scholarly journals Hydrothermal Alteration of Eudialyte-Hosted Critical Metal Deposits: Fluid Source and Implications for Deposit Grade

Minerals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 422 ◽  
Author(s):  
Mathijs van de Ven ◽  
Anouk Borst ◽  
Gareth Davies ◽  
Emma Hunt ◽  
Adrian Finch
Keyword(s):  
Rare Earth ◽  
Hydrothermal Alteration ◽  
Nepheline Syenite ◽  
Partial Replacement ◽  
Magmatic Fluid ◽  
High Field Strength ◽  
Nd Isotope ◽  
Critical Metal ◽  
Rock Alteration ◽  
Zircon Type

Eudialyte-hosted critical metal deposits potentially represent major sources of rare earth elements (REE), zirconium and niobium. Here, we study the chemical and isotopic composition of fresh and altered eudialyte in nepheline syenite from the Ilímaussaq Complex, Greenland, one of the world’s largest known eudialyte-hosted deposits. Late-magmatic hydrothermal alteration caused partial replacement of primary magmatic eudialyte by complex pseudomorph assemblages of secondary Zr-, Nb-, and REE-minerals. Three secondary assemblage types are characterised by the zirconosilicates catapleiite, gittinsite and zircon, respectively, of which the catapleiite type is most common. To investigate elemental exchange associated with alteration and to constrain the nature of the metasomatic fluids, we compare trace elements and Sm/Nd isotope compositions of unaltered eudialyte crystals and their replaced counterparts from five syenite samples (three catapleiite-type, one gittinsite-type, and one zircon-type assemblage). Trace element budgets for the catapleiite-type pseudomorphs indicate a 15–30% loss of REE, Ta, Nb, Zr, Sr and Y relative to fresh eudialyte. Moreover, the gittinsite- and zircon-type assemblages record preferential heavy REE (HREE) depletion (≤50%), suggesting that the metasomatic fluids mobilised high field strength elements. Initial Nd isotope ratios of unaltered eudialyte and catapleiite- and gittinsite-type pseudomorphs are indistinguishable, confirming a magmatic fluid origin. However, a higher initial ratio and stronger HREE depletion in the zircon-type pseudomorphs suggests a different source for the zircon-forming fluid. Although alteration reduces the metal budget of the original eudialyte volume, we infer that these elements re-precipitate nearby in the same rock. Alteration, therefore, might have little effect on overall grade but preferentially separates heavy and light REE into different phases. Targeted processing of the alteration products may access individual rare earth families (heavy vs. light) and other metals (Zr, Nb, Ta) more effectively than processing the fresh rock.

scholarly journals Magmatic volatiles episodically flush oceanic hydrothermal systems as recorded by zoned epidote

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Stephen Fox ◽  
Yaron Katzir ◽  
Wolfgang Bach ◽  
Lucy Schlicht ◽  
Justin Glessner
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Hydrothermal Systems ◽  
Ore Deposits ◽  
Strontium Isotope ◽  
Magmatic Fluid ◽  
Oceanic Spreading ◽  
Magmatic Volatiles ◽  
Rock Alteration

AbstractCirculation of seawater at oceanic spreading centers extracts heat, drives rock alteration, and transports leached metals to shallower levels of the crust, where they may precipitate and form ore deposits. Crystallization of the lower crust, may exsolve and introduce magmatic volatiles into the seawater-dominant system. However, the role of magmatic volatiles added to the hydrothermal system, including pathways of these fluids are lesser known. Here we present coupled in-situ strontium isotope and rare earth element data of distinct domains in epidote, a common hydrothermal mineral throughout the Troodos ophiolite, to track magmatic fluid input and flow. Epidote crystal domains characterize three distinct strontium isotope-rare earth element signatures—suggesting sequential growth from magma-derived fluids (0.704, negative europium anomalies), rock-buffered fluids (0.7055, positive europium anomalies) and seawater-derived fluids (0.7065, negative cerium anomalies). Epidote records episodic fluxing of magmatic fluids from plagiogranites, through epidosites in the upflow zone and into metal ore deposits.

Shoshonites, vaugnerites and potassic lamprophyres: similarities and differences between ‘ultra’-high-K rocks

2008 ◽  
Vol 99 (3-4) ◽  
pp. 159-175 ◽  
Author(s):  
J. H. Scarrow ◽  
F. Bea ◽  
P. Montero ◽  
J. F. Molina
Keyword(s):  
Rare Earth ◽  
Function Analysis ◽  
Crustal Contamination ◽  
High Field Strength ◽  
Nd Isotope ◽  
Radiogenic Heat ◽  
Arc Magmas ◽  
High K ◽  
Show Evidence ◽  
Subduction Setting

