Journal articles: 'REE geochemistry'

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Cruz, Armanda, Pedro A. Dinis, Alberto Gomes, and Paula Leite. "Influence of Sediment Cycling on the Rare-Earth Element Geochemistry of Fluvial Deposits (Caculuvar–Mucope, Cunene River Basin, Angola)." Geosciences 11, no. 9 (September 11, 2021): 384. http://dx.doi.org/10.3390/geosciences11090384.

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The rare-earth element (REE) geochemistry of sedimentary deposits has been used in provenance investigations despite the transformation that this group of elements may suffer during a depositional cycle. In the present investigation, we used the geochemistry and XRD mineralogy of a set of sand and mud fluvial deposits to evaluate the ability of REE parameters in provenance tracing, and the changes in REE geochemistry associated with weathering and sorting. The analyzed deposits were generated in a subtropical drainage basin where mafic and felsic units are evenly represented, and these crystalline rocks are covered by sedimentary successions in a wide portion of the basin. A few element ratios appear to hold robust information about primary sources (Eu/Y, Eu/Eu*, LaN/YbN, LaN/SmN, and GdN/YbN), and the provenance signal is best preserved in sand than in mud deposits. Sediment cycles, however, change the REE geochemistry, affecting mud and sand deposits differently. They are responsible for significant REE depletion through quartz dilution in sands and may promote discernible changes in REE patterns in muds (e.g., increase in Ce content and some light REE depletion relative to heavy REE).

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Gammons, Christopher H., and Scott A. Wood. "The aqueous geochemistry of REE." Chemical Geology 166, no. 1-2 (May 2000): 103–24. http://dx.doi.org/10.1016/s0009-2541(99)00186-2.

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Kalender, Leyla, and Gamze Aytimur. "REE Geochemistry of Euphrates River, Turkey." Journal of Chemistry 2016 (2016): 1–13. http://dx.doi.org/10.1155/2016/1012021.

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The study area is located on the Euphrates River at 38°41°32.48′′N–38°14′24.10′′N latitude and 39°56′4.59′′E–39°8°13.41′′E longitude. The Euphrates is the longest river in Western Asia. The lithological units observed from the bottom to the top are Permo-Triassic Keban Metamorphites, Late Cretaceous Kömürhan Ophiolites, Upper Cretaceous Elazığ Magmatic Complex, Middle Eocene Maden Complex and Kırkgeçit Formation, Upper Pliocene and Lower Eocene Seske Formation and Upper Miocene, Pliocene Karabakır and Çaybağı Formations, Palu Formation, and Holocene Euphrates River sediments. The geochemical studies show that87Sr/86Sr and143Nd/144Nd isotopic compositions in the Euphrates River bank sediments are 0.7053, 0.7048, and 0.7057 and 0.512654, 0.512836, and 0.512775, respectively. These values indicate mixing of both carbonate-rich shallow marine sediment and felsic-mafic rocks from Elazığ Magmatic Complex into the stream sediments. The positiveεNd (0)values (0.35, 3.9, and 2.7) are higher downstream in the studied sediments due to weathering of the mafic volcanic rocks. The chondrite, NAS, and UCC normalized patterns show that the REE compositions of the Euphrates River sediments are higher than chondrite composition but close to NAS and UCC. The river sediments in the tectonic zone and the weathered granodioritic rocks of the Elazığ Magmatic complex affect upstream water compositions.

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Bonev, Nikolay, Petyo Filipov, and Tanya Stoylkova. "Chemical composition of late Eocene–early Oligocene corals in reef buildups from the Thrace basin, Bulgaria–Greece: Paleoenvironmental implications." Geologica Balcanica 51, no. 1 (April 2022): 23–33. http://dx.doi.org/10.52321/geolbalc.51.1.23.

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Coral whole-rock geochemistry and in situ LA-ICP-MS analyses of coral skeletons were performed on late Eocene–early Oligocene coral reef buildups from the Eastern Rhodope–Thrace region of Bulgaria and Greece. Coral reefs are locally associated with voluminous Oligocene volcanism in the region. The reefs are subdivided into (i) eruption-associated reefs (Krumovgrad); (ii) pre-eruption reefs (Ivaylovgrad); and (iii) Metaxades-Didymotycho reefs from field relations, trace element and rare-earth element (REE) abundances. Coral assemblages are dominated by Cladocora sp., which is accompanied by Porites sp., Colpophyllia sp., Favites sp. and Leptoseris sp. Eruption-associated reefs are characterized by their higher REE content than the lower in all REE contents of pre-eruption reefs showing negative Ce anomaly, and Metaxades-Didymotycho reefs that have lower middle-heavy REE contents compared to previous groups. Trace element and REE geochemistry of the coral skeletons indicates volcanic contribution to seawater, mostly evident in the eruption associated reefs, and contribution from terrestrial input in the site of coral buildup deposition. Contribution from a different source of prior diagenetic nature, along with subsequent diagenetic modification, is inferred. The increase in REE+Y (ΣREY) from pre-eruption to eruption-associated reefs is well correlated with elevated amounts of terrigenous elements like Al and Fe.

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Wu, Chengyu, and Shunso Ishihara. "REE geochemistry of the Southern Thailand granites." Journal of Southeast Asian Earth Sciences 10, no. 1-2 (July 1994): 81–94. http://dx.doi.org/10.1016/0743-9547(94)90010-8.

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Suhua, Yu, and Wen Qizhong. "REE geochemistry of loess in Xinjiang, China." Chinese Journal of Geochemistry 11, no. 3 (July 1992): 277–87. http://dx.doi.org/10.1007/bf02842272.

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Salih, Makki Omer, Bo Wan, and David R. Lentz. "Geochemistry and petrogenesis of anorogenic REE-bearing peralkaline granitoids from Northern Sudan." Neues Jahrbuch für Mineralogie - Abhandlungen 197, no. 2 (October 22, 2021): 185–208. http://dx.doi.org/10.1127/njma/2021/0274.

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Green, T. H., and N. J. Pearson. "High-pressure, synthetic loveringite-davidite and its rare earth element geochemistry." Mineralogical Magazine 51, no. 359 (March 1987): 145–49. http://dx.doi.org/10.1180/minmag.1987.051.359.16.

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AbstractLoveringite-davidite members of the crichtonite group were synthesized at high pressure and temperature (7.5 kbar, 1000–1050 °C) from a melt of TiO2 and rare earth element (REE) enriched basaltic andesite composition. Four sets of partition coefficients for La, Srn, Ho, Lu and Sr (analogue for Eu2+) were obtained. These show that light and heavy REE are readily accommodated, but the intermediate REE are discriminated against in the loveringite—davidite structure. This confirms the previously proposed two sites (A and M) for REE substitution in the crichtonite group. Additional experiments verified the stability of REE-rich crichtonite group minerals to 20 kbar, 1300 °C and 30 kbar, 1000 °C, and indicate that this phase may be an important accessory repository for the light and heavy REE in the upper mantle.

