Academic literature on the topic 'REE-U enrichment'
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Journal articles on the topic "REE-U enrichment"
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Lentz, David. "Radioelement distribution in U, Th, Mo, and rare-earth-element pegmatites, skarns, and veins in a portion of the Grenville Province, Ontario and Quebec." Canadian Journal of Earth Sciences 28, no. 1 (January 1, 1991): 1–12. http://dx.doi.org/10.1139/e91-001.
Full textAbstract:
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.
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McLeod, Claire, and Barry Shaulis. "Rare Earth Elements in Planetary Crusts: Insights from Chemically Evolved Igneous Suites on Earth and the Moon." Minerals 8, no. 10 (October 16, 2018): 455. http://dx.doi.org/10.3390/min8100455.
Full textAbstract:
The abundance of the rare earth elements (REEs) in Earth’s crust has become the intense focus of study in recent years due to the increasing societal demand for REEs, their increasing utilization in modern-day technology, and the geopolitics associated with their global distribution. Within the context of chemically evolved igneous suites, 122 REE deposits have been identified as being associated with intrusive dike, granitic pegmatites, carbonatites, and alkaline igneous rocks, including A-type granites and undersaturated rocks. These REE resource minerals are not unlimited and with a 5–10% growth in global demand for REEs per annum, consideration of other potential REE sources and their geological and chemical associations is warranted. The Earth’s moon is a planetary object that underwent silicate-metal differentiation early during its history. Following ~99% solidification of a primordial lunar magma ocean, residual liquids were enriched in potassium, REE, and phosphorus (KREEP). While this reservoir has not been directly sampled, its chemical signature has been identified in several lunar lithologies and the Procellarum KREEP Terrane (PKT) on the lunar nearside has an estimated volume of KREEP-rich lithologies at depth of 2.2 × 108 km3. This reservoir therefore offers a prospective location for future lunar REE exploration. Within the context of chemically evolved lithologies, lunar granites are rare with only 22 samples currently classified as granitic. However, these extraterrestrial granites exhibit chemical affinities to terrestrial A-type granites. On Earth, these anorogenic magmatic systems are hosts to U-Th-REE-ore deposits and while to date only U-Th regions of enrichment on the lunar surface have been identified, future exploration of the lunar surface and interior may yet reveal U-Th-REE regions associated with the distribution of these chemically distinct, evolved lithologies.
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Dubyna, O. V., S. G. Kryvdik, I. A. Shvaika, I. D. Shvaika, and L. I. Proskurka. "APATITE GEOCHEMISTRY IN ROCKS OF KORSUN-NOVOMYRHOROD ANORTOSITE-RAPAKIVI GRANITE PLUTON." Mineralogical Journal 44, no. 3 (2022): 48–66. http://dx.doi.org/10.15407/mineraljournal.44.03.048.
Full textAbstract:
Trace element concentrations (REEs, Y, Sr, Th, U) in apatites from the most typical rocks of the Korsun-Novomyrhorod anorthosite-rapakivi pluton (KNP) were measured. Apatite was the last liquidous phase to crystallize in all the studied rocks because of the low P2O5 content in the primary melts. In the basic rocks, apatite is the main source of REEs, especially LREEs, except for Eu and Y. In intermediate and acidic rocks, apatites have minor influence on REEs concentrations, but they are more enriched in Th and U. All chondrite-normalized REE patterns of apatite show large negative Eu-anomalies (Eu/Eu* 0.03-0.21). This anomaly as well as increased Sr contents is less prominent (0.39) only in apatite from the norite of the external part of the pluton. With increased magmatic differentiation, apatite becomes more enriched in REEs, but Sr is depleted in the basic and intermediate rocks. In addition, all apatites from these rocks are LREE enriched and depleted in HREE and Sc which is consistent with earlier clino- or orthopyroxene fractionation, considering the minor amounts of in REE in plagioclase. REE patterns normalized to the primitive mantle indicate LREE enrichment ((La/Lu)N = 10.8-36) of apatites from all types of rocks with pronounced negative anomalies of Sr and Eu. This is the result of their low compatibility with apatite compared to other REEs. Inasmuch as the distribution of Eu is related to oxygen fugacity, we think that such unusually low Eu-anomalies reflect the initial melt differentiation under abyssal conditions. Thus, ubiquitous strong negative Eu-anomalies in apatites of all types of rocks are a result of two factors occurring during parent melt fractionation, namely early intensive plagioclase fractionation and highly reduced conditions during melt differentiation. By similar trace elements concentration and similarity of REE distribution in apatites it is probably that basic rocks and monzonitesare are derived from the same primary melt. At the same time, apatites from granites and syenites show maximum enrichment of REEs, especially HREE and Y. This indicates crystallization from residual differentiated melts (for syenites) or partial interaction of melts of various composition (basic and acidic) with migration of enriched LILE and REE solutions into acidic melts. The low content of P2O5 in ore-bearing rocks and ores of KNP, as well as the absence of Ti-magnetite and high iron enrichment of mafgic minerals and the unusually strong and negative Eu-anomalies in apatites, clearly distinguishes them from the Fe-Ti-P ores of the Korosten pluton. This suggests differences in the chemical composition of primary melts as well as the physical conditions of their differentiation.
