Geochemical investigation of the lower crustal rocks in Bamble Shear Belt, southern Norway: Implications for the source of gold in lode gold deposits.

The source of gold in lode gold deposits in metamorphic terrains is debatable. As a test of the "deep source model", the Bamble Shear Belt of southern Norway was studied. A transition from amphibolite to granulite facies takes place over the 30 km width of the Shear Belt. Some 400 samples from various rock units across the Belt were analyzed for a wide range of elements. The results, combined with petrographic studies and data from elemental and isotopic composition of sulfides, are interpreted with emphasis on the processes that have affected the distribution of gold. The oldest exposed rocks in Bamble are a sequence of sedimentary and volcanic materials of early- to mid-Proterozoic age. During the Kongsbergian, or Gothian, orogeny (1600--1450 Ma), all the supracrustal rocks were intruded by a suite of acid-intermediate magmas, and a series of basic dykes and sills known as metabasites. The highest grade portion of Bamble is dominated by tonalitic-trondhjemitic charnockites and subordinate metabasites and metasediments. All rocks in this zone are strongly depleted in LILE, LREE, and HFSE relative to their equivalent rocks from amphibolite and transition zones. Depletion of the elements can be explained by the presence of a CO2-rich fluid during magmatic crystallization, or metamorphic recrystallization. Both metabasites and hyperites are of low-Mg tholefitic nature (MgO < 10%), and bear features typical of destructive margin settings. On MORB-normalized plots, they exhibit marked enrichments in LILE and LREE. The absence of Mg-rich cumulates argues against a functional crystallization model. Both series are the products of low degrees of partial melting. Supracrustal rocks of varied type and origin in Bamble are strongly depleted in Au, As, Sb, and Se relative to the crustal abundance of these elements. The average Au in the Bamble rocks, 0.35 ppb, is only 25% of the crustal abundance of this element. Charnockites are also depleted in Au, As, Sb, and Se. The mean value of Au in these rocks (0.2 ppb) is 20% of the general abundance of this element in felsic rocks elsewhere. Lode gold deposits are commonly associated with alkaline and light REE metasomatism, and a significant enrichment in As, Sb, and Se. Neither special Au-enriched rocks, nor unreasonably large volumes of source rocks are required to produce a giant gold deposit. Shear zones serve as major source areas and principal conduits for extraction and transportation of Au. (Abstract shortened by UMI.

Geology, mineralogy and ore fluid characteristics of the Masjed Daghi gold bearing veins system, NW Iran

