scholarly journals Enrichment of heavy REE and Th in carbonatite-derived fenite breccia

2021 ◽  
pp. 1-17
Author(s):  
Sam Broom-Fendley ◽  
Holly AL Elliott ◽  
Charles D Beard ◽  
Frances Wall ◽  
Paul EB Armitage ◽  
...  
Keyword(s):  
Mineral Assemblage ◽  
Country Rock ◽  
Hydrothermal Fluids ◽  
Common Mechanism ◽  
Small Satellite ◽  
Heavy Rare Earth ◽  
Rock Interaction ◽  
Similar Composition ◽  
Heavy Rare Earth Elements ◽  
Existing Structure

Abstract Enrichment of the heavy rare earth elements (HREE) in carbonatites is rare as carbonatite petrogenesis favours the light (L)REE. We describe HREE enrichment in fenitized phonolite breccia, focusing on small satellite occurrences 1–2 km from the Songwe Hill carbonatite, Malawi. Within the breccia groundmass, a HREE-bearing mineral assemblage comprises xenotime, zircon, anatase/rutile and minor huttonite/thorite, as well as fluorite and apatite. A genetic link between HREE mineralization and carbonatite emplacement is indicated by the presence of Sr-bearing carbonate veins, carbonatite xenoliths and extensive fenitization. We propose that the HREE are retained in hydrothermal fluids which are residually derived from a carbonatite after precipitation of LREE minerals. Brecciation provides a focusing conduit for such fluids, enabling HREE transport and xenotime precipitation in the fenite. Continued fluid–rock interaction leads to dissolution of HREE-bearing minerals and further precipitation of xenotime and huttonite/thorite. At a maximum Y content of 3100 µg g−1, HREE concentrations in the presented example are not sufficient to constitute ore, but the similar composition and texture of these rocks to other cases of carbonatite-related HREE enrichment suggests that all form via a common mechanism linked to fenitization. Precipitation of HREE minerals only occurs where a pre-existing structure provides a focusing conduit for fenitizing fluids, reducing fluid – country-rock interaction. Enrichment of HREE and Th in fenite breccia serves as an indicator of fluid expulsion from a carbonatite, and may indicate the presence of LREE mineralization within the source carbonatite body at depth.

Magnetite texture and trace-element geochemistry fingerprint of pulsed mineralization in the Xinqiao Cu-Fe-Au deposit, Eastern China

2020 ◽  
Vol 105 (11) ◽  
pp. 1712-1723
Author(s):  
Yu Zhang ◽  
Pete Hollings ◽  
Yongjun Shao ◽  
Dengfeng Li ◽  
Huayong Chen ◽  
...  
Keyword(s):  
Trace Element ◽  
Triple Junction ◽  
Eastern China ◽  
Black Shales ◽  
Hydrothermal Fluids ◽  
Oscillatory Zoning ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
Rock Interaction ◽  
Multiple Pulses

Abstract The origin of stratabound deposits in the Middle-Lower Yangtze River Valley Metallogenic Belt (MLYRB), Eastern China, is the subject of considerable debate. The Xinqiao Cu-Fe-Au deposit in the Tongling ore district is a typical stratabound ore body characterized by multi-stage magnetite. A total of six generations of magnetite have been identified. Mt1 is commonly replaced by porous Mt2, and both are commonly trapped in the core of Mt3, which is characterized by both core-rim textures and oscillatory zoning. Porous Mt4 commonly truncates the oscillatory zoning of Mt3, and Mt5 is characterized by 120° triple junction texture. Mt1 to Mt5 are commonly replaced by pyrite that coexists with quartz, whereas Mt6, with a fine-grained foliated and needle-like texture, commonly cuts the early pyrite as veins and is replaced by pyrite that coexists with calcite. The geochemistry of the magnetite suggests that they are hydrothermal in origin. The microporosity of Mt2 and Mt4 magnetite, their sharp contacts with Mt1 and Mt3, and lower trace-element contents (e.g., Si, Ca, Mg, and Ti) than Mt1 and Mt3 suggest that they formed via coupled dissolution and reprecipitation of the precursor Mt1 and Mt3 magnetite, respectively. This was likely caused by high-salinity fluids derived from intensive water-rock interaction between the magmatic-hydrothermal fluids associated with the Jitou stock and Late Permian metalliferous black shales. The 120° triple junction texture of Mt5 suggests it is the result of fluid-assisted recrystallization, whereas Mt6 formed by replacement of hematite as a result of fracturing. The geochemistry of the magnetite suggests that the temperature increased from Mt2 to Mt3 and implies that there were multiple pulses of fluids from a magmatic-hydrothermal system. Therefore, we propose that the Xinqiao stratiform mineralization was genetically associated with multiple influxes of magmatic hydrothermal fluids derived from the Early Cretaceous Jitou stock. This study demonstrates that detailed texture examination and in situ trace-elements analysis under robust geological and petrographic frameworks can effectively constrain the mineralization processes and ore genesis.