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McCafferty, Anne E., Douglas B. Stoeser, and Bradley S. Van Gosen. "Geophysical interpretation of U, Th, and rare earth element mineralization of the Bokan Mountain peralkaline granite complex, Prince of Wales Island, southeast Alaska." Interpretation 2, no. 4 (November 1, 2014): SJ47—SJ63. http://dx.doi.org/10.1190/int-2014-0010.1.
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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.
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Molnár, Zsuzsa, Gabriella B. Kiss, István Dunkl, György Czuppon, Federica Zaccarini, and István Dódony. "Geochemical characteristics of Triassic and Cretaceous phosphorite horizons from the Transdanubian Mountain Range (western Hungary): genetic implications." Mineralogical Magazine 82, S1 (March 21, 2018): S147—S171. http://dx.doi.org/10.1180/minmag.2017.081.103.
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ABSTRACTThe carbonate-dominated Mesozoic sequence of the Transdanubian Mountain Range contains Triassic, uranium-enriched phosphorite layers and Cretaceous, REE-enriched nodular phosphorite. Detailed investigation of these deposits may have an economic benefit because of their large U and REE contents. The dominant minerals in the Triassic phosphorite are carbonate-bearing fluorapatite (CFA) and calcite. According to the electron-probe microanalysis (EPMA) the U is mainly associated with the CFA crystals. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) measurement shows that CFA contains 137–612 ppm U and 113–261 ppm total REE + Y. The LA-ICP-MS U-Pb age of the uppermost phosphorite horizon is 237 ± 11 Ma, which conforms with the stratigraphic age of the host limestone.The Cretaceous nodular phosphorite occurs on the base of an Aptian crinoid-bearing limestone mostly in the form of encrustations around bio- and silicic-clasts, but the clasts also contain phosphorite. The main minerals in these crusts are CFA, calcite, quartz, glauconite and Fe-oxide-hydroxides. Based on EPMA the REE enrichment is related to CFA and LA-ICP-MS measurements show that it contains 748–2953 ppm total REE + Y.The redox-sensitive proxies and the shape of NASC normalized REE patterns indicate that both phosphorites formed in anoxic environments. There are significant differences between these deposits such as appearance, rock-forming minerals, and U and REE contents which indicate differences in their sedimentary environments. The present results suggest that the Triassic phosphorite was formed by inorganic precipitation in a reducing environment close to sea-mounts. The Cretaceous occurrence resulted from a concentric growth mechanism in cold, ascending seawater at the continental margin environment during the anoxic Selli Event (OAE 1a) and/or Paquier Episode (OAE 1b). The critical raw material contents were derived from other sources.
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ΠΕΡΓΑΜΑΛΗΣ, Φ., Δ. Ε. ΚΑΡΑΓΕΩΡΓΙΟΥ, and Α. ΚΟΥΚΟΥΛΗΣ. "Συμβολή της ακτινοβολίας γ στον εντοπισμό αποθεματικού δυναμικού Ti, σπάνιων γαιών Th, U, Au παράκτιας ζώνης Νέας Περά- μου - Λουτρών Ελευθέρων, Ν. Καβάλας." Bulletin of the Geological Society of Greece 34, no. 3 (January 1, 2001): 1023. http://dx.doi.org/10.12681/bgsg.17707.
