Search

The Nanhua Basin of South China recorded complete Cryogenian stratigraphic sequence from the Sturtian Glaciation (~717-660 Ma) to the Marinoan Glaciation (~?654-635 Ma). The interglacial Datangpo Fm in the Nanhua Basin is divided into two members, and the first member consists of the Mn-carbonate unit and the overlying black shale unit, containing a series of large and superlarge manganese deposits. The metallogenic process of manganese deposits is not clear, and the Mn-carbonates formed through the precursor of Mn-oxide/oxyhydroxide reduction or directly precipitated from an anoxic water column. Moreover, the redox conditions in the deep Nanhua Basin during the precipitation of manganese deposits are also controversial. In this study, the high-resolution nitrogen contents (TN), isotope compositions, carbon isotope compositions of organic and inorganic matter from the first member of the Datangpo Fm are analyzed. The δ15N values of the Mn-carbonate unit (+1.53‰ to +5.26‰, mean +3.36‰) are higher than those of the overlying black shale unit (-3.74‰ to +3.54‰, mean +0.89‰). The Mn contents show a negative relationship with TN but a positive relationship with δ15N in the Mn-carbonate unit, implying that the formation of Mn-carbonates is related to redox variations. The relatively higher δ15N values in the Mn-carbonate unit indicated oxic conditions, and NH4+ can be released and partially oxidized during the mineralization of organic matter, resulting in the residual 15N-enriched NH4+ being transferred into clay minerals. Meanwhile, the lower δ15N values in the black shale unit indicated anoxic conditions, which recorded primary N isotope signals. The Mn-carbonate unit is characterized by negative δ13Ccarb values (-11.17‰ to -5.22‰, mean -8.30‰), which show a positive relationship with δ13Corg, but a negative relationship with Mn contents, implying that the negative δ13Ccarb excursions were related to the organic matter degradation during Mn-carbonate formation. The findings of this study indicated that the metallogenesis of manganese deposits in the Cryogenian Nanhua Basin was constrained mainly by the oxic interval in the deep basin. The nitrogen and carbon cycling process can provide new insights into geochemical cycling after the Sturtian Glaciation. [ABSTRACT FROM AUTHOR]

The Iberian Pyrite Belt (IPB) represents one of the largest districts of volcanogenic massive sulfide (VMS) deposits in the world, and is a critical source of base metals (Cu, Pb, and Zn) for Europe. Confirmed resources exceed 1700 Mt of massive sulfides with grades of around 1.2% Cu, 1% Pb, and 3% Zn as well as more than 300 Mt of stockwork-type copper mineralization. Significant resources of Sn, precious metals (Au and Ag), and critical metals (Co, Bi, Sb, In, and Se) have also been evaluated. The genesis of these deposits is related to a complex geological evolution during the late Devonian and Mississippian periods. The geological record of such evolution is represented by three main lithological units: Phyllite–Quartzite Group, the volcano–sedimentary Complex (VSC), and the so-called Culm Group. The sulfide deposits are located in the VSC, associated with felsic volcanic rocks or sedimentary rocks such as black shales. The massive sulfide deposits occur as tabular bodies and replacement masses associated with both volcanic and sedimentary rocks. Their mineralogical composition is relatively simple, dominated by pyrite, chalcopyrite, sphalerite, and galena. Their origin is related to three evolutionary stages at increasing temperatures, and a subsequent stage associated with the Variscan deformation. The present paper summarizes the latest developments in the IPB and revises research areas requiring further investigation. [ABSTRACT FROM AUTHOR]

The continental Asia is mainly composed of three major tectonic regimes, the Tethys, Paleo Asian Ocean, and West Pacific. It underwent multi‐stage plate convergences, ocean‐continent transformations, and subductions, collisions and/or collages, and post collisional (orogenic) extensions in Phanerozoic. Tectonic evolution of the Asia brings up a unique fault system and tectonic geomorphological features in the mainland China. Also, it provides a geodynamic background for the formation and evolution of metallogeneses and mineral systems, resulting in nonuniform distribution of tectono‐metallogenic systems and metallogenic belts. The spatiotemporal distribution of mineral deposits in China and adjacent areas exhibits periodic variation under controlling of the full life Wilson cycle and tectonic evolution, forming the plate convergence‐related mineral system in East Asia. Porphyry Cu deposits are mainly related to compressional systems in Paleozoic and early Mesozoic, and more closely related to post‐collision extensional settings in late Mesozoic and Cenozoic. Orogenic Au deposits mainly formed in post‐orogeny extensional setting. Alkaline rock related rare earth element deposits formed mainly at margins of the North China and Yangtze cratons. Granite‐pegmatite Li and other rare metal deposits formed mainly in early Mesozoic, related to Indosinian post‐orogeny extension. Tectono‐metallogenic systems provide important basis for the prospecting of mineral resources. [ABSTRACT FROM AUTHOR]

With the advancement of the global economy, the significance of cutting-edge technology and the pre- servation and development of future energy can be decisive in ensuring national energy security, homeland security, and economic development. Dispersed elements play an indispensable role in high-tech industries, but their unique characteristics contribute to their scarcity in the earth's crust and limited reserves. The research on the geochemical behavior of dispersed elements is relatively weak, and there is considerable controversy regarding their metallogenic mechanisms. With the progress of research, it has been found that the anomalous enrichment of dispersed elements shows a strong correlation with granite and pegmatite in both mineralization time and spatial distribution. Nevertheless, different dispersed elements exhibit significantly different geochemical behaviors during the enrichment process. During magmatic evolution, indium is influenced by the content of dark minerals and their iron and magnesium minerals and shows a strong correlation with tin. In the later stages of precipitation, indium enrichment is closely related to sphalerite and its iron and cadmium content. When present in granitic pegmatite, gallium shows a strong correlation with niobium, tantalum, lithium, and rubidium, mainly enriching in muscovite and microcline in pegmatite. In the later stages of magmatic evolution, germanium tends to enrich in highly volatile components but primarily associates with organic mat- ter to form germanium-containing organic compounds or complexes or dynamically recrystallizes in sphalerite to enrich. Tellurium mainly coexists with bismuth. Recently, large quantities of tellurium bismuth compounds have been found in pegmatite and tungsten deposits closely related to granite. The outlook of the research on dispersed element deposits is made, including the relationship between dispersed metals and primary minerals, detailed characterization of the migration and enrichment processes of dispersed metals, and detection technologies for enriched dispersed element deposits. These studies will provide new data and theoretical guidance for the further development and utilization of dispersed metals. [ABSTRACT FROM AUTHOR]

Copyright of Acta Petrologica et Mineralogica / Yanshi Kuangwuxue Zazhi is the property of Acta Petrologica et Mineralogica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, a compilation of the main Neoarchaean ore deposits, and their tectonic settings, in the northern São Francisco Craton, NE Brazil is presented. The Serrinha and Gavião blocks split up in the Neoarchaean, giving rise to juvenile rocks and metavolcanic-sedimentary sequences within the so-called Mundo Novo-Caraíba-Ibicuí sea. The rocks from the southern Gavião Block served as basement for the Contendas-Mirante sequence, where the Jacaré River Vanadium mine is situated in a stratified gabbro-anorthosite mafic sill, which intruded a Neoarchaean shear zone. On the northern part of the Gavião Block, where oceanic crust was identified by the presence of the Mundo Novo greenstone belt, hydrothermal mineralizations of both lead and zinc were mapped in calc-silicate rocks, which are associated to metamorphosed tholeiitic seafloor basalts and these metabasalts are tectonically intercalated with metadacites. In the Jequié Block, occurs the Ibicuí-Iguaí Iron District, which lies in the suture zone between this tectonic unit and the Itabuna-Salvador-Curaçá belt. These are rocks comprising a sequence of metabasalts and metavolcanic tuff, metakomatiites, kinzigites, quartzites and itabirites. In this belt also occurs the southern Bahia manganese district, where the mineralization is hosted in granulitized metavolcanic-sedimentary sequences. The ore protoliths are chemical sediments composed of spessartite, pyroxmangite, rhodonite, rhodochrosite, magnetite, mesoperthite and quartz. The reducing characteristics of the primary environment are confirmed by the presence of graphite and manganese sulphide (alabandite). This mineralogy produced through supergenic processes, ores with great reserves of pyrolusite and psilomelane. In the northern part of the Itabuna-Salvador-Curaçá Belt, an island arc was identified, where mafic-ultramafic bodies (2580 Ma) intruded at its base, giving rise to the Curaçá-Caraíba Valley Cupriferous District. These bornite and chalcopyrite-rich bodies were generated from a calc-alkaline magma that originated multiple Cu-rich gabbroic and pyroxenitic intrusions. [ABSTRACT FROM AUTHOR]

