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•Two groups of granitoids are differentiated: A1-type alkaline (180–160 Ma) and A2-type aluminous (160–150 Ma).•Group 1 magmas underwent crust–mantle interaction and contributed to ...the Cu-Mo mineralization.•Group 2 magmas experienced strong magmatic differentiation, resulting in W-Sn mineralization.•Group 1 granitoids have fast cooling and uplift rates, Group 2 granites received upper crustal contamination.•A comprehensive model of “centralized mantle upwelling & gradational crustal extension” is proposed.
The central Nanling region in South China was the site of uplift, extensional deformation, granite magmatism and hydrothermal activity from 180 to 150 Ma. Information on the age, petrological characteristics, major and trace element contents, whole rock Sr and Nd and zircon Hf isotopic compositions of granitic plutons were synthesized to constrain the sources, evolutionary processes, and uplift-cooling rates of intrusions that host Cu–Mo and W–Sn deposits in this region. The older (180–160 Ma) Cu–Mo related granitoids are less differentiated, A1 type alkaline rocks with faster cooling and uplift rates. They have younger Nd and Hf two-stage model ages and higher εNd(t) and εHf(t) values that indicate mantle derived magmas were moderately contaminated by upper crust. The younger (160–150 Ma) W–Sn related granites are more differentiated, A2 type aluminous rocks with slower cooling and uplift rates. They have older Nd and Hf two-stage model ages and lower εNd(t) and εHf(t) values that require more upper crustal contamination. The time–space distribution and characteristics of these granitoids and ore deposits are indicative of centralized mantle upwelling and gradational crustal extension. The older rapidly-uplifted, less contaminated granitoids with Cu–Mo mineralization occur near the center of an intra-continental extension bulge produced by mantle upwelling, whereas the younger, slowly-uplifted, more contaminated granitoids with W–Sn mineralization occur on the periphery. The results suggest that metals in the Cu–Mo deposits may have come from the mantle whereas those in the world-class Nanling W–Sn polymetallic deposits were derived from Early Mesoproterozoic (1.4–1.6 Ga) crustal basement of the Cathaysia Block in South China.
The Huangshaping world‐class W–Mo–Cu–Pb–Zn deposit formed during Jurassic intra‐continental extension in the central Nanling region (South Hunan), South China. In order to assess the role of fluids ...in ore genesis and the origin of polymetallic mineralization, three types of mineralized porphyries (quartz porphyry, granophyre, and granite porphyry) were studied. The multi‐method approach included whole‐rock Sr–Nd isotopic geochemistry and determination of the trace element content and gaseous and aqueous composition of ore minerals from the three stages of intrusion and ore emplacement. Geochemical results show that the Sr–Nd isotopes in these altered porphyries were strongly affected by fluid metasomatism. The 87Sr/86Sr and 147Sm/144Nd ratios for the quartz porphyry and granophyre range from 0.72894 to 0.83093 and 0.1524 to 0.2080, respectively, whereas higher and considerably more variable ratios were determined for the granite porphyry (0.90396 to 1.51943 and 0.2391 to 0.2914). These observations imply that granite porphyry‐associated W–Mo mineralization underwent more intensive fluid–rock interaction. The relatively low REE concentrations and high abundances of CH4 and H2 in the Cu ores associated with the quartz porphyry unambiguously suggest a deep‐sourced magmatic fluid for the Cu mineralization. The high REE concentrations, pronounced negative Eu anomalies, M‐type tetrad effects, and high CO2, H2O, and Ca2+ contents of the W–Mo ores associated with the granite porphyry imply that the W–Mo polymetallic mineralization was formed in a relatively oxidizing, high‐temperature environment with strong metasomatism. In contrast, the slightly negative Eu anomalies, W‐type tetrad effects, low CH4, and high F− and Cl− concentrations of the Pb–Zn ores indicate involvement of a sediment‐derived basinal brine and reducing mineralization conditions. Collectively, a three‐stage genetic model is proposed for the Huangshaping polymetallic deposit. Corresponding to initiation, development, and cessation of Jurassic intra‐continental extension, magmatic water, metasomatized fluids, and basinal brines played key sequential roles in Cu, W–Mo, and Pb–Zn mineralization.
