Large Ore Deposits Research Articles

A billion-year shift in the formation of Earth’s largest ore deposits

Banded iron formations (BIFs) archive the relationship between Earth's lithosphere, hydrosphere, and atmosphere through time. However, constraints on the origin of Earth's largest ore deposits, hosted by BIFs, are limited by the absence of direct geochronology. Without this temporal context, genetic models cannot be correlated with tectono-thermal and atmospheric drivers responsible for BIF upgrading through time. Utilizing in situ iron oxide U-Pb geochronology, we provide a direct timeline of events tracing development of all the giant BIF-hosted hematite deposits of the Hamersley Province (Pilbara Craton, Western Australia). Direct dating demonstrates that the major iron ore deposits in the region formed during 1.4 to 1.1 Ga. This is one billion to hundreds of millions of years later than previous age constraints based upon 1) the presence of hematite ore clasts in conglomerate beds deposited before ~1.84 Ga, and 2) phosphate mineral dating, which placed the onset of iron mineralization in the Province at ~2.2 to 2.0 Ga during the great oxidation event. Dating of the hematite clasts verified the occurrence of a ~2.2 to 2.0 Ga event, reflecting widespread, but now largely eroded iron mineralization occurring when the Pilbara and Kaapvaal cratons were proximal. No existing phosphate mineral dates overlap with obtained hematite dates and therefore cannot be related to hematite crystallization and ore formation. New geochronology conclusively links all major preserved hematite deposits to a far younger (1.4 to 1.1 Ga) formation period, correlated with the amalgamation of Australia following breakup of the Columbia supercontinent.

Nickel recovery in tailling from the Chromite beneficiation process in Mau Lam, Thanh Hoa by the reduction roasting-magnetic separation process

In Thanh Hoa province, large chromite ore deposits were discovered. These types of ores also contain significant quantity of nickel metal, with total nickel reserves estimated to be over three million tones. According to the practices of mining and beneficiation of these chromite ores, nickel is discarded in the waste dumps as a non-valuable metal and has not been recovered ever. Through many years of mining and processing of chromite ores, large dumps are formed to such huge volumes that can be considered as a significantly secondary resource of valuable nickel metal. Nickel exists in the form of laterite ores so that it is difficult to be recovered. Currently, there is no commercial technology available for recovery of nickel or other valuable metals from this type of raw material sources. This article presents some research results on applying the reduction calcination – magnetic separation process for recovery of nickel. In particular, some important reduction operating variables such as temperature, calcination time, fuel coal ratio, and Na2SO4 additive were investigated. From the tailing samples of the Mau Lam – Thanh Hoa chromite beneficiation process, important optimal reducing conditions have been determined including 1,1000C of reduction temperature, 8% of anthracite coal, 8% of Na2SO4 additive, and the reduction time of 90 minutes. The reduced product was finely grounded and separated at a magnetic field of 0.3T using the wet magnetic separator. At optimal operating variables, the nickel content of the final nickel concentrate was 4.02% Ni and the overall nickel recovery was 91.2%. The positive results necessarily lead to a need to continue researching the possibility of practical application to recover nickel and thus contribute to the rational utilization of mineral resources of the country.

Predictive maintenance on ball mill liner using 3D scanner and its analysis in the mining industry of Papua Indonesia

In the mining industry, the primary production process entails transforming large ore deposits into valuable concentrates. To get minerals from large ores, a grinding machine is needed to reduce the size of the ore, and then the minerals can be extracted. The ball mill is an important part of the grinder in the mining industry. Maintenance is required for the machine to continue to work effectively and optimally. One method of preventing ball mill failures and minimizing company losses on a large scale is to predict the life of ball mill liners or predictive maintenance. Using a 3D laser scan, it is possible to determine the ball mill liner's wear and tear. On the basis of liner wear analysis, this information can then be used to generate a liner replacement schedule or estimate the remaining life of the ball mill liner or relining and lifetime forecast. This study aims to compare the 3D laser scan method and ultrasonic testing method in terms of liner wear analysis and forecasting. This study also demonstrates that the laser scanning method will be more effective and efficient than ultrasonic testing.