The Gangdese metallogenic belt in Tibet is an important polymetallic metallogenic belt formed during the subduction of the Neo-Tethys Ocean and subsequent India–Asia collision. Adakitic rocks are widely distributed in this belt and are considered to be closely related to porphyry–skarn Cu-Mo polymetallic mineralization. However, the petrogenesis and geodynamic setting of the Late Cretaceous adakites in the Gangdese belt remain controversial. In this study, we focus on the quartz diorite in the Nuri Cu-W-Mo deposit along the southern margin of the eastern Gangdese belt. LA-ICP-MS zircon U-Pb dating yields a Late Cretaceous age of 93.6 ± 0.4 Ma for the quartz diorite. Whole-rock geochemistry shows that the quartz diorite possesses typical adakitic signatures, with high SiO2, Al2O3, and Sr contents, but low Y and Yb contents. The relatively low K2O content and high MgO, Cr, and Ni contents, as well as the positive zircon εHf(t) values (+6.58 to +14.52), suggest that the adakites were derived from the partial melting of the subducted Neo-Tethys oceanic slab, with subsequent interaction with the overlying mantle wedge. The Late Cretaceous magmatic flare-up and coeval high-temperature granulite-facies metamorphism in the Gangdese belt were likely triggered by Neo-Tethys mid-ocean ridge subduction. The widespread occurrence of Late Cretaceous adakitic intrusions and associated Cu mineralization in the Nuri ore district indicate a strong tectono-magmatic-metallogenic event related to the Neo-Tethys subduction during this period. This study provides new insights into the petrogenesis and geodynamic setting of the Late Cretaceous adakites in the Gangdese belt, and has important implications for Cu polymetallic deposit exploration in this region. [ABSTRACT FROM AUTHOR]

The Jiama deposit, a significant porphyry‐skarn‐type copper polymetallic deposit located within the Gangdese metallogenic belt in Tibet, China, exemplifies a typical porphyry metallogenic system. However, the mineral chemistry of its accessory minerals remains under‐examined, posing challenges for resource assessment and ore prospecting. Utilizing electron microprobe analysis and LA‐ICP‐MS analysis, this study investigated the geochemical characteristics of apatite in ore‐bearing granite and monzogranite porphyries, as well as granodiorite, quartz diorite, and dark diorite porphyries in the deposit. It also delved into the diagenetic and metallogenic information from these geochemical signatures. Key findings include: (1) The SiO2 content, rare earth element (REE) contents, and REE partition coefficients of apatite indicate that the dark diorite porphyry possibly does not share a cogenetic magma source with the other four types of porphyries; (2) the volatile F and Cl contents in apatite, along with their ratio, indicate the Jiama deposit, formed in a collisional setting, demonstrates lower Cl/F ratios in apatite than the same type of deposits formed in a subduction environment; (3) compared to non‐ore‐bearing rock bodies in other deposits formed in a collisional setting, apatite in the Jiama deposit exhibits lower Ce and Ga contents. This might indicate that rock bodies in the Jiama deposit have higher oxygen fugacity. Nevertheless, the marginal variation in oxygen fugacity between ore‐bearing and non‐ore‐bearing rock bodies within the deposit suggests oxygen fugacity may not serve as the decisive factor in the ore‐hosting potential of rock bodies in the Jiama deposit. [ABSTRACT FROM AUTHOR]

Accurately determining the timing and mechanism of metallogenesis of ore deposits is essential for developing a robust genetic model for their exploration. In this paper, we analyze the formation conditions of cassiterite in five major deposits of southern Hunan Province, one of the most important tungsten-tin (W-Sn) provinces in South China, using a combination of cathodoluminescence imaging, in situ U-Pb geochronology, and trace-element concentration data. In situ cassiterite U-Pb geochronology constrains the main period of Sn mineralization to between 155.4 and 142.0 Ma, demonstrating a temporal and genetic relationship to silicic intrusive magmatism in the same area. Three stages of magmatic activity and metallogenic evolution are recognized: (1) Early Paleozoic and Triassic: the initial enrichment stage of tungsten and tin; (2) Jurassic: the metasomatic mineralization stage; and (3) Cretaceous: the magmatic-hydrothermal superposition stage. The cassiterite in these deposits takes four forms, i.e., quartz vein-type, greisen-skarn-type, greisen-type, and granite-type, representing a progression characterized by the increasing content and decreasing range of variation of high field strength elements (HFSEs), and reflecting a general increase in the degree of evolution of the associated granites. Rare earth element (REE) concentrations suggest that precipitation of cassiterite was insensitive to the redox state of the fluid and that precipitation of cassiterite in the southern Hunan Sn deposits did not require a high-fO2 environment. These findings provide new insights into tin mineralization processes and exploration strategies. [ABSTRACT FROM AUTHOR]

The Xitieshan deposit, located in the central segment of the northern margin of the Qaidam Basin, is among the largest massive Pb-Zn sulfide deposits in China. This deposit, along with its ore-bearing rock series known as the Tanjianshan Group, underwent greenschist facies metamorphism due to subsequent orogeny. We investigated the in situ sulfur isotopes of sulfides with different occurrences to define the origin of ore-forming fluids. The δ34S values of sulfides from stratiform ores, massive ores in schist, stockwork ores in marble, schist and discolored altered rocks that constitute a typical double-mineralization structure range from −5.3‰ to +5.6‰ and from −1.7‰ to +32‰, respectively, indicating distinct biological and thermochemical reductions in seawater sulfates. These are similar to the sulfur isotopic characteristics of VSHMS deposits. Pyrite, whose LA-ICP-MS trace element compositions can provide significant information about metallogenic evolution and deposit genesis, is ubiquitous throughout the whole mineralization process. In these stratiform, massive and stockwork ores, three pyrite types were identified: colloform pyrite (Py0), fine-grained anhedral spongy pyrite (Py1) and coarse-grained euhedral pyrite (Py2). The contents of most metallogenic elements, such as Cu, Pb, Zn, Ag, Mo, Mn and Sn, decrease from Py0 to Py2 with the enhancement of metamorphic recrystallization. This suggests that the expelled elements appear as inclusions in primitive pyrite, contributing to the precipitation of new sulfide phases, such as sphalerite and galena. Orogenic metamorphism played an important role in controlling further Pb-Zn enrichment of the Xitieshan deposit. Moreover, there is another mineralization type, primarily occurring as sulfide veins in the undeformed Formation C siltstones of the Tanjianshan Group, which also crosscut early-formed sulfides, showing close-to-zero S isotopic compositions. In this mineralization type, pyrite (Py3) displays high Se/Tl (>10) and Co/Ni (>2.2) ratios, both indicating a minor superimposed post-orogenic magmatic–hydrothermal event. [ABSTRACT FROM AUTHOR]

The Gangdese metallogenic belt in Tibet is an important polymetallic metallogenic belt formed during the subduction of the Neo-Tethys Ocean and subsequent India–Asia collision. Adakitic rocks are widely distributed in this belt and are considered to be closely related to porphyry–skarn Cu-Mo polymetallic mineralization. However, the petrogenesis and geodynamic setting of the Late Cretaceous adakites in the Gangdese belt remain controversial. In this study, we focus on the quartz diorite in the Nuri Cu-W-Mo deposit along the southern margin of the eastern Gangdese belt. LA-ICP-MS zircon U-Pb dating yields a Late Cretaceous age of 93.6 ± 0.4 Ma for the quartz diorite. Whole-rock geochemistry shows that the quartz diorite possesses typical adakitic signatures, with high SiO2, Al2O3, and Sr contents, but low Y and Yb contents. The relatively low K2O content and high MgO, Cr, and Ni contents, as well as the positive zircon εHf(t) values (+6.58 to +14.52), suggest that the adakites were derived from the partial melting of the subducted Neo-Tethys oceanic slab, with subsequent interaction with the overlying mantle wedge. The Late Cretaceous magmatic flare-up and coeval high-temperature granulite-facies metamorphism in the Gangdese belt were likely triggered by Neo-Tethys mid-ocean ridge subduction. The widespread occurrence of Late Cretaceous adakitic intrusions and associated Cu mineralization in the Nuri ore district indicate a strong tectono-magmatic-metallogenic event related to the Neo-Tethys subduction during this period. This study provides new insights into the petrogenesis and geodynamic setting of the Late Cretaceous adakites in the Gangdese belt, and has important implications for Cu polymetallic deposit exploration in this region.

