scholarly journals Pre-Pegmatite Stage in Peralkaline Magmatic Process: Insights from Poikilitic Syenites from the Lovozero Massif, Kola Peninsula, Russia

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 974
Author(s):  
Julia A. Mikhailova ◽  
Yakov A. Pakhomovsky ◽  
Olga F. Goychuk ◽  
Andrey O. Kalashnikov ◽  
Ayya V. Bazai ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Kola Peninsula ◽  
Hydrothermal Solution ◽  
Rare Metal ◽  
Lovozero Massif ◽  
Accessory Minerals ◽  
Rare Elements ◽  
Hydrothermal Stage ◽  
Magmatic Stage ◽  
Residual Solution

The Lovozero peralkaline massif (Kola Peninsula, Russia) is widely known for its unique mineral diversity, and most of the rare metal minerals are found in pegmatites, which are spatially associated with poikilitic rocks (approximately 5% of the massif volume). In order to determine the reasons for this relationship, we have investigated petrography and the chemical composition of poikilitic rocks as well as the chemical composition of the rock-forming and accessory minerals in these rocks. The differentiation of magmatic melt during the formation of the rocks of the Lovozero massif followed the path: lujavrite → foyaite → urtite (magmatic stage) → pegmatite (hydrothermal stage). Yet, for peralkaline systems, the transition between magmatic melt and hydrothermal solution is gradual. In the case of the initially high content of volatiles in the melt, the differentiation path was probably as follows: lujavrite → foyaite (magmatic stage) → urtitization of foyaite → pegmatite (hydrothermal stage). Poikilitic rocks were formed at the stage of urtitization, and we called them pre-pegmatites. Indeed, the poikilitic rocks have a metasomatic texture and, in terms of chemical composition, correspond to magmatic urtite. The reason for the abundance of rare metal minerals in pegmatites associated with poikilitic rocks is that almost only one nepheline is deposited during urtitization, whereas during the magmatic crystallization of urtite, rare elements form accessory minerals in the rock and are less concentrated in the residual solution.

scholarly journals Zircon as a Mineral Indicating the Stage of Granitoid Magmatism at Northern Chukotka, Russia

Geosciences ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 194
Author(s):  
Viktor I. Alekseev ◽  
Ivan V. Alekseev
Keyword(s):  
Morphological Evolution ◽  
Rare Metal ◽  
Geochemical Evolution ◽  
Gradual Change ◽  
Granitoid Magmatism ◽  
Mineral Inclusions ◽  
Rare Elements ◽  
Multi Stage ◽  
Magmatic Stage ◽  
Cretaceous Magmatism

A comparative study of the zircon composition and texture in granites of a three-stage Late Cretaceous magmatism in the Chaun area, Chukotka, Russia, was conducted in biotite granites (BG), quartz monzonites-monzogranites (MG), and zinnwaldite granites (ZG). The significance of the study entails determining the mineralogical indicators of similar granitoids in areas of multi-stage petrogenesis. It is shown that in the rock series of Northern Chukotka, BG → MG → ZG, a morphological evolution of zircon takes place: a reduction in size, elongation, a growing complexity of the crystallography, and an individual texture. In later generations of zircon, as a result of the recrystallization and metasomatism, rare-metal overgrowths, defects in the crystal structure, pores and fissures, and mineral inclusions appear, whereas the crystal-face indices and patterns become more complicated. We can observe the geochemical evolution of zircon: a gradual change in the concentration of trace elements (Hf, U, Y, Th, Nb, and Ti), rare earth elements (Yb, Er, and Dy, as well as Ce and Nd), and uncommon elements (Ca and Al). Rare elements (REE, Y, Hf, Nb, U, and Th) at the post-magmatic stage of the regional history acquired economic abundances. Zircon is therefore indicative of productive ore-magmatic systems.

scholarly journals Eudialyte Group Minerals from the Lovozero Alkaline Massif, Russia: Occurrence, Chemical Composition, and Petrogenetic Significance

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1070
Author(s):  
Julia A. Mikhailova ◽  
Yakov A. Pakhomovsky ◽  
Taras L. Panikorovskii ◽  
Ayya V. Bazai ◽  
Victor N. Yakovenchuk
Keyword(s):  
Chemical Composition ◽  
Nepheline Syenite ◽  
Granite Gneiss ◽  
Lovozero Massif ◽  
Eudialyte Group ◽  
Magmatic Stage ◽  
Late Magmatic Stage ◽  
Volcaniclastic Rocks ◽  
Layered Complex ◽  
Alkaline Massif