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9

Bowerman, Melissa, Amy Christianson, Robert A. Creaser, and Robert W. Luth. "A petrological and geochemical study of the volcanic rocks of the Crowsnest Formation, southwestern Alberta, and of the Howell Creek suite, British Columbia." Canadian Journal of Earth Sciences 43, no. 11 (November 1, 2006): 1621–37. http://dx.doi.org/10.1139/e06-037.

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Alkaline igneous rocks of the Crowsnest Formation in southwestern Alberta and in the Howell Creek area in southeastern British Columbia have been suggested previously to be cogenetic. To test this hypothesis, samples of both suites were characterized petrographically and their major and trace element geochemistry was determined. A subset of the samples was analyzed for whole-rock Sr and Nd isotope geochemistry. The samples of the two suites are latites, trachytes, and phonolites based on the International Union of Geological Sciences (IUGS) total alkalis versus silica (TAS) diagram. Samples from both suites show similar patterns on mantle-normalized trace element diagrams, being enriched relative to mantle values but depleted in the high field-strength elements Nb, Ta, and Ti relative to the large-ion lithophile elements. The chondrite-normalized rare-earth element (REE) patterns for both suites are light REE enriched, with no Eu anomaly and flat heavy REE. The isotope geochemistry of both suites is characterized by low initial 87Sr/86Sr (SrT = 0.704 to 0.706) and low εNdT (–7 to –16). The Howell Creek samples have lower εNdT and higher SrT than do the Crowsnest samples. Based on the intra- and intersuite differences in the isotope geochemistry, we conclude that these samples are not cogenetic, but rather represent samples that have experienced similar evolutionary histories from a heterogeneous source region in the subcontinental lithospheric mantle.

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Chen, Wei, Huang Honghui, Tian Bai, and Shaoyong Jiang. "Geochemistry of Monazite within Carbonatite Related REE Deposits." Resources 6, no. 4 (September 27, 2017): 51. http://dx.doi.org/10.3390/resources6040051.

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11

Shuyi, Liang, and Xia Hongyuan. "Tungsten mineralization and mica REE geochemistry, Huangsha, Jiangxi." Chinese Journal of Geochemistry 10, no. 4 (October 1991): 326–34. http://dx.doi.org/10.1007/bf02841093.

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12

Barbey, P., J. Bernard-Griffiths, and J. Convert. "The Lapland charnockitic complex: REE geochemistry and petrogenesis." Lithos 19, no. 2 (June 1986): 95–111. http://dx.doi.org/10.1016/0024-4937(86)90002-2.

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13

Graupner, T., F. Melcher, H. E. Gäbler, M. Sitnikova, H. Brätz, and A. Bahr. "Rare earth element geochemistry of columbite-group minerals: LA-ICP-MS data." Mineralogical Magazine 74, no. 4 (August 2010): 691–713. http://dx.doi.org/10.1180/minmag.2010.074.4.691.

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AbstractNew data on rare earth element (REE) concentrations and distribution patterns of columbite-tantalite minerals from Ta-ore provinces worldwide are presented. The REE geochemistry was studied by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Five major types of chondrite-normalized REE distribution patterns are defined for columbite-group minerals (CGM) from lithium-caesium-tantalum (LCT) pegmatites and rare-metal granites. Features to discriminate between the types include (1) the shape of the pattern (e.g. flat or concave), (2) calculated ratios between groups of the REE (e.g. heavy REEN/middle REEN), and (3) the presence and intensity of anomalies (e.g. Ce*, Eu*). Four pegmatites in central and southern Africa are used as case studies to discuss application of the types of REE patterns in individual deposits. The REE fractionation during progressive evolution of the melt in a pegmatite body (either Nb → Ta or Fe → Mn fractionation lines, or both) results in smaller heavy REEN/middle REEN ratios whereas replacement of primary CGM by secondary CGM produces modifications in the light REEN patterns and the heavy REEN/middle REEN ratios also. Critical features of REE patterns such as highly variable heavy REEN/middle REEN ratios or striking differences in the appearance of Eu anomalies are discussed considering structural data of the host minerals and the differentiation behaviour of the pegmatitic melt. In general, CGM from each individual Ta-ore province are characterized by a predominance of one type of REE distribution pattern. Consequently, these patterns are suitable for tracing the origin of tantalum ore concentrates (e.g. as a forensic tool).

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Sadeghi, Martiya, Nikolaos Arvanitidis, and Anna Ladenberger. "Geochemistry of Rare Earth Elements in Bedrock and Till, Applied in the Context of Mineral Potential in Sweden." Minerals 10, no. 4 (April 18, 2020): 365. http://dx.doi.org/10.3390/min10040365.

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The Rare Earth Element (REE) mineralizations are not so “rare” in Sweden. They normally occur associated and hosted within granitic crystalline bedrock, and in mineral deposits together with other base and trace metals. Major REE-bearing mineral deposit types are the apatite-iron oxide mineralizations in Norrbotten (e.g., Kiruna) and Bergslagen (e.g., Grängesberg) ore regions, the various skarn deposits in Bergslagen (e.g., Riddarhyttan-Norberg belt), hydrothermal deposits (e.g., Olserum, Bastnäs) and alkaline-carbonatite intrusions such as the Norra Kärr complex and Alnö. In this study, analytical data of samples collected from REE mineralizations during the EURARE project are compared with bedrock and till REE geochemistry, both sourced from databases available at the Geological Survey of Sweden. The positive correlation between REE composition in the three geochemical data groups allows better understanding of REE distribution in Sweden, their regional discrimination, and genetic classification. Data provides complementary information about correlation of LREE and HREE in till with REE content in bedrock and mineralization. Application of principal component analysis enables classification of REE mineralizations in relation to their host. These results are useful in the assessment of REE mineral potential in areas where REE mineralizations are poorly explored or even undiscovered.

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Yaomin, Yang, Tu Guangzhi, and Hu Ruizhong. "REE and trace element geochemistry of Yinachang Fe-Cu-REE deposit, Yunnan Province, China." Chinese Journal of Geochemistry 23, no. 3 (July 2004): 265–74. http://dx.doi.org/10.1007/bf02842074.

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16

Shchukina, Elena V., Alexey M. Agashev, and Vladimir S. Shchukin. "Diamond-Bearing Root Beneath the Northern East European Platform (Arkhangelsk Region, Russia): Evidence from Cr-Pyrope Trace-Element Geochemistry." Minerals 9, no. 5 (April 30, 2019): 261. http://dx.doi.org/10.3390/min9050261.