The Bangbule skarn lead‐zinc (Pb‐Zn) deposit (>1 Mt Zn + Pb) is located in the western Nyainqentanglha polymetallic metallogenetic belt, central Tibet. Lenticular orebodies are all hosted in skarn and developed in the contact zone between the quartz porphyry and carbonate strata of the mid Paleozoic Middle to Upper Chaguoluoma Formation as well as in carbonate and sandstone beds of the Upper Paleozoic Laga Formation. As a newly discovered skarn deposit, the geological background and metallogenesis of this deposit remain poorly understood. Detailed petrological, geochemical and geochronological data of the ore‐related quartz porphyry, helps constrain the mineralization age and contributes to discussion on the ore genesis of the Bangbule deposit. Both endoskarn and exoskarn are identified in the Bangbule deposit. From quartz porphyry to carbonate formation, the exoskarn is zoned from proximal garnet skarn to distal pyroxene skarn. Zircon U‐Pb dating results show that the quartz porphyry formed at 73.9 ± 0.8 Ma. Geochemical analysis results show that the quartz porphyry has high contents of SiO2 (71.40–74.94 wt%) and K2O + Na2O (3.76–8.46 wt%) with A/CNK values of 0.69 to 1.06. Besides, the quartz porphyry is enriched in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) and have low εNd(t) (from –8.25 to –8.19) and high initial (87Sr/86Sr)i values (0.713611–0.714478). Major, trace elements and whole‐rock F concentration analysis results from the endoskarn samples show higher TFe2O3, MgO, CaO, Pb + Zn, W, Sn, Mo and F etc., and lower alkalis (K2O, Na2O, Sr and Ba) than those of fresh quartz porphyry, indicating that the early ore‐forming fluids were an Ca‐Fe‐F‐enriched fluid. Massive ore in the proximal skarn might be related to the high F content in the magma, which lowered the solidus temperature of the quartz porphyry magma and caused a lower temperature of the ore‐forming fluids, as well as facilitating the precipitation of sphalerite and galena. Based on the geochemical characteristics presented in this study, we propose that the ore‐related quartz porphyry was formed by partial melting of crust materials with some juvenile crustal component input. The partial melting of the middle‐upper crust after the initial enrichment of lead and zinc elements are important for the formation of Pb‐Zn deposits. The case study of the Bangbule deposit has proven that there is still a crust‐derived magmatic source region in the western segment of the central Lhasa terrane. Therefore, there is still great potential for Pb‐Zn mineralization and Pb‐Zn exploration. [ABSTRACT FROM AUTHOR]

By the end of 2020, 83 silver deposits (or ore occurrences), including four super-large-scale deposits, nine large-scale deposits, 33 medium-scale deposits and 37 small-scale deposits or ore occurrences, have been proved. The amount of silver metal exceeds 86000 t with average grade of 100 g/t, which makes Daxing’ anling region one of the the most important silver ore belt in China. However, the metallogenic characteristics and metallogenesis need to be clarified. The silver deposits in the study area are classified into three main types, which are magmatic hydrothermal vein type, continental volcano-subvolcanic type and skarn type, respectively. The supergiant deposits include the Shuangjianzishan deposit (silver metal amount of 15214 t with average grade of 138 g/t), the Baiyinchagandongshan deposit (silver metal amount of 9446 t with average grade of 187 g/t), the Huaobaote deposit (silver metal amount of 6852 t with average grade of 170 g/t), and the Fuxingtun deposit (silver metal amount of 5240 t with average grade of 196 g/t). The silver deposits are mainly distributed in the central and south of the Daxing’anling area, and mainly formed in the Yanshanian period. The silver polymetallic deposits in the Daxinganling area are significantly controlled by regional faults and the junction zone of volcanic rock basins and their margins. The north-east trending deep faults are the most important ore-controlling structures in this area. The distribution of silver polymetallic deposits along the main faults is obvious, and the intersection area of multiple groups of faults often form important mine catchments. The Permian is the most important ore-bearing formation in this area, but some important silver polymetallic deposits occur in Mesozoic volcanic basins or pre-Mesozoic strata. The magmatic rocks related to mineralization are mainly intermediate acidic or acidic intrusions, intermediate acidic lavas, pyroclastic rocks, and small intrusions of ultra-shallow or shallow facies of the Yanshanian Period. The mineralization element combination is mainly determined by the elemental geochemical background of surrounding rocks or source layers. In addition, the type of deposit, the distance from the mineralization center, and the degree of differentiation of ore-forming rock mass are also important influence factors. The article analyzes the prospecting prospects of each silver deposit type in the study area, discusses the relationship between mineralization center and deep prospecting, and proposes that porphyry silver deposits should be paid attention to. In the prospecting and exploration of silver deposits, comprehensive evaluation and multi-target prospecting need to be strengthened because silver can coexist or be associated with a variety of metals.©2022 China Geology Editorial Office.

The Dongnan Cu–Mo deposit, located in the southeast of the Zijinshan ore field (the largest porphyry–epithermal system in Southeast China), represents the complex magmatic and metallogenesis events in the region. The petrogenesis and metallogenesis of granitoids from the deposit are not determined, especially the interactions between ore-bearing (granodiorite porphyry) and barren samples (granodiorite and diorite). In the paper, the whole rock geochemical features shared a similar affinity to the middle-lower content and revealed that they derived from partial melting of the Cathaysian basement with the contribution of mantle materials, even represented that they generated in the plate subduction; LA-ICP-MS zircon U–Pb ages show that these granodiorites, granodioritic porphyry and diorite, were generated during 114–103 Ma. The ore-bearing samples mostly presented εHf(t) of negative values (peak value is −4 to −3) with old two-stage Hf model ages (tDM2) (peak value is 1.10–1.15 Ga), while the barren sample showed slightly negative εHf(t) (peak value is −1 to 0) values with young tDM2 (peak value is 1.00–1.05 Ga). The value of zircon Ce4+/Ce3+ ratio mostly higher than 450 was first verified for the ore-bearing samples in the Dongnan Cu–Mo deposit, and the values of ore-bearing were found to be higher than those from the barren, which suggests that the ore-bearing formed in more oxidized parental magma with higher oxygen fugacity. Based on the geochemical characteristic of the element and isotope, we concluded that the Early Cretaceous multi-phases magmatic activities, low melting temperature and low pressure of pluton, and high oxygen fugacity of zircon, were the favorable conditions for metallogenesis of Dongnan Cu–Mo deposit. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Mining Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Xitieshan deposit, located in the central segment of the northern margin of the Qaidam Basin, is among the largest massive Pb-Zn sulfide deposits in China. This deposit, along with its ore-bearing rock series known as the Tanjianshan Group, underwent greenschist facies metamorphism due to subsequent orogeny. We investigated the in situ sulfur isotopes of sulfides with different occurrences to define the origin of ore-forming fluids. The δ34S values of sulfides from stratiform ores, massive ores in schist, stockwork ores in marble, schist and discolored altered rocks that constitute a typical double-mineralization structure range from −5.3‰ to +5.6‰ and from −1.7‰ to +32‰, respectively, indicating distinct biological and thermochemical reductions in seawater sulfates. These are similar to the sulfur isotopic characteristics of VSHMS deposits. Pyrite, whose LA-ICP-MS trace element compositions can provide significant information about metallogenic evolution and deposit genesis, is ubiquitous throughout the whole mineralization process. In these stratiform, massive and stockwork ores, three pyrite types were identified: colloform pyrite (Py0), fine-grained anhedral spongy pyrite (Py1) and coarse-grained euhedral pyrite (Py2). The contents of most metallogenic elements, such as Cu, Pb, Zn, Ag, Mo, Mn and Sn, decrease from Py0 to Py2 with the enhancement of metamorphic recrystallization. This suggests that the expelled elements appear as inclusions in primitive pyrite, contributing to the precipitation of new sulfide phases, such as sphalerite and galena. Orogenic metamorphism played an important role in controlling further Pb-Zn enrichment of the Xitieshan deposit. Moreover, there is another mineralization type, primarily occurring as sulfide veins in the undeformed Formation C siltstones of the Tanjianshan Group, which also crosscut early-formed sulfides, showing close-to-zero S isotopic compositions. In this mineralization type, pyrite (Py3) displays high Se/Tl (>10) and Co/Ni (>2.2) ratios, both indicating a minor superimposed post-orogenic magmatic–hydrothermal event.

The Shimensi deposit is a recently discovered W-Cu-Mo polymetallic deposit located in the Jiangnan porphyry-skarn W belt in South China. The deposit has a resource of 0.74×106 t of WO3 accompanied by 0.4×106 t Cu and 28000 t Mo and other useful components like Ga, making it one of the largest W deposits in the world. This paper is aimed to reveal the ore-controlling mechanisms of the Shimensi deposit, involving the role of the ore-related granites, the tectonic background for its formation, and the metallogenesis model. The systematic geological survey suggests multi-types of alteration are developed in the deposit, mainly including greisenization, potassic-alteration, sericitization, chloritization, and silicification. Drilling engineering data and mining works indicate that the Shimensi deposit consists of two main orebodies of I and II. Therein, the W resource has reached a supergiant scale, and the accompanied Cu, Mo, Au, Bi, Ga, and some other useful components are also of economic significance. The main ore-minerals consist of scheelite, wolframite and chalcopyrite. Disseminated mineralization is the dominant type of the W-Cu-Mo polymetallic orebodies, and mainly distributes in the inner and external contact zone that between the Neoproterozoic biotite granodiorite and the Yanshanian granites. The main orebody occurs at the external contact zone, and the pegmatoid crust near the inner contact zone is an important prospecting marker of the W mineralization. Of them, the disseminated W ores within the wall rock of the Neoproterozoic biotite granodiorite is a new mineralization type identified in this paper. Combining previous geochronological and isotopic data, we propose that the mineralization of the Shimensi deposit is closely related to the intruding of the Yanshanian porphyritic biotite granite and granite porphyry. Geochemical data suggest that the biotite granodiorite is rich in Ca and had provided a large amount of Ca for the precipitation of scheelite in this area. Thus, it is a favorable wall rock type for W mineralization. The Shimensi deposit belongs to granitic-type W polymetallic deposit related to post-magmatic hydrothermal, and the ore-forming fluid was initially derived from the Yanshanian magmas.©2022 China Geology Editorial Office.