scholarly journals Rapid alteration of fractured volcanic conduits beneath Mt Unzen

2021 ◽  
Vol 83 (5) ◽  
Author(s):  
Tim I. Yilmaz ◽  
Fabian B. Wadsworth ◽  
H. Albert Gilg ◽  
Kai-Uwe Hess ◽  
Jackie E. Kendrick ◽  
...  
Keyword(s):  
Country Rock ◽  
Geophysical Methods ◽  
Hydrothermal Fluids ◽  
Deep Drilling ◽  
Stress Regime ◽  
Argillic Alteration ◽  
Carbon And Oxygen Isotope ◽  
Propylitic Alteration ◽  
Indirect Information

AbstractThe nature of sub-volcanic alteration is usually only observable after erosion and exhumation at old inactive volcanoes, via geochemical changes in hydrothermal fluids sampled at the surface, via relatively low-resolution geophysical methods or can be inferred from erupted products. These methods are spatially or temporally removed from the real subsurface and thus provide only indirect information. In contrast, the ICDP deep drilling of the Mt Unzen volcano subsurface affords a snapshot into the in situ interaction between the dacitic dykes that fed dome-forming eruptions and the sub-volcanic hydrothermal system, where the most recent lava dome eruption occurred between 1990 and 1995. Here, we analyse drill core samples from hole USDP-4, constraining their degree and type of alteration. We identify and characterize two clay alteration stages: (1) an unusual argillic alteration infill of fractured or partially dissolved plagioclase and hornblende phenocryst domains with kaolinite and Reichweite 1 illite (70)-smectite and (2) propylitic alteration of amphibole and biotite phenocrysts with the fracture-hosted precipitation of chlorite, sulfide and carbonate minerals. These observations imply that the early clay-forming fluid was acidic and probably had a magmatic component, which is indicated for the fluids related to the second chlorite-carbonate stage by our stable carbon and oxygen isotope data. The porosity in the dyke samples is dominantly fracture-hosted, and fracture-filling mineralization is common, suggesting that the dykes were fractured during magma transport, emplacement and cooling, and that subsequent permeable circulation of hydrothermal fluids led to pore clogging and potential partial sealing of the pore network on a timescale of ~ 9 years from cessation of the last eruption. These observations, in concert with evidence that intermediate, crystal-bearing magmas are susceptible to fracturing during ascent and emplacement, lead us to suggest that arc volcanoes enclosed in highly fractured country rock are susceptible to rapid hydrothermal circulation and alteration, with implications for the development of fluid flow, mineralization, stress regime and volcanic edifice structural stability. We explore these possibilities in the context of alteration at other similar volcanoes.

Selective recovery of heavy rare earth elements from apatite with an adsorbent bearing immobilized tridentate amido ligands

2016 ◽  
Vol 159 ◽  
pp. 157-160 ◽  
Author(s):  
Takeshi Ogata ◽  
Hirokazu Narita ◽  
Mikiya Tanaka ◽  
Mihoko Hoshino ◽  
Yoshiaki Kon ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Heavy Rare Earth ◽  
Amido Ligands ◽  
Selective Recovery ◽  
Heavy Rare Earth Elements

Magmatic-Hydrothermal Mineralization Processes at the Yidong Tin Deposit, South China: Insights from In Situ Chemical and Boron Isotope Changes of Tourmaline

2021 ◽  
Author(s):  
He-Dong Zhao ◽  
Kui-Dong Zhao ◽  
Martin R. Palmer ◽  
Shao-Yong Jiang ◽  
Wei Chen
Keyword(s):  
South China ◽  
Hydrothermal Fluids ◽  
Boron Isotope ◽  
Granitic Magma ◽  
Gangue Mineral ◽  
Rock Interaction ◽  
Hydrothermal Mineralization ◽  
Mineralization Processes ◽  
Tin Deposit