The Lovozero Alkaline Massif intruded through the Archean granite-gneiss and Devonian volcaniclastic rocks ca. 360 Ma ago and formed a large laccolith-type body. The lower part of the massif (the Layered complex) is composed of regularly repeating rhythms: melanocratic nepheline syenite (lujavrite, at the top), leucocratic nepheline syenite (foyaite), foidolite (urtite). The upper part of the massif (the Eudialyte complex) is indistinctly layered, and lujavrite enriched with eudialyte-group minerals (EGM) prevails there. In this article, we present the results of a study of the chemical composition and petrography of more than 400 samples of the EGM from the main types of rock of the Lovozero massif. In all types of rock, the EGM form at the late magmatic stage later than alkaline clinopyroxenes and amphiboles or simultaneously with it. When the crystallization of pyroxenes and EGM is simultaneous, the content of ferrous iron in the EGM composition increases. The Mn/Fe ratio in the EGM increases during fractional crystallization from lujavrite to foyaite and urtite. The same process leads to an increase in the modal content of EGM in the foyaite of the Layered complex and to the appearance of primary minerals of the lovozerite group in the foyaite of the Eudialyte complex.

scholarly journals Trace and Rare Earth Elements, and Sr Isotopic Compositions of Fluorite from the Shihuiyao Rare Metal Deposit, Inner Mongolia: Implication for Its Origin

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 882
Author(s):  
Zhen-Peng Duan ◽  
Shao-Yong Jiang ◽  
Hui-Min Su ◽  
Xin-You Zhu ◽  
Tao Zou ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Inner Mongolia ◽  
Mining Area ◽  
Rare Metal ◽  
Type I ◽  
Type Ii ◽  
Type Iii ◽  
Hydrothermal Stage ◽  
Magmatic Stage

Abundant fluorites occur in the Shihuiyao rare metal (Nb-Ta-Rb) deposit in Inner Mongolia of NE China, and they can be classified by their occurrence into three types. Type I occurs disseminated in greisen pockets of albitized granite. Type II occurs in the skarn zone between granite and carbonate host rocks, and it can be subdivided into different subtypes according to color, namely dark purple (II-D), magenta (II-M), green (II-G), light purple (II-P), and white (II-W). Type III are the fluorite-bearing veins in the silty mudstones. On the basis of petrography of the fluorites and their high contents of HFSEs (high field strength elements) and LILEs (large ion lithophile elements), strong negative Eu anomalies, and tetrad effects, we suggest that Type I fluorites crystallized in a late-magmatic stage with all the components derived from the granite. The high Y/Ho ratios suggest that the Type II fluorites crystallized in the early- or late-hydrothermal stage. The rare earth elements (REEs) characterized by various Eu anomalies of the Type II fluorites indicate a mixed origin for ore-forming metals from granite-related fluids and limestones, and the oxygen fugacity increased during fluid migration and cooling. Compared to the Type II fluorites, the similar trace element contents of the Type III suggest a similar origin, and remarkable positive Eu anomalies represent a more oxidizing environment. The Sr isotopic composition (87Sr/86Sr)i = 0.710861) of the Type I fluorites may represent that of the granite-derived fluids, whereas the (87Sr/86Sr)i ratios of the Type II (0.710168–0.710380) and Type III (0.709018) fluorites are lower than that of the Type I fluorites but higher than those of the Late Permian-Early Triassic seawater, suggesting a binary mixed Sr source, i.e., granite-derived fluids and marine limestones. Nevertheless, the proportion of limestone-derived Sr in the mixture forming the Type III fluorites is much higher than that of Type II. The rare metal Nb and Ta get into the granite-derived F-rich fluids by complexing with F and precipitate in the form of columbite-group minerals after the Type I fluorites crystallize. Most of Nb and Ta may have deposited as columbite-group minerals during the magmatic stage, resulting in no Nb-Ta mineralization in the hydrothermal stage when the Type II and III fluorites formed. Hence, the Type I fluorites in the Shihuiyao mining area can be used as an important exploration tool for the Nb-Ta mineralization.

scholarly journals Gemology, Mineralogy, and Spectroscopy of an Attractive Tremolitized Diopside Anorthosite Gem Material from the Philippines: A New Type of Material with Similarities to Dushan Jade

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 152
Author(s):  
Xiaomeng Ye ◽  
Feng Bai ◽  
Manyu Li ◽  
Hao Sun
Keyword(s):  
Hydrothermal Solution ◽  
The Philippines ◽  
Vis Spectroscopy ◽  
Raman Microprobe ◽  
Hydrothermal Stage ◽  
Magmatic Stage ◽  
New Type ◽  
Main Color ◽  
Three Stages ◽  
Early Fluid