The Delineation of Copper Geochemical Blocks and the Identification of Ore-Related Anomalies Using Singularity Analysis of Stream Sediment Geochemical Data in the Middle and Lower Reaches of the Yangtze River and Its Adjacent Areas, China

The middle and lower reaches of the Yangtze River and its adjacent areas contain abundant mineral resources, especially porphyry–skarn–stratabound Cu–Au–Mo–Fe deposits, and still have great potential for mineral prospecting. In this paper, geochemical blocks and local singularity mapping methods were used to delineate the spatial distribution pattern of Cu and identify the geochemical anomalies related to Cu deposits. Six copper geochemical blocks, each with an area of more than 1000 km2, were all spatially consistent with the locations of the five Cu ore districts (Edongnan, Jiurui, Anqing-Guichi, Tongling, and Ningzhen) and one ore field (Dexing) in the study area. Thus, geochemical blocks delineated with low-density geochemical data can effectively track the locations of ore districts or large ore deposits. Most of the known Cu deposits in the study area were located in anomalous areas with singularity indices less than 1.741 in the Cu singularity map. The singularity analysis could reduce the anomalous areas and identify the geochemical anomalies related to Cu deposits effectively. Geochemical blocks combining a local singularity mapping method is an effective tool for identifying prospecting targets.

Low-temperature thermochronology of the Longmala - Mengya’a Pb-Zn deposits (southern Tibet): Implications for ore exhumation and preservation

The large Gangdese metallogenic belt, located in the southern part of the Tibetan Plateau, hosts a variety of magmatic-hydrothermal ore deposits. Previous works in the area primarily concerned the ore genesis, while the exhumation history of these ore deposit has received less attention. In this contribution we explore the multi-stage thermo-tectonic evolution of the Longmala and Mengya’a Pb-Zn deposits, two large magmatic-hydrothermal ore deposits in the central Lhasa sub-terrane. In more detail, the thermal history of granitoids and deformed Paleozoic sediments inside and on the periphery of the ore districts have been constrained by low-temperature thermochronological methods, including the zircon (U-Th)/He and apatite fission track thermochronology. Additionally, zircon U-Pb geochronology was conducted on granitic host rocks to determine their emplacement ages. Our thermochronological data and inverse thermal history modeling results reflect two phases of accelerated basement cooling during the Cenozoic (i.e., ∼46–41 Ma and ∼20–5 Ma), interpreted as exhumation phases. The ore body was exhumed to the near surface during the Miocene, which provides essential information for ore exploration in the region. We also explore the degrees of basement rock exhumation along the Gangdese metallogenic belt and their spatio-temporal relations to major ore deposit distributions. It is suggested that complex interactions between tectonic-structural activities and surface erosion occurred during the late Oligocene-Miocene (∼25–5 Ma), which resulting in widespread exhumation along the Gangdese batholith. During this period, the ore-bearing rocks were gradually (with medium to high cooling rates) exhumed to the near-surface from ∼3–4 km crustal depth, making these ore deposits feasible for commercial mining.

The origin of mafic–ultramafic rocks and felsic plutons along the Clarke River suture zone: implications for porphyry exploration in the northern Tasmanides

The Clarke River Fault in northeast Queensland records an early Paleozoic history of subduction, accretion and continental suturing. Samples of mafic–ultramafic rocks collected proximal to the Clarke River Fault record oceanic geochemical affinities and comprise alteration assemblages consistent with an ophiolitic origin. The ca 456 Ma Falls Creek Tonalite records a continental-arc geochemical signature and was formed in response to long-lived subduction beneath the Thomson Orogen. Ordovician subduction beneath the Thomson Orogen is broadly coeval with arc magmatism documented in the Lachlan Orogen, which has been associated with the formation of several large porphyry ore deposits. The Falls Creek Tonalite yields adakite-like geochemical signatures that reflect a fertile melt source conducive to the formation of porphyry ore deposits. The outcropping plutons record ductile deformation consistent with mid-crustal depths, and they were emplaced during late syntectonic activity. This implies that the Falls Creek Tonalite was emplaced at too great a depth to have formed porphyry ore deposits. The northern Charters Towers Province shares many geological similarities to the Greenvale Province, where the erosional level may be shallower, and the potential for porphyry deposit formation and preservation may be greater.

