scholarly journals Thorium, uranium and rare earth mineralization in rocks of the Ugakhan gold deposit, Bodaibo ore region (Irkutsk oblast)

2021 ◽  
pp. 78-93
Author(s):  
E.V. l Shepe ◽  
N.R. Ayupova ◽  
M.A. Rassomakhin ◽  
P.V. Khvorov
Keyword(s):  
Thermal Analysis ◽  
Rare Earth ◽  
Gold Deposit ◽  
Greenschist Facies ◽  
Irkutsk Oblast ◽  
Formation Temperature ◽  
Carbonaceous Matter ◽  
Ree Mineralization ◽  
Carbonaceous Shales ◽  
Chlorite Geothermometer

The paper reports on the results of studies of ore-bearing rocks of the Ugakhan gold deposit (Bodaybo district): metasandstones, metasiltstones and carbonaceous shales. The rocks consist of quartz, feldspar (albite, orthoclase), Fe-Mg chlorite, mica (muscovite, sericite) and carbonates (calcite, dolomite, anker-ite) and accessory titanite, rutile, tourmaline, zircon and apatite. All rocks contain fragments of microfossils exhibiting striking concentric zonation with alternated dark (carbonaceous matter) and light (carbonate-mica material) layers. In a range from metasandstones to carbonaceous shales, the rocks exhibit an increase in mica amount and the content (up to 3%) of carbonaceous matter, as well as the formation of regeneration rims around relict tourmaline and zircon. The REE mineralization includes silicates (REE-bearing epidote, thorite), fuorocarbonates (bastnesite) and phosphates (monazite, xenotime, ankylite), which are closely related to U minerals (uraninite, cofnite). Bastnesite, ankylite and thorite formed due to the decomposition of earlier REE-bearing epidote, whereas monazite and xenotime are the products of decomposition of apatite. Uraninite formed during lithifcation of matrix of carbon-bearing rocks and is replaced by cofnite. The thermal analysis of carbonaceous matter and the formation temperature of chlorite calculated using chlorite geothermometer (296–371 °С) indicate the transformation of rocks under conditions of sericite-chlorite subfacies of greenschist facies of metamorphism.

Synthesis, Spectral Characterization and Luminescent Properties of Ternary Rare Earth Nitrates Complexes with 2-Acetylpyridine-tris(2-aminoethyl)amine and Pyridine-N-oxide Ligand

2011 ◽  
Vol 322 ◽  
pp. 337-340
Author(s):  
Lian Cai Du
Keyword(s):  
Thermal Analysis ◽  
Rare Earth ◽  
Luminescent Properties ◽  
Ternary Complexes ◽  
Molar Conductivity ◽  
Lanthanide Ions ◽  
Fluorescent Properties ◽  
Tripodal Ligand ◽  
Rare Earth Nitrates ◽  
The Eu

A tripodal ligand, 2-acetylpyridine-tris(2-aminoethyl)amine (L), pyridine-N-oxide and their ternary complexes with rare earth nitrates have been synthesized. These new complexes with the general formula of Ln·L·PyNO·(NO3)3·nH2O (where Ln = La, Nd, Tb, Pr, Eu, n = 1~3 ) were characterized by elemental analysis, IR spectra, thermal analysis and molar conductivity. All the complexes are stable in air. The results show that the lanthanide ions in each complex are coordinated by nitrogen atoms of the ligand, oxygen atoms of PyNO and the nitrates. The fluorescent properties of the Eu(III) and Tb(III) complexes in solid were investigated.

scholarly journals Geology and U-Th-Pb Dating of the Gakara REE Deposit, Burundi

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 394 ◽  
Author(s):  
Seconde Ntiharirizwa ◽  
Philippe Boulvais ◽  
Marc Poujol ◽  
Yannick Branquet ◽  
Cesare Morelli ◽  
...  
Keyword(s):  
Rare Earth ◽  
Lake Tanganyika ◽  
Hydrothermal Activity ◽  
Field Observations ◽  
Upper Crust ◽  
East African ◽  
Geochronological Data ◽  
Ree Mineralization ◽  
Pan African ◽  
African Rift

The Gakara Rare Earth Elements (REE) deposit is one of the world’s highest grade REE deposits, likely linked to a carbonatitic magmatic-hydrothermal activity. It is located near Lake Tanganyika in Burundi, along the western branch of the East African Rift. Field observations suggest that the mineralized veins formed in the upper crust. Previous structures inherited from the Kibaran orogeny may have been reused during the mineralizing event. The paragenetic sequence and the geochronological data show that the Gakara mineralization occurred in successive stages in a continuous hydrothermal history. The primary mineralization in bastnaesite was followed by an alteration stage into monazite. The U-Th-Pb ages obtained on bastnaesite (602 ± 7 Ma) and on monazite (589 ± 8 Ma) belong to the Pan-African cycle. The emplacement of the Gakara REE mineralization most likely took place during a pre-collisional event in the Pan-African belt, probably in an extensional context.