In recent years, a new type of material called Philippines “Dushan jade” has appeared in the gemstone market in China. This new type of material, very similar in appearance and physical properties to Dushan jade, an important ancient jade with a long history in China, is causing confusion in the market and poses identification difficulties. Microscopy, electron probe microanalysis, Fourier transform infrared (FTIR) spectroscopy, Raman microprobe spectroscopy, and ultraviolet-visible (UV-Vis) spectroscopy were used to study the gemology, mineralogy, and spectroscopy of rock samples from the Philippines in order to differentiate them from Dushan jade. The studies showed that Philippines rock is composed mainly of anorthite and minor amounts of diopside, tremolite, uvarovite, titanite, chromite, zoisite, prehnite, thomsonite-Ca, and chlorite, among which uvarovite, diopside, and tremolite are the main color causing minerals. The origin of the color is related to the electronic transitions involving Cr3+, Fe2+, Fe3+, and charge transfer between the ions. The paragenetic mineral formation sequence of Philippines rock can be divided into three stages: (1) the magmatic stage: anorthite phenocryst, diopside, chromite, and titanite are formed first in the magma; (2) the metamorphic stage: anorthite phenocryst undergo fracture and recrystallization; the early fluid intrusion transforms diopside into tremolite forming uvarovite-grossular-andradite solid-solution around the anorthite and chromite; and (3) the late hydrothermal stage: the late hydrothermal solution fills in fractures with prehnite, thomsonite-Ca, and zoisite being formed. From the comparison studies, it was established that Philippines rock and Dushan jade are two completely different type of material. Philippines rock should be called “tremolitized diopside anorthosite”.

scholarly journals Development of a method for forecasting the potential of placers by formalizing the factors of placer formation based on loparite placers of the Lovozero massif

2020 ◽  
pp. 54-65
Author(s):  
A.V. Lalomov ◽  
◽  
R.M. Chefranov ◽  
Keyword(s):  
Kola Peninsula ◽  
Numerical Evaluation ◽  
Rare Metal ◽  
Lovozero Massif ◽  
Placer Formation

Within the Northern periphery of the Lovozero massif (Kola Peninsula), the authors have identified the main formation factors of proximal (near drift) rare-metal loparite placers. They have performed the formalization (numerical evaluation) of factors; developed multiplicative indicators that reflect the placer potential of territories; and assessed the effectiveness of the developed indicators on the reference objects of the Northern periphery of the massif. The developed method allows automating the process of forecasting of placer parameters.

scholarly journals Mineralization of rare metals in the lakes of East Kazakhstan

2020 ◽  
pp. 16-21
Author(s):  
B. B Amralinova ◽  
O. V Frolova ◽  
I. E Mataibaeva ◽  
B. B Agaliyeva ◽  
S. V Khromykh
Keyword(s):  
Chemical Composition ◽  
Inductively Coupled Plasma ◽  
Digital Terrain Model ◽  
Rare Metal ◽  
Rare Metals ◽  
Inductively Coupled ◽  
Terrain Model ◽  
Digital Terrain ◽  
East Kazakhstan ◽  
Lake Waters

Purpose. Study on the chemical composition of lake waters, salt brines, brine and bottom sediments to identify the mineralization of rare metals and other types of minerals. Methodology. Mass spectrometric studies (mass spectrometer with inductively coupled plasma ICP-MS 7500cx from AgilentTechnologies) for the purpose of high-precision analytical studies on the chemical composition of salt lake water in order to assess the content of rare elements. The use of unmanned aerial vehicles for linking and geometrizing lakes. Findings. Field surveys on the geometrization and linking of lakes were carried out. From the materials obtained with the help of the drone, orthophotoplans were created (with a measurement accuracy of up to 1 centimeter), as well as a digital terrain model and a digital terrain model. A complex of analytical works was carried out using inductively coupled plasma spectrometry. When analyzing the distribution graphs of the absolute content of micro-components in the waters of the lakes of the Delbegeteysky massif, it was found that all samples were enriched with sodium, phosphorus, iron, magnesium and barium. The results of the analyses revealed the predominance of sulfates and chlorides in the composition of the surface waters of most of the water bodies of the Delbegeteysky massif. At the Burabai site, lake waters are characterized by an alkaline reaction of the environment (on average = 8.71). At the same time, the salinity of water bodies varies from 05 to 9 g/dm3. Originality. Large-scale outcrops of granites of the Kalba complex (P1), with which a rare-metal type of mineralization is genetically associated, are known to be on the selected study sites. Quartz-wire-greisen and quartz-wire tin, tin-tungsten and tungsten formations are also widely developed. Considering the large geochemical migration ability of rare alkaline elements in the thickness of loose sediments as a result of intensive geodynamic processes in the East Kazakhstan region, it is possible to assume the possibility of their migration to the upper horizons and accumulation in salt lakes localized within the area of development of granite intrusions of Permian age and associated deep tectonic faults. Practical value. The results of the research can serve as a revival of the rare metal industry in the region, which will allow developing new high-tech industries and creating new jobs in this area. The obtained results can be used for setting up further exploration and operational work on the selected promising areas.