Abstract Owing to the superimposition of water-rock interaction and external fluids, magmatic source signatures of ore-forming fluids for vein-type tin deposits are commonly overprinted. Hence, there is uncertainty regarding the involvement of magmatic fluids in mineralization processes within these deposits. Tourmaline is a common gangue mineral in Sn deposits and can crystallize from both the magmas and the hydrothermal fluids. We have therefore undertaken an in situ major, trace element, and B isotope study of tourmaline from the Yidong Sn deposit in South China to study the transition from late magmatic to hydrothermal mineralization. Six tourmaline types were identified: (1) early tourmaline (Tur-OE) and (2) late tourmaline (Tur-OL) in tourmaline-quartz orbicules from the Pingying granite, (3) early tourmaline (Tur-DE) and (4) late tourmaline (Tur-DL) in tourmaline-quartz dikelets in the granite, and (5 and 6) core (Tur-OC) and rim (Tur-OR), respectively of hydrothermal tourmaline from the Sn ores. Most of the tourmaline types belong to the alkali group and the schorl-dravite solid-solution series, but the different generations of magmatic and hydrothermal tourmaline are geochemically distinct. Key differences include the hundredfold enrichment of Sn in hydrothermal tourmaline compared to magmatic tourmaline, which indicates that hydrothermal fluids exsolving from the magma were highly enriched in Sn. Tourmaline from the Sn ores is enriched in Fe3+ compared to the hydrothermal tourmaline from the granite and displays trends of decreasing Al and increasing Fe content from core to rim, relating to the exchange vector Fe3+Al–1. This reflects oxidation of fluids during the interaction between hydrothermal fluids and the mafic-ultramafic wall rocks, which led to precipitation of cassiterite. The hydrothermal tourmaline has slightly higher δ11B values than the magmatic tourmaline (which reflects the metasedimentary source for the granite), but overall, the tourmaline from the ores has δ11B values similar to those from the granite, implying a magmatic origin for the ore-forming fluids. We identify five stages in the magmatic-hydrothermal evolution of the system that led to formation of the Sn ores in the Yidong deposit based on chemical and boron isotope changes of tourmaline: (1) emplacement of a B-rich, S-type granitic magma, (2) separation of an immiscible B-rich melt, (3) exsolution of an Sn-rich, reduced hydrothermal fluid, (4) migration of fluid into the country rocks, and (5) acid-consuming reactions with the surrounding mafic-ultramafic rocks and oxidation of the fluid, leading to cassiterite precipitation.

scholarly journals Effect of acid mine drainage on dissolved rare earth elements geochemistry along a fluvial–estuarine system: the Tinto-Odiel Estuary (S.W. Spain)

2012 ◽  
Vol 43 (3) ◽  
pp. 262-274 ◽  
Author(s):  
J. Borrego ◽  
B. Carro ◽  
N. López-González ◽  
J. de la Rosa ◽  
J. A. Grande ◽  
...  
Keyword(s):  
Rare Earth ◽  
Acid Mine Drainage ◽  
Rare Earth Elements ◽  
Mine Drainage ◽  
Drainage System ◽  
Estuarine System ◽  
Mixing Zone ◽  
Heavy Rare Earth ◽  
Acid Mine ◽  
Heavy Rare Earth Elements

The concentration of rare earth elements together with Sc, Y, and U, as well as rare earth elements fractionation patterns, in the water of an affected acid mine drainage system were investigated. Significant dissolved concentrations of the studied elements were observed in the fluvial sector of this estuary system (Sc ∼ 31 μg L−1, Y ∼ 187 μg L−1, U ∼ 41 μg L−1, Σ rare earth elements ∼621 μg L−1), with pH values below 2.7. In the mixing zone of the estuary, concentrations are lower (Sc ∼ 2.1 μg L−1; Y ∼ 16.7 μg L−1; U ∼ 4.8 μg L−1; Σ rare earth elements ∼65.3 μg L−1) and show a strong longitudinal gradient. The largest rare earth elements removal occurs in the medium-chlorinity zone and it becomes extreme for heavy rare earth elements, as observed for Sc. Samples of the mixing zone show a North American Shale normalized pattern similar to the fluvial zone water, while the samples located in the zone with pH between 6.5 and 7.7 show a depletion of light rare earth elements relative to middle rare earth elements and heavy rare earth elements, similar to that observed in samples of the marine estuary.

scholarly journals Separation and Adsorption-Desorption Characteristics of Heavy Rare Earth Elements (Gd, Tb, Dy) using P507 Resin

2016 ◽  
Vol 25 (4) ◽  
pp. 60-67
Author(s):  
Sungeun Lee ◽  
Joung Woon Kim ◽  
Jong Hyuk Jeon ◽  
Hong Myeong Jun ◽  
Jin Young Lee ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Heavy Rare Earth ◽  
Heavy Rare Earth Elements ◽  
Adsorption Desorption

High specific surface 1-(2-pyridylazo) 2-naphthol (PAN) modified Carbon-based silicon film with cellulose nanocrystalline structure for efficient adsorption of rare earth elements

2021 ◽  
Author(s):  
Bin Wang ◽  
Yuzhe Zhang ◽  
Wen Sun ◽  
Xudong Zheng ◽  
Zhongyu Li
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Specific Surface ◽  
Cellulose Nanocrystals ◽  
Silicon Film ◽  
Nanocrystalline Structure ◽  
Heavy Rare Earth ◽  
Beneficial Result ◽  
Waste Products ◽  
Heavy Rare Earth Elements

The recovery of rare earth elements, especially heavy rare earth elements, from rare earth waste products has a high economic and environmental beneficial result. In this paper, cellulose nanocrystals used...

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