Introduction The Masjed- Daghi gold deposit lies in an area of widespread Cenozoic volcanic and plutonic rocks at the intersection of the Alborz- Azarbaijan and Urumieh- Dokhtar belts. The area was covered by a detailed exploration program, including geological maps at 1:1,000 scales (~8 km²), several hundred meters of trenches and systematic sampling for Au, Ag, Pb, Zn, Cu, As, Hg analysis, and 16 diamond drill holes at a total of 1200 meters (Mohammadi et al, 2005). The vein type gold deposit in Masjed- Daghi is closely associated with a porphyry type Cu-Au deposit. Our study focuses on the gold bearing veins system in an attempt to understand the characteristics of ore fluids and mechanisms of ore formation, and to develop exploration criteria for Masjed Daghi and similar occurrences in Alborz and other Cenozoic magmatic assemblages in Iran. Materials and methods Various rock types, alteration assemblages and mineral parageneses were characterized by transmitting and reflected light microscopy, X-ray diffraction (XRD) and electron microprobe analysis. Microprobe analyses were performed using a JEOL 8600 Superprobe electron microprobe at Saskatchewan University. Operating conditions were an accelerating voltage of 15 kV and a beam current of 50 nA. Representative samples from drill holes were selected for fluid inclusion studies. Fluid inclusion data were obtained using a fluid Inc. adapted USGS gas flow heating and freezing system at the Department of Geological Science at the University of Saskatchewan, Canada. To investigate the source of ore fluids, representative sulfidic samples from drill holes were selected for sulfur isotope studies. Isotopic analyses were performed using a Thermo Finnigan DeltaPlus at the G.G. Hatch Stable Isotope Laboratories, University of Ottawa. The standard error of analyses is less than ±0.1 per mil. Results Auriferous quartz veins in Masjed- Daghi are associated with porphyry style mineralization. Various alteration assemblages including argillic, silicic, potassic, phyllic, and propylitic occur in the district (Emamalipour et al., 2010). The auriferous quartz veins are hosted by silicified and kaolinitized volcanic rocks, dominated by trachyandesite. The mean grade of Cu is 0.15% the gold assay varies from <2 to 30 ppm. The veins were covered by 16 diamond drill holes, and the drill cores were analyzed for Au, Ag, Mo, Cu, Hg, As, Pb, Zn and Sb (Mohammadi et al, 2005). The V3 vein, about 700 m long, and on the average 5 m wide, is the largest vein in the district. Two types of quartz occur in the veins: an early medium to coarse grained grey quartz joined by milky quartz in later stages. Ore minerals include chalcopyrite, galena, and sphalerite. Fluid inclusion data from the ore stage quartz and sphalerite yielded Th values in the range 123-298 and 112-218 oC, and salinities in the range 1.9-12.8 and 1.9-11.2wt% NaCl equivalent. The wide range in salinity can be explained by mixing of two fluids with different salinities, and/or condensation of vapor. The δ34S values for pyrite, galena and sphalerite from the main mineralization stage, fall in a narrow range around (-0.2 to -1.1 per mil) around 0.0 permil, implying a magmatic source for sulfur. Discussion Hydrothermal activity in the Masjed Daghi epithermal veins can be divided into two stages: an early stage of acid leaching that is responsible for vuggy silica and advanced argillic alteration, and a later stage when gold and sulfide minerals were deposited. Considering the ore mineralogy and hydrothermal alteration products (the occurrence of barite in the veins, low Pb and Zn contents, lack of carbonates), the Masjed Daghi can be classified as a high- sulfidation epithermal vein system. In most high sulfidation systems, ore fluid is considered to be of a mixed magmatic- meteoric origin, resulting from the adsorption of magmatic vapors or brines by shallow meteoric water (Hedenquist et al, 2000). The involvement of a magmatic fluid component in Masjed Daghi is supported by the sulfur isotope ratios, the relatively high salinity and oxidizing nature of ore fluids, as well as the large variation in salinity, 1.9- 12.8 wt% NaCl equivalent, that can be explained by concurrent boiling and condensation of vapor, fluid mixing. Acknowledgments We thank J. Fan, and T. Bonli of the University of Saskatchewan for assistance with electron microprobe analysis, and colleagues at GG-Hatch stable isotope laboratories, University of Ottawa, for sulfur isotope analysis. Financial support for the work was supplied by Geological Survey of Iran, and NSRC grant to Y.P. References Emamalipour, A., Abdoli Eslami, H. and Hajalilou, B., 2010. Geochemistry investigation of hydrothermal alteration related to gold epithermal mineralization in the Masjed Daghi area, west Julfa, northwest Iran. Journal of Economic Geology, 3(2): 199-213. (in Persian with English abstract) Hedenquist, J.W., Arribas, A. and Gozales-Urien, E., 2000. Exploration for epithermal gold deposits. In: S.G. Hagemann and P.E. Brown (Editors), Reviews in Economic Geology. Society of Economic Geologists, Special Publication 13, Littleton, pp. 245- 277. Mohammadi, B., Aliakbari, H., Fard., M. and Samaee, A., 2005. Geology and drilling report of Masjed Daghi area (scale 1:1000). Geological Survey of Iran, Tehran, Report 340, 130 pp. (in Persian

Study of Petrogenesis, Modeling And Involved Fluids in Igneous Rocks in The area of Tanurjeh Deposit

Tanurjeh porphyry copper-gold deposit is located in Khorasan Razavi province, south of Neishabour and 5 km south of Tanurjeh village. The types of rocks in the study area include andesite, porphyry diorite, quartz porphyry diorite, porphyry granodiorite, rhyolite, rhyodacite and tuff, and metal minerals include magnetite, chalcopyrite, pyrite, iron oxides and hydroxides, covellite, malachite, galena, sphalerite, malachite, rutile and gold particles. To accurately detect copper and gold anomalies from the field, the fractal geometry-number method was used. A combination of exploratory layers was performed to identify suitable areas for exploratory drilling. To determine the temperature of the deposit formation and its chemical properties, salinity of the trapped fluids was taken. Evaluation of the involved fluids indicates that the primary fluids have high salinity and the secondary fluids have medium salinity and primary fluids homogenize at 319 to 514 ° C and secondary fluids at 138 to 345 ° C. These results show the mineralization of copper and gold in terms of porphyry system type and mineralization can continue to depths of more than 350 meters. However, the absence of stock quartz veins, the presence of a large siliceous zone and the lack of mineralization of copper are some of the things that make a difference compared to porphyry copper systems. As a result, this area can be considered as a porphyry copper-gold mineralization area in which mineralization has been done in depth and in the vicinity of the intrusion mass and in some places points are seen as streaks on the surface