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In this study, we reconstruct the composition and metasomatic evolution of the lithospheric mantle beneath the poorly-studied southern Arkhangelsk region, based on the geochemistry of 145 Cr-pyrope grains recovered from samples of modern rivers and stream sediments, to evaluate the diamond exploration potential of these territories. Based on the concentrations of Cr2O3, CaO, TiO2, and rare earth elements (REEs), the garnets are divided into four groups: (1) low-chromium lherzolitic pyropes with fractionated heavy REE patterns; (2) low- to medium-chromium pyropes of lherzolitic and megacryst associations with flat heavy REE patterns; (3) high-chromium lherzolitic pyropes with “humped” REE patterns; and (4) high-chromium and low-chromium lherzolitic and harzburgitic pyropes with sinusoidal REE patterns. The pyrope geochemistry suggests a multi-stage model for the evolution of the lithospheric mantle, including partial melting to different degrees and further metasomatic overprints by silicate and carbonatite melts. The results confirm that the lithospheric mantle beneath the study area is suitable for the formation and preservation of diamonds. The significant percentage of diamond-associated pyropes (15%) emphasizes the likelihood of high diamond contents in kimberlites to be discovered within the study area.

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Álvarez-Vázquez, Miguel Ángel, Elena De Uña-Álvarez, and Ricardo Prego. "Patterns and Abundance of Rare Earth Elements in Sediments of a Bedrock River (Miño River, NW Iberian Peninsula)." Geosciences 12, no. 3 (February 24, 2022): 105. http://dx.doi.org/10.3390/geosciences12030105.

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Bedrock rivers, whose sedimentary geochemistry has been scarcely investigated, are suitable to test geochemical approaches in order to assess the existence and extent of human alterations in the natural abundance of rare earth elements. This work presents the study of REE contents in fine-grained sediments of the (bedrock) Miño River, in an urban reach of its middle course. Different statistical procedures were employed in order to decipher the abundances and patterns of distribution of REE in different environments, showing a higher REE accumulation in surface sediments trapped by potholes and other rock cavities. Background contents were estimated by iterative simple regression. After checking several possible reference elements, Y showed the highest potential for the series of REE from La to Lu. The regression result, namely background function, is very useful to minimize the effect of the natural variability in sediment contents. Background functions also allow for environmental assessment by the calculation of the so-called local enrichment factors. As a general conclusion, contamination, if it exists, is negligible in the area and low enrichments can be attributed to postdepositional processes related to organic matter and the geochemistry of Fe and Mn.

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Wei, Zhang, and Nian Qiao Fang. "The Geochemistry Research on Eocene Volcanic Rocks in Sanshui Basin." Applied Mechanics and Materials 275-277 (January 2013): 322–25. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.322.

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Guangdong Sanshui Basin evoluted with extreme volcanic activities. Eruptions between Paleocene to Eocene were concentrated on Xinzhuang, Buxin, Baoyue and Huayong formations. For realized the relationship between various kind of rocks, Geochemistry analysis such as multi-element and rare-earth element determination were launched on Basalt, Trachyte and Rhyolite samples from the research area. Geochemistry diagram suggest that: REE distribution of Basalt followed as mid-plate alkali Basalt mode, while their trace element spider diagrams act as continental alkali Basalt with Nb, Ti rich and Sr loss. REE distribution of Trachyte and Rhyolite are similar, which indicate the same crystalization separation process. S-B diagram and Pearce diagram show that: Granite were partial melted from source region, while Trachyte in ZMY and Rhyolite in LBS originated from the same source region, and occur with the process of crystallization separation with plagioclase adventage.

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Prudêncio, Maria Isabel, Francisco Ruiz, Rosa Marques, Maria Isabel Dias, Joaquín Rodríguez Vidal, Ana Luísa Rodrigues, Luis Miguel Cáceres, et al. "REE Geochemistry of Neogene–Holocene Sediments of La Fontanilla Cove (Tinto Estuary, SW Spain)." Minerals 12, no. 4 (March 29, 2022): 417. http://dx.doi.org/10.3390/min12040417.

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The Tinto and Odiel rivers (SW Spain) drain from a vast sulfide mining district and join at a 20-km-long estuary that enters the Atlantic Ocean. In this work, the contents of rare earth elements (REE) and fractionation in Neogene–Holocene sediment cores from La Fontanilla cove (Tinto estuary) were studied. The sediments were collected from a depth of 18 m at different distances from the recent river flow and were analyzed for new information on the temporal development of the REE load in the sediment column. Results show that the ∑ REE is higher in the finer sediments and during periods of mining activity from prehistoric to recent times. Marine influence appears to increase the light REE (LREE) relative to the heavy REE (HREE). The REE patterns of these estuarine sediments show convex curvatures in the MREE relative to the LREE and HREE, indicating the presence of acid-mixing processes between the fluvial waters affected by acid mine drainage (AMD) and seawater, as well as the precipitation of poorly crystalline mineral phases. Significant positive Eu anomalies were found in ebb-tide channels and marsh deposits, which can reflect the mineralogical composition and/or a strong localized salinity gradient combined with organic matter degradation. Sedimentological characteristics of the deposits appear to play the main role in accumulation and fractionation of the REE.

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Reinhardt, Nils, Joaquín Proenza, Cristina Villanova-de-Benavent, Thomas Aiglsperger, Telm Bover-Arnal, Lisard Torró, Ramon Salas, and Annika Dziggel. "Geochemistry and Mineralogy of Rare Earth Elements (REE) in Bauxitic Ores of the Catalan Coastal Range, NE Spain." Minerals 8, no. 12 (December 1, 2018): 562. http://dx.doi.org/10.3390/min8120562.

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Karst bauxite deposits are currently investigated as a new resource for rare earth elements (REE) in order to avoid present and future supply shortfalls of these critical metals. The present work focuses on the geochemistry and mineralogy of the REE in karst bauxite deposits of the Catalan Coastal Range (CCR), NE-Spain. It is revealed that the studied bauxitic ores have a dominant breccia and local ooido-pisoidic and pelitomorphic texture. The bauxitic ores are mostly composed of kaolinite and hematite, as well as of lesser amounts of boehmite, diaspore, rutile and calcite. The mineralogy and major element composition indicate incomplete bauxitization of an argillaceous precursor material possibly derived from the erosion of the Mesozoic Ebro massif paleo-high. The studied bauxites are characterized by ∑REE (including Sc, Y) between 286 and 820 ppm (av. 483 ppm) and light REE to heavy REE (LREE/HREE) ratios up to 10.6. REE are mainly concentrated in phosphate minerals, identified as monazite-(Ce) and xenotime-(Y) of detrital origin and unidentified REE-phosphates of a possible authigenic origin. REE remobilization presumably took place under acidic conditions, whereas REE entrapment in the form of precipitation of authigenic rare earth minerals from percolating solutions was related to neutral to slightly alkaline conditions. During the bauxitization process no significant REE fractionation took place and the REE distribution pattern of the bauxitic ores was governed by the REE budget of the precursor material. Finally, adsorption as a main REE scavenging mechanism in the studied CCR bauxite deposits should not be considered, since the presented data did not reveal significant REE contents in Fe-and Mn-oxyhydroxides and clay minerals.