The Sanjiang orogenic belt, located in southwestern China and the southeastern Tibetan Plateau, includes a variety of economically important metal deposits. Previous studies have focused on Lu-Hf isotopic mapping to suggest its lithospheric architecture and mineralization. In this study, we provide the results of Nd isotopic mapping and compare them with the results of Hf isotopic mapping based on the similarity of Sm-Nd and Lu-Hf isotope systems, which indicate three juvenile domains with high εNd(t) and young Nd model ages within the Eastern Qiangtang-Simao terrane, while presenting negative εNd(t) values over the entire horizon. The very negative εNd(t) and old Nd model ages found in the Tengchong-Baoshan terrane and Changning-Menglian suture suggest that these terranes are old and might be reworked. The Nd isotopic mapping of the Sanjiang orogenic belt also suggests a relationship between different lithospheric architectures and the locations of distinct ore deposits. Porphyry-skarn Cu–Mo–(Au) deposits occur in the juvenile crust, which has relatively high εNd(t) (−3.3–5.1) and young TDM ages, whereas skarn and hydrothermal vein-type W–Sn deposits and Pb‒Zn‒Cu‒Ag deposits are located in the low-εNd(t) area.

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work is based on the unprecedented Tectonic-Geochronological Map of Bahia (TGMBA): metallogenic implications. In the TGMBA, sixteen tectonic domains were identified, and the main mineral occurrences and deposits in each were recorded. Of the Palaeo-Mesoarchean blocks, the Gavião (GB), Serrinha (SB) and Uauá (UB) blocks were highlighted. The southern GB was formed by plate tectonics, in two stages, at ca. 3403–3378 and 3259–3240 Ma. These rocks served as basement for the Umburanas Greenstone Belt, which comprises felsic metavolcanic rocks (3147 Ma) interspersed with ocean floor mafic metavolcanics and could have been the source of the recently found orogenic gold. This crust could also have formed the basal section of the Brumado metavolcanic-sedimentary sequence, which hosts one of the most important magnesite mines in the world. The northern part of the GB hosts TTGs with ages of ca. 3642–3520 Ma, the oldest known rocks in the whole São Francisco Craton. This region served as a passive margin for the Jacobina-Umburanas Sea, where quartzites and conglomerates (3305 Ma) with detrital gold were deposited and, in the deeper portions of this sea, Mesoarchean ocean floor or Island-arc basalts (3200 Ma) with pillow-lava structures were formed. On the platform of this basin, Mn deposits were formed in association with pelites and sandstones [ABSTRACT FROM AUTHOR]

The Yangzhuang iron deposit is a Kiruna-type iron oxide-apatite (IOA) deposit within the Ningwu mining district of the Middle and Lower Yangtze River Metallogenic Belt (MLYRMB), China. This study applies a numerical modeling approach to identify the key processes associated with the formation of the deposit that cannot be easily identified using traditional analytical approaches, including the duration of the mineralizing process and the genesis of iron orebodies within intrusions associated with the deposit. This approach highlights the practical value of numerical modeling in quantitatively analyzing mineralizing processes during the formation of mineral deposits and assesses how these methods can be used in future geological research. Our numerical model links heat transfer, pressure, fluid flow, chemical reactions, and the movement of ore-forming material. Results show that temperature anomaly and structure (occurrence of the contact of intrusion and the Triassic Xujiashan group) are two key factors controlling the formation of the Yangzhuang deposit. This modeling also indicates that the formation of the Yangzhuang deposit only took some 8000 years, a reaction that is likely to be controlled by temperature and diffusion rates within the system. The dynamic changes of temperature and the distribution of mineralization also indicate that the orebodies located inside the intrusions most likely formed after magma ascent rather than representing blocks of existing mineralization that descended into the magma as a result of stoping or other similar processes. All these data form the basis for future research into the forming processes of Kiruna-type IOA systems as well as magmatic–hydrothermal systems more broadly, including providing useful insights for future exploration for these systems. The simulation approach used in this study has several limitations, such as oversimplified chemical reactions, uncertainty of pre-metallogenic conditions and limitation of 2D model. Future development into both theories and methods will definitely improve the practical significance of numerical simulation of ore-forming processes and provide quantitative results for more geological issues.

New zircon U-Pb geochronology (SHRIMP) and geochemistry combined with geochronology (LA-ICP-MS) of titanite data are provided to investigate the metallic sources (whether igneous or sedimentary) and the temporal evolution of one of the most relevant Precambrian metallogenic provinces of the South American Platform, the Seridó Mineral Province. The granites of Serra de João do Vale pluton, calc-silicate "skarnoid" rocks and paragneiss related to the Bonito W-Mo-Cu exoskarn deposit were investigated. It was analyzed titanites of magmatic (Serra de João do Vale), hydrothermal (calc-silicate rocks) and metamorphic (paragneiss) origin. The magmatic titanite is wedge-shaped with larger grain size (up to 250 μm), richer in HFSE elements, Al and Fe, and manifests negative Eu anomalies (Eu/Eu × averaging 0.31–0.60). The hydrothermal titanite is found alongside epidote and calcite, have subhedral shapes and medium grain size (up to 150 μm). The metamorphic titanite is anhedral, generally smaller than 100 μm and appear as thin coronae in ilmenite or as inclusions in biotite. Both metasomatic and metamorphic titanites manifest positive Eu anomalies (Eu/Eu × averaging 1.20 and 1.06, respectively) and are enriched in Ti, Rb and U in relation to the magmatic. Conventional mineral thermobarometry (Al-in-titanite independent barometer, and Zr-in-titanite thermobarometer) provided pressures between 400 and 550 MPa and temperatures between 720 and 787 °C for the crystallization history of the granite, coeval with the regional peak metamorphism at 568–624 °C and 300–500 MPa (Ti in biotite independent barometer and biotite-muscovite thermobarometer). Conditions for the titanite-epidote calc-silicate assemblage were constrained through thermodynamic modelling in NCKFMAST + COH pseudosection at 439 ± 35 °C and 190 ± 50 MPa. The zircon U-Pb age registered the magmatism between 585.5 and 580.5 Ma. Titanite U-Pb ages from granite and calc-silicate rocks timed the closure of U-Pb system at the isotherm of 550 °C between 562 and 557 Ma. (20 m.y. after the intrusion), which marks the metasomatic process. The average W content in paragneisses and calc-silicate titanites (35.8–35.5 ppm) is 4 times higher than in the granite (6.76 ppm), reaching a maximum of 328 ppm. Mo and Cu mirrors this behavior, with concentrations that exceed nearly double that of titanites from Serra de João do Vale granites, peaking at 308 ppm of Mo and 162 ppm of Cu. Metal contents in titanite disclose the metasiliciclastic rocks of the Jucurutu Formation as, at least partially, a source of metals (mainly for W, but also Cu and Mo) in the skarn mineralization during the terrane exhumation at the end of Ediacaran period. • Titanite geochronology works as a temporal marker for metasomatism in W-skarn systems. • Titanite and bulk rock metallic contents disclose meta sedimentary rocks as sources for W-Mo-Cu skarn mineralization in the Seridó Mineral Province. • Conventional thermobarometry and phase equilibria modelling reveals that the metasomatic event occurred during terrane exhumation 20 My. after the metamorphic peak in the Seridó Mineral Province. • The occurrence of skarns, deformational style and metamorphic evolution nail the Seridó Belt as foreland basin. [ABSTRACT FROM AUTHOR]

The Huangtan (including Jinling) Au–Cu–Zn deposit is an auriferous volcanogenic massive sulfide (VMS) deposit discovered in East Tianshan, Central Asian Orogenic Belt. The deposit is hosted in volcanic breccia and tuff of the Silurian Hongliuxia Formation. The ore bodies consist of concordant massive sulfide lenses and discordant sulfide veins. Chalcopyrite Re–Os dating constrained the age of mineralization in the Huangtan deposit at 432 Ma. Quartz and barite host abundant liquid-rich, liquid-only and minor vapor-rich aqueous fluid inclusions. The fluid inclusions in barite from the exhalative–sedimentary units mainly have homogenization temperatures at 140–260 °C, and calculated salinities of 3–9 wt% NaCl equiv.; Those values are at 120–300 °C, and 1–9 wt% NaCl equiv. for varieties in quartz from the vein ores and alteration assemblages. Fluid inclusions extract from pyrite have 3He/4He ratios of 0.929–1.374 Ra, 40Ar/36Ar of 388–520, and 40Ar/4He of 0.355–0.836. The quartz and barite yielded δ18O values of 7.4‰ to 10.1‰ and the δDV-SMOW values of the fluid inclusions in the quartz and barite range from − 69 to − 42‰. The He–Ar and H–O isotopes imply that the ore-forming fluids were derived from a magmatic source with the addition of deeply circulating seawater. The δ34SV-CDT values of pyrite and chalcopyrite range from − 2.0 to 1.5‰, and those of barite samples range from 24.1 to 24.8‰, which indicates that sulfur was derived from magmatic sulfur, and was subjected to fractionation between sulfide and sulfate. Linked to the ore geology, geochronology data, isotope compositions and fluid inclusions obtained in this study with those of previously published adjacent VMS deposits in the Kalatag area suggest that the Huangtan deposit and adjacent VMS deposits formed in the same metallogenic system. [ABSTRACT FROM AUTHOR]