Application of chemical factors for acceleration of consolidation phase of the distraction osteogenesis: a scoping review

Purpose This study aimed to analyze the effect of injecting chemical factors compared to conventional distraction osteogenesis (DO) treatment on the bone formation of the distracted area of the maxillofacial region in human and animal studies. Method Electronic search was done in PubMed, Scopus, Embase, and Cochrane database for studies published until September 2021. The studies’ risk of bias (ROB) was assessed using the Cochrane Collaborations and NIH quality assessment tools. Meta-analyses were performed to assess the difference in the amount of bone formation and maximal load tolerance. Results Among a total of 58 included studies, eight studies analyzed the bone formation rate of the distracted area in human models and others in animal models. Results of the human studies showed acceptable outcomes in the case of using bone morphogenic protein-2 (BMP-2), autologous bone-platelet gel, and calcium sulfate. However, using platelet reach plasma does not increase the rate of bone formation significantly. Quantitative analyses showed that both BMP-2 (SMD = 26.57; 95% CI = 18.86 to 34.28) and neuron growth factor (NGF) (SMD = 16.19; 95% CI = 9.64 to 22.75) increase the amount of bone formation. Besides, NGF increased the amount of load tolerance significantly (SMD = 30.03; 95% CI = 19.91 to 40.16). Additionally, BMP-2 has no significant impact on the post-treatment maxillary length (SMD = 9.19; 95% CI =  − 2.35 to 20.73). Conclusion Limited number of human studies with low quality used chemical factors to enhance osteogenesis and showed acceptable results. However, more studies with higher quality are required

Age revision of the Neotethyan arc migration into the southeast Urumieh-Dokhtar belt of Iran: Geochemistry and U–Pb zircon geochronology

The Urumieh-Dokhtar magmatic belt of Central Iran runs parallel to the Zagros orogenic belt and has been resulted from Neotethys ocean subduction underneath Eurasia. The Bahr Aseman volcanic-plutonic complex (BAC), covering an area ~ 2000 km^2 in the Kerman magmatic belt (KMB) in the southern section of the Urumieh-Dokhtar belt, has long been considered as the earliest manifestation of extensive Cenozoic arc magmatism in KMB. The nature and timing of the magmatism, however, is poorly constrained. An area ~ 1000 km^2, in BAC and adjacent Razak volcaniclastic complex and Jebal Barez-type granitoids, was mapped and sampled for geochemistry and geochronology. Andesite and basaltic andesite are the main volcanic components in the study area; plutonic bodies vary from tonalite to quartz diorite, granodiorite and biotite-granite. The rocks in BAC display dominantly normal calc-alkaline character. On spider diagrams, the rocks are characterized by enrichments in LILE relative to HFSE and enrichments in LREE relative to HREE. These features suggest a subduction related setting for the BAC. La_N/Yb_N ratios for the intrusive and volcanic rocks range from 1.41 to 5.16 and 1.01 to 6.42, respectively. These values are lower than those for other known granitoids in KMB, namely the abyssal, dominantly Oligocene Jebal Barez-type (La_N/Yb_N = 1.66–9.98), and the shallow, dominantly late Miocene Kuh Panj-type (La_N/Yb_N = 12.97–36.04) granitoids. This suggests a less evolved magma source for the BAC igneous rocks. In Y vs. Nb and Th/Yb vs. La/Yb discrimination diagrams, an island-arc setting is defined for the BAC rocks. The rocks further plot in primitive island-arc domain in Nb vs. Rb/Zr and Y/Nb vs. TiO_2 diagrams. The BAC volcanic and plutonic rocks yielded zircon U–Pb ages of 78.1 to 82.7 Ma and 77.5 to 80.8 Ma, respectively. Zircon U–Pb dating of volcanic rocks and granitoids from the adjacent Razak complex and the Jebal Barez-type granitoids indicated 48.2 Ma and 26.1 Ma ages, respectively, consistent with earlier works on similar rocks elsewhere in KMB. The new data allow a revision of the chronostratigraphy/tectonic history of KMB. In Late Cretaceous, a back arc rift developed extending from Nain to Baft (NB back arc) to the northeast of the Sanandaj-Sirjan magmatic arc. Along with shrinking of the Neotethys Ocean, the dip angle of the subducting slab decreased during the Late Cretaceous, and arc magmatism moved from the Sanandaj-Sirjan zone landward. Meanwhile, Bahr Aseman volcanic-plutonic complex formed as an island-arc in NB back arc rift. Later with arc shift, due to shallowing of subducted slab, magmatism moved toward continent leading to extensive volcanism in Kerman magmatic arc during Eocene and Oligocene, represented by volcanic-sedimentary Razak and Hezar Complexes, respectively

