scholarly journals The Petyayan-Vara Carbonatite-Hosted Rare Earth Deposit (Vuoriyarvi, NW Russia): Mineralogy and Geochemistry

Minerals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 73 ◽  
Author(s):  
Evgeniy Kozlov ◽  
Ekaterina Fomina ◽  
Mikhail Sidorov ◽  
Vladimir Shilovskikh ◽  
Vladimir Bocharov ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Late Stage ◽  
Rock Type ◽  
Ti Oxides ◽  
Metasomatic Event

The Vuoriyarvi Devonian carbonatite–ijolite–pyroxenite–olivinite complex comprises several carbonatite fields: Neske Vara, Tukhta-Vara, and Petyayan-Vara. The most common carbonatites in the Tukhta-Vara and Neske-Vara fields are calciocarbonatites, which host several P, Fe, Nb, and Ta deposits. This paper focuses on the Petyayan-Vara field, in which the primary magmatic carbonatites are magnesian. The least altered magnesiocarbonatites are composed of dolomite with burbankite and are rich in REE (up to 2.0 wt. %), Sr (up to 1.2 wt. %), and Ba (up to 0.8 wt. %). These carbonatites underwent several stages of metasomatism. Each metasomatic event produced a new rock type with specific mineralization. The introduction of K, Si, Al, Fe, Ti, and Nb by a F-rich fluid (or fluid-saturated melt) resulted in the formation of high-Ti magnesiocarbonatites and silicocarbonatites, composed of dolomite, microcline, Ti-rich phlogopite, and Fe–Ti oxides. Alteration by a phosphate–fluoride fluid caused the crystallization of apatite in the carbonatites. A sulfate-rich Ba–Sr–rare-earth elements (REE) fluid (probably brine-melt) promoted the massive precipitation of ancylite and baryte and, to a lesser extent, strontianite, bastnäsite, and synchysite. Varieties of carbonatite that contain the highest concentrations of REE are ancylite-dominant. The influence of sulfate-rich Ba-Sr-REE fluid on the apatite-bearing rocks resulted in the dissolution and reprecipitation of apatite in situ. The newly formed apatite generation is rich in HREE, Sr, and S. During late-stage transformations, breccias of magnesiocarbonatites with quartz-bastnäsite matrixes were formed. Simultaneously, strontianite, quartz, calcite, monazite, HREE-rich thorite, and Fe-hydroxides were deposited. Breccias with quartz-bastnäsite matrix are poorer in REE (up to 4.5 wt. % total REE) than the ancylite-dominant rocks (up to 11 wt. % total REE).

Synthetic zircon doped with hafnium and rare earth elements: A reference material for in situ hafnium isotope analysis

2011 ◽  
Vol 286 (1-2) ◽  
pp. 32-47 ◽  
Author(s):  
Christopher M. Fisher ◽  
John M. Hanchar ◽  
Scott D. Samson ◽  
Bruno Dhuime ◽  
Janne Blichert-Toft ◽  
...  
Keyword(s):  
Rare Earth ◽  
Reference Material ◽  
Rare Earth Elements ◽  
Isotope Analysis

Simultaneous determination of Sm–Nd isotopes, trace-element compositions and U–Pb ages of titanite using a laser-ablation split-stream technique with the addition of water vapor

2021 ◽  
Author(s):  
Le Zhang ◽  
Jia-Lin Wu ◽  
Yanqiang Zhang ◽  
Ya-Nan Yang ◽  
Pengli He ◽  
...  
Keyword(s):  
Rare Earth ◽  
Water Vapor ◽  
Laser Ablation ◽  
Rare Earth Elements ◽  
Trace Element ◽  
Simultaneous Determination ◽  
Nd Isotopes ◽  
Trace Element Contents

Titanite is a widespread accessory nesosilicate with high trace-element contents including rare-earth elements, Th, and U, and is thus suitable for in situ isotopic and trace-element analyses and U–Pb dating....

scholarly journals Orthopyroxene-enrichment in the lherzolite-websterite xenolith suite from Paleogene alkali basalts of the Poiana Ruscă Mountains (Romania)

2015 ◽  
Vol 66 (6) ◽  
pp. 499-514
Author(s):  
Zsuzsanna Nédli ◽  
Csaba Szabó ◽  
Júlia Dégi
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Type A ◽  
Mantle Xenoliths ◽  
Alkali Basalts ◽  
Enriched Mantle ◽  
Low Degree ◽  
Melt Composition ◽  
Subsequent Passage ◽  
Metasomatic Event

