Geophysical interpretation of U, Th, and rare earth element mineralization of the Bokan Mountain peralkaline granite complex, Prince of Wales Island, southeast Alaska

2014 ◽  
Vol 2 (4) ◽  
pp. SJ47-SJ63 ◽  
Author(s):  
Anne E. McCafferty ◽  
Douglas B. Stoeser ◽  
Bradley S. Van Gosen
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Gamma Ray ◽  
Outer Edge ◽  
Peralkaline Granite ◽  
Ree Mineralization ◽  
Granite Complex ◽  
Oxide Minerals ◽  
High Concentrations

A prospectivity map for rare earth element (REE) mineralization at the Bokan Mountain peralkaline granite complex, Prince of Wales Island, southeastern Alaska, was calculated from high-resolution airborne gamma-ray data. The map displays areas with similar radioelement concentrations as those over the Dotson REE-vein-dike system, which is characterized by moderately high %K, eU, and eTh (%K, percent potassium; eU, equivalent parts per million uranium; and eTh, equivalent parts per million thorium). Gamma-ray concentrations of rocks that share a similar range as those over the Dotson zone are inferred to locate high concentrations of REE-bearing minerals. An approximately 1300-m-long prospective tract corresponds to shallowly exposed locations of the Dotson zone. Prospective areas of REE mineralization also occur in continuous swaths along the outer edge of the pluton, over known but undeveloped REE occurrences, and within discrete regions in the older Paleozoic country rocks. Detailed mineralogical examinations of samples from the Dotson zone provide a means to understand the possible causes of the airborne Th and U anomalies and their relation to REE minerals. Thorium is sited primarily in thorite. Uranium also occurs in thorite and in a complex suite of [Formula: see text] oxide minerals, which include fergusonite, polycrase, and aeschynite. These oxides, along with Y-silicates, are the chief heavy REE (HREE)-bearing minerals. Hence, the eU anomalies, in particular, may indicate other occurrences of similar HREE-enrichment. Uranium and Th chemistry along the Dotson zone showed elevated U and total REEs east of the Camp Creek fault, which suggested the potential for increased HREEs based on their association with U-oxide minerals. A uranium prospectivity map, based on signatures present over the Ross-Adams mine area, was characterized by extremely high radioelement values. Known uranium deposits were identified in the U-prospectivity map, but the largest tract occurs over a radioelement-rich granite phase within the pluton that is likely not related to mineralization. Neither mineralization type displays a well-defined airborne magnetic signature.

scholarly journals Rare earth element mobility in and around carbonatites controlled by sodium, potassium, and silica

2020 ◽  
Vol 6 (41) ◽  
pp. eabb6570 ◽  
Author(s):  
Michael Anenburg ◽  
John A. Mavrogenes ◽  
Corinne Frigo ◽  
Frances Wall
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Element Mobility ◽  
Sodium Potassium ◽  
Ree Mineralization ◽  
Anionic Species ◽  
Ree Mobility ◽  
Modern Technologies

Carbonatites and associated rocks are the main source of rare earth elements (REEs), metals essential to modern technologies. REE mineralization occurs in hydrothermal assemblages within or near carbonatites, suggesting aqueous transport of REE. We conducted experiments from 1200°C and 1.5 GPa to 200°C and 0.2 GPa using light (La) and heavy (Dy) REE, crystallizing fluorapatite intergrown with calcite through dolomite to ankerite. All experiments contained solutions with anions previously thought to mobilize REE (chloride, fluoride, and carbonate), but REEs were extensively soluble only when alkalis were present. Dysprosium was more soluble than lanthanum when alkali complexed. Addition of silica either traps REE in early crystallizing apatite or negates solubility increases by immobilizing alkalis in silicates. Anionic species such as halogens and carbonates are not sufficient for REE mobility. Additional complexing with alkalis is required for substantial REE transport in and around carbonatites as a precursor for economic grade-mineralization.

