rich magma may exist between Nirich magma and ore pulp during liquation differentiation in deep-stage chambers, which derives from deep-mantle Hi-MgO basalt magma. It is concluded that the type of ore body has features of both magmatic liquation and late reconstruction action. It has experienced three stages： deep liquation and pulsatory injection of the Cu- and PPGE-rich magma, concentration of tectonic activation, and the later magma hydrothermal superimposition. In addition, the Pb and S isotopes indicate the magma of I6 concealed Cu-rich ore body originates predominantly from mantle; however, it is interfused by minute crust material. Finally, it is inferred that the genesis of the Cu-Ni sulfide deposit is complex and diverse, and the prospect of seeking new deep ore bodies within similar deposits is promising, especially Cu-rich ore bodies.

The 982 Ma Re-Os age of copper-nickel sulfide ores in the Baotan area,Guangxi and its geological significance

Re-Os dating on copper-nickel sulfide ores from the Baotan area, Guangxi, yielded an ore-forming age of 982±21 Ma(2σ), which demonstrates that copper-nickel sulfide deposits and their related mafic-ultramafic rocks occurred in the same period of time with the ophiolites in northeastern Jiangxi. Both of them are the products of collision-convergence between the Cathaysian plate and Yangtze plate and the subsequent extensional environment. Calculation of the γOs of the 982 Ma copper-nickel sulfide ores and its correlation with Re/Os indicate that injection-type massive ores display lower γOs values(-15.6 to -8.2) and lower Re/Os ratios(0.32 to 0.43), while basal liquation-type ores have γOs= -27.9 to -7.3 and Re/Os=5.36 to 11.24. This suggests that these copper-nickel sulfide ores and their related mafic-ultramafic rocks were derived from a Re-depleted mantle source and that contamination with some crustal material occurred during their intrusion.

ACTIVATION MECHANISM OF AlCl_3 DURING THE LEACHING OF Cu-Ni ORE WITH FeCl_3

After Cu-Ni ore powder pre-soaked in AlCl3 solution.the leaching ratios of copper andnickel can increase obviously.By X-ray diffraction analyses,electron energy spectrum analysesand electrochemical experiments,it is affirmed that,the activation of aluminum ion includestwo aspects:one is the surface change of the ore by the absorption of hydrolysates,and the oth-er is the change of semiconductor characteristics of the metal sulfides by impurity aluminum ionentering the lattice,so that leaching reactions are accelerated.

Relations of Uranium Enrichment and Metal Sulfides within the Shuanglong Uranium Deposit,Southern Ordos Basin

Large quantities of metal sulfides are widely distributed in uranium ores from the Middle Jurassic Zhiluo Formation of the Shuanglong uranium deposit,southern Ordos Basin,providing a convenient condition to study the relationship between metal sulfides and uranium minerals.The morphology and composition of uranium minerals and metal sulfides are illustrated to study uranium mineralization and mechanisms of metallogenesis.Uranium minerals can be broadly categorized as pitchblende,coffinite and brannerite.Metal sulfides associated with uranium minerals are pyrite,sphalerite,chalcopyrite and galena.Some assemblages of various metal sulfides and uranium minerals indicate that they are coeval,but the order of formation is different.Based on mineralogical observations,paragenetic sequences for mineral assemblages are discussed.Alteration of Fe-Ti oxides forms Ti oxides,brannerite and pyrite.The formation of chalcopyrite was later than that of pyrite.Clausthalite(Pb Se)replaces sphalerite or shows isomorphism with galena.There are three genetic types of galena,of which typeⅠis related to tectonic thermal events and can interact with uranyl ions to form uranium oxides and Pb;.When sulfur activity is relatively high,Pb;can form new anhedral galena,that is,typeⅡ.TypeⅢof galena is related to the decay of uranium minerals.The genetic order of the main minerals was determined as follows:Fe-Ti oxides>Ti oxides/sphalerite/pyrite>clausthalite/galenaⅠ/chalcopyrite>galenaⅡ/uranium minerals>galenaⅢduring the diagenetic stage.Hydrogen sulfide(H;S)is a decisive factor in the interaction between metal sulfides and uranium.Metal ions can react with H;S,accompanied by precipitation and enrichment of uranium minerals.