Geochemical evolution of basaltic rocks subjected to weathering: Fate of the major elements, rare earth elements, and thorium

Trace and Rare Earth Elements (REEs) data are used to constrain the geochemical evolution of the amphibolites from Ifewara in the Ife-Ilesha schist belt of southwestern Nigeria. The amphibolites can be grouped into banded and sheared amphibolites. Major element data show SiO2 (48.34%), Fe2O3 (11.03-17.88%), MgO (5.76-9.90%), CaO (7.76-18.6%) and TiO2 (0.44-1.77%) contents which are similar to amphibolites in other schist belts in Nigeria. The Al2O3 (2.85-15.55%) content is varied, with the higher values suggesting alkali basalt protolith. Trace and rare earth elements composition reveal Sr (160-1077ppm), Rb (0.5-22.9ppm), Ni (4.7-10.2ppm), Co (12.2-50.9 ppm) and Cr (2-7ppm). Chondrite-normalized REE patterns show that the banded amphibolites have HREE depletion and both negative and positive Eu anomalies while the sheared variety showed slight LREE enrichment with no apparent Eu anomaly. The study amphibolites plot in the Mid Oceanic Ridge Basalts (MORB) and within plate basalt fields on the Zr/Y vs Zr discriminatory diagrams. They are further classified as volcanic arc basalt and E-type MORB on the Th- Hf/3- Ta and the Zr-Nb-Y diagrams. The amphibolites precursor is considered a tholeiitic suite that suffered crustal contamination, during emplacement in a rifted crust.

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Vulcânicas potássicas intemperizadas como protólitos dos filitos hematíticos da Serra do Espinhaço Meridional (Minas Gerais)

Geochimica Brasiliensis ◽

10.21715/gb2358-2812.2020342183 ◽

2020 ◽

Vol 34 (2) ◽

pp. 183-194

Author(s):

Alexandre Chaves ◽

Luiz Knauer

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Volcanic Rocks ◽

Alkaline Rock ◽

Major Elements ◽

Volcanic Origin ◽

Espinhaço Range ◽

Weathering Processes ◽

Igneous Layering ◽

Hematitic Phyllite

The hematitic phyllite is a rock that occurs in the São João da Chapada and Sopa-Brumadinho formations of the southern Espinhaço range. Its origin is widely discussed in papers on Espinhaço, but there is no consensus on its protolith due to certain characteristics of the lithotype, such as its chemical composition and textural features. The pattern of rare earth elements strongly enriched [(La/Yb)N 6.80-17.68], with light rare earth elements [(La/Sm)N 2.54-4.83] richer than heavy ones [(Gd/Yb)N 1.28-3,32], suggests that the protolith was an alkaline volcanic rock formed during the rift that generated the Espinhaço basin. The major elements indicate that the alkaline rock met weathering processes, becoming a regolith. During the Brasiliano metamorphism, it finally became hematitic phyllite. Other characteristics of the lithotype, such as the presence of sericite-bearing rounded parts (possibly formed by alteration and deformation of leucite crystals) and the preservation of igneous layering, suggest a potassic volcanic origin for hematitic phyllite. In diagram that allows identifying altered and metamorphic volcanic rocks, the investigated samples have composition similar to a feldspathoid-rich alkali-basalt, probably a leucite tephrite, a leucitite or even a lamproite, rocks from mantle source.

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Allanite Geochemical Response to Hydrothermal Alteration by Alkaline, Low-Temperature Fluids

Minerals ◽

10.3390/min10050392 ◽

2020 ◽

Vol 10 (5) ◽

pp. 392 ◽

Cited By ~ 1

Author(s):

Katarzyna Gros ◽

Ewa Słaby ◽

Petras Jokubauskas ◽

Jiří Sláma ◽

Gabriela Kozub-Budzyń

Keyword(s):

Rare Earth ◽

Low Temperature ◽

Rare Earth Elements ◽

Geochemical Evolution ◽

Additional Component ◽

Second Stage ◽

Ce Anomaly ◽

Hydrothermal Processes ◽

Fluid Infiltration ◽

Two Stages

Allanite is one of the main rare earth elements (REE)-rich accessory minerals in composite dykes from the granitoid pluton of Karkonosze. These dykes differ in composition from the bulk of the pluton by elevated rare earth elements (REE), Y, Zr, and alkali contents, suggesting contribution of an additional component. Allanite exhibits complex alteration textures, which can be divided into two stages. The first stage is represented by allanite mantles, formed by fluid infiltration into previously crystallized magmatic allanite. These zones have low totals, are Ca-, Al-, Mg-, and light REE (LREE)-depleted, and Y-, heavy REE (HREE)-, Th-, Ti-, and alkali-enriched. The fractionation between LREE and HREE was caused by different mobility of complexes formed by these elements in aqueous fluids. The second stage includes recrystallized LREE-poor, Y-HREE-rich allanite with variable Ca, Al, Mg, and REE-fluorocarbonates. The alteration products from both stages demonstrate higher Fe3+/(Fe2+ + Fe3+) ratios and a negative Ce anomaly. These features point to the alkaline, low-temperature, and oxidized nature of the fluids. The differences in mobility and solubility of respective ligands show that the fluids from the first stage may have been dominated by Cl, whereas those of the second stage may have been dominated by F and CO2 (and PO4 in case of one sample). The inferred chemistry of the fluids resembles the overall geochemical signature of the composite dykes, indicating a major contribution of the hydrothermal processes to their geochemical evolution.