Understanding of the mechanism between magma sources and metallogeny is still vague. As an important gold and molybdenum producing area, the Chifeng–Chaoyang district, located at the northern margin of the North China Craton (NCC), is a key place for this issue. New geochemical data relating to Taijiying gold-deposit-related granites are presented. These data, coupled with previous studies, are used to explore the relationship between magma sources and mineralization processes. Two major magmatic periods, the Middle Triassic (220–230 Ma) and Late Jurassic (150–160 Ma), are identified based on the compiled data. The Triassic magmatic rocks are mostly fractionated I-type and A-type granites, including monzogranite, biotite granite, and syenogranite. They have low initial 87Sr/86Sr values (0.7050), moderately enriched εNd(t)–εHf(t) values (−8.5 and −5.6), and relatively young Nd–Hf model ages (TDM2-TDMC) (1.47–1.57 Ga). These features indicate that more Archean–Paleoproterozoic mantle-derived materials were involved in their sources. On the other hand, Jurassic granites are high-K calc-alkaline of the calc-alkaline series and mainly consist of granite, monzogranite, leucogranite, and granodiorite. They have high Na2O/K2O, Sr/Y, and La/Yb ratios and low Y and Yb contents. The adakitic features suggest the existence of a thickened lower crust. Their significant negative εNd(t)–εHf(t) values (−15.0 and −12.8) and older Nd–Hf model ages (TDM2–TDMC) (2.17–2.11 Ga) are consistent with their derivation from thickened ancient lower crust, indicating the initial activation of NCC. It is proposed that the change in the main source resulted from the tectonic transition during the early Mesozoic initial decratonization, that is, from the post-collisional extension to the subduction of the Paleo-Pacific plate beneath the East Asia plate from the Triassic to the Jurassic. Comparative analysis suggests that the medium–large-scale gold deposits with a high grade are closely related to the Triassic granites; however, most molybdenum deposits formed in the Jurassic. The decratonization of the NCC in the early Mesozoic experienced tectonic transition and controlled the gold and molybdenum mineralizations in the different stages by the changing magma sources. This pattern is beneficial to understanding the metallogenesis in the Chifeng–Chaoyang district. [ABSTRACT FROM AUTHOR]

The Li-bearing pegmatites of the Pampean Pegmatite Province (PPP) occur in a rare-element pegmatite belt developed mainly in the Lower Paleozoic age on the southwestern margin of Gondwana. The pegmatites show Li, Rb, Nb ≤ Ta, Be, P, B, Bi enrichment, and belong to the Li-Cs-Ta (LCT) petrogenetic family, Rare-Element-Li (REL-Li) subclass; most of them are of complex type and spodumene subtype, some are of albite-spodumene type, and a few of petalite subtype. The origin of the pegmatites is attributed predominantly to fractionation of fertile S-type granitic melts produced by either fluid-absent or fluid-assisted anatexis of a thick pile of Gondwana-derived turbiditic sediments. Most of the pegmatites are orogenic (530–440 Ma) and developed during two overlapped collisional orogenies (Pampean and Famatinian); a few are postorogenic (~370 Ma), related to crustal contaminated A-type granites. The pegmatites were likely intruded in the hinterland, preferably in medium-grade metamorphic rocks with PT conditions ~200–500 MPa and 400–650 °C, where they are concentrated in districts and groups. Known combined resources add up 200,000 t of spodumene, with variable grades between 5 and 8 wt.% Li2O. The potential for future findings and enlargement of the resources is high, since no systematic exploration program has yet been developed. [ABSTRACT FROM AUTHOR]

East China can be divided into two parts: the North China Block (or North China Craton) (NCC) and the South China Block (SCB). The mechanism for the destruction of the NCC and the large-scale magmatic activity in the SCB during the Mesozoic is a major focus in the geosciences; however, related scientific issues, such as gold mineralization in the NCC and the metallogenesis in the SCB, remain enigmatic. Recently, receiver function analysis and tomography have been used to define the vestiges of an upwelling mantle plume beneath the NCC and large-scale mantle upwelling beneath the SCB in the Mesozoic, which may be related to gold mineralization and metallogenesis in this area. In this study, the dynamic processes of the mantle plume and upwelling mantle are analysed, and the relationships between the mantle plume and gold mineralization as well as between mantle upwelling and metallogenesis are discussed. Finally, it is suggested that gold mineralization in the NCC might be linked to a Mesozoic mantle plume while metallogenesis in the SCB might be related to Mesozoic mantle upwelling.

The Yaojialing Zn-Au‑Cu deposit is a porphyry-skarn-epithermal vein-type compound deposit that consists of epithermal vein-type lead‑zinc‑silver orebodies, skarn Zn-Cu-Au orebodies, and porphyry Cu Au orebodies from shallow level to depth. We decipher the source and metallogenic mechanism by studying the trace element and S isotopic compositions of sulfides (pyrite, sphalerite, chalcopyrite, and galena) from three types of orebodies. The collected pyrite can be divided into two types. PyI coexists with chalcopyrite, and PyII coexists with sphalerite or galena. In addition, PyI was further divided into PyIa (collected from porphyry copper bodies) and PyIb (collected from skarn copper bodies). PyII can be further divided into PyIIa (collected from skarn-type lead‑zinc ore body) and PyIIb (collected from vein lead‑zinc ore body in strata). Sphalerite and galena from skarn-type Pb Zn ore bodies and shallow vein-type Pb Zn ore bodies are named SpI and GnI, and SpII and GnII, respectively. Pyrite and sphalerite trace element thermometers revealed that the temperature of the ore-forming fluids decreased from 500 to 600 °C in the porphyry ore body to 300– 360 °C in the skarn ore body and then to 240– 280 °C in the shallow vein ore body. The decrease in the Co and Ni contents of pyrite collected from deep to shallow depths may indicate that meteoric water precipitated in the late ore-forming hydrothermal system. Rapid crystallization and variations in the physicochemical states (such as temperature, pH, fO 2 , and geochemical composition) of the fluids resulted in an obvious oscillating zone of euhedral PyI pyrite particles. It also affects the solubility of trace metal elements and leads to the selective entry of these elements into pyrite. PyII also shows obvious zonation characteristics rather than oscillating zonation, indicating that the growth rate of pyrite is relatively slow. Moreover, the relationships between the Au and As contents in the two types of pyrite are different. PyI is coupled, while PyII shows decoupling. We believe that this phenomenon is due to the high content of As in ore-forming fluid systems, which may inhibit the absorption of Au on the surface of pyrite rather than the decoupling of Au and As caused by rapid crystallization, based on the rapid increase in As content and non-oscillating zonation in PyII. According to the analysis of the sulfur isotopes of various sulfides, the solid evidences suggest that the ore-forming materials of each type of orebody in the Yaojialing deposit were mainly derived from magmatic-hydrothermal processes and that the fractionation of sulfur isotopes was the result of variations in physicochemical conditions caused by magma-hydrothermal evolution rather than the addition of foreign sulfur sources. [Display omitted] • Yaojialing deposit mainly derived from magmatic hydrothermal fluid • High content of As may inhibit the absorption of Au on the surface of pyrite. • Trace element scanning of pyrite can reflect hydrothermal evolution and metallogenic history [ABSTRACT FROM AUTHOR]

Copyright of Journal of Geomechanics is the property of Journal of Geomechanics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Central Asian Orogenic Belt (CAOB) is among the world's largest Phanerozoic accretionary collage systems and hosts one of the three best-known porphyry metallogenic domain. Relatively few Devonian porphyry Cu (±Au) deposits (such as Oyu Tolgoi, Lailisigao'er, Halasu, Yulekenhalasu, etc) have been found in the CAOB, and the geological characteristics, fluid evolution and metallogenesis of Devonian porphyry Cu deposits are still uncertain. In this work, we undertake a fluid inclusion and isotopic study of the Xiaotuergen Devonian porphyry Cu deposit and present a comprehensive analysis of the ore-forming fluids to better understood Devonian porphyry deposits in the CAOB. The Devonian porphyry copper (±gold) deposits in the CAOB formed during the Early and Late Devonian (366–412 Ma) and have two peaks (375 Ma and 405 Ma). The Xiaotuergen porphyry Cu deposit, located in the Altay orogenic belt, Xinjiang, NW China, is mainly hosted by an Early Devonian granodiorite porphyry. The ore-forming fluids of the main copper mineralization stages (II and III) in Xiaotuergen were characterized by high to intermediate temperatures (190–320°C) and low to intermediate salinities (3.5–15.7 wt.% NaCl eqv.), similar to those of other the Devonian porphyry copper (±gold) deposits in the CAOB (T = 120–500°C, salinities = 0–21.7 wt.% NaCl eqv. and 33.5–51.0 wt.% NaCl eqv.). The temperatures and salinities of the ore-forming fluids changed, and phase separation might have been one of the important factors in the precipitation of chalcopyrite and pyrite. The Devonian porphyry copper (±gold) deposits in the CAOB have similar hydrogen and oxygen isotope characteristics, and the ore-forming fluids were dominated by magmatic fluids, with some minor contributions from meteoric water. The coexistence of CO2-bearing fluid inclusions with aqueous fluid inclusions in stage III suggests that fluid phase separation occurred at pressures of 110 to 320 bar (depths of 0.4–1.3 km). The formation depths of the Xiaotuergen deposit are shallower than those of the Lailisigao'er Cu deposits (palaeodepths of 1.7–2.2 km). The total sulphur value in the Xiaotuergen deposit is +12.2‰, indicating that the sulphur could have originated from crust. The δ34SV-CDT values of the most Devonian porphyry copper (±gold) deposits in the CAOB are concentrated near 0 ± 7‰, indicating a homogeneous sulphur source and derivation of sulphur from deep-seated magmas. [ABSTRACT FROM AUTHOR]