Multiple Stage Ore Formation in the Chadormalu Iron Deposit, Bafq Metallogenic Province, Central Iran: Evidence from BSE Imaging and Apatite EPMA and LA-ICP-MS U-Pb Geochronology

The Chadormalu magnetite-apatite deposit in Bafq metallogenic province, Central Iran, is hosted in the late Precambrian-lower Cambrian volcano-sedimentary rocks with sodic, calcic, and potassic alterations characteristic of iron oxide copper-gold (IOCG) and iron oxide-apatite (IOA) ore systems. Apatite occurs as scattered irregular veinlets and disseminated grains, respectively, within and in the marginal parts of the main ore-body, as well as apatite-magnetite veins in altered wall rocks. Textural evidence (SEM-BSE images) of these apatites shows primary bright, and secondary dark areas with inclusions of monazite/xenotime. The primary, monazite-free fluorapatite contains higher concentrations of Na, Si, S, and light rare earth elements (LREE). The apatite was altered by hydrothermal events that led to leaching of Na, Si, and REE + Y, and development of the dark apatite. The bright apatite yielded two U-Pb age populations, an older dominant age of 490 ± 21 Ma, similar to other iron deposits in the Bafq district and associated intrusions, and a younger age of 246 ± 17 Ma. The dark apatite yielded a U-Pb age of 437 ± 12 Ma. Our data suggest that hydrothermal magmatic fluids contributed to formation of the primary fluorapatite, and sodic and calcic alterations. The primary apatite reequilibrated with basinal brines in at least two regional extensions and basin developments in Silurian and Triassic in Central Iran

Zircon U–Pb and molybdenite Re–Os geochronology, with S isotopic composition of sulfides from the Chah-Firouzeh porphyry Cu deposit, Kerman Cenozoic arc, SE Iran

The Chah-Firouzeh deposit with about 100 Mt ore reserves @ 0.5% Cu is a porphyry copper deposit located 14 km west of the Meiduk deposit in the northern section of the Kerman Cenozoic Magmatic Assemblage (KCMA), southeastern Iran. The mineralization is associated with a porphyry quartz-monzodiorite to quartz-diorite stock, which intruded into Eocene volcanic rocks consisting of andesite, basalt, and andesitic to dacitic tuff. Hydrothermal alteration types in the area include potassic, phyllic, and propylitic varieties. Silicic alteration locally occurred at the surface, while supergene argillic alteration overprinted the other alterations at shallow levels. Mineralization occurs as quartz-sulfide veinlets and stockworks, as well as disseminations in the porphyry body and volcanic host rocks, in association with potassic and phyllic alteration. Hypogene minerals in the deposit include pyrite, chalcopyrite, magnetite, molybdenite, and bornite. Supergene enrichment is irregularly developed in the Chah-Firouzeh deposit. Zircon U–Pb dating of two representative samples from the Chah-Firouzeh porphyry stock yielded emplacement ages of 16.9 ± 0.4 Ma and 16.5 ± 0.2 Ma, respectively. The Early-Middle Miocene epoch marks the most important period of porphyry Cu mineralization in the KCMA. During this period, many adakitic magmas intruded the Eocene volcano-sedimentary sequences and formed some of the largest porphyry copper deposits in Iran, such as Sarcheshmeh and Meiduk. Molybdenite Re–Os dating on two samples separated from “B and D type” veinlets show that mineralization occurred at 16.60 ± 0.06 Ma and 15.99 ± 0.06 Ma, implying a time span of about 0.6 Ma for mineralization. The δ^(34)S values for molybdenite, chalcopyrite, and pyrite from “A, B, and D type” veinlets vary from −1.4 to +2.5‰ suggesting a magmatic source for sulfur. The calculated temperatures for sulfide pairs are compatible with those obtained from fluid inclusion microthermometry and show isotope equilibrium due to fluid evolution