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Xuexin, Song, Xu Qingsheng, Guo Yuemin, Mao Xueying, and Ouyang Hong. "REE Geochemistry of VMS and SEDEX Ores in China." Acta Geologica Sinica - English Edition 71, no. 3 (September 7, 2010): 263–72. http://dx.doi.org/10.1111/j.1755-6724.1997.tb00367.x.

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CHEN, Zhihua. "REE geochemistry of surface sediments in the Chukchi Sea." Science in China Series D 46, no. 6 (2003): 603. http://dx.doi.org/10.1360/03yd9053.

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Zhihua, Chen, Gao Aiguo, Liu Yanguang, Sun Haiqing, Shi Xuefa, and Yang Zuosheng. "REE geochemistry of surface sediments in the Chukchi Sea." Science in China Series D: Earth Sciences 46, no. 6 (June 2003): 603–11. http://dx.doi.org/10.1007/bf02984538.

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Zhu, Zhaozhou, Congqiang Liu, Zhongliang Wang, Bo Gao, Zhihua Zhou, and Jun Li. "REE geochemistry of Chaohu and Longgan lakes, eastern China." Chinese Journal of Geochemistry 25, S1 (March 2006): 150. http://dx.doi.org/10.1007/bf02840031.

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SuZhen, Wu. "REE geochemistry of precambrian metamorphic rocks in Wutaishan region." Chinese Journal of Geochemistry 8, no. 1 (January 1989): 72–83. http://dx.doi.org/10.1007/bf02842216.

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Barrett, T. J., P. W. Fralick, and I. Jarvis. "Rare-earth-element geochemistry of some Archean iron formations north of Lake Superior, Ontario." Canadian Journal of Earth Sciences 25, no. 4 (April 1, 1988): 570–80. http://dx.doi.org/10.1139/e88-055.

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Rare-earth-element (REE) compositions of iron formation from two Archean terrains in western Ontario have been determined in order to assess the possible influence of hydrothermal activity on the REE patterns of chemical sediments. One terrain is characterized by sulfide-facies iron formation in association with volcanic flows and volcaniclastic sediments, whereas the other is dominated by oxide-facies iron formation intercalated within submarine-fan clastic sediments. Mineral separates of chert, magnetite, and pyrite from the iron formations have low ΣREE concentrations (< 20–30 ppm) and display moderate to strong positive Eu anomalies (relative to Archean shale). The positive anomalies (and lack of negative Ce anomalies) indicate that Archean sea water from which iron formation locally precipitated was reduced, although to varying degrees.The REE patterns of mineral separates from a given locality are almost identical, but the patterns for various localities differ in detail. A number of iron-formation samples interbedded within volcanics and at the volcanic–sediment interface show a distinct positive La anomaly and near-flat to slightly heavy-REE (HREE)-enriched patterns. The only modern environment where metalliferous sediments are accumulating with these combined characteristics is the Red Sea brine deeps. By contrast, limited data from iron formation interbedded within the clastic submarine fan suggest a fairly flat pattern with a moderate positive Eu anomaly and no La enrichment. We therefore suggest that the latter pattern typifies nonhydrothermal Archean seawater.Where seawater was influenced by a direct hydrothermal contribution, La enrichment and enhancement of the Eu anomaly could result. However, since periods of low-intensity discharge and (or) bottom-water mixing could eliminate the hydrothermal signal, not all samples from volcanic associations need show these features. By analogy with the Red Sea, preservation of a hydrothermal signal is most likely where circulation in the depositional basin is restricted and bottom waters are strongly reducing. Evidence for such conditions in the volcanic association is provided by the nature of the associated sediments (e.g., carbonaceous slates and unreworked distal turbidites).

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Kozlov, Evgeniy, Ekaterina Fomina, Mikhail Sidorov, Vladimir Shilovskikh, Vladimir Bocharov, Alexey Chernyavsky, and Miłosz Huber. "The Petyayan-Vara Carbonatite-Hosted Rare Earth Deposit (Vuoriyarvi, NW Russia): Mineralogy and Geochemistry." Minerals 10, no. 1 (January 17, 2020): 73. http://dx.doi.org/10.3390/min10010073.

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The Vuoriyarvi Devonian carbonatite–ijolite–pyroxenite–olivinite complex comprises several carbonatite fields: Neske Vara, Tukhta-Vara, and Petyayan-Vara. The most common carbonatites in the Tukhta-Vara and Neske-Vara fields are calciocarbonatites, which host several P, Fe, Nb, and Ta deposits. This paper focuses on the Petyayan-Vara field, in which the primary magmatic carbonatites are magnesian. The least altered magnesiocarbonatites are composed of dolomite with burbankite and are rich in REE (up to 2.0 wt. %), Sr (up to 1.2 wt. %), and Ba (up to 0.8 wt. %). These carbonatites underwent several stages of metasomatism. Each metasomatic event produced a new rock type with specific mineralization. The introduction of K, Si, Al, Fe, Ti, and Nb by a F-rich fluid (or fluid-saturated melt) resulted in the formation of high-Ti magnesiocarbonatites and silicocarbonatites, composed of dolomite, microcline, Ti-rich phlogopite, and Fe–Ti oxides. Alteration by a phosphate–fluoride fluid caused the crystallization of apatite in the carbonatites. A sulfate-rich Ba–Sr–rare-earth elements (REE) fluid (probably brine-melt) promoted the massive precipitation of ancylite and baryte and, to a lesser extent, strontianite, bastnäsite, and synchysite. Varieties of carbonatite that contain the highest concentrations of REE are ancylite-dominant. The influence of sulfate-rich Ba-Sr-REE fluid on the apatite-bearing rocks resulted in the dissolution and reprecipitation of apatite in situ. The newly formed apatite generation is rich in HREE, Sr, and S. During late-stage transformations, breccias of magnesiocarbonatites with quartz-bastnäsite matrixes were formed. Simultaneously, strontianite, quartz, calcite, monazite, HREE-rich thorite, and Fe-hydroxides were deposited. Breccias with quartz-bastnäsite matrix are poorer in REE (up to 4.5 wt. % total REE) than the ancylite-dominant rocks (up to 11 wt. % total REE).

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Chirkova, Evgenia, Ekaterina Baranovskaya, Natalia Kharitonova, Vasily Lavrushin, Georgy Chelnokov, and Ivan Bragin. "Geochemistry of the rare earth elements in the sparkling groundwaters of the Caucasus ridge, Russia." E3S Web of Conferences 98 (2019): 01009. http://dx.doi.org/10.1051/e3sconf/20199801009.

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The paper presents data on the content and distribution of rare earth elements (REE) in the high pCO2 mineral waters of the Caucasus mountain-folded region. It is shown that the concentrations of REEtotal are rather high in the studied waters. However, they vary in a very wide range (from 0.46 to 50.37 µg/L). A characteristic feature of these waters is the predominance of light REE in comparison with heavy REE in them. The distinct correlation of REEtotal in the solution from the concentration of iron and aluminum in it indicates that the absolute contents of REE in the mineral waters of the region are regulated not only by pH and Eh of the solution but also by the content of these elements in it.

