Main Minerals of Abnormally High-Grade ores of the Tomtor Deposit (Arctic Siberia) Full article
Journal |
Russian Geology and Geophysics
ISSN: 1068-7971 |
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Output data | Year: 2015, Volume: 56, Number: 6, Pages: 844-873 Pages count : 30 DOI: 10.1016/j.rgg.2015.05.003 | ||||||||||
Tags | Carbonatites, Halloysite, Minerals of the crandallite group, Monazite, Pyrochlore, REE deposit | ||||||||||
Authors |
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Affiliations |
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Funding (5)
1 | Siberian Branch of the Russian Academy of Sciences | 40 |
2 | Siberian Branch of the Russian Academy of Sciences | 94 |
3 | Russian Foundation for Basic Research | 13-05-12056 (01201369163) |
4 | Russian Foundation for Basic Research | 14-05-00668 (01201451216) |
5 | The Ministry of Education and Science of the Russian Federation |
Abstract:
The Tomtor massif of Paleozoic ultramafic alkaline rocks and carbonatites is located in the northern part of the Sakha Republic (Yakutia). The massif (its total area is ~ 250 km2) is ~ 20 km in diameter, with a rounded shape and a concentrically zoned structure. The core of the massif consists of carbonatites surrounded by a discontinuous ring of ultramafic rocks and foidolites. The outer part is composed of alkali and nepheline syenites. All rocks are weathered and covered with eluvium, which is the thickest after carbonatites enriched in phosphates and REE. The weathering profile consists of four layers, from the top: kaolinite-crandallite, siderite, goethite, and francolite. The highest-grade ores are observed in the bedded deposit which fills depressions in “sagging” eluvium. The ores are laminated and cryptogranular, with high Nb, Y, Sc, and REE contents (on average, 4.5% Nb2O5, 7-10% REE2O3, 0.75% Y2O3, and 0.06% Sc2O3). The highest-grade ores are natural Nb and REE concentrates. The total REE content in some layers is > 10%. The morphologic features of the highest-grade phosphate ores from the northern part of the Burannyi site were studied. The ore-forming minerals belong to the pyrochlore group, crandallite group (goyazite), and monazite-Ce. The pyrochlore group minerals occur mainly as crystals that were completely replaced by barium-strontium pyrochlore and/or plumbopyrochlore but retained the original faces; also, they occur as numerous conchoidal fragments. The grains of the pyrochlore group minerals sometimes have a zonal structure, with an unaltered pyrochlore core and a reaction rim. Goyazite occurs predominantly as colloform grains. According to SEM and TEM data, monazite occurs in the ores as ~ 50 nm particles, which cover the outer part of halloysite tubes (800–3000 nm long and 300 nm in diameter) as a dense layer and make up peculiar biomorphic aggregates. The mineralogical data, the occurrence of biomorphic aggregates, and the close association of organic remains with ore minerals suggest that the high-grade ores of the Tomtor deposit, including the Burannyi site, resulted from a hydrothermal-sedimentary process with a presumably important role of bioaccumulation of REE phosphates.
Cite:
Lazareva E.V.
, Zhmodik S.M.
, Dobretsov N.L.
, Tolstov A.
, Shcherbov B.L.
, Karmanov N.S.
, Gerasimov E.Y.
, Bryanskaya A.V.
Main Minerals of Abnormally High-Grade ores of the Tomtor Deposit (Arctic Siberia)
Russian Geology and Geophysics. 2015. V.56. N6. P.844-873. DOI: 10.1016/j.rgg.2015.05.003 WOS Scopus РИНЦ
Main Minerals of Abnormally High-Grade ores of the Tomtor Deposit (Arctic Siberia)
Russian Geology and Geophysics. 2015. V.56. N6. P.844-873. DOI: 10.1016/j.rgg.2015.05.003 WOS Scopus РИНЦ
Original:
Лазарева Е.
, Жмодик С.М.
, Добрецов Н.Л.
, Толстов А.
, Щербов Б.
, Карманов Н.
, Герасимов Е.Ю.
, Брянская А.В.
Главные рудообразующие минералы аномально богатых руд месторождения Томтор (Арктическая Сибирь)
Геология и геофизика. 2015. Т.56. №6. С.1080-1115. DOI: 10.15372/GiG20150603 RSCI РИНЦ
Главные рудообразующие минералы аномально богатых руд месторождения Томтор (Арктическая Сибирь)
Геология и геофизика. 2015. Т.56. №6. С.1080-1115. DOI: 10.15372/GiG20150603 RSCI РИНЦ
Dates:
Submitted: | Sep 30, 2014 |
Accepted: | Jan 29, 2015 |
Published print: | Jun 1, 2015 |
Published online: | Jun 6, 2015 |
Identifiers:
Web of science | WOS:000355922000003 |
Scopus | 2-s2.0-84930579852 |
Elibrary | 24043719 |
OpenAlex | W648054171 |