scholarly journals Supplemental Material: Cumulate olivine: A novel host for heavy rare earth element mineralization

2020 ◽  
Author(s):  
Sönke Brandt ◽  
et al.
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Atom Probe Tomography ◽  
Earth Element ◽  
Analytical Data ◽  
Atom Probe ◽  
Heavy Rare Earth ◽  
Heavy Rare Earth Element ◽  
Novel Host ◽  
Analytical Procedures

Atom probe tomography 3-D videos, analytical data, and details on analytical procedures<br>

scholarly journals Supplemental Material: Cumulate olivine: A novel host for heavy rare earth element mineralization

2020 ◽  
Author(s):  
Sönke Brandt ◽  
et al.
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Atom Probe Tomography ◽  
Earth Element ◽  
Analytical Data ◽  
Atom Probe ◽  
Heavy Rare Earth ◽  
Heavy Rare Earth Element ◽  
Novel Host ◽  
Analytical Procedures

Atom probe tomography 3-D videos, analytical data, and details on analytical procedures<br>

Cumulate olivine: A novel host for heavy rare earth element mineralization

Geology ◽  
2020 ◽  
Author(s):  
S. Brandt ◽  
M.L. Fassbender ◽  
R. Klemd ◽  
C. Macauley ◽  
P. Felfer ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Inductively Coupled Plasma ◽  
Earth Element ◽  
Atom Probe ◽  
Ore Deposits ◽  
Large Igneous Province ◽  
Heavy Rare Earth Element ◽  
Inductively Coupled ◽  
Novel Host

Olivine is one of the most important minerals used to reconstruct magmatic processes, yet the rare earth element (REE) systematics of Fe-rich olivine in igneous rocks and ore deposits is poorly understood. As detected by in situ laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) analysis, cumulate fayalite (Fe2SiO4) in the Paleoproterozoic Vergenoeg F-Fe-REE deposit of the Bushveld large igneous province (LIP) in South Africa contains the highest heavy REE (HREE) contents ever recorded for olivine, with HREE enrichment of as much as 6000× chondritic values. Atom probe tomography maps confirm the incorporation of the HREEs into the fayalite crystal lattice, facilitated by lithium acting as a main charge balancer and by high REE contents in the highly fractionated felsic parental melt that is related to the Bushveld LIP. The high HREE concentrations of fayalite in concert with its high modal abundance (&gt;95 vol%) indicate that the fayalite cumulates are the main host for the HREE mineralization of the Vergenoeg deposit. Fayalites of Vergenoeg demonstrate that Fe-rich olivine may fractionate large amounts of HREEs, and we propose fayalite cumulates as potential future targets for HREE exploration.

Rare-earth crystal chemistry of thalénite-(Y) from different environments

2018 ◽  
Vol 82 (2) ◽  
pp. 313-327
Author(s):  
Markus B. Raschke ◽  
Evan J. D. Anderson ◽  
Jason Van Fosson ◽  
Julien M. Allaz ◽  
Joseph R. Smyth ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Spatial Scales ◽  
Structure Refinement ◽  
X Ray Diffraction ◽  
Heavy Rare Earth ◽  
Heavy Rare Earth Element ◽  
X Ray ◽  
Golden Horn

ABSTRACTThalénite-(Y), ideally Y3Si3O10F, is a heavy-rare-earth-rich silicate phase occurring in granite pegmatites that may help to illustrate rare-earth element (REE) chemistry and behaviour in natural systems. The crystal structure and mineral chemistry of thalénite-(Y) were analysed by electron microprobe analysis, X-ray diffraction and micro-Raman spectroscopy from a new locality in the peralkaline granite of the Golden Horn batholith, Okanogan County, Washington State, USA, in comparison with new analyses from the White Cloud pegmatite in the Pikes Peak batholith, Colorado, USA. The Golden Horn thalénite-(Y) occurs as late-stage sub-millimetre euhedral bladed transparent crystals in small miarolitic cavities in an arfvedsonite-bearing biotite granite. It exhibits growth zoning with distinct heavy-rare-earth element (HREE) vs. light-rare-earth element (LREE) enriched zones. The White Cloud thalénite-(Y) occurs in two distinct anhedral and botryoidal crystal habits of mostly homogenous composition. In addition, minor secondary thalénite-(Y) is recognized by its distinct Yb-rich composition (up to 0.8 atoms per formula unit (apfu) Yb). Single-crystal X-ray diffraction analysis and structure refinement reveals Y-site ordering with preferential HREE occupation of Y2 vs. Y1 and Y3 REE sites. Chondrite normalization shows continuous enrichment of HREE in White Cloud thalénite-(Y), in contrast to Golden Horn thalénite-(Y) with a slight depletion of the heaviest REE (Tm, Yb and Lu). The results suggest a hydrothermal origin of the Golden Horn miarolitic thalénite-(Y), compared to a combination of both primary magmatic followed by hydrothermal processes responsible for the multiple generations over a range of spatial scales in White Cloud thalénite-(Y).