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The radiometric study allowed the survey of γ-radiation, pinpointed the areas of highest or irregular radiation values, and finally acquired a very important drawing specifying the geochemistry of U, Th, Ti, REE, Auetc.In today's shoreside zone, very high surficial levels of U with an average value of 22 and highest of 92 ppm were found, while in the sublittoral old zone all the g-radiation values found were irregular and much higher of those of the radiometric background, of the all-round subaqueous environment (mean values of residual sands 250 and 305 opposite to <60 (c/s)/grxl04 for the "background". The enrichment of sand with trace elements of U is a result of today's and mainly older wave-action, in the lower parts of sandy shoreside formations, with an expected highest enrichment in the bedrock cavities. Initial samples of sands enriched with U elements up to 50 ppm are considered to be a naturally grated multimetal mineral of Ti, U-Th, REE, Au and other metals for high-value technological applications.The concentrations of the above metals are higher of those internationally known to similar minerals(2.5%, 50-1600 ppm, 11.000 ppm and 250 mg/m3 respectively) and can be multiplied with lightwatermetallurgical processes. The concentrations of sands with highγ-radiation in today's shoreside zone can be differentiated between fine, medium and thick grains of sand particles with a slight inclination towards the waveaction. Their thickness has characteristic fluctuations, with a growth tendency up to a depth of 1.5 m and a decreasing tendency for depths under 2 m.On an horizontal region these concentrations values appear to grow continuously from the periphery towards the center and the γ-radiation values of the periphery seem to grow with the remotion of the present sediments. The γ-radiation in the sublittoral zone present a recurrent enrichment in the lower parts of the formations and is covered in the deepest points from the surface of the sea from younger age sediments.In the present sublittoral zone as well as in the shoreside zone, lower layers of sands formed out of natural grate actions, are mainly the medium grain and secondarily the fine grain variety. These natural enrichments due to waveaction, form selective concentrations of less important minerals U-Th, allanite rich in U02 and uraninite low in Th02 , which are responsible for the γ-radiation rise.
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Hassan, Kamaleldin M. "Trace elements and REE enrichment at Seboah Hill, SW Egypt." Mineralogia 49, no. 1-4 (December 1, 2018): 47–65. http://dx.doi.org/10.2478/mipo-2018-0007.
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Abstract Seboah Hill - a small body of peralkaline granite (< 0.1 km2) in south-western Egypt containing aegirine minerals ± magnesiohornblende ± riebeckite, cut by dikes of riebeckite-aegirine rhyolite, and exhibiting high radioactivity in veins of K-feldspar-aegirine-chalcedony-quartz ± trace hematite ± trace goethite was sampled and analyzed using inductively coupled plasma methods. Whole-rock chemical compositions of 5 granite, 3-rhyolitedike and 10 radioactive vein samples are presented. Of special significance is the enrichment of trace elements and rare earth elements (REE) in the radioactive veins. These include up to 6081 ppm Zr, 4252 ppm Ce, 1514 ppm Nd, 1433 ppm La, 1233 ppm Nb, 875 ppm Y, 388 ppm Pr, 350 ppm Th, 222 ppm Sm, 189 ppm Gd, 159 ppm Dy, 153 ppm Hf, 83 ppm Er, 76 ppm Yb and 58 ppm U. The chondrite-normalized patterns of REE in all samples show only limited variation and have negative europium (Eu) anomalies. These findings suggest that the sources of the REE are genetically related. Values of the Eu anomalies vary from 0.38-0.41 for the radioactive veins, 0.39-0.53 for the granite and 0.31-0.44 for the rhyolite dikes. Eu variations are consistent for different paragentic stages.
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Dupuy, C., J. Dostal, and J. L. Bodinier. "Geochemistry of spinel peridotite inclusions in basalts from Sardinia." Mineralogical Magazine 51, no. 362 (October 1987): 561–68. http://dx.doi.org/10.1180/minmag.1987.051.362.10.
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AbstractThe spinel peridotite inclusions in basalts from Sardinia are upper-mantle residues affected by metasomatism which led to an enrichment particularly of U and light REE. The metasomatism took place prior to the recrystallization which produced the primary mineral assemblage of the inclusions. The compositional variations imply that the xenoliths are residual after at least two melting events.