The Trepca Pb-Zn-Ag skarn deposit in Kosovo is spatially and temporarily related to the phreatomagmatic breccia of Oligocene age (~23Ma). The deposit shows features typical for skarn deposits ...worldwide, including a stage of isochemical metamorphism, a prograde stage of an anhydrous, low oxygen and low sulfur fugacity character, and a retrograde stage characterized by an increase in the water activity as well as by an increase in oxygen and sulfur fugacities. The mineralization is hosted by the recrystallized Upper Triassic limestone. The prograde mineralization consists mainly of Ca-Fe-Mn + or - Mg pyroxenes. The phreatomagmatic breccia was developed along a NW dipping contact between the ore bearing recrystallized limestone and the overlying schist. It has an inverted cone shape with vertical extension up to 800 m and a diameter of up to 150 m. The upper part of the diatreme is characterized by the presence of a hydrothermally altered rootless quartz-latite dyke surrounded by an unsorted polymict breccia mantle. Despite the alteration processes, the dyke has a preserved porphyritic texture.
Early-intracontinental rifting of Pangea was a result of thermal doming in Uppermost Permian time giving rise to the formation of horst-graben structures, followed by slow subsidence, marine ...transgression and evaporite deposition. The consequences of incipient magmatism and a high heat flow are numerous geothermal fields and subterrestrial hydrothermal siderite-barite-polysulfide deposits (PALINKAS et al., 2016). Advanced rifting magmatism as a successive stage in the Middle Triassic brought intensive submarine volcanism, accompanied by coeval sedimentation of chert and siliciclastics, building up volcanogenic-sedimentary formations. Volcanic activity with explosive phases and the generation of large volumes of pyroclastic rocks in the rifts produced concomitant ization with sedimentary exhalative (SEDEX) deposits of Fe-Mn-Ba-polysulfides. The passive continental margin of northern Gondwanaland is flanked by the AdriaDinaridic carbonate platfom, while the Moesian carbonate platform is a counterpart on the European passive continental margin. They were divergently drifted in the course of the advanced rifting. A fast growing carbonate platform, developing gradually, covered evidence of the earlier intracontinental rifting and their ore formations. However, the carbonate platforms themselves host specific Pb-Zn deposits, well known as a Mississippi valley type, (MVT) or Bleiberg-Mezica type according the traditional european terminology. Triassic MVT and SEDEX deposits are symmetrically situated on the both sides of the divergent passive margins in this early history of the Tethyan ocean. The paper gives a brief description of the MVT and SEDEX deposits, in the two carbonate platforms and rifts in between, formed synchronously and in a similar manner on opposing sides of the diverging continental margin.
The Sasa Pb-Zn-Ag deposit belongs to the group of distal base metal skarn deposits. The deposit is located within the Serbo-Macedonian massif, a metamorphosed crystalline terrain of Precambrian to ...Paleozoic age. The mineralization, hosted by Paleozoic marbles, shows a strong lithological control. It is spatially and temporally associated with the calc-alkaline to shoshonitic post-collisional magmatism that affected the Balkan Peninsula during the Oligocene–Miocene time period and resulted in the formation of numerous magmatic–hydrothermal ore deposits. The mineralization at the Sasa Pb-Zn-Ag deposit shows many distinctive features typical for base metal skarn deposits including: (1) a carbonate lithology as the main immediate host of the mineralization; (2) a close spatial relation between the mineralization and magmatic bodies of an intermediate composition; (3) a presence of the prograde anhydrous Ca-Fe-Mg-Mn-silicate and the retrograde hydrous Ca-Fe-Mg-Mn ± Al-silicate mineral assemblages; (4) a deposition of base metal sulfides, predominately galena and sphalerite, during the hydrothermal stage; and (5) a post-ore stage characterized by the deposition of a large quantity of carbonates. The relatively simple, pyroxene-dominated, prograde mineralization at the Sasa Pb-Zn-Ag skarn deposit represents a product of the infiltration-driven metasomatism which resulted from an interaction of magmatic fluids with the host marble. The prograde stage occurred under conditions of a low water activity, low oxygen, sulfur and CO2 fugacities and a high K+/H+ molar ratio. The minimum pressure–temperature (P–T) conditions were estimated at 30 MPa and 405 °C. Mineralizing fluids were moderately saline and low density Ca-Na-chloride bearing aqueous solutions. The transition from the prograde to the retrograde stage was triggered by cooling of the system below 400 °C and the resulting ductile-to-brittle transition. The brittle conditions promoted reactivation of old (pre-Tertiary) faults and allowed progressive infiltration of ground waters and therefore increased the water activity and oxygen fugacity. At the same time, the lithostatic to hydrostatic transition decreased the pressure and enabled a more efficient degassing of magmatic volatiles. The progressive contribution of magmatic CO2 has been recognized from the retrograde mineral paragenesis as well as from the isotopic composition of associated carbonates. The retrograde mineral assemblages, represented by amphiboles, epidote, chlorites, magnetite, pyrrhotite, quartz and carbonates, reflect conditions of high water activity, high oxygen and CO2 fugacities, a gradual increase in the sulfur fugacity and a low K+/H+ molar ratio. Infiltration fluids carried MgCl2 and had a slightly higher salinity compared to the prograde fluids. The maximum formation conditions for the retrograde stage are set at 375 °C and 200 MPa. The deposition of ore minerals, predominantly galena and sphalerite, occurred during the hydrothermal phase under a diminishing influence of magmatic CO2. The mixing of ore-bearing, Mg-Na-chloride or Fe2+-chloride, aqueous solutions with cold and diluted ground waters is the most plausible reason for the destabilization of metal–chloride complexes. However, neutralization of relatively acidic ore-bearing fluids during the interaction with the host lithology could have significantly contributed to the deposition. The post-ore, carbonate-dominated mineralization was deposited from diluted Ca-Na-Cl-bearing fluids of a near-neutral pH composition. The corresponding depositional temperature is estimated at below 300 °C.