FEASIBILITY OF VISIBLE SHORT-WAVE INFRARED REFLECTANCE SPECTROSCOPY TO CHARACTERIZE REGOLITH-HOSTED RARE EARTH ELEMENT MINERALIZATION

2021 ◽  
Author(s):  
Wei Tan ◽  
Xiaorong Qin ◽  
Jiacheng Liu ◽  
Mei-Fu Zhou ◽  
Hongping He ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Short Wave ◽  
Chemical Compositions ◽  
Infrared Reflectance ◽  
Spectral Parameters ◽  
Ree Mineralization ◽  
Abrupt Changes ◽  
Short Wave Infrared

Abstract Regolith-hosted rare earth element (REE) deposits predominate global resources of heavy REEs. Regoliths are underlain by various types of igneous rocks and do not always host economically valuable deposits. Thus a feasible and convenient method is desired to identify REE mineralization in a particular regolith. This study presents a detailed visible short-wave infrared reflectance (VSWIR) spectroscopic study of the Renju regolith-hosted REE deposit, South China, to provide diagnostic parameters for targeting REE orebodies in regoliths. The results show that the spectral parameters, M794_2nd and M800_2nd, derived from the VSWIR absorption of Nd3+ at approximately 800 nm, can be effectively used to estimate the total REE concentrations in regolith profiles. M1396_2nd/M1910_2nd ratios can serve as proxies to evaluate weathering intensities in a regolith. Abrupt changes of specific spectral features related to mineral abundances, chemical compositions, and weathering intensities can be correlated with variations of protolith that formed a regolith. These VSWIR proxies are robust and can be used for exploration of regolith-hosted REE deposits.

Radioelement distribution in U, Th, Mo, and rare-earth-element pegmatites, skarns, and veins in a portion of the Grenville Province, Ontario and Quebec

1991 ◽  
Vol 28 (1) ◽  
pp. 1-12 ◽  
Author(s):  
David Lentz
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Gamma Ray ◽  
Grenville Province ◽  
Heterogeneous Distribution ◽  
Granitic Pegmatites ◽  
Gamma Ray Spectrometer ◽  
Calcite Veins ◽  
Secondary Enrichment

Gamma-ray spectrometer measurements were obtained at and in the vicinity of 104 of the 124 U, Th, Mo, and rare-earth-element (REE) occurrences examined in the Central Metasedimentary Belt of the Grenville Province. Spatial, temporal, mineralogical, and geochemical relationships among granitic pegmatites, phlogopite – scapolite – Ca pyroxene skarns, and fluorite – apatite – calcite veins hosting U, Th, Mo, and REE minerals indicate a common magmatic–hydrothermal origin. Quartz–feldspar gneisses in the Central Metasedimentary Belt (n = 54) have low abundances of uranium (1–7 ppm) and thorium (4–27 ppm) suggesting that partial melting, fractional crystallization, and volatile phase separation were responsible for the enrichment of uranium (2–37 ppm) and thorium (5–102 ppm) in uncontaminated granitic pegmatites (n = 163) derived during ultrametamorphism. The U/Th ratio is probably inherited from the source quartz–feldspar gneiss protolith and enhanced during fractionation.Average U and Th concentrations and U/Th ratios at numerous localities show significant positive correlations among pegmatites, skarns, and veins, providing further evidence for a related origin. The interaction of the pegmatite-derived hydrothermal fluids with host rocks produced a spectrum of types and styles of alteration, which include (i) hybridization and (or) endoskarnification along pegmatite margins; (ii) marble- and clinopyroxenite-hosted exoskarn; and (iii) fluorite–apatite–calcite veins. The deposition of U, Th, Mo, and REE from the evolving hydrothermal fluid is responsible for the heterogeneous distribution of U, Th, and REE minerals and molybdenite within pegmatites, skarns, and veins at each locality. Secondary enrichment of uranium in association with hematitized sheared pegmatites and veins may be responsible for the observed large variation in U/Th ratios at some sites.

scholarly journals Combined Mining and Pulp-Lifting of Ferromanganese Nodules and Rare-Earth Element-Rich Mud around Minamitorishima Island in the Western North Pacific: A Prefeasibility Study