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Schneider, Petra, Dražen Balen, Joachim Opitz, and Hans-Joachim Massonne. "Dating and geochemistry of zircon and apatite from rhyolite at the UNESCO geosite Rupnica (Mt. Papuk, northern Croatia) and the relationship to the Sava Zone." Geologia Croatica 75, no. 2 (June 23, 2022): 249–67. http://dx.doi.org/10.4154/gc.2022.19.
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The Rupnica geosite, a key locality of the UNESCO-protected Papuk Geopark in northern Croatia, is well-known for an excellent exposure of columnar jointing in volcanic rock. This rock is defined as an albite rhyolite that comprises almost pure albite phenocrysts within a fine-grained matrix composed of microphenocrysts of albite, quartz and devitrified volcanic glass. Primary accessory minerals are clinopyroxene, apatite, zircon and magnetite. Haematite, apatite and anatase were found as inclusions in zircon. The albite rhyolite is characterized by a highly siliceous, peraluminous, oxidized (ferroan), dry, alkali-calcic to alkalic composition, with low CaO, MgO, and MnO contents and high FeOT/(FeOT+MgO) ratios. Normalized trace element contents display positive anomalies of K, Pb, and Zr as well as negative anomalies of Nb, P, Ti, Ba and Eu, together with an enrichment of light rare-earth elements (REE) relative to heavy REE. Zircon from the rhyolite of Rupnica is characterized by ratios of Th/U=1.13 and Zr/Hf=55 and contents of HfO2=1.04 wt. % typical for an early-stage igneous zircon crystallized from a dry high-temperature magma in a deep magma chamber. Apatite REE patterns show enrichment of light REE over heavy REE and a pronounced Eu anomaly, typical for apatite from granitoids formed in an oxidizing environment. The magma is of A-type and was generated at high temperatures at 800–900 °C by partial melting of lower- to mid-crustal rocks. The age of the albite rhyolite of Rupnica is Late Cretaceous at 80.8±1.8 (2σ) Ma, according to U-Pb dating of zircon, coeval with geochemically similar igneous rocks of Mt. Požeška Gora and Mt. Kozara within the Sava Zone.
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Platt, R. G., F. Wall, C. T. Williams, and A. R. Woolley. "Zirconolite, chevkinite and other rare earth minerals from nepheline syenites and peralkaline granites and syenites of the Chilwa Alkaline Province, Malawi." Mineralogical Magazine 51, no. 360 (June 1987): 253–63. http://dx.doi.org/10.1180/minmag.1987.051.360.07.
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AbstractFive rare earth-bearing minerals found in rocks of the Chilwa Alkaline Province, Malawi, are described. Zirconolite, occurring in nepheline syenite, is unusual in being optically zoned, and microprobe analyses indicate a correlation of this zoning with variations in Si, Ca, Sr, Th, U, Fe, Nb and probably water; it is argued that this zoning is a hydration effect. A second compositional zoning pattern, neither detectable optically nor affected by the hydration, is indicated by variations in Th, Ce and Y such that, although total REE abundances are similar throughout, there appears to have been REE fractionation during zirconolite growth from relatively heavy-REE and Th-enrichment in crystal cores to light-REE enrichment in crystal rims.Chevkinite is an abundant mineral in the large granite quartz syenite complexes of Zomba and Mulanje, and analyses are given of chevkinites from these localities. There is little variation in composition within each complex, and only slight differences between them; they are all typically light-REE-enriched. The Mulanje material was shown by X-ray diffraction to be chevkinite and not the dimorph perrierite, but chemical arguments are used in considering the Zomba material to be the same species. Other rare earth minerals identified are monazite, fluocerite and bastnäsite. These are briefly described and microprobe analyses presented.
Dissertations / Theses on the topic "REE-U enrichment"
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Kontonikas-Charos, A. "Albitization and REE-U-enrichment in IOCG systems: insights from Moonta-Wallaroo, Yorke Peninsula, South Australia." Thesis, 2013. http://hdl.handle.net/2440/106289.