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Rae, David A., Ian M. Coulson, and Andrew D. Chambers. "Metasomatism in the North Qôroq centre, South Greenland: apatite chemistry and rare-earth element transport." Mineralogical Magazine 60, no. 398 (February 1996): 207–20. http://dx.doi.org/10.1180/minmag.1996.060.398.14.

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AbstractThe North Qôroq syenite centre forms part of the Gardar Province of South Greenland. Extensive metasomatism, associated with the evolution of syenitic magmas, has resulted in redistribution of the rare-earth elements (REE), originally concentrated by magmatic processes, in both the syenites and surrounding granite-gneiss and quartzite country rocks. An important host for REE is apatite which can occur in significant quantities. Metasomatic apatites show complex, concentric, but irregular patterns of zonation, clearly seen using CL and BSE imaging. This zonation is related to successive pulses of metasomatising fluids. Electron microprobe analysis confirms the presence of significant quantities of REE in the apatites. The dominant cation exchange mechanism proposed is Ca2+ + P5+ ⇌ REE3+ + Si4+. In contrast to apatites from the nearby Ilímaussaq intrusion, there is no significant Na present in the structure and exchange reactions involving Na+ and REE3+ for Ca2+ have not occurred.Apatites from the quartzite are fluor-apatites, while those from the granite-gneiss are more Cl-rich. These differences reflect the fact that granite-gneiss apatites are original and modified by metasomatism, whereas, those in the quartzite are metasomatic in origin. REE were probably transported as carbonate, fluoride or fluor-carbonate complexes, and reflect the activity of a F−-rich, CO2−3-rich fluid phase.

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Souissi, Fouad, Radhia Sassi, Jean-Louis Dandurand, Salah Bouhlel, and Sami Ben Hamda. "Fluid inclusion microthermometry and rare earth element distribution in the celestites of the Jebel Doghra ore deposit (Dome Zone, northern Tunisia): towards a new genetic model." Bulletin de la Société Géologique de France 178, no. 6 (November 1, 2007): 459–71. http://dx.doi.org/10.2113/gssgfbull.178.6.459.

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Abstract The celestite ore of Jebel Doghra occurs as stratabound deposits within the cap-rock of a diapiric structure of Triassic salt-rocks. The celestite deposits result mainly from the late diagenetic to epigenetic replacement of the carbonated host-rocks giving rise to a dolomite-celestite “banded ore”. Celestite is locally observed within fractures. This study proposes a new genetic model based on fluid inclusion (FI) microthermometry and REE geochemistry. FI show that celestite, occurring either as stratabound bodies or lodes, was deposited from a highly saline (20.7 ± 1.3 wt%NaCl equivalents) and warm (174 ± 3oC) basinal fluid, which contains hydrocarbon droplets and CO2. The geochemistry of the REE shows that the deposition of celestite is due to the mixing between a deep-sourced fluid which has acquired high Sr concentrations by leaching feldspar-rich series in depth and a sulfate-rich solution associated with the Triassic evaporites.

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Wang, Xiaomei, Fan Deng, Haijian Cheng, Shuzheng Ning, Baoqing Li, Sidong Pan, and Xuebo Yin. "Effects of Heating on the Binding of Rare Earth Elements to Humic Acids." Energies 15, no. 19 (October 7, 2022): 7362. http://dx.doi.org/10.3390/en15197362.

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In deep underground environments, temperature is one of the key factors affecting the geochemistry behaviors of rare earth elements (REE) in organic-rich fluid. However, the influence of temperature on the interaction between humic acids (HA) and REE is not well known. In the present study, the influence of temperature on the HA–REE-binding behavior was evaluated based on heating experiments of REE-doped HA solution. Lignite-extracted HA and REE-binding experiments were conducted over a temperature range of 20 to 200 °C to quantify HA–REE complexation and the influence of temperature on HA binding sites. Results showed that increasing temperature and decreasing [REE]/[HA] ratio cause an increase of Kd value (the partition coefficient of REE between HA and aqueous solution). During heating KREE d KREE d patterns gradually change from middle REE-enriched-type (M-type) at 20 °C to light and middle REE-enriched-type (L-M-type) at 50 and 100 °C, and to light REE-enriched-type (L-type) at 150 °C and 200 °C. The increase of REE bonded with HA and modifications of KREE d patterns during the thermal treatment may be attributed to the increase of REE-binding sites, especially carboxylic sites, as a consequent of HA decomposition. This study provides a glimpse into the HA–REE-binding behaviors in the deep underground environment, which may shed light on the geochemical characteristics of REE in some organic-bearing rocks, and their changes during the coalification process.

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Dostal, J., C. Dupuy, and J. L. Poidevin. "Geochemistry of Precambrian basaltic rocks from the Central African Republic (Equatorial Africa)." Canadian Journal of Earth Sciences 22, no. 5 (May 1, 1985): 653–62. http://dx.doi.org/10.1139/e85-072.

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The two Archaean greenstone belts (Bandas and Bogoin) in the Central African Republic (Equatorial Africa) are 250 and 150 km long. The metavolcanic rocks in the belts are predominantly komatiitic and tholeiitic basalts. Komatiites include both Al-depleted and Al-undepleted types. The komatiites and light-REE-depleted tholeiites were probably derived from a similar upper mantle source. However, the tholeiitic basalts enriched in light REE from the upper volcanic strata of the Bandas belt were generated from a different source. The dolerites from Proterozoic dyke swarms and sills differ from the basalts mainly in their abundances and ratios of several incompatible elements such as K, Rb, Th, and light REE. They were derived from a distinct, incompatible-element-enriched upper mantle source.The average background gold levels in the Bandas belt and dolerite dyke swarms are comparable to those in equivalent rocks from North America. The exception is the Bogoin greenstone belt, which has anomalously high gold abundances.

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Simandl, George J., Suzanne Paradis, Johnathan Savard, Deanna Miller, Rameses D'Souza, Daisuke Araoka, Carlee Akam, Mihoko Hoshino, and Yoshiaki Kon. "Mineral control on the geochemistry of the Rock Canyon Creek REE-F-Ba deposit, British Columbia, Canada." Geochemistry: Exploration, Environment, Analysis 21, no. 2 (February 15, 2021): geochem2020–010. http://dx.doi.org/10.1144/geochem2020-010.