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 310
Author(s):  
Tetsuo Yamazaki ◽  
Naoki Nakatani ◽  
Rei Arai ◽  
Tsunehiro Sekimoto ◽  
Hiroyuki Katayama
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Construction Materials ◽  
Economic Feasibility ◽  
Northwest Pacific ◽  
Ferromanganese Nodules ◽  
Riser Pipe ◽  
High Concentrations ◽  
Lifting System

An examination of the technical and economic feasibility of the combined mining of the rare-earth element-rich mud (REE-rich mud) and ferromanganese nodules (FN) around Minamitorishima (Marcus) Island in Northwest Pacific is introduced. A previous study showed that the mining of REE-rich mud around Minamitorishima Island was not economically feasible. Therefore, in this study, three changes from the previous mining model to improve its economy are proposed. The first one is combined mining with FN in the area. The second one is introducing a pulp-lifting system that can lift both REE-rich mud and FN at high concentrations through a riser pipe. The third one is the reuse of waste mud and processed slag for construction materials. The economic evaluation results show a change from a slightly negative to quite positive economy depending on the mixing ratio of REE-rich mud and FN in the pulp-lifting. In addition, some technical approaches necessary to realize the combined mining method are introduced.

scholarly journals Zirconosilicates in the kakortokites of the Ilímaussaq complex, South Greenland: Implications for fluid evolution and high-field-strength and rare-earth element mineralization in agpaitic systems

2016 ◽  
Vol 80 (1) ◽  
pp. 5-30 ◽  
Author(s):  
A. M. Borst ◽  
H. Friis ◽  
T. Andersen ◽  
T. F. D. Nielsen ◽  
T. E. Waight ◽  
...  
Keyword(s):  
Rare Earth ◽  
High Field ◽  
Earth Element ◽  
Secondary Mineral ◽  
High Field Strength ◽  
Ree Mineralization ◽  
Subsequent Decrease ◽  
Fluoride Complexes ◽  
Mineral Assemblages ◽  
High Concentrations

AbstractThe layered agpaitic nepheline syenites (kakortokites) of the Ilímaussaq complex, South Greenland, host voluminous accumulations of eudialyte-group minerals (EGM). These complex Na-Ca-zirconosilicates contain economically attractive levels of Zr, Nb and rare-earth elements (REE), but have commonly undergone extensive autometasomatic/hydrothermal alteration to a variety of secondary mineral assemblages. Three EGM alteration assemblages are recognized, characterized by the secondary zirconosilicates catapleiite, zircon and gittinsite. Theoretical petrogenetic grid models are constructed to assess mineral stabilities in terms of component activities in the late-stage melts and fluids. Widespread alteration of EGM to catapleiite records an overall increase in water activity, and reflects interaction of EGM with late-magmatic Na-, Cl- and F-rich aqueous fluids at the final stages of kakortokite crystallization. Localized alteration of EGM and catapleiite to the rare Ca-Zr silicate gittinsite, previously unidentified at Ilímaussaq, requires an increase in CaO activity and suggests post-magmatic interaction with Ca-Sr bearing aqueous fluids. The pseudomorphic replacement of EGM in the kakortokites was not found to be associated with significant remobilization of the primary Zr, Nb and REE mineralization, regardless of the high concentrations of potential transporting ligands such as F and Cl. We infer that the immobile behaviour essentially reflects the neutral to basic character of the late-magmatic fluids, in which REE-F compounds are insoluble and remobilization of REE as Cl complexes is inhibited by precipitation of nacareniobsite-(Ce) and various Ca-REE silicates. A subsequent decrease in F– activity would furthermore restrict the mobility of Zr as hydroxyl-fluoride complexes, and promote precipitation of the secondary zirconosilicates within the confines of the replaced EGM domains.

scholarly journals Using yttrium as an indicator to estimate total rare earth element concentration: a case study of anthracite-associated clays from northeastern Pennsylvania

2020 ◽  
Vol 7 (4) ◽  
pp. 652-661
Author(s):  
Xiaojing Yang ◽  
Daniel Kozar ◽  
Daniel Gorski ◽  
Anthony Marchese ◽  
James Pagnotti ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Gamma Ray ◽  
Distribution Patterns ◽  
Large Sample Size ◽  
Similar Distribution ◽  
Screening Process ◽  
Site Specific ◽  
Icp Ms

