Rare earth elements in high-grade metamorphic rocks from the western Alps

Lithos ◽  
1979 ◽  
Vol 12 (1) ◽  
pp. 41-49 ◽  
Author(s):  
J. Dostal ◽  
S. Capedri
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Western Alps ◽  
Metamorphic Rocks ◽  
High Grade

GENESIS AND AGE OF THE TOMTOR Nb AND RARE-EARTH DEPOSIT ORE SEQUENCE, NORTHEASTERN SIBERIAN PLATFORM

2021 ◽  
pp. 32-44
Author(s):  
Alexander Tolstov ◽  
Vladimir Cherenkov ◽  
Leonid Baranov
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Siberian Platform ◽  
High Grade ◽  
Geological Data ◽  
Magmatic System ◽  
Humid Climate ◽  
Stratigraphic Unit ◽  
Sedimentary Deposits ◽  
Hot Humid Climate

The northeastern Siberian platform (Republic of Sakha, Yakutia) hosts the Udzhinskaya province of alkaline ultrabasic massifs with carbonatites as final phases of magmatic system evolution; they form i ts central carbonatite core and are characterized by elevated Fe, Al and P concentrations. They also contain a complex of rare and rare-earth elements. Crust of laterite weathering of up to 400 m thick is present within the massifs. Phosphate, Nb, Y, Sc and TR content in crust of carbonatite weathering is much higher compared to unaltered rock differences. Their maximum values are in the sequence of specific sedimentary deposits f ormed a s denudation products of ore-bearing carbonatite crust precipitated in minor lake depressions and due to their intensive chemogenic transformation in hot humid climate. They are unique high-grade ores, with no world analogs in terms of mineral potential. Sometimes, these rocks are their natural concentrates averaging (in weight %) 7,21 Nb2O5, 0,578 Y2O3, 0,045 Sc2O3 and 10,16 TR2O3. The rocks composing the ore-bearing sequence show distinct evidence of sedimentary genesis: well-pronounced layered texture and facial zoning, presence of carbonized vegetable detrite and bacteriomorphic aggregates. Therefore, it is reasonable to regard a set of these formations as an independent stratigraphic unit, Tomtor sequence. Geological data suggest that it formed 340-280 Ma. Tomtor sequence can be an important prospecting criteria in prospecting for rare and rare-earth elements.

scholarly journals Garnets from Val d’Ala Rodingites, Piedmont, Italy: An Investigation of Their Gemological, Spectroscopic and Crystal Chemical Properties

Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 728 ◽  
Author(s):  
Valeria Diella ◽  
Rosangela Bocchio ◽  
Nicoletta Marinoni ◽  
Franca Caucia ◽  
Maria Iole Spalla ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Inductively Coupled Plasma ◽  
Chemical Properties ◽  
Western Alps ◽  
Drift Spectroscopy ◽  
X Ray ◽  
Heavy Rare Earth Elements ◽  
Diffuse Reflectance Infrared

In Val d’Ala (Piedmont, Western Alps, Italy), the more interesting rocks for the mineralogical research are represented by rodingites (rich in mineralized veins and fractures) associated with serpentinites in the eclogitized oceanic crust of Piemonte Zone, south of Gran Paradiso Massif. Among the vein-filling minerals, garnets are the most appreciated as mineral specimens and, in less degree despite their vivid and rich colors, for their potential as gem-quality materials. This study provides a complete gemological characterization of five faceted samples and offers new information by means of Synchrotron X-ray computed micro-tomography imaging gem features. Electron-probe microanalysis (EMPA) and laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) established that the chemical composition of garnets from different localities, resulted both close to pure andradite, enriched in light rare earth elements (LREE) with a positive Eu anomaly, and grossular-andradite solid solution (grandite), enriched in heavy rare earth elements (HREE). X-ray powder diffraction analyses indicate the possible coexistence of almost pure grossular and andradite. A spectroscopic approach, commonly used with gem-like material, by Raman and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, completes the characterization of the samples. The new data on the textural and geochemical features of the grandite and andradite garnets suggest local growth processes under various chemical and oxidation conditions of metasomatic and metamorphic fluids interacting with the host-rocks. Garnets represent long-lasting mineral records of the complex geological history of the Val d’Ala rodingitic dikes during their oceanic- and subduction-related metamorphic evolution.

