scholarly journals Ecosystem Composition Controls the Early Fate of Rare Earth Elements during Incipient Soil Genesis

2016 ◽  
Author(s):  
Dragos G Zaharescu ◽  
Carmen I Burghelea ◽  
Katerina Dontsova ◽  
Jennifer K Presler ◽  
Raina M Maier ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
General Pattern ◽  
Great Promise ◽  
Soil Genesis ◽  
Element Abundances ◽  
Abiotic Control ◽  
Rapid Transition ◽  
Ree Fractionation ◽  
Water Plants

The rare earth elements (REE) are of increasing importance in a variety of science and economic fields, including (bio)geosciences, paleoecology, astrobiology, and mining. Despite their great promise, REE fractionation in early plant-microbe-rock systems has largely remained elusive. We tested the hypothesis that REE mass-partitioning during the incipient weathering of basalt, rhyolite, granite and schist depends on the activity of microbes, plant, and arbuscular mycorrhiza. Pore-water element abundances reflected a rapid transition from abiotic to biotic weathering, the latter associated with lower aqueous loss and higher uptake. Abiotic dissolution contributed 38.6+/-19% to total denudation. Microbes incremented denudation, particularly in rhyolite, this effect associating with decreased bioavailable solid fractions in this rock. Total mobilization (aqueous+uptake) was ten times greater in planted treatments compared to abiotic control, REE masses in plant generally exceeding those in water. Plants of larger biomass further increased solid fractions, consistent with soil genesis. Mycorrhiza had a generally positive effect on total mobilization. The incipient REE weathering was dominated by inorganic dissolution enhanced by biotic respiration, the patterns of denudation largely dictated by mineralogy. A consistent biotic signature was observed in La:phosphate, mobilization:solid fraction in all rocks, as well as in the general pattern of denudation and uptake.

Quantitative Cathodoluminescence Mapping with Application to a Kalgoorlie Scheelite

2009 ◽  
Vol 15 (3) ◽  
pp. 222-230 ◽  
Author(s):  
Colin M. MacRae ◽  
Nicholas C. Wilson ◽  
Joel Brugger
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Trace Element Level ◽  
Gaussian Peak ◽  
X Ray ◽  
Element Abundances ◽  
Inductively Coupled ◽  
Peak Fitting

AbstractA method for the analysis of cathodoluminescence spectra is described that enables quantitative trace-element-level distributions to be mapped within minerals and materials. Cathodoluminescence intensities for a number of rare earth elements are determined by Gaussian peak fitting, and these intensities show positive correlation with independently measured concentrations down to parts per million levels. The ability to quantify cathodoluminescence spectra provides a powerful tool to determine both trace element abundances and charge state, while major elemental levels can be determined using more traditional X-ray spectrometry. To illustrate the approach, a scheelite from Kalgoorlie, Western Australia, is hyperspectrally mapped and the cathodoluminescence is calibrated against microanalyses collected using a laser ablation inductively coupled plasma mass spectrometer. Trace element maps show micron scale zoning for the rare earth elements Sm3+, Dy3+, Er3+, and Eu3+/Eu2+. The distribution of Eu2+/Eu3+ suggests that both valences of Eu have been preserved in the scheelite since its crystallization 1.63 billion years ago.

Two-stage evolution in an Archean tonalite suite: the Taschereau stock, Abitibi (Quebec, Canada)

1991 ◽  
Vol 28 (2) ◽  
pp. 172-183 ◽  
Author(s):  
Michel Jébrak ◽  
Luc Harnois
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Trace Element ◽  
Greenstone Belt ◽  
Shear Zones ◽  
Granitic Rocks ◽  
Element Abundances ◽  
Abitibi Greenstone Belt ◽  
Rock Types ◽  
End Members

The Taschereau stock occurs north of Timmins and Val-d'Or, Quebec, in the Abitibi greenstone belt of the Superior Province. This late Archean composite pluton is composed mainly of diorite–tonalite–trondhjemite cut by granitic rocks. Gold–molybdenum occurrences are associated with a zone of albite-rich rocks surrounding the granitic rocks. Diabase dykes and shear zones postdate all rock units. Field and geochemical evidence suggests that the Taschereau stock was emplaced diachronously. Trace-element geochemical modelling shows that trace-element abundances (rare-earth elements, Ti, Zr) of Taschereau granitic rocks are consistent with partial melting of preexisting Taschereau tonalitic rocks and implies that these two rock types are not end members of a single magma that evolved through fractional crystallization.

scholarly journals Ecosystem Composition Controls the Fate of Rare Earth Elements during Incipient Soil Genesis

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Dragos G. Zaharescu ◽  
Carmen I. Burghelea ◽  
Katerina Dontsova ◽  
Jennifer K. Presler ◽  
Raina M. Maier ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Soil Genesis