ABSTRACT: In this study, we present systematic petrological, geochemical, LA-ICP-MS zircon U-Pb ages and Nd isotopic data for the A-type granites and syenites from Suizhou-Zaoyang region. The results ...show that the peralkaline A-type granites and syenites were episodically emplaced in Suizhou-Zaoyang region between 450±3 and 441±7 Ma which corresponds to Late Ordovician and Early Silurian periods, respectively. Petrologically, the syenite-peralkaline granite association comprises of nepheline normative-syenite and alkaline granite in Guanzishan and quartz normative syenite and alkaline granite in Huangyangshan. The syenite-granite associations are ferroan to alkali in composition. They depict characteristics of typical OIB (oceanic island basalts) derived A-type granites in multi-elements primitive normalized diagram and Yb/Ta vs. Y/Nb as well as Ce/Nb vs. Y/Nb binary plots. Significant depletion in Ba, Sr, P, Ti and Eu indicates fractionation of feldspars, biotite, amphiboles and Ti-rich augite. The values of
ɛ
Nd
(
t
) in Guanzishan nepheline syenite and alkaline granite are +1.81 and +2.26, respectively and the calculated two-stage model age for these rocks are 1 040 and 1 003 Ma, respectively. On the other hand, the Huangyangshan alkaline granite has
ɛ
Nd
(
t
) values ranging from +2.61 to +3.46 and a relatively younger two-stage Nd model age values ranging from 906 to 975 Ma, respectively. Based on these data, we inferred that the Guanzishan nepheline syenites and granites were formed from fractional crystallization of OIB-like basic magmas derived from upwelling of metasomatized lithospheric mantle. The Huangyangshan quartz syenite and granite on the other hand, were formed from similar magmas through fractional crystallization with low input from the ancient crustal rocks. Typically, the rocks exhibit A1-type granite affinity and classified as within plate granites associated with the Ordovician crustal extension and the Silurian rifting.
The paper presents data about geology, geochemistry, structure, genesis and specific features of the Bučim, porphyry Cu deposit with active mining in Macedonia. The porphyry mineralization (0.3 % Cu, ...0.3-0.5 ppm Au) is spatially and temporarily associated with Tertiary subvolcanic intrusions of latitic and latitic-andesitic composition. The intrusions took place during Oligo-Miocene time (24 to 27 Ma), a period of intensive tectono-magmatic and ore-forming processes..
The latest results of this study to an array of major ore (hypogen) minerals such chalcopyrite, pyrite, magnetite, hematite, cubanite, valleriite, native Au and bornite and secondary enrichment zone minerals (within Čukar ore body) chalcocite, covellite, tenorite, native Cu, malachite, azurite etc added minerals such calaverite, krennerite, electrum, petzite and bismuth±selenium minerals (bismuthinite, galenobismutite, krupkaite, friedrichite, emplectite, cosalite, laitakarite and native bismuth). Variations of the δ34S values for the whole Bučim ore deposit ranged from +0.2 ‰ to +2.5 ‰ while δ13C‰ and δ18O‰ isotope values ranged from -10.8 to -3.8‰ and from +14.0 to +22.7 ‰, respectively. In regards to fluid inclusions it was confirmed that beside dominated gas-liquid, two-phase inclusions, there are also three-phase fluid inclusions (gas + liquid + solid phase). Also, recent Sr and Nd isotope ratios (87Sr/86Sr 0.70666-0.70741 and 143Nd/144Nd 0.512487–0.512489) indicated slight contamination of the magmatic products by continental crust material, due to a partial melting of the deep parts of continental crust underthrusted by collision of continental blocks. In direction were results from the REE data, manifested through high contents of large ion lithophile elements (LILE), high Ba/Nb ratio (116.72-190.72) and depletion in high field strength elements (HFSE) and Europium negative anomaly (0.68893-0.91251).