U-Pb and Re-Os geochronology and geochemistry of the Ulgen hidden porphyry Mo deposit in the Derbugan metallogenic belt (NE China): Insights into petrogenesis and tectonic setting

The Ulgen porphyry Mo deposit, recently discovered in the northeastern segment of the Derbugan metallogenic belt, NE China, is a large and hidden ore deposit. Investigation of this deposit provides insights into the geodynamic background and metallogenic mechanism of Mesozoic porphyry Mo deposits that are exposed elsewhere in NE China. The host rocks consist of muscovite monzonitic granite (MMG) and biotite granitic porphyry (BGP), which are intruded into Lower and/or Middle Jurassic intermediate-felsic volcanic-sedimentary rocks and pre-ore monzogranitic porphyry (MP). Zircon laser ablation−inductively coupled plasma−mass spectrometric (LA-ICP-MS) U-Pb age dating indicates that the MMG and BGP were emplaced at 144.9 Ma and 144.7 Ma, ca. 14 m.y. younger than the intrusion age of MP (159.3 Ma). Molybdenite Re-Os isotopic dating indicates that Mo mineralization occurred at 144.9 Ma, almost simultaneously with the 145 Ma magmatic activity. Geochemically, all of the Ulgen granitoids are enriched in large ion lithophile elements (e.g., Rb, Th, U, and K) and light rare earth elements, and are depleted in high field strength elements (e.g., Nb, Ta, and Ti). The pre-ore MPs belong to I-type granites with moderately negative Eu anomalies (Eu/Eu* = 0.62−0.65), whereas the syn-ore MMGs exhibit S-type affinity with pronounced negative Eu anomalies (Eu/Eu* = 0.29−0.39). The ore-forming BGPs display adakite-like geochemical features in terms of high-Sr, low-Y, and low-Yb contents, and slightly negative Eu anomalies (Eu/Eu* = 0.72−0.74). All intrusive rocks have relatively low initial (87Sr/86Sr)i ratios (0.7044−0.7055) and positive εNd(t) values (+1.15 to +2.65), positive εHf(t) values (+4.0 to +9.4), young two-stage Nd and Hf model ages (tDM2(Nd) = 841−731 Ma, tDM2(Hf) = 943−604 Ma), and moderate (206Pb/204Pb)i (18.300−18.402), (207Pb/204Pb)i (15.557−15.564), and (208Pb/204Pb)i (38.180−38.307) ratios. Therefore, it is most likely that these intrusive rocks originated from a mixture of two sources of magma derived from the mantle and juvenile lower crust, in which there were variable degrees of the fractional crystallization of ilmenite, apatite, and plagioclase. Rather than the partial melting of oceanic slabs, the fractional crystallization of hornblende and accessory minerals (e.g., ilmenite and apatite) induces the adakitic geochemical signature of BGPs. Compared with the BGPs, the MPs had a relatively deeper magma source region, whereas the MMGs had a relatively shallower magma source region. The BGPs and the Mo-bearing fluids of the Ulgen deposit were most probably derived simultaneously from magma that was generated at an extensional setting following the closure of the Mongol-Okhotsk Ocean during the latest Jurassic. Enrichment of Mo by late-stage fractional crystallization most likely played an important role in concentrating Mo during the formation of the Ulgen hidden Mo deposit.

Stages of formation of gold mineralization and large gold ore deposits in Kyrgyzstan

There are about 100 gold deposits in Kyrgyzstan, including large and super large ones. According to the time of their formation, several stages are distinguished, the main of which are Paleozoic. A brief overview of these stages, the geodynamic setting, and examples of the gold deposits with description of several large objects are provided.

Criterias for the formation of large ore deposits in Uzbekistan

The article presents new data on the study of ore deposits in Uzbekistan in recent years in the laboratory “Structure of the lithosphere”. Based on the complex of regional geophysical data, a three-dimensional geological and geophysical analysis of the relief, basement and Mohorovicic surfaces was carried out in software ArcGIS 10.1. A three-dimensional spatial dynamic model of the Central Kyzylkum Ore-Magmatic concenter was developed on the basis of a complex methodology, including an integrated analysis of the placement of deep structures, the relationships of objects and phenomena using modern methods of spatial analysis and geomodelling. New potentially promising areas for gold mineralization of the Muruntau type have been elucidated within the Central Kyzylkum Ore-Magmatic Concentre (CKOMC).