Geochemistry of two metavolcanic arc suites from the Central Metasedimentary Belt of the Grenville Province, southeastern Ontario, Canada

1991 ◽  
Vol 28 (9) ◽  
pp. 1429-1443 ◽  
Author(s):  
Luc Harnois ◽  
John M. Moore
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Trace Element ◽  
Partial Melting ◽  
Volcanic Rocks ◽  
Parental Magma ◽  
Major Elements ◽  
Grenville Province ◽  
Element Abundances ◽  
Felsic Rocks

Samples of two subalkaline metavolcanic suites, the Tudor formation (ca. 1.28 Ga) and the overlying Kashwakamak formation, have been analysed for major elements and 27 trace elements (including rare-earth elements). The Tudor formation is tholeiitic and contains mainly basaltic flows, whereas the Kashwakamak formation is calc-alkaline and contains mainly andesitic rocks with minor felsic rocks. The succession has been regionally metamorphosed to upper greenschist – lower amphibolite facies. Trace-element abundances and ratios indicate that rocks of the Tudor and Kashwakamak formations are island-arc type. Geochemical modelling using rare-earth elements, Zr, Ti, and Y indicates that the Tudor volcanic rocks are not derived from a single parental magma through simple fractional crystallization. Equilibrium partial melting of a heterogeneous Proterozoic upper mantle can explain the trace-element abundances and ratios of Tudor formation volcanic rocks. The intermediate to felsic rocks of the Kashwakamak formation appear to have been derived from a separate partial melting event. The data are consistent with an origin of the arc either on oceanic crust or on thinned continental crust, and with accretion of the arc to a continental margin between the time of extrusion of Tudor volcanic rocks and that of Kashwakamak volcanic rocks.

Clay minerals control rare earth elements (REE) fractionation in Brazilian mangrove soils

CATENA ◽  
2022 ◽  
Vol 209 ◽  
pp. 105855
Author(s):  
Gabriel Ramatis Pugliese Andrade ◽  
Javier Cuadros ◽  
Jorge Marcos Peniche Barbosa ◽  
Pablo Vidal-Torrado
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Clay Minerals ◽  
Ree Fractionation ◽  
Mangrove Soils

scholarly journals Fractionation of Rare Earth Elements in Greisen and Hydrothermal Veins Related to A-Type Magmatism

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-20 ◽  
Author(s):  
Mikael Tillberg ◽  
Olga M. Maskenskaya ◽  
Henrik Drake ◽  
Johan K. Hogmalm ◽  
Curt Broman ◽  
...  
Keyword(s):  
Rare Earth ◽  
Fluid Inclusion ◽  
Rare Earth Elements ◽  
Coarse Grained ◽  
Isotopic Signatures ◽  
Vein Formation ◽  
Noteworthy Feature ◽  
Carbonate Complexation ◽  
Ree Fractionation ◽  
Multiple Pulses

This study focuses on concentrations and fractionation of rare earth elements (REE) in a variety of minerals and bulk materials of hydrothermal greisen and vein mineralization in Paleoproterozoic monzodiorite to granodiorite related to the intrusion of Mesoproterozoic alkali- and fluorine-rich granite. The greisen consists of coarse-grained quartz, muscovite, and fluorite, whereas the veins mainly contain quartz, calcite, epidote, chlorite, and fluorite in order of abundance. A temporal and thus genetic link between the granite and the greisen/veins is established via high spatial resolution in situ Rb-Sr dating, supported by several other isotopic signatures (δ34S, 87Sr/86Sr, δ18O, and δ13C). Fluid-inclusion microthermometry reveals that multiple pulses of moderately to highly saline aqueous to carbonic solutions caused greisenization and vein formation at temperatures above 200–250°C and up to 430°C at the early hydrothermal stage in the veins. Low calculated ∑REE concentration for bulk vein (15 ppm) compared to greisen (75 ppm), country rocks (173–224 ppm), and the intruding granite (320 ppm) points to overall low REE levels in the hydrothermal fluids emanating from the granite. This is explained by efficient REE retention in the granite via incorporation in accessory phosphates, zircon, and fluorite and unfavorable conditions for REE partitioning in fluids at the magmatic and early hydrothermal stages. A noteworthy feature is substantial heavy REE (HREE) enrichment of calcite in the vein system, in contrast to the relatively flat patterns of greisen calcite. The REE fractionation of the vein calcite is explained mainly by fractional crystallization, where the initially precipitated epidote in the veins preferentially incorporates most of the light REE (LREE) pool, leaving a residual fluid enriched in the HREE from which calcite precipitated. Fluorite occurs throughout the system and displays decreasing REE concentrations from granite towards greisen and veins and different fractionation patterns among all these three materials. Taken together, these features confirm efficient REE retention in the early stages of the system and minor control of the REE uptake by mineral-specific partitioning. REE-fractionation patterns and fluid-inclusion data suggest that chloride complexation dominated REE transport during greisenization, whereas carbonate complexation contributed to the HREE enrichment in vein calcite.