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The Rock Canyon Creek carbonate-hosted REE-F-Ba deposit has tectonic, stratigraphic and structural similarities with Mississippi Valley-type and sparry magnesite deposits in the SE Rocky Mountains. The main REE-fluorite zone is a steeply dipping body, extending 1100 m along-strike, 50 m wide and 100 m deep. It spatially coincides with pre-existing crackle breccias in carbonate rocks, and consists of dolomite, fluorite, barite, pyrite, quartz, K-feldspar, calcite, porous apatite, REE-fluorocarbonates and REE-phosphates. The main fluorocarbonates are bastnaesite, parisite and synchysite. Monazite, crandallite group minerals and apatite are the main phosphates. Fluorite content varies from less than 1 to 13.5% (by weight) and ∑REE + Y concentrations vary from trace to 1.95% (by weight). The mineralized zone is heterogeneous on the deposit scale, as indicated by three-dimensional geochemical modelling combined with a geochemical assessment based on 89 mineralized samples and detailed downhole mineral and geochemical profiles of a key borehole. Chemical heterogeneity and key elemental co-variations are explained by strong mineralogical control and have implications for the design of exploration and development programmes for this type of deposit. The chondrite-normalized REE pattern of samples from the mineralized zone shows enrichment in LREE, similar to typical carbonatite-related mineralization; however, no carbonatite is exposed nearby.

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XU, Cheng. "Geochemistry of carbonatites in Maoniuping REE deposit, Sichuan Province, China." Science in China Series D 46, no. 3 (2003): 246. http://dx.doi.org/10.1360/03yd9023.

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Zhao, Zhenhua, and Lingdi Zhou. "REE geochemistry of some alkali-rich intrusive rocks in China." Science in China Series D: Earth Sciences 40, no. 2 (April 1997): 145–58. http://dx.doi.org/10.1007/bf02878373.

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Akagi, Tasuku, and Akimasa Masuda. "Isotopic studies and REE geochemistry on alluvial diamonds from Zaire." Chemical Geology 70, no. 1-2 (August 1988): 2. http://dx.doi.org/10.1016/0009-2541(88)90169-6.

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Hongyuan, Xia, and Liang Shuyi. "Evolution and REE geochemistry of Huangsha-Tieshanlong ore-bearing granite." Chinese Journal of Geochemistry 7, no. 3 (July 1988): 207–19. http://dx.doi.org/10.1007/bf02840963.

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Fan, Qicheng, Ruoxin Liu, Huimin Li, Ni Li, Jianli Sui, and Zhuoran Lin. "Zircon chronology and REE geochemistry of granulite xenolith at Hannuoba." Chinese Science Bulletin 43, no. 18 (September 1998): 1510–15. http://dx.doi.org/10.1007/bf02883438.

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Amangeldykyzy, A., A. N. Kopobayeva, N. S. Askarova, D. S. Ozhigin, and V. S. Portnov. "Study of rare earth elements in the coals of the Shubarkol deposit." Kompleksnoe Ispolʹzovanie Mineralʹnogo syrʹâ/Complex Use of Mineral Resources/Mineraldik Shikisattardy Keshendi Paidalanu 4, no. 319 (October 28, 2021): 48–56. http://dx.doi.org/10.31643/2021/6445.40.

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The work studies mineralogical and geochemical features of the Jurassic coals of the Shubarkol deposit. The samples were examined using the method of scanning electron microscopy (SEM-EDX) Hitachi S-3400N, which was carried out at the Uranium Geology Research and Development Center at the Department of Geoecology and Geochemistry of TPU. Coal geochemistry was studied by instrumental neutron activation analysis (INAA) at the nuclear geochemical laboratory of the Department of Geoecology and Geochemistry of National Research Tomsk Polytechnic University (TPU). The choice of this object of study was determined by the tasks of research including the study of the patterns of accumulation of abnormal concentrations of REE, the effect of various factors of the geological environment on the levels of their accumulation in coals, as well as the conditions of its concentration and forms of occurrence in coals to expand the mineral resource base of Kazakhstan for rare earth elements. According to the results of scanning microscopic analysis, aluminosilicates, sulfides and sulfates with inclusions of microparticles of rare and rare earth elements were found in the composition of the Shubarkol deposit coals. According to the INNA results, abnormal concentrations of Sc, Ta, Nb, Hf, Zr, Ba, Sr, Ce and REE were found. Weathering processes led mainly to the loss and redistribution of REE in the coal seams of the Shubarkol deposit, which in turn led to increasing the content of rare earth elements from the bottom up the section. As a result of the action of multiple processes, increased concentrations of rare earth metals, mainly of the yttrium group, were formed. The absence of negative europium anomaly was determined, which confirms the original rocks composition peculiarity. The maximum contents of rare-earth metals are confined to weathered coals; for the medium-heavy group (Nd, PM, Sm, Eu), they are almost a hundredfold higher than the clarke in the upper continental crust. The tenfold excess of the clarke for elements from Gd to Lu was found in clayey sandstones and siltstones; for the rest of the rocks of the deposit the excess over the clarke is significantly lower. It was found that the coals of the deposit belong to the H-type and L-type of REE distribution. During the formation of oxidized H-type coals, clayey matter of terrigenous ash predominated as a carrier of REE, while unoxidized L-type coals were formed with the introduction of REE into the coal accumulation basin mainly in the composition of clay minerals and LREE-phosphates. Here the main source of REE was apparently the weathering crust over acidic rocks.

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Lorenz, Melanie, Uwe Altenberger, Robert B. Trumbull, Raúl Lira, Mónica López de Luchi, Christina Günter, and Sascha Eidner. "Chemical and textural relations of britholite- and apatite-group minerals from hydrothermal REE mineralization at the Rodeo de los Molles deposit, Central Argentina." American Mineralogist 104, no. 12 (December 1, 2019): 1840–50. http://dx.doi.org/10.2138/am-2019-6969.

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Abstract Britholite group minerals (REE,Ca)5[(Si,P)O4]3(OH,F) are widespread rare-earth minerals in alkaline rocks and their associated metasomatic zones, where they usually are minor accessory phases. An exception is the REE deposit Rodeo de los Molles, Central Argentina, where fluorbritholite-(Ce) (FBri) is the main carrier of REE and is closely intergrown with fluorapatite (FAp). These minerals reach an abundance of locally up to 75 modal% (FBri) and 20 modal% (FAp) in the vein mineralizations. The Rodeo de los Molles deposit is hosted by a fenitized monzogranite of the Middle Devonian Las Chacras-Potrerillos batholith. The REE mineralization consists of fluorbritholite-(Ce), britholite-(Ce), fluorapatite, allanite-(Ce), and REE fluorcarbonates, and is associated with hydrothermal fluorite, quartz, albite, zircon, and titanite. The REE assemblage takes two forms: irregular patchy shaped REE-rich composites and discrete cross-cutting veins. The irregular composites are more common, but here fluorbritholite-(Ce) is mostly replaced by REE carbonates. The vein mineralization has more abundant and better-preserved britholite phases. The majority of britholite grains at Rodeo de los Molles are hydrothermally altered, and alteration is strongly enhanced by metamictization, which is indicated by darkening of the mineral, loss of birefringence, porosity, and volume changes leading to polygonal cracks in and around altered grains. A detailed electron microprobe study of apatite-britholite minerals from Rodeo de los Molles revealed compositional variations in fluorapatite and fluorbritholite-(Ce) consistent with the coupled substitution of REE3+ + Si4+ = Ca2+ + P5+ and a compositional gap of ~4 apfu between the two phases, which we interpret as a miscibility gap. Micrometer-scale intergrowths of fluorapatite in fluorbritholite-(Ce) minerals and vice versa are chemically characterized here for the first time and interpreted as exsolution textures that formed during cooling below the proposed solvus.