Fluid Inclusions and Rare Earth Elements of the Badu Gold Deposit, Guangxi, China: Implications for Mineralization

2014 ◽  
Vol 88 (s2) ◽  
pp. 1118-1119 ◽  
Author(s):  
Peirong LI ◽  
Baocheng PANG ◽  
Baohua WANG ◽  
Yuanqiang LI ◽  
Yequan ZHOU ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Gold Deposit ◽  
Fluid Inclusions

scholarly journals Rare earth element mobility in and around carbonatites controlled by sodium, potassium, and silica

2020 ◽  
Vol 6 (41) ◽  
pp. eabb6570 ◽  
Author(s):  
Michael Anenburg ◽  
John A. Mavrogenes ◽  
Corinne Frigo ◽  
Frances Wall
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Element Mobility ◽  
Sodium Potassium ◽  
Ree Mineralization ◽  
Anionic Species ◽  
Ree Mobility ◽  
Modern Technologies

Carbonatites and associated rocks are the main source of rare earth elements (REEs), metals essential to modern technologies. REE mineralization occurs in hydrothermal assemblages within or near carbonatites, suggesting aqueous transport of REE. We conducted experiments from 1200°C and 1.5 GPa to 200°C and 0.2 GPa using light (La) and heavy (Dy) REE, crystallizing fluorapatite intergrown with calcite through dolomite to ankerite. All experiments contained solutions with anions previously thought to mobilize REE (chloride, fluoride, and carbonate), but REEs were extensively soluble only when alkalis were present. Dysprosium was more soluble than lanthanum when alkali complexed. Addition of silica either traps REE in early crystallizing apatite or negates solubility increases by immobilizing alkalis in silicates. Anionic species such as halogens and carbonates are not sufficient for REE mobility. Additional complexing with alkalis is required for substantial REE transport in and around carbonatites as a precursor for economic grade-mineralization.

scholarly journals Determination of Au(III) and Ag(I) in Carbonaceous Shales and Pyrites by Stripping Voltammetry

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 78 ◽  
Author(s):  
Nina Kolpakova ◽  
Zhamilya Sabitova ◽  
Victor Sachkov ◽  
Rodion Medvedev ◽  
Roman Nefedov ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
High Pressures ◽  
Silver Content ◽  
Background Electrolyte ◽  
Stripping Voltammetry ◽  
Gold Content ◽  
Carbonaceous Matter ◽  
Standard Samples ◽  
Carbonaceous Shales

Techniques of stripping voltammetry (SV) determination of silver and gold in pyrites and carbonaceous matter are developed. The problem of quantitative transfer of the analytes into the solution is solved. For this purpose, the ore matrix of carbonaceous shales was decomposed by mineral acids in autoclaves at high pressures. The element to be determined from the sample matrix was separated by extraction. Ag(I) ions from the solutions were extracted in the form of a dithizonate complex in CCl4. Au(III) ions were extracted by diethyl ether. The extracts were decomposed thermally. The dry residue was dissolved in the background electrolyte, and the element was determined by the SV method. The graphite electrode (GE) impregnated with polyethylene was used as a working electrode in the SV determination of silver. The SV determination of gold was carried out using a GE modified by bismuth. The limits of detection (LOD) of Ag(I) and Au(III) contents were equal to 0.016 mg L−1 and 0.0086 mg L−1, respectively. The results of SV determination of gold and silver in standard samples, pyrites, and carbonaceous shales were presented. The silver content in the pyrite was 13.6 g t−1, and in carbon shale it was 0.34 g t−1. The concentration of gold in the pyrite of the Kirovsko–Kryklinskaya ore zone was 1.15 g t−1, while in carbonaceous shales it was 2.66 g t−1. The obtained data were consistent with the data of atomic emission spectroscopy (AES) and inductively-coupled plasma mass spectrometry (ICP–MS). The error of determination of elements by stripping voltammetry was calculated as ranging from 10 to 6 g t−1 (less than 12%) in pyrite and carbonaceous material when determining the silver content, and from 1 to 3 g t−1 (less than 22%) when determining the gold content in pyrite and carbonaceous matter.

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