Effects of fluorine on dynamic reaction interfaces in hydrothermal feldspar alteration

Fluid-induced mineral reactions exert an important control on the physico-chemical properties of the crust and hydrothermal plumbing systems. Feldspars are the most abundant minerals in the Earth's crust and a major host of the main cations found in geofluids (Na, K, Ca). In previous work, we discovered that K-feldspar-albite-sanidine zonation textures developed dynamically when sanidine ((K,Na)AlSi3O8) was reacted with NaCl or NaF in H216O- and H218O-enriched solutions at 600 °C and 2 kbar in a closed system. Based on a detailed SEM and TEM characterisation, the present study aims to constrain the reaction mechanism and the effect of fluorine on reaction kinetics and overall reaction textures in alkali feldspar replacement reaction interfaces. Replacement of high-sanidine (Sa) by albite (Ab) and/or K-feldspar (Kfs) proceeded via an interface-coupled dissolution-reprecipitation reaction, with the products preserving the crystallographic orientation of the parent Sa in both NaCl- and NaF-bearing solutions. Mineral interfaces with different micro-textures were observed depending on the nature of the interface (Ab-Sa, Kfs-Ab, Kfs-Sa) and whether the reaction occurred in NaCl-only or NaF-bearing solutions. Abundant amorphous domains (25–50 nm thick) occur both within Ab and at Ab-Sa and Kfs-Ab interfaces formed in NaF-bearing solutions. At the Kfs-Sa interface formed in NaCl-only solutions, a complex interfacial zone characterised by a high density of defects may represent sealed fluid pathways. These results reveal that the nature of the reaction interface depends on both mineral properties, in particular microtextures (i.e. polysynthetic twinning in Ab); and solution chemistry; this directly affects porosity development, the chemical environment at the interface, and chemical exchanges between the reaction front and the bulk solution. Fluorine aids the formation of amorphous layers that modify nucleation mechanisms; and facilitates element transport by forming Na-Si-Al-fluoride complexes, resulting in accelerated reaction rates relative to chloride-solutions. These nm- to μm-level processes contribute to efficient coupling between fluid-flow and mass transfer, explaining why sodic and potassic alteration associated with metal and fluid transport in some of the world's largest ore deposits can develop extensively, and subsequently access metals locked within silicate mineral assemblages.

The advisability of an underground processing facility at the Voronets iron ore deposit

Relevance. When mining large iron ore deposits of the Kursk Magnetic Anomaly, one of the main problems is environmental safety, in particular, the maximum preservation of fertile soil. The underground mining method reduces the technogenic load on the natural environment and allows most of the mining waste to be placed in the mined-out space. However, main source of negative environmental impact is the processing production, which occupies large areas and is characterized by intense harmful emissions. Processing facilities placed underground significantly reduce this impact. Research objective is to assess the advisability of building an underground processing facility at the Voronets iron ore deposit. Methods of research. The work uses a comprehensive research method, including rational ore processing scheme justification, underground processing facility design, and a technical and economic comparison. Results. A scheme of ore processing with the production of a high-quality concentrate is presented, and a chain of mechanisms and apparatus for all stages of ore processing is selected, including its crushing, grinding, magnetic separation and dehydration of the resulting products. Based on the parameters of the selected equipment, its underground layout is shown, the volume the processing facility chambers is calculated. It is shown that the entire volume of tailings is located in the chamber goafs of the underground mine and are not lifted to the surface. Conclusions. An approximate assessment of the effectiveness of the processing facility underground location has been made. It has been shown that the cost of building that facility is comparable to the cost of building a similar processing facility on surface. Placing the processing in underground makes it possible to significantly reduce the area of land allotment of the enterprise, to lift only concentrate on the surface, and to eliminate the negative environmental impact of processing production.

Comment on: Baddeleyite U-Pb age and Hf isotopes, and constraints on genesis of the Panzhihua carbonatite in SW China by Wang et al. (2023)

Wang et al. (2023) propose that rocks adjacent to the Panzhihua intrusion are not marbles and skarns, but carbonatites. If true, this interpretation could have important implications for models explaining the origin of the large Fe-Ti ore deposits in the intrusion. We reject this interpretation for two principal reasons: 1) the objects described as “mantle xenoliths”, and considered, incorrectly, as diagnostic of carbonatite, are in fact deformed and altered mafic/ultramafic intrusions; 2) the concentrations of incompatible trace elements in the marbles are low and typical of metasedimentary rocks, not carbonatite.