The origin of the Dexing porphyry Cu deposit is hotly debated. Zircon and apatite are important accessory minerals that record key information of mineralization processes. SHRIMP zircon U-Pb analyses of granodiorite porphyries yield ages of 168.9 ± 1.2 Ma, 168.0 ± 1.0 Ma, and 172.8 ± 1.3 Ma, whereas zircons in the volcanic rocks of the Shuangqiaoshan Group have Neoproterozoic ages of 830 ± 7 Ma, 829 ± 8 Ma, and 899 ± 12 Ma. The porphyry displays zircon in situ δ18O of mantle values (5.5 ± 0.2‰), low apatite 87Sr/86Sr ratios (0.7058 ± 0.0005), and high εHf values (5.1 ± 1.5), which are consistent with mantle-derived magmatic rocks. Apatite from the porphyries has relatively high total rare earth elements (REEs) and negative Eu anomalies, with relatively high Cl and As contents. These features are distinctly different from apatite in the Shuangqiaoshan Group, which shows lower total REE, Cl, and As contents but higher F content and positive Eu anomalies. Zircon in porphyries yields a relative high oxygen fugacity of ∆FMQ + 1.5 based on zircon Ce4+/Ce3+. Apatite in porphyries also shows high oxygen fugacity based on its SO3 and Mn compositions, reaching ∆FMQ + 2, which is different from that of the lower continental crust in general, but similar to subduction-related magmas. In contrast, the oxygen fugacity of the Shuangqiaoshan Group is much lower, suggesting a different origin for its wall rock. Therefore, the Dexing porphyries were not derived from the lower crust but derived from partial melting of the subducting Paleo-Pacific plate.

Understanding of the mechanism between magma sources and metallogeny is still vague. As an important gold and molybdenum producing area, the Chifeng–Chaoyang district, located at the northern margin of the North China Craton (NCC), is a key place for this issue. New geochemical data relating to Taijiying gold-deposit-related granites are presented. These data, coupled with previous studies, are used to explore the relationship between magma sources and mineralization processes. Two major magmatic periods, the Middle Triassic (220–230 Ma) and Late Jurassic (150–160 Ma), are identified based on the compiled data. The Triassic magmatic rocks are mostly fractionated I-type and A-type granites, including monzogranite, biotite granite, and syenogranite. They have low initial 87Sr/86Sr values (0.7050), moderately enriched εNd(t)–εHf(t) values (−8.5 and −5.6), and relatively young Nd–Hf model ages (TDM2-TDMC) (1.47–1.57 Ga). These features indicate that more Archean–Paleoproterozoic mantle-derived materials were involved in their sources. On the other hand, Jurassic granites are high-K calc-alkaline of the calc-alkaline series and mainly consist of granite, monzogranite, leucogranite, and granodiorite. They have high Na2O/K2O, Sr/Y, and La/Yb ratios and low Y and Yb contents. The adakitic features suggest the existence of a thickened lower crust. Their significant negative εNd(t)–εHf(t) values (−15.0 and −12.8) and older Nd–Hf model ages (TDM2–TDMC) (2.17–2.11 Ga) are consistent with their derivation from thickened ancient lower crust, indicating the initial activation of NCC. It is proposed that the change in the main source resulted from the tectonic transition during the early Mesozoic initial decratonization, that is, from the post-collisional extension to the subduction of the Paleo-Pacific plate beneath the East Asia plate from the Triassic to the Jurassic. Comparative analysis suggests that the medium–large-scale gold deposits with a high grade are closely related to the Triassic granites; however, most molybdenum deposits formed in the Jurassic. The decratonization of the NCC in the early Mesozoic experienced tectonic transition and controlled the gold and molybdenum mineralizations in the different stages by the changing magma sources. This pattern is beneficial to understanding the metallogenesis in the Chifeng–Chaoyang district.

The Niederschlag fluorite-barite vein deposit in the Western Erzgebirge, Germany, has been actively mined since 2013. We present the results of a first comprehensive study of the mineralogy, petrography, fluid inclusions, and trace element geochemistry of fluorite related to the Niederschlag deposit. Two different stages of fluorite mineralization are recognized. Stage I fluorite is older, fine-grained, associated with quartz, and forms complex breccia and replacement textures. Conversely, the younger Stage II fluorite is accompanied by barite and often occurs as banded and coarse crystalline open-space infill. Fluid inclusion and REY systematics are distinctly different for these two fluorite stages. Fluid inclusions in fluorite I reveal the presence of a low to medium saline (7–20% eq. w (NaCl+CaCl2)) fluid with homogenization temperatures of 140–180 °C, whereas fluorite II inclusions yield distinctly lower (80–120 °C) homogenization temperatures with at least two high salinity fluids involved (18–27% eq. w (NaCl+CaCl2)). In the absence of geochronological data, the genesis of the earlier generation of fluorite-quartz mineralization remains enigmatic but is tentatively related to Permian magmatism in the Erzgebirge. The younger fluorite-barite mineralization, on the other hand, has similarities to many fluorite-barite-Pb-Zn-Cu vein deposits in Europe that are widely accepted to be related to the Mesozoic opening of the northern Atlantic Ocean. [ABSTRACT FROM AUTHOR]

[Display omitted] • The spatio-temporal variation of deposits in the BNMB is constrained by the lithospheric structure and geodynamic processes. • The closed relationship between the magmatism and the regional mineralization in the BNMB has been revealed. • The Jurassic–Cretaceous tectonic–magmatic–metallogenic evolution history in the BNMB was reconstructed. The Bangong–Nujiang metallogenic belt (BNMB) is one of the vital metallogenic belts in the Tibetan Plateau. At present, the metallogenic regularity on the scale of the whole metallogenic belt is still poorly understood. In this contribution, the geological, geochronological, geochemical, and isotopic data of 87 magmatism-related polymetallic deposits in the BNMB have been systematically collected to summarize the metallogenesis of polymetallic deposits in this belt. Our research shows that different segments of the BNMB have distinct metallogenic differences. The western, central, and eastern segments of the BNMB are characterized by the development of abundant Cu–Au, Fe–Cu–Cr–Ni, and W–Pb–Zn deposits, respectively. These various types of magmatism-related polymetallic deposits in the BNMB were formed between 188 Ma and 76 Ma, and the mineralization has two peak periods of 125–110 Ma and 90–75 Ma. The spatio-temporal variation of different types of magmatism-related polymetallic deposits in the BNMB is likely to be constrained by the lithospheric architecture and deep geodynamic processes. The elemental and Sr–Nd–Hf–S–Pb isotopic results indicate that various kinds of mineralization are closely related to relevant magmatism. The Cu–Au mineralization is related to dominantly mantle-derived, highly-oxidized, and less-evolved granitic intrusions; the Pb–Zn–W mineralization is genetically associated with dominantly ancient middle–upper crust-derived, relatively reduced, and highly-evolved granitic intrusions; the characteristics of the ore-causative intrusions related to Fe–Cu–Mo polymetallic mineralization are between those of the above two end members. In combination with previous studies, we propose a comprehensive model that includes four stages (>145 Ma, ∼145–125 Ma, ∼125–105 Ma, and ∼105–74 Ma) to illustrate the Jurassic–Cretaceous tectonic–magmatic–metallogenic evolution history in the whole BNMB. [ABSTRACT FROM AUTHOR]

The Li-bearing pegmatites of the Pampean Pegmatite Province (PPP) occur in a rare-element pegmatite belt developed mainly in the Lower Paleozoic age on the southwestern margin of Gondwana. The pegmatites show Li, Rb, Nb ≤ Ta, Be, P, B, Bi enrichment, and belong to the Li-Cs-Ta (LCT) petrogenetic family, Rare-Element-Li (REL-Li) subclass; most of them are of complex type and spodumene subtype, some are of albite-spodumene type, and a few of petalite subtype. The origin of the pegmatites is attributed predominantly to fractionation of fertile S-type granitic melts produced by either fluid-absent or fluid-assisted anatexis of a thick pile of Gondwana-derived turbiditic sediments. Most of the pegmatites are orogenic (530–440 Ma) and developed during two overlapped collisional orogenies (Pampean and Famatinian); a few are postorogenic (~370 Ma), related to crustal contaminated A-type granites. The pegmatites were likely intruded in the hinterland, preferably in medium-grade metamorphic rocks with PT conditions ~200–500 MPa and 400–650 °C, where they are concentrated in districts and groups. Known combined resources add up 200,000 t of spodumene, with variable grades between 5 and 8 wt.% Li2O. The potential for future findings and enlargement of the resources is high, since no systematic exploration program has yet been developed.

