Morphology and mineral chemistry of monazite–zircon-bearing stream sediments of continental placer deposits (SE Germany): Ore guide and provenance marker

Dill, Harald G.; Weber, B.; Klosa, Detlev

doi:10.1016/j.gexplo.2011.10.006

Cited by 42 publications

(17 citation statements)

References 58 publications

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“…Owing to resistance to weathering, large monazite placers are known (Dill et al, 2012;Nash, 1984;Overstreet, 1967;Rosenblum and Mosier, 1983). Monazite group minerals also form in hydrothermal veins and hydrothermally altered rocks.…”

Section: Minerals and Formsmentioning

confidence: 99%

Main minerals of abnormally high-grade ores of the Tomtor deposit (Arctic Siberia)

Лазарева

Жмодик

Добрецов

et al. 2015

Russian Geology and Geophysics

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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 km 2 ) 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% Nb 2 O 5 , 7-10% REE 2 O 3 , 0.75% Y 2 O 3 , and 0.06% Sc 2 O 3 ). 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.

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Section: Minerals and Formsmentioning

confidence: 99%

Main minerals of abnormally high-grade ores of the Tomtor deposit (Arctic Siberia)

Лазарева

Жмодик

Добрецов

et al. 2015

Russian Geology and Geophysics

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“…The slope can also favour the concentration of heavy minerals from detritus (Sengupta & van Gosen, 2016). The abundant monazite in granitic rocks might have contributed significantly to the mineral assemblage (Dill et al, 2012). Wood (1998) revealed that REE re-precipitate in a high pH environment.…”

Section: Discussionmentioning

confidence: 99%

“…Dill and Ludwig (2008) revealed eight landform types according to their geomorphology, geometry, grain size parameters, stratification, fabric, and rock contacts. Monazite and zircon are heavy minerals, stable in fluvial placers, associated with xenotime, ilmenite, rutile, magnetite, garnet, cassiterite, and others (Dill, Weber, & Klosa, 2012).…”

Section: Introductionmentioning

confidence: 99%

TiO₂–Zr–Th–Y–rare‐earth elements ore deposit in unconsolidated fine‐grained sediments from Tongo Gandima in the Bétaré Oya Gold district, Eastern Cameroon

2020

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is an area located in the southeastern part of the Bétaré Oya Gold district (Eastern Cameroon). Geochemical investigations on rare metals (TiO 2 , Th, Y, and rare-earth elements [REE]) were carried out on sample types (source rocks, unconsolidated fine-grained sediments, and concentrated sediments) using X-ray diffraction (XRD), X-ray fluorescence (XRF), inductively coupled plasma-mass spectrometry (ICP-MS), and scanning electron microscope equipped with EDAX spectrometer (SEM-EDS) methods. In this study, five layers of river terraces were selected (organic matter layer, clayey layer, fine sandy layer, coarse sandy layer, and gravel layer). One of them, the gravel layer, is mineralized. TiO 2 , Zr, and REE are more enriched in monzonites than in granites. Unconsolidated sediments derive mainly from the erosion of weathered materials developed on monzonites and granites. The mineral assemblage of fine-grained sediments from the gravel layer is muscovite, kaolinite, quartz, rutile, smectite, and others, and the average concentrations in Th, Zr, and Y are high. Fifty

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“…Among them, automorphic, subautomorphic, and xenomorphic grains can be observed, indicating that the distance from the alimentation area was variable. The dominating tabular shape of automorphic monazite crystals indicates a granitic, as opposed to a pegmatitic, provenance (Dill et al 2012). High secondary porosity of polished grains of monazite and xenotime and their sharp-edged cavities on crystal faces indicate that these minerals have low chemical and mechanical resistance against transportation and weathering in comparison with, e.g., zircon.…”

Section: Discussionmentioning

confidence: 99%

New potential source of rare earth elements

Szamałek¹,

Konopka²,

Zglinicki³

et al. 2013

Gospodarka Surowcami Mineralnymi - Mineral Resources Management

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Morphology and mineral chemistry of monazite–zircon-bearing stream sediments of continental placer deposits (SE Germany): Ore guide and provenance marker

Cited by 42 publications

References 58 publications

Main minerals of abnormally high-grade ores of the Tomtor deposit (Arctic Siberia)

Main minerals of abnormally high-grade ores of the Tomtor deposit (Arctic Siberia)

TiO₂–Zr–Th–Y–rare‐earth elements ore deposit in unconsolidated fine‐grained sediments from Tongo Gandima in the Bétaré Oya Gold district, Eastern Cameroon

New potential source of rare earth elements

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Morphology and mineral chemistry of monazite–zircon-bearing stream sediments of continental placer deposits (SE Germany): Ore guide and provenance marker

Cited by 42 publications

References 58 publications

Main minerals of abnormally high-grade ores of the Tomtor deposit (Arctic Siberia)

Main minerals of abnormally high-grade ores of the Tomtor deposit (Arctic Siberia)

TiO2–Zr–Th–Y–rare‐earth elements ore deposit in unconsolidated fine‐grained sediments from Tongo Gandima in the Bétaré Oya Gold district, Eastern Cameroon

New potential source of rare earth elements

Contact Info

Product

Resources

About

TiO₂–Zr–Th–Y–rare‐earth elements ore deposit in unconsolidated fine‐grained sediments from Tongo Gandima in the Bétaré Oya Gold district, Eastern Cameroon