How greisenization could trigger the formation of large vein-and-greisen Sn-W deposits: A numerical investigation applied to the Panasqueira deposit

The formation of large tin-tungsten (Sn-W) deposits around granitic intrusions requires the circulation of large volumes of fluids within permeable structures. Half of the world’s tungsten production originates from highly mineralized veins above granitic intrusions and from the altered part of the granite (the greisen), whose formation results from intense fluid-rock interactions. During greisenization processes, mineral reactions involve a decrease in the rock volume and thus an increase in porosity and permeability. To understand the complex fluid-rock interactions leading to the formation of large Sn-W ore deposits, we conducted numerical modeling accounting for magmatic fluid production and realistic permeability changes due to granite alteration and overpressure in the hosting rocks. The water/rock ratio is computed to constrain the rate of greisenization and therefore the porosity and permeability evolution laws. Four model results are presented: with and without fluid production exsolved from the granitic magma, and with and without dynamic reaction-enhanced permeability. The formation of greisen is reproduced, and greisen thickness reaches 200 m for the more sophisticated model. The interplay between greisenization and fluid production creates zones of overpressure above the granite that could localize the permeable structures such as the veins swarm observed at Panasqueira. Dynamic permeability promotes high fluid velocity and intense fluid-rock exchanges that could result in the formation of large ore deposits by enhancing mass transfer within and above granitic intrusions.

Was the Panzhihua Large Fe‐Ti Oxide Deposit (SW China) Formed by Silicate Immiscibility?

AbstractThe Panzhihua mafic intrusion, which hosts a world‐class Fe‐Ti‐V ore deposit, is in the western Emeishan large igneous province, SW China. The formation age (∼260 Ma), Sr, and Nd isotopes indicate that the Panzhihua intrusion is part of the Emeishan large igneous province and has little crustal contamination. However, the ore genesis of the Panzhihua Fe‐Ti‐V ore deposit has been extensively debated. Two different models have been provided to explain the formation of the Panzhihua oxide deposit, namely silicate immiscibility and normal fractional crystallization. Silicate immiscibility occurrings around 1,000 °C at the late stage of basaltic magma evolution argues against the silicate immiscibility model. Apatite‐hosted melt inclusion research indicates that silicate immiscibility occurred at the late stage of Panzhihua magma evolution. However, this may have little potential to form large ore deposits like Panzhihua. However, the continuous compositional variations of the Panzhihua intrusion and the calculations by thermodynamic modelling software support the Panzhihua deposit being formed by normal fractional crystallization. The reciprocal trace element patterns of the Panzhihua intrusion and the nearby felsic rocks also coincide with the fractional crystallization model. Normal fractional crystallization of high‐Ti basaltic magma played a key role in the formation of the Panzhihua Fe‐Ti‐V ore deposit.

Petrogenesis and Tectonic Implications of the Ore-Associated Intrusions in Bayanbaolege Ag Polymetallic Deposit, Inner Mongolia, NE China

The large Bayanbaolege Ag polymetallic ore deposit is located in the Tuquan-Linxi Fe (Sn)-Cu-Pb-Zn-Ag-Nb (Ta) polymetallic metallogenic belt, which is an important part of the Great Xing’an Range metallogenic province, northeast China. The sulfide–quartz vein-type orebodies in the deposit are mainly hosted in the Cretaceous granodiorite porphyry and Late Permian Linxi formation. The U-Pb dating of the zircon from the post-ore diorite porphyrite yields an age of 124.8 ± 1.1 Ma, which constrains the mineralization time at the Early Cretaceous. The Sr-Nd isotope values (87Sr/86Sr)i = 0.708576~0.710536; εNd (t) = −0.51~+0.69; the Hf isotope values 176Hf/177Hf = 0.2827278~0.2830095, the εHf (t) = +3.1~+11.2, TDM2 = 615~1341 Ma of the metallogenic granodiorite porphyry. The Hf isotope values 176Hf/177Hf = 0.2828596~0.2829451, and the εHf (t) = +5.7~+8.8 of the diorite porphyrite, TDM2 = 827~1108 Ma, indicating that the ore-forming materials were the possible involvement of heterogeneous juvenile sources including moderately depleted mantle and newly underplated lower crust. The major and trace elements (including REEs) implied that these intrusions are the I-type granite and linked intimately to the westward subduction of the Paleo-Pacific Ocean plate. From these whole-rock major and trace elements and zircon U-Pb ages, as well as Sr-Nd-Hf isotope data, we conclude that the ore-associated I-type granites in the Bayanbaolege deposit formed in an extensional tectonic setting of the Early Cretaceous, and are compactly related to the retreat of the Paleo-Pacific Ocean subducted plate linked intimately to the westward subduction of the Paleo-Pacific Ocean plate rather than the closure of the Mongol–Okhotsk Ocean. Furthermore, by integrating geological background work and previous research work, implying the mineralization age of the Bayanbaolege deposit should have been formed in the 125–130 Ma.