Allchar ore deposit, a well-known polymetallic mineralisation, is drained by the Majdanska River characterized by elevated concentrations of heavy metals and metalloids, particularly As, Tl and Sb. ...The present study was conducted at the spot of the confluence of spring water, heavily loaded with toxic metals, which joins the Majdanska River by a few meters short stream. The spring water is outflow of underground water drained by passage through polymetallic mineralisation. The chemical characteristics of the Majdanska River water and the associated periphyton were used to evaluate and explain the abiotic response to the intrusion of toxicants and its impact on biota.
At the site of the stream inflow, thorough mixing of Majdanska River water and incoming spring water resulted in an increase of Eh and pH close to the average river value. This geochemical barrier causes significant changes in the mobility of metal species. Moreover, the output composition of water is further modified by biological processes.
The examined biota community was found to consist of algae Audouinella sp. and Spirogyra sp., with coexisting freshwater snails Radix labiata, diatoms and bacteria.
While the carbonate bedrock controls the pH of the river water by effective buffering, it seems that bioconcentration and biomineralisation of algae exerted control on toxicants along the entire river flow. The highest bioconcentration factors were obtained for Fe, Mn and Ti which implies the biomineralisation of iron as a product of extracellular deposition on the cell walls on the organic matrices. Bioconcentration of As, Cr, Cs, Cu and Se was more important in Audouinella sp., while Cd, Co, Sr, and Zn preferentially accumulated in Spirogyra sp. High accumulation of Ba (3 mg/g d.w.) in Spirogyra sp. was associated with the intracellular biomineralisation. These findings suggest the potential use of Spirogyra sp. in the remediation of waters polluted by barium or as the biological pathfinder indicator for metal deposits associated with barite.
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•Interaction of acid mine drainage and biota in the Majdanska River water•Geochemical barrier at mixing point causes changes in mobility of metal species.•Output composition of water further modified by biological processes•Algae exerted control on toxicants along the entire river flow.•High accumulation of Ba (3 mg/g d.w.) in Spirogyra sp. due to biomineralisation
The Dinaridic metallogenic province is a part of the Alpine–Himalayan orogenic system, developed as a result of opening and closure of the Tethys Ocean by convergence of the African and Eurasian ...plates. The northern boundary of the Dinarides is related to the northern African margin (Adria–Apulia). The Tisia mega-unit, a small continental block, positioned between the Dinarides and the Carpathians, is genetically related to the South Eurasian edge.
The geology of the Dinarides is constrained by the Alpine Wilson cycle. The major stages of the cycle are: (a) Permian early intra-continental rifting; (b) Triassic advanced rifting; (c) Jurassic oceanization; (d) Cretaceous subduction; (e) Paleogene collision; and (f) Neogene post-collision and extension followed by orogenic collapse. Each stage creates characteristic ore deposits related to the specific geological environments. Stage (a) bears hydrothermal siderite–barite–polysulphide deposits, epigenetic sedimentary uranium deposits, red bed-type, sabkha-type copper and barite deposits and evaporites. Stage (b) favored SEDEX and hydrothermal iron–polysulphide–barite–mercury and MVT deposits. Stage (c) developed chromites, asbestos, talc and magnesite deposits. The spatial position of stage (d) remains poorly constrained. The Southern Tisia unit might be a possible candidate for the Tethyan active continental margin with the Cretaceous subduction zone positioned beneath. Absence of voluminous subduction-related magmatism and mineral deposits, however, favors subduction within the Vardar zone (the easternmost Dinarides), adjoined to the Serbomacedonian ensialic terrain with its large Cu-porphyry deposits. Stage (e) was a prelude to the prolific phase (f) with its numerous hydrothermal Pb, Zn and Sb deposits that mostly occur in the western Vardar zone. The geology and metallogeny of Southern Tisia, with medium/high grade metamorphics, I-type, S-type granites, resembles the Middle Austro-Alpine unit, formed during the main Carboniferous collisional stage.
This contribution provides a review of the metallogenic characteristics of the Northwestern and Central Dinarides and Southern Tisia mega-units, based on recently-gained knowledge on the regional geology, petrology and genesis of mineral deposits. Establishment of the plate tectonic model several decades ago greatly contributed to an integrated interpretation of ore deposit genesis. In turn, basic research in the field of ore genesis generated new data that can be used to improve the plate tectonic model.
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