scholarly journals Petrogenesis of Heavy Rare Earth Element Enriched Rhyolite: Source and Magmatic Evolution of the Round Top Laccolith, Trans-Pecos, Texas

Minerals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 423 ◽  
Author(s):  
Brent Elliott
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Geochemical Evolution ◽  
Magmatic Differentiation ◽  
Magmatic System ◽  
Heavy Rare Earth ◽  
Heavy Rare Earth Element ◽  
Element Concentrations ◽  
Stage Crystallization

The Round Top rhyolite located in Trans-Pecos Texas is enriched in Be, F, Li, Nb, Rb, Sn, Th, U, Y, Zr, and rare earth elements (REEs). REE-bearing minerals are mainly ubiquitous nano-scale accessory phases throughout the groundmass, incorporated in synchysite-group minerals, xenotime-(Y), Y- and Ce-rich fluorite, and zircon. The rhyolite is peraluminous, high-silica, alkaline (not peralkaline), with elevated heavy rare earth element concentrations and anonymously negative Eu values. Pervasive spongy groundmass and recrystallization textures are consistent with the elevated and remobilized Zr, Th, and Y + HREE (heavy rare earth element) concentrations and a high field strength element (HFSE) soluble, sub-alkalic, F-rich, magmatic system. REE-bearing minerals are present as late-magmatic, interstitial phases and attributed with closed-system, post-magmatic, hydrothermal alteration. Petrogenetic modeling provides scenarios that explain the geochemical evolution and REE complexing behavior in evolved rhyolite magmas, and determines possible source compositions and evolution. Trace element models suggest a system typical of having extensive magmatic differentiation. The resulting rhyolite magma is indicative of a silica-rich magmatic system enriched in H2O, Li, and/or F that could be considered transitional between pure silicate melt and hydrothermal fluid, where fluorine-ligand complexing was prevalent through late magmatic cooling and crystallization processes. Thorough differentiation and high fluorine activity contributed to the late stage crystallization of REE-bearing minerals in the Round Top rhyolite.

The role of clay minerals in formation of the regolith-hosted heavy rare earth element deposits

2020 ◽  
Vol 105 (1) ◽  
pp. 92-108 ◽  
Author(s):  
Martin Yan Hei Li ◽  
Mei-Fu Zhou
Keyword(s):  
Rare Earth ◽  
Adsorption Capacity ◽  
Clay Minerals ◽  
Rare Earth Element ◽  
Earth Element ◽  
Modern Society ◽  
Heavy Rare Earth ◽  
Heavy Rare Earth Element ◽  
Adsorption Sites ◽  
Shallow Soils

Abstract Rare earth elements (REEs) have become increasingly important to our modern society due to their strategical significance and numerous high technological applications. Regolith-hosted heavy rare earth element (HREE) deposits in South China are currently the main source of the HREEs, but the ore-forming processes are poorly understood. In these deposits, the REEs are postulated to accumulate in regolith through adsorption on clay minerals. In the Zudong deposit, the world's largest regolith-hosted HREE deposit, clay minerals are dominated by short, stubby, nanometer-scale halloysite tubes (either 10 or 7 Å) and microcrystalline kaolinite in the saprolite and lower pedolith and micrometer-sized vermicular kaolinite in the humic layer and upper pedolith. A critical transformation of the clay minerals in the upper pedolith is coalescence and unrolling of halloysite to form vermicular kaolinite. Microcrystalline kaolinite also transformed to large, well-crystalline vermicular kaolinite. This transformation could result in significant changes in different physicochemical properties of the clay assemblages. Halloysite-abundant clay assemblages in the deep regolith have specific surface area and porosity significantly higher than the kaolinite-dominant clay assemblages in the shallow soils. The crystallinity of clay minerals also increased, exemplified by decrease in Fe contents of the kaolinite group minerals (from ~1.2 wt% in the lower saprolite to ~0.35 wt% in the upper pedolith), thereby indicative of less availability of various types of adsorption sites. Hence, halloysite-abundant clay minerals of high adsorption capacity in deep regolith could efficiently retain the REEs released from weathering of the parent granite. Reduction in adsorption capacity during the clay transformation in shallow depth partially leads to REE desorption, and the released REEs would be subsequently transported to and adsorbed at deeper part of the soil profile. Hence, the clay-adsorbed REE concentration in the lower pedolith and saprolite (~2500 ppm on average) is much higher than the uppermost soils (~400 ppm on average). Therefore, weathering environments that favor the release of the REEs in the shallow soils but preservation of halloysite in the deep regolith can continuously adsorb REEs in the clay minerals to form economically valuable deposits.

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