The C-O and Zn isotopic compositions of the Laochang Ag-Pb-Zn ore bodies in the Changning-Menglian suture zone, and its geological implications

老厂矿床是昌宁-孟连缝合带内唯一大型矿床，本文报道了老厂矿床Ag-Pb-Zn矿体中Ⅰ号矿体群下部块状矿体和上部网脉状矿体的方解石C-O同位素组成，以及Ⅰ、Ⅱ、Ⅳ三个矿体群内闪锌矿的Zn同位素组成。Ⅰ号矿体群下部块状矿体和上部网脉状矿体方解石δ¹³C_PDB的范围分别为-6.17‰~2.71‰和-2.18‰~3.87‰，δ¹⁸O_PDB的范围分别为-19.57‰~-17.23‰和-22.10‰~-16.21‰；计算获得对应成矿流体的δ¹³C_CO₂为-6.16‰~1.53‰和-2.39‰~6.43‰，δ¹⁸O_H₂O分别为1.62‰~7.62‰和4.36‰~16.92‰，通过与岩浆CO₂（δ¹³C=-2‰~-8‰）和围岩灰岩（δ¹³C=-1.6‰~4.0‰）的δ¹³C值相比较，指示块状矿体成矿流体中的碳主要来自岩浆，网脉状矿体成矿流体中的碳则主要来自围岩，说明老厂矿床深部水岩反应较强。10件闪锌矿的δ⁶⁶Zn和δ⁶⁸Zn值分别为0.17‰~0.25‰和0.33‰~0.49‰，与VMS型矿床以及现代海底热液流体的Zn同位素组成重合，不同标高均一的Zn同位素组成寓示老厂矿床Ag-Pb-Zn矿体中闪锌矿形成过程中几乎未受到温度、分馏和微生物作用的影响，可以直接反映金属源区的Zn同位素组成，揭示老厂矿床Ag-Pb-Zn矿体为VMS成因，成矿金属主要来自于下石炭统海底火山作用。;The Laochang deposit is the only large ore deposit in the Changning-Menglian suture zone. In this study, the C-O isotopic compositions of calcites from the lower massive ore bodies and the upper stockwork ore bodies of No.Ⅰ ore bodies in Laochang Ag-Pb-Zn ore bodies and the Zn isotopic compositions of sphalerites from No.Ⅰ, Ⅱ, Ⅳ ore bodies are investigated. The range of δ¹³C_PDB of calcites from the lower massive ore bodies and the upper stockwork ore bodies of No.Ⅰ ore bodies is -6.17‰~2.71‰ and -2.18‰~3.87‰, respectively, and the range of δ¹⁸O_PDB is -19.57‰~-17.23‰ and -22.10‰~-16.21‰, respectively. The δ¹³C_CO₂ of the corresponding ore-forming fluids are calculated to be -6.16‰~1.53‰ and -2.39‰~6.43‰, respectively, and the δ¹⁸O_H₂O are calculated to be 1.62‰~7.62‰ and 4.36‰~16.92‰, respectively. By comparison with the δ¹³C of magmatic CO₂ (δ¹³C=-2‰~-8‰) and wall-rock limestone (δ¹³C=-1.6‰~4.0‰), it indicates that the carbon in the ore-forming fluids of massive ore bodies mainly comes from magma, while the carbon in the ore-forming fluids of stockwork ore bodies mainly comes from limestone, which further shows that there is strong water-rock reaction in the deep part of Laochang deposit. The δ⁶⁶Zn and δ⁶⁸Zn values of ten sphalerites are 0.17‰~0.25‰ and 0.33‰~0.49‰, respectively, which coincides with the Zn isotopic compositions of VMS deposits and modern submarine hydrothermal fluids. The homogeneous Zn isotopic compositions at different elevations implies that the Zn isotopic compositions of sphalerite from Ag-Pb-Zn orebodies in Laochang deposit are almost unaffected by temperature, fractionation and microbial action. And it can directly reflect the Zn isotopic compositions of the metal source, revealing the genesis type of the Laochang Ag-Pb-Zn ore body as VMS-type, and the metallogenic metal mainly comes from the Lower Carboniferous submarine volcanism.