scholarly journals Magmatic and Postmagmatic Mineral Associations of the Malyutka Massif Rocks (Khudolazovkiy Complex of the South Urals)

2021 ◽  
Vol 20 (2) ◽  
pp. 99-109
Author(s):  
I.R. Rakhimov ◽  
Keyword(s):  
Chemical Composition ◽  
Crystallization Temperature ◽  
Equilibrium Temperature ◽  
South Urals ◽  
The South ◽  
Accessory Minerals ◽  
Rock Formation ◽  
Genetic Interpretation ◽  
Mineral Associations ◽  
Ore Minerals

The results of detailed mineralogical studies of the Malyutka massif altered rocks of the Khudolazovskiy differentiated complex are presented. The morphology and chemical composition of many rock-forming and accessory minerals are described. According to the study, the magmatic and post-magmatic (hydrothermal-metasomatic) stages of rock formation are distinguished. The problems associated with the genetic interpretation of a number of rock-forming and ore minerals are discussed. The conclusion about the polygenic nature of the formation of spinelids is made. The equilibrium temperature in the «Ti-magnetite–ilmenite» system (633–650 °C), as well as the crystallization temperature of chlorite, replacing phlogopite and hornblende (145–185 °C), were estimated.

CARYOCHROITE, A NEW HETEROPHYLLOSILICATE MINERAL SPECIES RELATED TO NAFERTISITE, FROM THE LOVOZERO MASSIF, KOLA PENINSULA, RUSSIA

2006 ◽  
Vol 44 (6) ◽  
pp. 1331-1339 ◽  
Author(s):  
P. M. Kartashov ◽  
G. Ferraris ◽  
S. V. Soboleva ◽  
N. V. Chukanov
Keyword(s):  
Kola Peninsula ◽  
Mineral Species ◽  
Lovozero Massif

scholarly journals Zoned Laurite from the Merensky Reef, Bushveld Complex, South Africa: “Hydrothermal” in Origin?

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 373 ◽  
Author(s):  
Federica Zaccarini ◽  
Giorgio Garuti
Keyword(s):  
South Africa ◽  
Hydrothermal Solution ◽  
Layered Intrusion ◽  
Accessory Mineral ◽  
Sulfur Fugacity ◽  
Thermal Range ◽  
Merensky Reef ◽  
Magmatic Stage ◽  
Placer Deposits ◽  
Local Enrichment

Laurite, ideally (Ru,Os)S2, is a common accessory mineral in podiform and stratiform chromitites and, to a lesser extent, it also occurs in placer deposits and is associated with Ni-Cu magmatic sulfides. In this paper, we report on the occurrence of zoned laurite found in the Merensky Reef of the Bushveld layered intrusion, South Africa. The zoned laurite forms relatively large crystals of up to more than 100 µm, and occurs in contact between serpentine and sulfides, such as pyrrhotite, chalcopyrite, and pentlandite, that contain small phases containing Pb and Cl. Some zoned crystals of laurite show a slight enrichment in Os in the rim, as typical of laurite that crystallized at magmatic stage, under decreasing temperature and increasing sulfur fugacity, in a thermal range of about 1300–1000 °C. However, most of the laurite from the Merensky Reef are characterized by an unusual zoning that involves local enrichment of As, Pt, Ir, and Fe. Comparison in terms of Ru-Os-Ir of the Merensky Reef zoned laurite with those found in the layered chromitites of the Bushveld and podiform chromitites reveals that they are enriched in Ir. The Merensky Reef zoned laurite also contain high amount of As (up to 9.72 wt%), Pt (up to 9.72 wt%) and Fe (up to 14.19 wt%). On the basis of its textural position, composition, and zoning, we can suggest that the zoned laurite of the Merensky Reef is “hydrothermal” in origin, having crystallized in the presence of a Cl- and As-rich hydrous solution, at temperatures much lower than those typical of the precipitation of magmatic laurite. Although, it remains to be seen whether the “hydrothermal” laurite precipitated directly from the hydrothermal fluid, or it represents the alteration product of a pre-existing laurite reacting with the hydrothermal solution.

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