The study on continental collision process will shed light on plate tectonics within continent. However, there are some problems about the timing of the initial collision, such as the division about collisional phases and the dynamics of collisional metallogenesis. Comparing Zagros and Himalayan orogens in terms of their deformation, magmatism, and metallogenesis, it is noted that there is a time lag between intense collisional related shorting and initial collision. In the meanwhile, arc-like magmatic activity can also occur within collisional continental zone. It is suggested that the lag time between tectonic-magmatic activities and initiation of continental collision reflects the effects of a collision process involving the "soft" collision. Thus the collision processes can be divided into three phases, including soft collision, hard collision, and post collision. Among them, the soft collision phase is characterized by low-rate contractional deformation and magmatism related to sub ducted oceanic slab. In contrast, high-rate contractional deformation and magmatism related to subduction of continental lithosphere occur during the hard collision phase. There are lots of extensional structures during post collision phase, and magmatic activity of this phase is mainly induced by delamination, breakoff and tearing of the continental lithosphere. The hydrothermal Pb-Zn ore deposits occur in the fold and thrust belt during soft and hard collision phases. The porphyry Cu deposits are controlled by large strike-slip faults during hard and post collision phases, whereas the detachment-faultrelated polymetallic deposits form related to crustal extension during post collision phase. The juvenile crust form during the early subduction phase and subsequent collisional phase, and supply metal for ore-forming system within continental collision zones [ABSTRACT FROM AUTHOR]

The predominant types of high-grade iron deposits in China include skarn, sedimentary metamorphic (banded iron-formation, BIF-type), continental/submarine volcanic-hosted and magmatic Fe-Ti-V oxide deposits. Based on a comprehensive review of current studies on these deposits, this paper suggests that the oxygen concentration in atmosphere played an important role for the formation of BIFs, whereas the tectonic setting and deep magmatic differentiation processes are more important for the other types. Notably, both high temperature and high pressure experiments and melt inclusion studies indicate that during the differentiation, high temperature magmas could develop iron-rich magma via liquid immiscibility but not pure oxide melt ("iron ore magma"). Fe-P melt could be generated directly by liquid immiscibility under hydrous and oxidized condition. The formation of high-grade iron deposits is mostly associated with the processes related to multiple stages of superimposition, e.g., desiliconization and iron enrichment, removal of impurity, and remobilization and re-precipitation of iron. According to the temporal evolution, the high-grade iron deposit could be divided into multi-episode superimposition type (temporally discontinuous mineralization) and multi-stage superimposition type (temporally continuous mineralization). The former is represented by the sedimentary metamorphic iron deposit, and the latter includes those related to magmatic-hydrothermal fluids (e.g., skarn, volcanic-hosted and magmatic types). [ABSTRACT FROM AUTHOR]

Adakitic rocks are intermediate-acid magmatic rocks characterized by enrichment in light rare-earth elements, depletion in heavy rare-earth elements, positive to negligible Eu and Sr anomalies, and high La/Yb and Sr/Y ratios. Cenozoic adakitic rocks generated by partial melting of subducted oceanic crust (slab) under eclogite-facies conditions (i.e., the original definition of "adakite") occur mainly in Pacific Rim volcanic arcs (intra-oceanic, continental, and continental-margin island arcs), whereas those generated by partial melting of thickened lower crust occur mainly in Tethyan Tibetan collisional orogens. In volcanic arcs, adakitic melts derived from the melting of subducted oceanic crust metasomatize the mantle wedge to form a unique rock suite comprising adakite-adakite-type high-Mg andesite-Piip-type high-Mg andesite-Nb-rich basalt-boninite. This suite differs from the basalt-andesite-dacite-rhyolite suite formed from mantle wedge metasomatized by fluids derived from subducted oceanic crust. Previously published data indicate that partial melting of mafic rocks can generate adakitic magmas under pressure, temperature, and hydrous conditions of 1.2–3.0 GPa, 800–1000°C, and 1.5–6.0 wt.% H2O, respectively, leaving residual minerals of garnet and rutile with little or no plagioclase. Cenozoic Au and Cu deposits occur proximally to adakitic rocks, with host rocks of some deposits actually being adakitic rocks. Adakitic rocks thus have important implications for both deep-Earth dynamics and Cu-Au mineralization/exploration. Although studies of Cenozoic adakitic rocks have made many important advances, there remain weaknesses in some important areas such as their tectonic settings, petrogenesis, magma sources, melt-mantle interactions of pre-Cenozoic adakitic rocks, and their relationship with the onset of plate tectonics and crustal growth. Future research directions are likely to involve (1) the generation of adakitic magmas by experimental simulations of partial melting of different types of rock (including intermediate-acid rocks) and magma fractional crystallization at different temperatures and pressures, (2) the relationship between magma reservoir evolution and the formation of adakitic rocks, (3) the tectonic setting and petrogenesis of pre-Cenozoic adakitic rocks and related geodynamic processes, (4) interactions between slab melts and the mantle wedge, (5) the formation of Archean adakitic tonalite-trondhjemite-granodiorite and its link to the onset of plate tectonics and crustal growth, and (6) the relationship between the formation of adakitic rocks and metal mineralization in different tectonic settings. [ABSTRACT FROM AUTHOR]

The gold mineralization at the Enche Concha and Tunel prospects, northwestern portion of the Gurupi Belt, is hosted in dacites and phyllites that belong to the ca. 2160 Ma-old metavolcano-sedimentary Chega Tudo Formation. These host rocks are variably deformed, from a spaced cleavage to schistose and mylonitic varieties. The hosting structures have previously been defined as produced in the Paleoproterozoic. The hydrothermal alteration processes include carbonatization, sericitization, sulfidation, and quartz veining. These processes are both pervasive and fissure-filling in style. Pyrite is largely predominant over chalcopyrite and sphalerite and gold occurs as a refractory phase in pyrite. Fluid inclusion, stable (O, H, C) and Sr isotopes studies indicate that the hydrothermal alteration and gold mineralization occurred between 260 and 370°C (mostly ~328°C), and 0.85 to 2.8 kbar, from a low-salinity (~5% NaCl), aqueous-carbonic (XCO2 = 0.03-0.13), relatively reduced (log fO2 = -32.1), and near neutral (pH = 5.0-6.2) metamorphic fluid (d18O = +9.4 to +11.3‰, dD = -25 to -28‰). Contributions from deep-seated (lower crust and mantle) sources are suggested by a d13CCO2 value of -7.6‰, and 87Sr/86Sr ratios between 0.702699 and 0.705141, which are lower than those found in the country rocks. Gold was transported by the Au(HS)2- complex and precipitation occurred in response to phase separation, identified by fluid inclusions, and fluid-rock interactions, given by the lowering of the d13CCO2 values. The geological and genetic characteristics are equivalent to those of the orogenic gold system previously defined for the Gurupi Belt.

Studies on the most southern and complete Carnian sequence of the Bergamasc Alps (S. Gallo well) and of several exposed stratigraphic sections throw new light on the paleogeographic evolution and the metallogenesis of the Pb—Zn—Fluorite—Barite Gorno district. In the Early Carnian (Calcare Metallifero Bergamasco and Basal Tongue of the Gorno Fm.) , an open lagoon with mixed calcareous—terrigenous sedimentation passed northward to carbonate tidal flats and was fringed by karstified carbonate paleo—highs. Next, the great supply of terrigenous detritus from a southern volcanic belt brought about the progradation of a fluviodeltaic body (Val Sabbia Sandstone) and confined carbonate sedimentation to an outer zone.

The Mociços Cu-deposit is part of a cluster of ancient copper mines in the Sousel-Barrancos metallogenic belt in the Ossa-Morena Zone at the SW Iberia. The orebodies develop along NNW-SSE quartz-carbonate-sulfides veins with pyrite and chalcopyrite as the main sulfide phases, and ore emplacement has been attributed to copper remobilization from the metasedimentary host-rocks, though no detailed studies were conducted. A novel multi-stage fluid circulation model is hereby proposed, supported by petrography and fluid inclusion data evidencing the P–T–V-x evolution of the deposit. Stage (i) is an early metamorphic stage with a predominance of carbonic fluids, identified in highly deformed milky quartz (QzI), with estimated pressures between 338 and 486 MPa compatible to the regional metamorphic events (greenschist facies). Stage (ii) corresponds to a late-metamorphic manifestation of H2O–NaCl–CO2 fluids, with low-salinity (eq. w(NaCl) from 0.4 to 5.0%) and CO2 dominated. Stage (iii) in which ore emplacement took place and is characterized by dominant multisolid H2O–NaCl hypersaline, halite-bearing fluid inclusions (eq. w(NaCl) from 29.3 to 44.3%) with an H2O–NaCl–CO2 endmember and features indicative of magmatic-hydrothermal brines. Many of these inclusions homogenize by halite dissolution, with pressures as high as 320 MPa, and the coexistence of both fluids in the same fluid inclusion assemblages (FIA) could indicate phase separation caused by fluid pressure variations. Although there is no direct evidence of the magmatism responsible for these fluids, the geodynamic settings could favor deep-seated magmatism. Stage (iv) is characterized by low-salinity (eq. w(NaCl) from 0.18 to 15.57%) and low-temperature (68 to 160°C) primary two-phase fluid inclusions hosted by late-stage quartz (QzIV), suggesting a late-meteoric fluid circulation phase responsible for the leaching, oxidation and supergene enrichment observed at surficial levels. Throughout the P–T evolution of the system a decrease in pressure and temperature was registered, especially in fluid inclusions hosted in quartz from the sulfide bearing veins, suggesting that the transition from ductile to brittle regimes might have favored ore deposition. [ABSTRACT FROM AUTHOR]