ABSTRACTA comparative study of three main igneous rock associations that plot in the K2O–SiO2 diagram shoshonite field: shoshonite series absarokites–shoshonites–banakites (henceforth referred to as shoshonites s.l.), vaugnerites, and potassic lamprophyres, reveals that similarities between the associations are superficial. Vaugnerites and lamprophyres are more magnesian, richer in large ion lithophile and high field strength elements and have higher light rare earth/heavy rare earth ratios than shoshonites. Furthermore, shoshonites have low radiogenic heat production, typical of subduction-related rocks, but most vaugnerites and some lamprophyres are highly radioactive. Relative to bulk-Earth, shoshonites have depleted, asthenospheric mantle-like Sr and Nd isotope signatures, whereas vaugnerites and potassic lamprophyres have enriched, crust or lithospheric mantle-like compositions. Though vaugnerites and some lamprophyres show evidence of crustal contamination, the contaminated magma was not originally shoshonitic. Their composition is consistent with derivation from a metasomatised upper mantle source enriched long before melting, thus precluding an active subduction setting. In conclusion, the term shoshonite, implying late-stage arc magmas, cannot be applied to a rock series simply because it plots into the K2O–SiO2 diagram shoshonite field. Shoshonites with a subduction-related source may, however, be identified by discriminant function analysis.

scholarly journals Influence of Sample Pretreatment on the Analysis of High Contents of Rare-Earth and High Field Strength Elements in Geological Samples by ICP-AES and ICP-MS (Case Study of the Tomtor Deposit)

2020 ◽  
pp. 593-605
Author(s):  
Bagai-ool Yu. Saryg-ool ◽  
Lidiya N. Bukreeva ◽  
Irina N. Myagkaya ◽  
Aleksandr V. Tolstov ◽  
Elena V. Lazareva ◽  
...  
Keyword(s):  
Rare Earth ◽  
Field Strength ◽  
Inductively Coupled Plasma ◽  
High Field ◽  
Sample Pretreatment ◽  
Emission Spectrometry ◽  
Geological Samples ◽  
High Field Strength ◽  
Inductively Coupled ◽  
Icp Ms

Influence of sample pretreatment on the analysis of the high contents of rare earth (REE) and high field strength (HFSE) elements in geological samples by inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) was studied. The rocks and rich ores of the Tomtor Nb-REE deposit were explored. Complete dissolution of the geological samples with a high content of “refractory” minerals has been achieved using fusion with a sodium peroxide. The results obtained by ICP-AES and ICP-MS after chemical dissolution are comparable with the results obtained by the XRF-SR without chemical pretreatment

Rare earth elements and critical metal content of extracted landfilled material and potential recovery opportunities

2015 ◽  
Vol 42 ◽  
pp. 128-136 ◽  
Author(s):  
Silvia C. Gutiérrez-Gutiérrez ◽  
Frédéric Coulon ◽  
Ying Jiang ◽  
Stuart Wagland
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Metal Content ◽  
Critical Metal

scholarly journals Stability relationships of REE-bearing phosphates in an alkali-rich system (nepheline syenite from the Mariupol Massif, SE Ukraine)

2012 ◽  
Vol 62 (2) ◽  
pp. 247-265 ◽  
Author(s):  
Magdalena Dumańska-Słowik ◽  
Bartosz Budzyń ◽  
Wiesław Heflik ◽  
Magdalena Sikorska
Keyword(s):  
Host Rock ◽  
Nepheline Syenite ◽  
Partial Replacement ◽  
Metasomatic Alteration ◽  
Chemical Evidence

ABSTRACT Dumańska-Słowik, M., Budzyń, B., Heflik, W. and Sikorska, M. 2012. Stability relationships of REE-bearing phosphates in an alkali-rich system (nepheline syenite from the Mariupol Massif, SE Ukraine). Acta Geologica Polonica, 62 (2), 247-265. Primary REE-enriched fluorapatite and fluorbritholite-(Ce) in nepheline syenite from the Mariupol Massif (SE Ukraine), contain textural and chemical evidence of late- to post-magmatic metasomatic alteration. REE mobilization and replacement of the primary phases by fluid-mediated coupled dissolution-reprecipitation strongly depended on the distance between the altered minerals in the host rock. Fluorapatite and fluorbritholite-(Ce) forming individual pristine grains were partially replaced by the same phase with a new composition, resulting in the presence of patchy zoning in altered grains. The increased REE contents in altered fluorapatite rim domains are related to REE mobilization from the altered REE-depleted rim domains of the fluorbritholite-(Ce). The REEs were transported by a fluid with high F activity. The alteration of fluorapatite and fluorbritholite-(Ce) grains in contact resulted in the partial replacement of the primary phases by the same phase with a new composition, but also in the partial replacement of the fluorapatite by secondary monazite and fluorite. The REE mobilized from the fluorbritholite-(Ce) in the presence of a F-rich fluid in an alkali-rich system promoted formation of monazite as the new phosphate REE-host. The presence of secondary parisite in the altered domains of the fluorapatite and fluorbritholite-(Ce) indicates a CO 2 component in the fluid during metasomatic alteration.

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