Mkango Advances To Phase II Of Neodymium Alloy Project With Metalysis And Raises £500,000 In Placing

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Calgary, Alberta: September 29, 2017 – Mkango Resources Ltd. (AIM / TSX-V: MKA) (the \’Company\’ or \’Mkango\’) is pleased to announce that it has commenced Phase II of its research and development (\’R+D\’) programme with Metalysis Limited (\’Metalysis\’) and has raised £500,000 (C$833,333) at 3.5 pence (C$0.058) per share in a placing (t

Zircon U–Pb geochronology and geochemistry of Devonian plagiogranites in the Kuerti area of southern Chinese Altay, northwest China: Petrogenesis and tectonic evolution of late Paleozoic ophiolites

This study presents zircon U–Pb geochronology with major, trace, rare earth element and Sr–Nd isotope geochemistry for plagiogranite dyke swarms occurring within the gabbro unit of the lower part of the Kuerti ophiolite in southern Chinese Altay, Northwest China. These intrusive plagiogranites cut across the metamorphic zone consisting of amphibolites that are related to hydrothermal alteration and shearing of gabbros. LA-ICP-MS zircon U–Pb dating of 2 plagiogranite samples yields approximately 390 Ma age of origin. They are geochemically characterized by relatively high SiO2 and Na2O, low K2O, TiO2, and Al2O3 contents, with marked enrichment in light rare earth elements and depletion in Nb, Ta, and Ti. They have slightly higher initial 87Sr/86Sr ratios (0.7040 to 0.7049), lower εNd(t) values (+3.6 to +6.3), and higher Th contents (2.84–11.9 ppm) than those (0.7034 to 0.7048, +7.2 to +10.3, and 0.04 to 1.79) of closely associated amphibolites. Geological and geochemical attributes suggest that the plagiogranites were generated by the anatexis of hydrated and hydrothermally altered amphibolites and minor sediments from oceanic crust during shearing at low pressure (<0.1 GPa) and temperature (<850 °C) conditions in a suprasubduction zone setting. The ridge subduction at approximately 390 Ma caused the upwelling of the hot asthenosphere and triggered the spreading of the Kuerti back-arc basin, followed by the formation of the plagiogranites in the Kuerti ophiolite.

Stanniferous magnetite composition from the Haobugao skarn Fe–Zn deposit, southern Great Xing’an Range: Implication for mineral depositional mechanism

The Great Xing’an Range in north-eastern China hosts numerous super-large Ag–Pb–Zn deposits and some Fe–Sn deposits. The Mesozoic Haobugao Fe–Zn polymetallic skarn deposit in the southern Great Xing’an Range is contemporaneous with the regional Ag–Pb–Zn mineralization. Numerous ore bodies are hosted in the Lower Permian carbonate strata or along the contact with the Early Cretaceous granite. According to the field and systematic petrography and mineralography research, the Haobugao mineralization phases are divided into 3 paragenetic stages: prograde stage, retrograde stage, and sulphide stage. Magnetite mainly occurred in the retrograde stage and replaced the anhydrous skarn minerals (e.g., garnet and diopside). Two types of magnetite (Mag1 and Mag2), including 6 subtypes, can be distinguished based on the scanning electron microscopy and back scattered electron images. Electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometer analysis were used to determine major and trace elements in different types of magnetite. Mag1 has higher Ti and V concentrations than Mag2, indicating a relatively higher depositional temperature. Mag1 also contains relatively higher Mg and Mn concentrations, coupled with much lower Si and Al concentrations, which reflects a low fluid/rock ratio at the site of Mag1 deposition. Element variation features of Mag1 and Mag2 reveal that the Haobugao mineralization fluids gradually evolved from high-temperature and low fluid/rock ratio fluids to relatively low-temperature and high fluid/rock ratio fluids. However, electron probe microanalysis data of Mag2 display significantly higher Sn concentrations (up to 2.82 wt.%) than that in Mag1, which indicates that Sn can be incorporated into magnetite crystal lattice. We propose a possible substitution mechanism of Sn4+ + Mn2+ = 2Fe3+, supported by the strongly positive correlation between Sn4+ and Mn2+, whereby a substitution of Sn4+ for Fe3+ in octahedral sites of magnetite requires a compensatory substitution of Mn2+ for Fe3+ to maintain the charge balance.