ОЦЕНКА ПЕРСПЕКТИВ РАЗВИТИЯ ЧЕРНОЙ МЕТАЛЛУРГИИ ИРКУТСКОЙ ОБЛАСТИ НА ОСНОВЕ РЕСУРСОВ ВОСТОЧНЫХ САЯН И ИННОВАЦИОННЫХ ТЕХНОЛОГИЙ

The creation of the East Siberian metallurgical base is an indispensable condition for the implementation of reindustrialization processes, including industrial and civil construction, engineering for the mining industry, the chemical industry, etc. The existing opportunities are the formation of a promising heavy-duty iron ore base for the Urals and Western Siberia based on the Bakcharskoye deposit causes the creation in Eastern Siberia of mining and metallurgical enterprises, mainly of local importance. Perspective restrictions on the use of natural gas in iron production, environmental and investment restrictions for blast-furnace production determine the use of liquid-phase iron reduction technologies using thermal coals. The concentration of groups of iron ore deposits in the Irkutsk region makes it possible to create mining and metallurgical plants near the cities of Ust-Ilimsk, Taishet, Tulun. The involvement of significant resources of titanomagnetites is possible when solving the problem of developing more efficient technologies for producing metallic titanium. The object of the research is resources of iron-ore and coal deposits in the Irkutsk region in the process of assessing the possibility and efficiency of their use in the prospective mining and metallurgical industries. The subject of the research is technological and resource prerequisites for location of large objects of mining-metallurgical complexes for direct production of iron in Irkutsk region. The aim of the research is to identify promising deposits and occurrences of iron ore and coal raw materials, taking into account the possibilities of application of existing technical and technological solutions for transportation, enrichment and metallurgical processing for complex processing. The objectives of the research are: to assess the potential of large iron ore deposits of Western Siberia using new technologies to meet the needs of metallurgical enterprises in the Urals and Kemerovo region; to determine a new concept of promising metallurgical base of Eastern Siberia; to determine a promising base for the placement of mining and metallurgical plants in the Irkutsk region. Methodology and research methods. The research methodology is based on a systematic representation of the mining-metallurgical complex created on the territorial combination of raw materials and fuel in accordance with the theory of energy-production cycles, in which promising (innovative) technologies are implemented. When determining the degree of priority development of titanium-magnetite deposits, the possibility of using the resulting titanium-containing products is taken into account. It is also shown that the main metallurgical base of the Irkutsk region can be created in the area of the city of Tulun on the basis of the use of iron ore resources of the Eastern Sayan. The fuel base is provided by the resources of the Irkutsk coal basin. To reduce investment and current costs associated with the transportation of coal and ore or concentrates, it is proposed to use slurry pipelines

Porphyry Cu mineralization processes of Xinqiao deposit, Tongling ore district: Constraints from the geochronology and geochemistry of zircon, apatite, and rutile

Xinqiao is a large ore deposit that is well known for its stratabound massive sulfide and skarn ores. Recently, deep drilling has shown that Xinqiao also has typical porphyry mineralization and alteration features. The Cu grade is 0.3–0.6% and occurs as quartz-pyrite-chalcopyrite in potassic and phyllic alteration zones. The characteristics and genetic processes of the porphyry mineralization at Xinqiao have not previously been reported.Three intrusion types are recognized; pyroxene diorite, quartz diorite and quartz monzodiorite porphyry; Cu mineralization is associated with the quartz diorite and quartz monzodiorite porphyry. Zircon U-Pb dating shows that the three intrusions were all emplaced at about 140 Ma. Zircons from the quartz diorite and quartz monzodiorite porphyry show higher Ce4+/Ce3+ and Eu/Eu* (>0.5), 10,000(Eu/Eu*)/Y (>5), and (Ce/Nd)/Y (>0.01), than the pyroxene diorite, and apatites from the mineralized intrusions have slightly higher SO3 (average 0.40) contents than ones from the pyroxene diorite (average 0.33). These results indicate that the fertile magmas were more oxidized, hydrous, and S-rich than the barren pyroxene diorite, consistent with their association with porphyry Cu mineralization. U-Pb dating of hydrothermal rutile from the porphyry mineralization and garnet from the skarn ore both yield ages of about 140 Ma, suggesting that the porphyry and skarn mineralization belong to same system. The geochemistry of hydrothermal rutile and apatite in the porphyry mineralization zone also indicates that Xinqiao ores were produced from a S-rich magmatic-hydrothermal fluid system. Our results highlight huge porphyry Cu mineralization potential beneath stratabound and skarn deposits in the Middle-Lower Yangtze River metallogenic belt.