AbstractThis study demonstrated using yttrium (Y) as an indicator to estimate the total rare earth element and Y contents (REY) in coal-associated samples and to facilitate selection of samples with high REY assays in a fast and inexpensive manner. More than 10 anthracite-associated samples were collected from each of three Pennsylvanian sites (sites B, J and C) based on Thorium gamma ray logging suggesting high REY content. Several samples from each site were analyzed by ICP-MS to determine the rare earth distribution patterns and to establish the site-specific linear equations of Y and REY. The Y contents of the remaining samples were measured by a portable X-ray fluorescence analyzer, and the REY values were estimated based on the site-specific linear equation developed earlier. R-squared values above 0.70 were obtained for all the estimation equations from all three sites on both a whole sample basis and an ash basis. Previously, ash content has been widely used as an indicator of high REY content. This may not be applicable for a specific site. Site B in this study is an example where ash contents could not be statistically correlated with REY, so using Y for estimation is more applicable. The demonstrated sample screening process is suitable for samples from sites that share more similar distribution patterns (either MREY or LREY or HREY) as well as for samples from sites that share multiple distribution patterns (LREY/MREY/HREY) depending on the desirable accuracy. The demonstrated process lowers the analytical cost from $70 to 80 dollars per sample to $10–15 per sample while significantly reducing the processing time and acid consumption for ICP digestion. This is particularly true when a relatively large sample size is involved, for example, 100 samples from one site analyzed by ICP-MS/OES.

scholarly journals Crystallization and destabilization of eudialyte-group minerals in peralkaline granite and pegmatite: a case study from the Ambohimirahavavy complex, Madagascar

2018 ◽  
Vol 82 (2) ◽  
pp. 375-399 ◽  
Author(s):  
Guillaume Estrade ◽  
Stefano Salvi ◽  
Didier Béziat
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Parental Magma ◽  
Accessory Minerals ◽  
Eudialyte Group ◽  
Peralkaline Granite ◽  
Rich Material ◽  
Highly Evolved

AbstractEudialyte-group minerals (EGM) are very common in highly evolved SiO2-undersaturated syenites and are characteristic minerals of agpaitic rocks. Conversely, they are extremely rare in peralkaline granites, with only a handful of EGM occurrences reported worldwide. Here, we study two new examples of EGM occurrence in two types of peralkaline pegmatitic granites from the Cenozoic Ambohimirahavavy complex, and assess the magmatic conditions required to crystallize EGM in peralkaline SiO2-oversaturated rocks. In the transitional granite (contains EGM as accessory minerals) EGM occur as late phases and are the only agpaitic and major rare-earth element (REE) bearing minerals. In the agpaitic granite (contains EGM as rock-forming minerals) EGM are early-magmatic phases occurring together with two other agpaitic minerals, nacareniobsite-(Ce) and turkestanite. In these granites, EGM are partly-to-completely altered and replaced by secondary assemblages consisting of zircon and quartz in the transitional granite and an unidentified Ca-Na zirconosilicate in the agpaitic granite. Ambohimirahavavy EGM, as well as those from other peralkaline granites and pegmatites, are richer in REE and poorer in Ca than EGM in nepheline syenites. We infer that magmatic EGM are rare in SiO2-oversaturated rocks because of low Cl concentrations in these melts. At Ambohimirahavavy, contamination of the parental magma of the agpaitic granite with Ca-rich material increased the solubility of Cl in the melt promoting EGM crystallization. In both granite types, EGM were destabilized by the late exsolution of a fluid and by interaction with an external Ca-bearing fluid.

Mineral chemistry of Rare Earth Element (REE) mineralization, Browns Ranges, Western Australia

Lithos ◽  
2013 ◽  
Vol 172-173 ◽  
pp. 192-213 ◽  
Author(s):  
Nigel J. Cook ◽  
Cristiana L. Ciobanu ◽  
Daniel O'Rielly ◽  
Robin Wilson ◽  
Kevin Das ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Western Australia ◽  
Earth Element ◽  
Mineral Chemistry ◽  
Ree Mineralization
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