Full textAbstract:
This item is only available electronically.Iron Oxide Copper Gold (IOCG) deposits are the products of crustal-scale metasomatic alteration, generally considered to be associated with the emplacement of large felsic intrusions. These systems are typified by zoned, broad alteration haloes comprising the products of an early, barren albitization event, and late, ore-hosting potassic/calcic (skarn) alteration associated with mineralization. Yttrium and rare earth elements (REY), and also uranium, are prominent components of most IOCG systems. The REY-signatures of feldspars and accessory apatite, Fe-(Ti)-oxides and other minerals are geochemical tracers of alteration stages within a magmatic-hydrothermal system. This study sets out to identify links between magmatism and initiation of hydrothermal activity, and to test the hypothesis that albitization is a pre-requisite stage for REE-U enrichment in magmatically-derived IOCG systems. The compositions and trace element concentrations in key minerals have been analysed using scanning electron microscopy, electron probe microanalysis and laser-ablation inductively-coupled plasma mass spectrometry in a varied range of magmatic to metasedimentary lithologies from the Moonta-Wallaroo region, an area in which broad regional-scale alkali alteration is recognised. Results confirm a strong link between albitization and REE-U-enrichment. The process of albitization is seen to consume, redistribute and lock-in REY, LILE and HFSE via complex fluid-rock reactions dependent on the pre-existing mineral assemblages and fluid characteristics, providing a holistic model for IOCG-driven alkali metasomatism. The trace element signatures recorded by K-feldspar reflect a transition from magmatic to hydrothermal stages within an evolving IOCG system. Although further constraints on these signatures are required, they could prove invaluable in mineral exploration as they suggest a quantifiable distinction between alteration associated with mineralization, and regional background. This hypothesis requires testing elsewhere in the Olympic Province and in analogous terranes.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2010
Conference papers on the topic "REE-U enrichment"
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Karl, Susan M., George Case, Elizabeth Drewes-Todd, Douglas C. Kreiner, Thomas P. Miller, and Alan Pongratz. "MINERALOGIC AND GEOCHEMICAL IMPLICATIONS FOR ENRICHMENT OF U-TH-REE IN SYENITE DIKES ON THE EASTERN SEWARD PENINSULA, ALASKA." In GSA Annual Meeting in Phoenix, Arizona, USA - 2019. Geological Society of America, 2019. http://dx.doi.org/10.1130/abs/2019am-335299.
Full textReports on the topic "REE-U enrichment"
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Gadd, M. G., J. M. Peter, T A Fraser, and D. Layton-Matthews. Paleoredox and lithogeochemical indicators of the environment of formation and genesis of the Monster River hyper-enriched black shale showing, Yukon. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/328004.
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Northern Yukon hosts occurrences of Middle Devonian hyper-enriched black shale (HEBS) Ni-Mo-Zn-platinum-group element-Au-Re mineralization, including the Monster River showing in the Ogilvie Mountains. This mineralization has been documented predominantly in the Paleozoic Richardson trough; however, the Monster River showing is atypical, occurring within the Blackstone trough, more than 200 km to the west on the southern margin of the Yukon block. The ambient paleoredox conditions of the marine water column and sediments may be primary controlling factors in HEBS formation. We use major and trace element lithogeochemistry to better understand ambient paleoenvironmental redox conditions through the application of robust redox proxies to HEBS mineralization and host rocks. Uniformly negative Ce anomalies (0.6-0.9) indicate that the water column was predominantly suboxic throughout the deposition interval, even during HEBS mineralization. Although there is a strong terrigenous influence on the rare earth element-yttrium (REE-Y) abundances of the sedimentary rocks, superchondritic Y/Ho ratios (&gt;27) indicate that seawater contributed REE-Y to the host rocks and HEBS. High (&gt;10) authigenic Mo/U ratios indicate that a Fe-Mn particulate shuttle operated in the water column; this is corroborated by negative Ce anomalies and high Y/Ho ratios. The data indicate that metalliferous sedimentary rocks formed by hydrogenous metal enrichment (e.g. Ni, Mo, Pt) caused by ferromanganese oxyhydroxide particulate shuttling as chemical sediments; moreover, the REE- and Mo-based paleoenvironmental indicators suggest a complexly redox-stratified depositional environment with an abundant supply of metals, metalloids, and sulfur.