Porphyry copper±molybdenum±gold deposits (PCDs) are the most representative magmatic-hydrothermal metallogenic system above subduction zones with important economic value. Previous studies revealed that large PCDs are generally formed from initial arc magmas (from subduction-induced partial melting of the mantle wedge), which eventually ascend to the shallow crust (3–5 km) for mineralization after a series of complex evolution processes. These processes include (1) the dehydration or partial melting of subducting slab, which induces partial melting of the metasomatized mantle wedge; (2) the ascent of mantle-derived magma to the bottom of the lower crust, which subsequently undergoes crustal processes such as assimilation plus fractional crystallization (AFC) or melting, assimilation, storage and homogenization (MASH); (3) the magma chamber formation at the bottom of the lower, middle and upper crust; (4) the final emplacement and volatilization of porphyry stocks; and (5) the accumulation of ore-forming fluids and metal precipitation. Despite the many decades of research, many issues involving the PCD metallogenic mechanism still remain to resolve, such as (1) the tectonic control on the geochemical characteristics of ore-forming magma; (2) the reason for the different lifespans of the long-term magmatic arc evolution and geologically "instantaneous" mineralization processes; (3) the source of ore-forming materials; (4) the relative contributions of metal pre-enrichment to mineralization by the magma source and by magmatic evolution; and (5) the decoupling behaviors of Cu and Au during the pre-enrichment. These issues point out the direction for future PCD metallogenic research, and the resolution to them will deepen our understanding of the metallogenesis at convergent plate boundaries. [ABSTRACT FROM AUTHOR]

As one of the largest Phanerozoic orogens in the world, the Central Asian Orogenic Belt (CAOB) is a natural laboratory for studies of continental dynamics and metallogenesis. This paper summarizes the research progresses of the accretionary processes and metallogenesis of the CAOB since the People's Republic of China was founded, and puts forward the prospect for future research. During the early period (1950s–1970s), several geological theories were applied to explain the geological evolution of Central Asia. In the early period of China's reform and opening-up, the plate tectonics theory was applied to explain the evolution of the northern Xinjiang and Xingmeng regions, and the opinion of subduction-collision between Siberian, Kazakhstan, and China-North Korea-Tarim plates was proposed. The idea of the Solonker-Yanbian suture zone was established. In the 1990s, the study of the CAOB entered a period of rapid development. One school of scholars including geologists from the former Soviet Union proposed a multi-block collision model for the assemblage of the CAOB. In contrast, another school of scholars, led by a Turkish geologist, Celal Şengör, proposed that the Altaids was formed through the growth and strike-slip duplicates of a single island arc, and pointed out that the Altaids is a special type of collisional orogen. During this period, Chinese geologists carried out a lot of pioneering researches on ophiolites and high-pressure metamorphic rocks in northern China, and confirmed the main suture zones accordingly. In 1999, the concept of "Central Asian metallogenic domain" was proposed, and it became one of the three major metallogenic domains in the world. Since the 21st century, given the importance for understanding continental accretion and metallogenic mechanism, the CAOB has become the international academic forefront. China has laid out a series of scientific research projects in Central Asia. A large number of important scientific research achievements have been spawned, including the tectonic attribution of micro-continents, timing and tectonic settings of ophiolites, magmatic arcs, identification and anatomy of accretionary wedges, regional metamorphism-deformation, (ultra)high-pressure metamorphism, ridge subduction, plume-plate interaction, archipelagic paleogeography and spatio-temporal framework of multiple accretionary orogeny, continental growth, accretionary metallogenesis, structural superposition and transformation, etc. These achievements have made important international influences. There still exist the following aspects that need further study: (1) Early evolution history and subduction initiation of the Paleo-Asian Ocean; (2) The accretionary mechanism of the extroversion Paleo-Asian Ocean; (3) The properties of the mantle of the Paleo-Asian Ocean and their spatiotemporal distribution; (4) The interaction between the Paleo-Asian Ocean and the Tethys Ocean; (5) Phanerozoic continental growth mechanism and its global comparison; (6) Accretionary metallogenic mechanism of the Central Asian metallogenic domain; and (7) Continental transformation mechanism. [ABSTRACT FROM AUTHOR]

This paper aims to reveal the formation process of pitchblende by analyzing its microstructural features on the nanoscale and atomic scale. Herein, we selected pitchblende samples from drilling cores from the Miaoershan area, southern China, as the research objects. The microstructural features of pitchblende particle cores were analyzed using high-resolution transmission electron microscopy (HRTEM), electron diffraction, energy spectrum (EDS) and electron microprobe analysis (EMPA), combined with density functional theory calculations. The results of this study reveal that the pitchblende grain boundaries are not clear, as they exhibit a cloudy distribution and some preferred orientations under HRTEM. The selected area electron diffraction (SAED) analyses show discontinuous ring patterns that are coherent with the presence of a preferred orientation. The HRTEM results reveal that pitchblende is a complex aggregate composed of nanocrystals with a diameter of 3–7 nm and unit cell parameters of a0 = 0.556 nm. The elements in the pitchblende are characterized by an irregular and scattered distribution of Ca, As, S, Fe, Mn, and Si. We assume that the formation of pitchblende is related to hard-base fluid in a reduced environment containing As and S. We used density functional theory calculations to obtain the pitchblende crystal structure model and simulated the positions of the U and O atoms to provide a reference for further analysis of the pitchblende crystal structure. We conjecture that uranium ions of U4+, U5+ and U6+ may coexist in pitchblende (stoichiometry U3O7). [ABSTRACT FROM AUTHOR]

The eastern Jilin and Heilongjiang provinces in China are located at the junction between the Paleo-Asian Ocean and Circum-Pacific metallogenic domains, and have been affected by the temporal transition between these domains and their superposition, resulting in intensive and complicated mineralization events. This paper provides a progress in exploration for, and geological research into, endogenic metal deposits and related magmatite in the eastern Jilin and Heilongjiang provinces. Four richly mineralized areas are recognized: (1) the Lesser Xing'an–Zhuangguangcai Range metallogenic belt; (2) the Jiamusi–Khanka metallogenic belt; (3) the Yanbian metallogenic belt; and (4) the Wandashan metallogenic belt. Four temporal peaks in magmatism and metallogenesis are identified: (1) Hercynian orogenic Au deposits (260–250 Ma) show a close relationship with magmatism related to a transitional syn- to post-collisional tectonic setting; (2) Indosinian orthomagmatic ore deposits (230–210 Ma) show a close relationship to mafic–ultramafic magmatism in a post-collision extensional setting; (3) porphyry Mo deposits and skarn deposits of the Late Triassic to the Early Jurassic (200–170 Ma) formed in a continental arc setting, triggered by slab subduction; and (4) late Yanshanian large-scale mineralization was caused by tectonic extension at 133–106 Ma. Yanshanian felsic magmatism shows clear metallogenetic specialization; i.e. each rock type hosts a different type of deposit. [ABSTRACT FROM AUTHOR]

Abstract The Cristalino deposit is located 40 km east of Sossego mine, Carajás. The orebody lies along a NW-SE-striking shear zone and is mainly hosted by the Neoarchean bi-modal volcanics of the Grão Pará Group. Field work and petrographic data seconded by SEM-EDS analysis allowed recognizing an early sodic metasomatism that was followed by calcic-ferric, potassic and propylitic alterations, and finally by carbonatization. The volcanic rocks were altered under deformation regimes that changed from ductile-brittle to brittle. The deposit resulted from two mineralizing stages. The early stage took place at a greater depth and produced an ore association composed chiefly of chalcopyrite, pyrite, and magnetite as disseminations, breccia and veins particularly in Ca-Fe altered rocks. The later stage occurred at a shallower depth and formed a practically magnetite-free ore association, consisting essentially of chalcopyrite ± pyrite ± hematite in breccias and veins generated mostly during the potassic alteration. These ore associations indicate that the hydrothermal system evolved with temperature decrease and increase in fO 2, Cu/Fe ratio and sulfur activity. Cristalino is conceived as a multi-stage IOCG deposit similar to others lying in the Carajás E-W corridor of IOCG systems.

The Altai‐Junggar‐Tianshan collage in southern Altaids is an important metallogenic domain in Central Asia that contain world‐class copper‐iron‐nickel deposits. As an accretionary‐type metallogenic system, the metallogenic processes of the Altai‐Junggar‐Tianshan collage is essential in understanding the genetic mechanism of ore deposits in general. Here in this paper we present a brief introduction to the project on the western part of the Southern Altaids, entitled "The deep structure and metallegenic processes of the North China accretionary metallogenic systems". This project mainly focuses on the deep structure and metallogenic background of the Altai‐Junggar‐Tianshan collage by integrated studies from field geology, structural mapping, geochemistry and geophysical exploration. Multiple new geological and geophysical methods will be applied to make transparency of the Kalatongke and Kalatage ore clusters. This will update our understanding of the geodynamic processes of metallogenesis and lead to the development and foundation of new metallogenic theories in accretionary orogens. [ABSTRACT FROM AUTHOR]