scholarly journals DISTRIBUTION OF RARE EARTH ELEMENTS IN METAMORPHIC ROCKS OF PLATTENKALK GROUP AT CENTRAL CRETE, GREECE

2017 ◽  
Vol 50 (2) ◽  
pp. 977
Author(s):  
F. Stathogianni ◽  
E. Manoutsoglou ◽  
I. Staboliadis ◽  
O. Pantelaki ◽  
N. Kallithrakas-Kontos
Keyword(s):  
Grain Size ◽  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earths ◽  
Size Fraction ◽  
Mineral Processing ◽  
Metamorphic Rocks ◽  
Light Rare Earth ◽  
Processing Data ◽  
Light Rare Earth Elements

Within the metamorphic rocks of the Plattenkalk Group, in an occurrence at Tallaia Mountains, central Crete, light rare earth elements Cerium and Lanthanum are found. The studied rare earths are seen in an epidote group mineral, allanite. Scanning Electron Microscopy of the samples showed clearly the crystals of allanite (prekinematic crystals) and their grain size. Mineral processing was conducted for the size fractions: (<10 μm), (10-212 μm) and (212-1000 μm), according to the magnetic properties and grain size of allanite. After magnetic separation of the fraction (<10 μm) and (212-1000 μm) rare earths Ce and La were observed to have higher concentrations in the magnetic products. In conclusion, (according to the microscopic and mineral processing data) the optimum grain size for the beneficiation of allanite is the size fraction (10-212 μm).

scholarly journals The Malene metasedimentary rocks on Rypeø, and their relationship to Amîtsoq gneisses

1983 ◽  
Vol 112 ◽  
pp. 53-69
Author(s):  
R.F Dymek ◽  
R Weed ◽  
L.P Gromet
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Field Observation ◽  
Small Island ◽  
High Grade ◽  
Vertical Crustal Movement ◽  
Metasedimentary Rocks ◽  
Near Shore ◽  
Petrographic Study ◽  
Unconformable Contact

Two groups of Malene metasedimentary rocks on Rypeø, a small island south of Godthåb, have been studied in detail in order to evaluate their origin and relationship to older, adjacent Amîtsoq gneiss. Field observation shows that the metasediments range from massive to finely layered, and include an unusual pod-rock ('pseudoconglomerate'), which probably represents a series of deformed sedimentary layers (or lenses) of contrasting competence. Petrographic study indicates that the metasediments are quartz-rich, contain abundant plagioclase and biotite, and small but variable amounts ofsillimanite, muscovite, microcline and garnet. Rare earth elements (REE) in samples of four metasedimentary lithologies are similar to some published analyses of 'tonalitic' Amîtsoq gneiss. These observations suggest that the protolith of the Malene metasediments on Rypeø was dominated by sandstone type lithologies which evolved in a near-shore tidal to fiuviatile environment. These sediments were probably derived by weathering and erosion of Amitsoq gneiss and deposited unconformably on such a gneissic basement. Petrological study indicates that the Rypeø metasediments were metamorphosed to the beginning of Muse + Qtz breakdown (Musc-Sill-Kfsp transition zone), and locally underwent minor amounts of melting. The proposed original unconformable contact relationships, coupled with high-grade polymetamorphism - not only of the supracrustal rocks but also of Amitsoq gneiss - indicates substantial vertical crustal movement, perhaps as much as 75 km since the time of formation of Amitsoq gneiss at - 3750 Ma.

Rare earth elements in volcanic rocks of the Buchans area, Newfoundland

1984 ◽  
Vol 21 (7) ◽  
pp. 775-780 ◽  
Author(s):  
D. F. Strong
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Volcanic Rocks ◽  
Ore Deposits ◽  
High Grade ◽  
Sulphide Deposits ◽  
General Tool ◽  
The Rare Earth

Rare earth elements (REE) were determined for 57 samples representative of the range of stratigraphic units, both mineralized and unmineralized, associated with the high-grade polymetallic volcanogenic sulphide deposits at Buchans, Newfoundland. These data do not indicate any features indicative of magmatic fractionation processes, e.g., enrichment of total REE or any europium depletion anomaly, in the mineralized relative to the unmineralized volcanics, suggesting that such processes did not play an important role in the formation of these ore deposits. These results also emphasize the need for caution in any attempts to use the rare earth elements as a general tool for discrimination between barren and mineralized volcanic sequences.

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