Abstract In this paper we present the petrography and geochemistry of a recently collected lherzolite-websterite xenolith series and of clinopyroxene xenocrysts, hosted in Upper Cretaceous–Paleogene basanites of Poiana Ruscă (Romania), whose xenoliths show notable orthopyroxene-enrichment. In the series a slightly deformed porphyroclastic-equigranular textured series could represent the early mantle characteristics, and in many cases notable orthopyroxene growth and poikilitic texture formation was observed. The most abundant mantle lithology, Type A xenoliths have high Al and Na-contents but low mg# of the pyroxenes and low cr# of spinel suggesting a low degree (< 10 %) of mafic melt removal. They are also generally poor in overall REE-s (rare earth elements) and have flat REY (rare earth elements+ Y) patterns with slight LREE-depletion. The geochemistry of the Type A xenoliths and calculated melt composition in equilibrium with the xenolith clinopyroxenes suggests that the percolating melt causing the poikilitization can be linked to a mafic, Al-Na-rich, volatile-poor melt and show similarity with the Late Cretaceous–Paleogene (66–72 Ma) subduction-related andesitic magmatism of Poiana Ruscă. Type B xenoliths, with their slightly different chemistry, suggest that, after the ancient depletion, the mantle went through a slight metasomatic event. A subsequent passage of mafic melts in the mantle, with similar compositions to the older andesitic magmatism of Poiana Ruscă, is recorded in the pyroxenites (Fe-rich xenoliths), whereas the megacrysts seem to be cogenetic with the host basanite. The Poiana Ruscă xenoliths differ from the orthopyroxene-enriched mantle xenoliths described previously from the Carpathian-Pannonian Region and from the Dacia block.

U–Pb garnet and titanite age for the Bristol Township lamprophyre suite, western Abitibi Subprovince, Canada

1990 ◽  
Vol 27 (11) ◽  
pp. 1451-1456 ◽  
Author(s):  
C. Tucker Barrie
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Fault Zone ◽  
Late Stage ◽  
Gold Mineralization ◽  
Light Rare Earth ◽  
Upper Limit ◽  
Abitibi Subprovince ◽  
Brittle Fractures ◽  
Light Rare Earth Elements

A U–Pb age of 2687 ± 3 Ma has been determined for a garnetite dike, using melanite garnet and titanite mineral separates. This is the first primary igneous U–Pb age reported using garnet. The garnetite dike is part of the Bristol Township lamprophyre suite, which is extremely enriched in large-ion lithophile elements and light rare earth elements and which is located within the Destor Porcupine fault zone of the western Abitibi Subprovince. The age represents an upper limit for late-stage gold mineralization found along brittle fractures that cut the lamprophyre suite and it coincides with regional transpression documented in several locations in the southern Superior Province.

scholarly journals Saprolitization’s Characteristics of Rare Earth Elements in Volcanic Regolith on Drill Core #65 in Western Sulawesi, Indonesia

2019 ◽  
Vol 7 (4) ◽  
Author(s):  
Shaban Godang ◽  
Arifudin Idrus ◽  
Fadlin, Bambang Priadi ◽  
Nurcahyo Indro Basuki
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Chemical Weathering ◽  
Gradual Increase ◽  
Drill Core ◽  
High Concentration ◽  
Adsorption Ability ◽  
Ti Oxides ◽  
Weathering Degree ◽  
The Relationship

The enrichment of Rare Earth Elements (REEs) in regolith depends on greatly number of chemical weathering degree, the ability of the ion-adsorption on clay, precipitation of REEs, minimum uptake by plants, and minor REE leaching out by lessivage. The degree of chemical weathering depends on the decaying of four base weathering elements (Mg, Ca, Na, K) in minerals and is relatively less dependent on the slow leaching of silica. Therefore, a study of regolith profile from weathering’s Adang Volcanics (western Sulawesi, Indonesia) is performed to understand the relationship between degree of chemical weathering, nature migration of REE and the characteristics of saprolitization REEs. The result of drill core samples shows the increasing of degree of chemical weathering (Degree of Saprolitization; DOS) is equal to gradual increasing of alumina by saprolitization, and has also gradual increase in Fe-Ti-oxides by ferruginization; furthermore, there is also a gradual enrichment of REEs occurred in the saprolite zone on Adang Volcanics regolith. The enrichment of REEs in the saprolite zones (E and B horizons) is 2.73 times (TREY = 2,579 ppm, in avg) compared to the parent mafic trachytic rocks (944 ppm) reveal the high adsorption ability on lateritic-ferruginous clay. The thickness of high concentration REEs (2,435 ppm, in avg) is starting from A to E, and B-horizon which is about 5 m. The ratio of LREE and HREE is 87.42% and 12.58%, respectively in parent rock which indicates the genesis of rare-earth is more influenced by replacement of Ca2+, Na+ and K+ in minerals of diopside, apatite and leucite/pseudoleucite rather than the substitution by zircon (Zr4+).

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