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Anenburg, Michael. "Rare earth mineral diversity controlled by REE pattern shapes." Mineralogical Magazine 84, no. 5 (September 11, 2020): 629–39. http://dx.doi.org/10.1180/mgm.2020.70.

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AbstractThe line connecting rare earth elements (REE) in chondrite-normalised plots can be represented by a smooth polynomial function using λ shape coefficients as described by O'Neill (2016). In this study, computationally generated λ combinations are used to construct artificial chondrite-normalised REE patterns that encompass most REE patterns likely to occur in natural materials. The dominant REE per pattern is identified, which would lead to its inclusion in a hypothetical mineral suffix, had this mineral contained essential REE. Furthermore, negative Ce and Y anomalies, common in natural minerals, are considered in the modelled REE patterns to investigate the effect of their exclusion on the relative abundance of the remainder REE. The dominant REE in a mineral results from distinct pattern shapes requiring specific fractionation processes, thus providing information on its genesis. Minerals dominated by heavy lanthanides are rare or non-existent, even though the present analysis shows that REE patterns dominated by Gd, Dy, Er and Yb are geologically plausible. This discrepancy is caused by the inclusion of Y, which dominates heavy REE budgets, in mineral name suffixes. The focus on Y obscures heavy lanthanide mineral diversity and can lead to various fractionation processes to be overlooked. Samarium dominant minerals are known, even though deemed unlikely by the computational model, suggesting additional fractionation processes that are not well described by λ shape coefficients. Positive Eu anomalies only need to be moderate in minerals depleted in the light REE for Eu to be the dominant REE, thus identifying candidate rocks in which the first Eu dominant mineral might be found. Here, I present an online tool, called ALambdaR that allows interactive control of λ shape coefficients and visualisation of resulting REE patterns.

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Fendy, Nur Afikah, and Roniza Ismail. "Mineralogy and Geochemistry of Clay in Sokor and Jeli, Kelantan." IOP Conference Series: Earth and Environmental Science 1102, no. 1 (November 1, 2022): 012024. http://dx.doi.org/10.1088/1755-1315/1102/1/012024.

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Clay is considered as fine-grained, natural and earthy argillaceous material which are widely distributed in sediments as the products of sedimentation and diagenesis. The sample of rocks and clay soil from Sokor and several areas in Jeli, Kelantan have been analysed for geochemical and mineralogical properties. For geochemical analysis, the concentration of major elements was analysed using X-Ray Diffraction Fluorescene (XRF) and X-Ray Diffraction (XRD) Spectroscopy in order to validate the clay mineral existence. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) also was used for trace element determination while the Scanning Electron Microscopy (SEM) were used to study the mineralogy of clay as well as petrography. From mineralogy and petrography studies using optical microscope and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS) analysis show that the mineral distribution in the sample from both Sokor and Jeli area dominantly by quartz, biotite and K-feldspar mineral. It is supported by XRD analysis which showing the prominent peaks of quartz on 27Å and kaolinite on 12Å from the graph is easily identified. Chondrite normalise pattern is generated from ICP-MS result to constrain rare earth element (REE) behaviour and geochemical information. The normalised fractionation trends recorded below than usual REE deposition. This is because there is no mineral association of REE such as apatite and titanite found from the sample.

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Ayupova, N. R., V. V. Maslennikov, and K. A. Filippova. "REE geochemistry and mineralogy of ores from the Talgan Cu-Zn massive sulfide deposit, South Urals." Доклады Академии наук 487, no. 6 (September 10, 2019): 659–62. http://dx.doi.org/10.31857/s0869-56524876659-662.

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The high REE contents (57,23-561,2 ppm) of thin-layered sulfide ores of the Talgan Cu-Zn massive sulfide deposit (South Urals) are related to the presence of REE minerals: galgenbergite, parisite, bastnesite, synchysite and xenotime, which were found for the first time in massive sulfide deposits of the Urals. These minerals occur in quartz-carbonate-chlorite matrix of sulfide layers, as well as pyrite nodules and sub- and euderal crystals. The chondrite-normalized REE patterns are enriched in LREEs relatively to HREEs and the presence of weak negative cerium and positive europium anomalies. The LREE contents decrease by an order of magnitude and the LREE and HREE contents become similar with decreasing amount of hyaloclastic material in sulfide layers. The REEs for the formation of REE minerals are derived from mixed carbonate-hyaloclastic and ore material during the formation of layered sulfide ores.

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Zhmodik, Sergey, Elena Lazareva, Nikolay Dobretsov, Viktor Ponomarchuk, and Alexander Tolstov. "Mineralogical, geochemical and isotopic (C, O, Sr) features of the unique high-grade REE-Nb ores from the Tomtor deposit (Arctic Siberia, Russia)." E3S Web of Conferences 98 (2019): 12027. http://dx.doi.org/10.1051/e3sconf/20199812027.

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The mineralogy (SEM), geochemistry (LA-ICP-MS) and isotopic composition of C, O and Sr in carbonates from uniquely high-grade REE-Nb ores of the Tomtor massif is presented. Testing of the formation conditions for uniquely high-grade ores from the Tomtor deposit was conducted.

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Chelnokov, G. A., N. A. Kharitonova, I. V. Bragin, A. V. Aseeva, K. Yu Bushkareva, and L. A. Liamina. "Geochemistry of rees in the natural waters and the secondary phases from thermal fields of Kamchatka." Moscow University Bulletin. Series 4. Geology, no. 1 (February 28, 2020): 88–96. http://dx.doi.org/10.33623/0579-9406-2020-1-88-96.

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A study of the distribution of rare-earth elements in surface and underground waters, waterbearing rocks, as well as secondary mineral formed by the thermal waters of the Paratunka and Viluchinsky hydrothermal systems of Kamchatka was carried out. It was found that the REE content, their distribution and fractionation differ depending on the geochemical type of water, as well as the pH–Eh of the aquifer. All waters are characterized by the predominance of the dissolved form of the REE water transfer, which exceeds the transfer of REE with colloids by a factor of a thousand. It has been shown that in the discharge areas of the studied thermal waters carbonates, sulfates and silicates, including calcite, gypsum, and amorphous opal, are widespread. The intensity of the REE redistribution process in the rock-water-secondary deposits system is very weak in waters where REEs are associated with sulfates. At the same time, REEs bound in water with carbonate complexes most actively accumulate in newly formed mineral phases.

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46

Galán, E., J. C. Fernández-Caliani, A. Miras, P. Aparicio, and M. G. Márquez. "Residence and fractionation of rare earth elements during kaolinization of alkaline peraluminous granites in NW Spain." Clay Minerals 42, no. 3 (September 2007): 341–52. http://dx.doi.org/10.1180/claymin.2007.042.3.07.