Crustal electrical structure and deep metallogenic mechanism in the Xiongcun and Niangre districts of the Tibetan Plateau

The Gangdese metallogenic belt in the Tibetan Plateau hosts many large ore deposits, of which the Xiongcun and Niangre ore concentration districts are two typical examples. Due to the insufficient geophysical evidence about the deep metallogenic dynamics across these two districts, the electrical structure was obtained by modeling magnetotelluric data to study the relationship of the crustal structure and metallogenic dynamics. Although the mineralization occurred in the past, the continuous magmatic activities after the mineralization could reactivate the previous migration channels to remain some traces, which can be revealed by some geophysical methods. The resistors at depths of less than 20 km may represent the multiple overlapping volcanic rocks related to a serious of magmatic events in the Lhasa-Gangdese terrane. Some conductors that revealed at different depths may be related to the partial melt, aqueous fluids and/or formation of metallic minerals, and were also further indicated as the possible magma chambers. Connecting the conductors at different depths may be further indicated as some ancient migration channels which were probably related to the shear zones and faults. As the ore deposits in both districts belonged to the magmatic-hydrothermal type, the upwelling magma played a crucial role in the metallogenic dynamics. These possible magma chambers at different depths and channels may be also related to the evolution and emplacement of the deep-seated magma, and contributed to the mineralization of both districts. This study can also offer a reference of significance for the deposits in the eastern Gangdese metallogenic belt.

Geochronology, geochemistry and genesis of the Early-Middle Triassic Dongping-Zurong large manganese ore deposit, southwestern Guangxi

广西东平-足荣大型锰矿床位于桂西南锰矿带上，是广西重要的锰矿富集区。其含矿地层为三叠系北泗组，是一套以硅-泥-灰为主浅海台盆相含锰碳酸盐岩沉积，含锰矿物主要为钙菱锰矿、锰方解石和锰白云石。本文对矿区锰矿层顶部的沉凝灰岩及含锰岩系开展了详细的岩石学、岩石地球化学和锆石U-Pb年代学研究，进而对锰矿成矿时代、成因、沉积环境、沉凝灰岩源区和大地构造背景进行了探讨。锆石SHRIMP U-Pb定年结果显示，3件沉凝灰岩样品的锆石呈自形-半自形板柱状，发育良好的岩浆锆石振荡环带结构。²⁰⁶Pb/²³⁸U年龄加权平均值分别为250.8±2.1Ma（MSWD=0.98）、250.6±2.2Ma（MSWD=0.49）和243.6±2.3Ma（MSWD=0.44）。进一步限定了"东平"式锰矿的成矿时代为早-中三叠世（不晚于241~246Ma的范围内）。沉凝灰岩的构造环境判别图解及微量、稀土元素特征显示其岩浆可能形成于与俯冲消减作用相关的碰撞-弧相关或活动大陆边缘相关背景，推测东平-足荣锰矿的形成可能受到广西凭祥-东兴火山作用的影响。含锰岩系的U、V和Mo元素含量及U/Th、V/Cr、V/（V+Ni）、Ni/Co比值显示东平-足荣锰矿形成于氧化-次氧化的沉积环境。logU-logTh、Fe/Ti-Al/（Al+Fe+Mn）图解及微量元素Ba含量、Ba/Sr值均指示成矿作用受到热水作用的影响。综合矿床地质研究，东平-足荣锰矿形成于弧后盆地拉张构造背景中，锰成矿受同期火山及海底热液作用影响，水体沉积环境为氧化-次氧化条件。