Alkaline-Silicate REE-HFSE Systems

Beard, Charles D.; Goodenough, Kathryn; Borst, A.; Wall, Frances; Siegfried, Pete R.; Deady, Eimear; Pohl, Claudia; Hutchison, William R.; Finch, Adrian A.; Walter, Benjamin F.; Elliott, Holly A. L.; Brauch, Klaus

doi:10.5382/econgeo.4956

Cited by 36 publications

(7 citation statements)

References 360 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The metal signature of hydrothermal REE-Nb-Zr mineralization at Pennington Mountain is similar to that of many deposits hosted in alkaline granites and syenites (e.g., Dostal, 2016;Beard et al, 2023). We speculate that a mineralized intrusion with this geochemical signature may exist at depth beneath the trachyte and could have been the source for the hydrothermal fluids that formed the occurrence.…”

Section: Potential For Similar Ree-nb-zr Occurrences Elsewhere In Nor...supporting

confidence: 61%

A Recently Discovered Trachyte-Hosted Rare Earth Element-Niobium-Zirconium Occurrence in Northern Maine, Usa

et al. 2023

View full text Add to dashboard Cite

Reported here are geological, geophysical, mineralogical, and geochemical data on a previously unknown trachyte-hosted rare earth element (REE)-Nb-Zr occurrence at Pennington Mountain in northern Maine, USA. This occurrence was newly discovered by a regional multiparameter, airborne radiometric survey that revealed anomalously high equivalent Th (eTh) and U (eU), confirmed by a detailed ground radiometric survey and by portable X-Ray fluorescence (pXRF) and whole-rock analyses of representative rock samples. The mineralized area occurs within an elongate trachyte body (~1.2 km2) that intrudes Ordovician volcanic rocks. Geologic constraints suggest that the trachyte is also Ordovician in age. The eastern lobe (~900 × ~400 m) of the trachyte is pervasively brecciated with a matrix containing seams, lenses, and veinlets composed mainly of potassium feldspar, albite, and fine-grained zircon and monazite. Barite is locally abundant. Minor minerals within the matrix include columbite, bastnäsite, euxenite, chlorite, pyrite, sphalerite, and magnetite. The pXRF analyses of 22 samples (App. Table A1) collected from the eastern lobe demonstrate that this entire part of the trachyte is highly mineralized. Whole-rock geochemical analyses for samples from the eastern lobe document high average contents of Zr (1.17 wt %), Nb (1,656 ppm), Ba (3,132 ppm), Y (1,140 ppm), Hf (324 ppm), Ta (122 ppm), Th (124 ppm), U (36.5 ppm), Zn (689 ppm), and Sn (106 ppm). Among light REE, the highest average concentrations are shown by La (763 ppm) and Ce (1,479 ppm). For heavy REE (HREE), Dy and Er are the most abundant on average (167 and 114 ppm, respectively). No HREE-rich minerals such as xenotime have been identified; the HREE may reside chiefly in monazite and bastnäsite, and within the fine-grained zircon. Very strong positive correlations (R2) of 0.92 to 0.98 exist between Th and Zr, Nb, Y, Ce, Yb, and Sn, indicating that the radiometric data for eTh are valid proxies for concentrations of these metals in the mineralized rocks. Trachyte-hosted REE-Nb-Zr deposits like the occurrence at Pennington Mountain also are known in eastern Australia and in the south Qinling belt of Central China. Based on comparisons with these deposits, and the lack of detailed geologic mapping in the Pennington Mountain region, we suggest that other rare-metal occurrences contained in trachyte may exist elsewhere in northern Maine, and more widely in the Appalachian-Caledonian orogen where volcanic and subvolcanic trachytes have been recognized.

show abstract

Section: Potential For Similar Ree-nb-zr Occurrences Elsewhere In Nor...supporting

confidence: 61%

A Recently Discovered Trachyte-Hosted Rare Earth Element-Niobium-Zirconium Occurrence in Northern Maine, Usa

et al. 2023

View full text Add to dashboard Cite

show abstract

“…Lithospheric thickness exerts control on fractional crystallization and thereby metal enrichment of carbonatite magmas (Beard et al, 2023). Depth to lithosphere-asthenosphere boundary, defined based on deep reflection seismic data (Czarnota et al, 2020), was, therefore, used as a vector to model favorable deep-seated structures (Table 1).…”