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Geochemistry of garnet megacrysts from the Mir kimberlite pipe (Yakutia) and the nature of prothokimberlite melt

Доклады Академии наук ◽

10.31857/s0869-56524865583-587 ◽

2019 ◽

Vol 486 (5) ◽

pp. 583-587

Author(s):

A. M. Agashev

Keyword(s):

Trace Elements ◽

Rare Earth ◽

Rare Earth Elements ◽

Negative Correlation ◽

Kimberlite Pipe ◽

Major And Trace Elements ◽

Major Elements ◽

Incompatible Elements ◽

Composition Study ◽

Melt Composition

The paper presents the results of major and trace elements composition study of garnet megacrysts from Mir kimberlite pipe. On the major elements composition those garnets classified as low Cr and high Ti pyropes. Concentrations of TiO2 show a negative correlation with MgO и Cr2O3 contents in megacrysts composition. Fractional crystallization modeling indicates that the most appropriate melt to reproduce the garnet trace elements signatures is the melt of picritic composition. Composition of garnets crystallized from kimberlite melt do not correspond to observed natural garnets composition. Kimberlites contain less of Ti, Zr, Y and heavy REE (rare earth elements) but more of very incompatible elements such as light REE, Th, U, Nb, Ba then the model melt composition that necessary for garnet crystallization.

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The distribution of the trace element contents in lignite and ash from Drama lignite deposit, using multivariate statistical analysis

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.17202 ◽

2001 ◽

Vol 34 (3) ◽

pp. 1255

Author(s):

S. PANILAS ◽

G. HATZIYANNIS

Keyword(s):

Trace Elements ◽

Rare Earth ◽

Statistical Analysis ◽

Rare Earth Elements ◽

Multivariate Statistical Analysis ◽

Major And Trace Elements ◽

Major Elements ◽

Geochemical Data ◽

Multivariate Statistical ◽

Inorganic Matter

Multivariate statistical analysis was used on existing geochemical data of the Drama lignite deposit, eastern Macedonia, Greece. Factor analysis with varimax rotation technique was applied to study the distribution of major, trace and rare earth elements in the lignite and 850°C lignitic ash, to find a small set of factors that could explain most of the geochemical variability. The study showed that major elements AI, Na, Κ, contained in the lignite samples, presented high correlation with most of the trace and rare earth elements. In 850°C lignitic ashes major and trace elements present different redistribution. Only Al remained correlated with the trace elements Co, Cr, Rb, Ta, Th, Ti, Sc and rare earths related with inorganic matter in the lignite beds. Trace elements Fe, Mo, U, V, W, and Lu were associated with organic matter of lignite and had also been affected by the depositional environment.

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

Canadian Journal of Earth Sciences ◽

10.1139/e91-126 ◽

1991 ◽

Vol 28 (9) ◽

pp. 1429-1443 ◽

Cited By ~ 12

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.

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Partitioning and Leaching Behavior of Actinides and Rare Earth Elements in a Zirconolite-bearing Hydrothermal Vein System

MRS Proceedings ◽

10.1557/proc-985-0985-nn11-05 ◽

2006 ◽

Vol 985 ◽

Author(s):

Timothy E Payne ◽

Reto Giere ◽

Kaye P Hart ◽

Gregory R Lumpkin ◽

Peter J McGlinn

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Major Elements ◽

Chemical Extraction ◽

Extraction Techniques ◽

Leaching Behavior ◽

Bulk Chemical Composition ◽

Major Vein ◽

Bulk Chemical ◽

And Behavior

AbstractChemical extraction techniques and scanning electron microscopy were used to study the distribution and behavior of actinides and rare earth elements (REE) in hydrothermal veins at Adamello, (Italy). The six samples discussed in this paper were from the phlogopite zone, which is one of the major vein zones. The samples were similar in their bulk chemical composition, mineralogy, and leaching behavior of major elements (determined by extraction with 9M HCl). However, there were major differences in the extractability of REE and actinides. The most significant influence on the leaching characteristics appears to be the amounts of U, Th and REE incorporated in resistant host phases. Uranium and Th are very highly enriched in zirconolite grains. Actinides were more readily leached from samples with a higher content of U and Th, relative to the amount of zirconolite. The results show that REE and actinides present in chemically resistant minerals can be retained under aggressive leaching conditions.

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Geochemical evolution of the Chatham–Grenville stock, Quebec

Canadian Journal of Earth Sciences ◽

10.1139/e85-091 ◽

1985 ◽

Vol 22 (6) ◽

pp. 872-880 ◽

Cited By ~ 4

Author(s):

Michael Denis Higgins

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Mass Balance ◽

Major Element ◽

Parental Magma ◽

Alkali Feldspar ◽

Geochemical Evolution ◽

Wide Range ◽

The Mean

The Chatham–Grenville stock is an anorogenic multiple intrusion that shows a complete gradation from early cumulate and noncumulate syenites to slightly peralkaline granites. It can be divided into four units. Unit 1, the first unit, is a noncumulate syenite with modal quartz less than 5%. Unit 2 has a wide range in composition from cumulate syenites (no modal quartz) to noncumulate syenites and quartz syenites (modal quartz = 20%). Units 3 and 4 are granites with modal quartz up to 25 and 30%, respectively. The parental magma of the whole complex was syenitic. Differentiation occurred as a result of crystal fractionation by filter pressing both at depth and in situ. Ba, Sr, Rb, and Eu abundances and major-element mass-balance calculations show that alkali feldspar, mafic minerals, and apatite were fractionated. At least 79% fractionation is necessary to transform the mean composition of the first unit (1) into the mean composition of the last unit (4). The rare-earth elements, Th, Ta, Hf, and Zr, did not behave in a residual fashion but may have been fractionated in minor accessory phases such as apatite, zircon, monazite, allanite, and xenotime.

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