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AbstractA geochemical and mineralogical study has allowed us to address the factors controlling distribution pattern, residence and behaviour of rare earth elements (REE) during kaolinization of Variscan granitoids in NW Spain. Mineral composition of the deeply weathered samples is dominated by kaolinite, with minor amounts of quartz, muscovite-illite, alkaline feldspar and traces of resistant minerals (rutile, ilmenite, zircon and monazite). Variable amounts of Si, Na, Ca, K, Rb, Cs, Ba, U and P were lost from the weathering profile, as a result of feldspars, mica and apatite breakdown, whereas Al, Fe, Ti, Zr, Th, Hf and REE were concentrated in the residual kaolin. Chondrite-normalized REE patterns of the kaolins show an overall enrichment of light REE (LaN/SmN = 1.22–2.53), heavy REE depletion (GdN/YbN = 2.42–15.10) and a strong negative Eu anomaly (Eu/Eu* = 0.11–0.25), probably inherited from the parent granite. Nevertheless, the normalization to the parent granite reveals some REE fractionation and increasing positive Eu anomalies with advancing weathering, in response to the breakdown of feldspars. Different grain-size fractions show similar REE distribution patterns, but differ in concentration levels. Although the fine fractions are the most important REE reservoir, there is no positive correlation with clay mineralogy. The correlative behaviour among P2O5, Th and REE in the <2 mm fraction suggests that monazite plays a dominant role controlling the REE budget in the weathering profile.

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Mckay, G., J. Wagstaff, and S. R. Yang. "Clinopyroxene REE distribution coefficients for shergottites: The REE content of the Shergotty melt." Geochimica et Cosmochimica Acta 50, no. 6 (June 1986): 927–37. http://dx.doi.org/10.1016/0016-7037(86)90374-1.

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Marien, C., A. H. Dijkstra, and C. Wilkins. "The hydrothermal alteration of carbonatite in the Fen Complex, Norway: mineralogy, geochemistry, and implications for rare-earth element resource formation." Mineralogical Magazine 82, S1 (February 28, 2018): S115—S131. http://dx.doi.org/10.1180/minmag.2017.081.070.

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ABSTRACTThe Fen Complex in Norway consists of a ~583 Ma composite carbonatite-ijolite-pyroxenite diatreme intrusion. Locally, high grades (up to 1.6 wt.% total REE) of rare-earth elements (REE) are found in a hydrothermally altered, hematite-rich carbonatite known as rødbergite. The progressive transformation of primary igneous carbonatite to rødbergite was studied here using scanning electron microscopy and inductively coupled plasma-mass spectrometry trace-element analysis of 23 bulk samples taken along a key geological transect. A primary mineral assemblage of calcite, dolomite, apatite, pyrite, magnetite and columbite with accessory quartz, baryte, pyrochlore, fluorite and REE fluorocarbonates was found to have transformed progressively into a secondary assemblage of dolomite, Fe-dolomite, baryte, Ba-bearing phlogopite, hematite with accessory apatite, calcite, monazite-(Ce) and quartz. Textural evidence is presented for REE fluorocarbonates and apatite breaking down in igneous carbonatite, and monazite-(Ce) precipitating in rødbergite. The importance of micro-veins, interpreted as feeder fractures, containing secondary monazite and allanite, is highlighted. Textural evidence for included relics of primary apatite-rich carbonatite are also presented. These acted as a trap for monazite-(Ce) precipitation, a mechanism predicted by physical-chemical experiments. The transformation of carbonatite to rødbergite is accompanied by a 10-fold increase in REE concentrations. The highest light REE (LREE) concentrations are found in transitional vein-rich rødbergite, whereas the highest heavy REE (HREE) and Th concentrations are found within the rødbergites, suggesting partial decoupling of LREE and HREE due to the lower stability of HREE complexes in the aqueous hydrothermal fluid. The hydrothermal fluid involved in the formation of rødbergite was oxidizing and had probably interacted with country-rock gneisses. An ore deposit model for the REE-rich rødbergites is presented here which will better inform exploration strategies in the complex, and has implications for carbonatite-hosted REE resources around the world.

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Edahbi, M., B. Plante, M. Benzaazoua, and A. Cayer. "Geoenvironmental characterization of two REE deposits: the Montviel carbonatites and Kipawa silicates, Quebec Canada." IOP Conference Series: Earth and Environmental Science 1090, no. 1 (October 1, 2022): 012013. http://dx.doi.org/10.1088/1755-1315/1090/1/012013.

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Abstract Drainage water quality is the significant environmental concern for the rare earth elements (REE) mining industry. REE deposits are associated with other metals and radioactive bearing minerals. REE mining and refining activities can generate significant quantities of liquid and solid wastes. Therefore, a long-term integrated approach covering the full mine-life cycle is required to mitigate possible environmental concerns. In the present study, two REE concentrates were prepared and all deposit lithologies of carbonatites and silicates sampled and investigated for their mineralogy, geochemistry, and their environmental behavior using kinetic testing. For the Montviel carbonatite (enriched in light rare earth elements, or LREE), the majority of REE-bearing minerals are associated with carbonates (i.e., monazite, kukharenkoite, burbankite, etc.), whereas the REE-bearing minerals associated with the Kipawa silicates (enriched in heavy rare earth elements, or HREE) are fluorbritholite, eudyalite, mosandrite, etc. The kinetic tests showed a neutral to alkaline pH of leachates and a low leachability of REE (carbonatites <140 μg/L; silicates <15 μg/L) with a higher mobility of HREE than LREE. The reactivity of REE carbonates are one to two orders of magnitude higher than REE silicates. For sustainable mineral development, geological and environmental data was integrated into the geometallurgical model to identify and control the environmental risks associated with mining those two deposits.

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Mitchell, Roger H., and Stephen J. B. Reed. "Ion Microprobe Determination of Rare Earth Elements in Perovskite from Kimberlites and Alnöites." Mineralogical Magazine 52, no. 366 (June 1988): 331–39. http://dx.doi.org/10.1180/minmag.1988.052.366.04.

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AbstractIon microprobe analysis ofperovskite from kimberlites and alnöites permits the accurate determination of La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Er and Yb at the part per million level. Other rare earth elements (REE) are subject to interferences in the mass spectrum caused by matrix-derived molecular ions and cannot easily be determined with comparable precision. Chondrite-normalized plots of the ion probe REE data are smooth curves, confirming the superiority of this technique over electron microprobe methods at the levels of REE abundance found in these perovskites. The perovskites analysed contain between 2.8 and 7.1 wt. % REE oxides and are highly enriched in the light REE, having La/Yb ratios of 577–3229. These La/Yb ratios are not representative of the parental magmas but result from REE fractionation during crystallization of the perovskite. Parental magma La/Yb ratios are estimated to be of the order of 120–650. The lower La/Yb ratios (80–200) found for whole-rock kimberlites are considered to result from contamination by relatively heavy REE-enriched crustal material.

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Journal articles on the topic 'REE geochemistry'

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