Section: Deep and Crustal Architecturesmentioning

confidence: 99%

Predictive Modeling of Canadian Carbonatite-Hosted REE +/− Nb Deposits

Parsa,

Lawley,

Cumani

et al. 2024

Nat Resour Res

View full text Add to dashboard Cite

Carbonatites are the primary geological sources for rare earth elements (REEs) and niobium (Nb). This study applies machine learning techniques to generate national-scale prospectivity models and support mineral exploration targeting of Canadian carbonatite-hosted REE +/− Nb deposits. Extreme target feature label imbalance, diverse geological settings hosting these deposits throughout Canada, selecting negative labels, and issues regarding the interpretability of some machine learning models are major challenges impeding data-driven prospectivity modeling of carbonatite-hosted REE +/− Nb deposits. A multi-stage framework, exploiting global hierarchical tessellation model systems, data-space similarity measures, ensemble modeling, and Shapley additive explanations was coupled with convolutional neural networks (CNN) and random forest to meet the objectives of this work. A risk–return analysis was further implemented to assist with model interpretation and visualization. Multiple models were compared in terms of their predictive ability and their capability of reducing the search space for mineral exploration. The best-performing model, derived using a CNN that incorporates public geoscience datasets, exhibits an area under the curve for receiver operating characteristics plot of 0.96 for the testing labels, reducing the search area by 80%, while predicting all known carbonatite-hosted REE +/− Nb occurrences. The framework used in our study allows for an explicit definition of input vectors and provides a clear interpretation of outcomes generated by prospectivity models.

show abstract

“…The use of Nb in high-tech applications calls for a comprehensive understanding of the processes that govern the concentration of this element in mineral deposits. Carbonatite-alkaline complexes, the most important Nb (and/or REEs) carriers (Mitchell 2015;Verplanck et al 2016;Anenburg et al 2021;Beard et al 2023), have attracted inordinate attention from researchers. Numerous studies documented that the Nb mineralization (particularly with grade < 1 wt% Nb 2 O 5 ) is commonly concentrated through differentiation of carbonatitic or alkaline melts, even though some of them may have been reworked to various extents by later hydrothermal overprinting (Chakhmouradian et al 2015;Mitchell 2015;Tremblay et al 2017;Liu et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Magmatic and hydrothermal controls on diverse Nb mineralization associated with carbonatite-alkaline complexes in the southern Qinling orogenic belt, Central China

Ma,

Chen,

Tang

2024

American Mineralogist

View full text Add to dashboard Cite

Although carbonatite-alkaline complexes are the primary source of the world's Niobium (Nb) supply, the mineralization style is largely variable in these complexes and the processes behind are still poorly understood. Exemplifying with the ~430 Ma Miaoya and Shaxiongdong carbonatite-syenite complexes in the southern Qinling orogenic belt, central China, our new observations show that Nb mineralization in these two deposits is persuasively throughout the entire complexes on both syenite and carbonatite in disseminated form. Both the magmatic and hydrothermal processes have attributed to Nb mineralization in both deposits, despite different in the mineralization style. The Nb-bearing minerals in the mineralized Miaoya syenites include magmatic U-poor pyrochlore, rutile, and ilmenite with minor amounts of columbite, and hydrothermal columbite and rutile, whereas those in the mineralized carbonatites are mainly magmatic U-poor pyrochlore, uranpyrochlore, U-rich betafite, and rutile with minor amounts columbite, and hydrothermal columbite and rutile. On the other hand, the Nb-bearing minerals in the mineralized Shaxiongdong syenites include magmatic U-poor pyrochlore, titanite, rutile, and ilmenite, and hydrothermal fersmite, rutile, and ilmenite, whereas those in the mineralized carbonatites are mainly magmatic U-poor pyrochlore without any hydrothermal Nb-bearing minerals. Field observations, whole-rock chemical and Sr-Nd isotopic compositions strongly constrained that assimilation of U-rich rocks (e.g., the hosting Yaolinghe and Meiziya Groups) and magma differentiation are responsible for diverse magmatic Nb mineralization in the two deposits. On the other hand, the diverse This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America.The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

show abstract

Alkaline-Silicate REE-HFSE Systems

Cited by 36 publications

References 360 publications

A Recently Discovered Trachyte-Hosted Rare Earth Element-Niobium-Zirconium Occurrence in Northern Maine, Usa

A Recently Discovered Trachyte-Hosted Rare Earth Element-Niobium-Zirconium Occurrence in Northern Maine, Usa

Predictive Modeling of Canadian Carbonatite-Hosted REE +/− Nb Deposits

Magmatic and hydrothermal controls on diverse Nb mineralization associated with carbonatite-alkaline complexes in the southern Qinling orogenic belt, Central China

Contact Info

Product

Resources

About