scholarly journals Heterogeneity in lunar anorthosite meteorites: implications for the lunar magma ocean model

2014 ◽  
Vol 372 (2024) ◽  
pp. 20130241 ◽  
Author(s):  
Sara S. Russell ◽  
Katherine H. Joy ◽  
Teresa E. Jeffries ◽  
Guy J. Consolmagno ◽  
Anton Kearsley
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Ocean Model ◽  
Magma Source ◽  
The Moon ◽  
Magma Ocean ◽  
Element Abundances ◽  
Wide Range ◽  
Lunar Meteorites

The lunar magma ocean model is a well-established theory of the early evolution of the Moon. By this model, the Moon was initially largely molten and the anorthositic crust that now covers much of the lunar surface directly crystallized from this enormous magma source. We are undertaking a study of the geochemical characteristics of anorthosites from lunar meteorites to test this model. Rare earth and other element abundances have been measured in situ in relict anorthosite clasts from two feldspathic lunar meteorites: Dhofar 908 and Dhofar 081. The rare earth elements were present in abundances of approximately 0.1 to approximately 10× chondritic (CI) abundance. Every plagioclase exhibited a positive Eu-anomaly, with Eu abundances of up to approximately 20×CI. Calculations of the melt in equilibrium with anorthite show that it apparently crystallized from a magma that was unfractionated with respect to rare earth elements and ranged in abundance from 8 to 80×CI. Comparisons of our data with other lunar meteorites and Apollo samples suggest that there is notable heterogeneity in the trace element abundances of lunar anorthosites, suggesting these samples did not all crystallize from a common magma source. Compositional and isotopic data from other authors also suggest that lunar anorthosites are chemically heterogeneous and have a wide range of ages. These observations may support other models of crust formation on the Moon or suggest that there are complexities in the lunar magma ocean scenario to allow for multiple generations of anorthosite formation.

Fractionation of rare-earth elements in the processes of hydrothermal ore formation

2018 ◽  
pp. 59-64
Author(s):  
M. V. Borisov ◽  
D. A. Bychkov ◽  
N. F. Pchelintseva ◽  
E. A. Ivleva
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Maximum Amount ◽  
Hydrothermal Solutions ◽  
Ore Formation ◽  
Distribution Of Elements ◽  
Sharp Growth ◽  
Ree Fractionation ◽  
Host Rocks ◽  
North Ossetia

Data on the distribution of elements across the Pb-Zn section of the Gatsyrovskaya vein (Upper Zgid, North Ossetia, Russia) showed that during the formation of the vein significant changes in the spectra of rare-earth elements (REE) occur in ore samples. The sharp growth of ratios LaN/YbN, LaN/NdN, GdN/HoN, and GdN/YbN is confined to the vein intervals, where the maximum amount of ore components is deposited. A comparison of the REE spectra of ores with the characteristics of the spectra of the near-vein and host rocks suggests that the deposition of the vein material occurred from solutions whose compositions with respect to the REE varied with time. REE fractionation occurred due to the mobilization of components by hydrothermal solutions during their reaction with the host Paleozoic granites.

scholarly journals Carbonatites from the Southern Brazilian platform: I

2020 ◽  
Vol 12 (1) ◽  
pp. 452-478
Author(s):  
Sergio Speziale ◽  
Francesca Castorina ◽  
Paolo Censi ◽  
Celso de Barros Gomes ◽  
Leila Soares Marques ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Hydrothermal Fluids ◽  
Evolutionary Trend ◽  
Compelling Evidence ◽  
Isotopic Data ◽  
Comprehensive Overview ◽  
Element Abundances ◽  
Compositional Variability ◽  
Formation And Evolution

AbstractWe present a comprehensive overview of the geochemical characteristics and evolution of the carbonatites from the southern Brazilian Platform (Paraná Basin). The carbonatites from different complexes display large compositional variability in terms of abundances of incompatible and rare earth elements. This is in agreement with an origin from heterogeneous lithospheric sources, as confirmed by isotopic data (see Speziale et al., this issue). The characteristic major and trace element abundances of these carbonatites present compelling evidence for invoking liquid unmixing as the main mechanism of their formation and evolution albeit few exceptions. We propose an evolutionary trend for the Brazilian carbonatites, which can be summarized as following: exsolution of the primary Ca- or Mg-carbonatitic liquids systematically takes place at the phonolite-peralkaline phonolite stage of magma differentiation; this is followed by progressive Fe-enrichment and by final emplacement of fluorocarbonatites associated with hydrothermal fluids.

Sign in / Sign up

Export Citation Format

Share Document