Aqueous and Sedimentary Geochemistry of the Rare Earth Elements

Fleet, Andrew

doi:10.1016/b978-0-444-42148-7.50015-0

Cited by 169 publications

(126 citation statements)

References 64 publications

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“…KH30 and KH38 show the greatest shift toward the high-REE field, whereas KH47 shifts considerably toward the low-REE field. This is consistent with the observation that deep-sea Fe-Mn nodules usu ally contain REE 2 to 4 time of the shale (Fleet, 1984). Two possibilities may explain the poorer A1203 E REE correlation and reduced regression coefficient; one is the high sulfide abundance as sulfides usually contain extremely low REE con centrations (Graf, 1977;Morgan and Wandless, 1980); and the other is the dominance of REE depleted albite as the A1203-bearing minerals in the Kambalda rocks (Bavinton and Taylor, 1980).…”

Section: Witwatersrandsupporting

confidence: 78%

Al2O3-REE correlations in sedimentary rocks.

Gao

Benren

1991

Geochem. J.

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Linear correlations between A1203 and.E REE (14 REEs) are defined for post-Archean fine-grained clastic sedimentary rocks from the Qinling region, Central China and Australia: E REE = -16(± 71) + 12A12O3, and for Archean fine-grained clastic sedimentary rocks worldwide:One important property of such correlations is the additivity, i.e., the correlation equation for E REE is equal to the sum of the correlation equations for individual REE, and each REE shows a roughly con stant slope. These correlations indicate that the REE of fine-grained clastic sedimentary rocks or metamorphosed equivalents are in general dominantly contained in clay minerals or their metamorphos ed products. Using these correlations, the REE abundances of the upper continental crust, sedimentary cover and Devonian strata were calculated for different tectonic units of the Qinling region. The results generally agree with the estimate from direct sampling within 18%.

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Section: Witwatersrandsupporting

confidence: 78%

Al2O3-REE correlations in sedimentary rocks.

Gao

Benren

1991

Geochem. J.

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“…Chrysoprase specimens were collected from the Kwahemu, Senato and Msani hills about 10 km richment from serpentinites during weathering processes (e.g., Fleet 1984). Beside these trace elements, the NAA determination showed the Au contents of 0.019 ppm, Th below 0.4 ppm and U 0.3 ppm.…”

mentioning

confidence: 99%

Gem-quality chrysoprase from Haneti-Itiso area, Central Tanzania

Kinnunen¹,

Malisa²

1990

Bull Geol Soc Finland

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Gem-quality, apple-green, Ni-bearing chalcedonic quartz occurs as near-surface veins in silicified serpentinite in the Haneti-Itiso area, Central Tanzania. AAS determinations revealed a high Ni content, 0.55 wt.%, and low Co and Cr contents of 120 and 1 ppm respectively. NAA determination revealed near chondritic REE contents. X-ray diffraction determinations showed that the Chrysoprase consists mainly of alpha quartz with some opal-CT. The gemmological properties are: refractive indices from 1.548 to 1.553 (±0.002), mean specific gravity 2.56, hardness about 7 on Moh's scale, inert to ultraviolet radiation, green through Chelsea filter, and absorption in the deep red and violet part of the optical absorption spectrum. The results confirm the identity of the material as Chrysoprase.Microscopically the Tanzanian Chrysoprase consists of spherules which are highly disordered, concentric, and composed of bipyramidal quartz, chalcedony, quartzine, and opal-A. They were classified into four main types according to the shell arrangement. The diameter of the spherules ranged from 40 um to 77 um. Fluid inclusion types in the bipyramidal quartz were monophasic, low-temperature type. The spherules, silica types and REE contents suggest that this Chrysoprase was deposited by evaporation of surface waters connected with the silicification of the serpentinites. Genetically analogous formations, common in Africa, include M-fabric type, weathering profile silcretes.

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“…According to the same authors, pH is the dominant parameter controlling REE behaviour. Under acidic conditions, REE are easily removed from weathering products, but they are fixed by major scavengers under neutral to alkaline conditions [39].…”

Section: Behaviour Of Reementioning

confidence: 99%

Geochemical Features of the Weathered Materials Developed on Gabbro in a Semi-Arid Zone, Northern Cameroon

Tsozué

Ndjigui

2017

Geosciences

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Investigation on the mobilization and the redistribution of major, trace and rare-earth elements (REE) was performed along a soil profile developed on gabbro in the semi-arid zone (Northern Cameroon), using mineralogical and geochemical analyses. The gabbro has high contents in Ba, Cr, V, Sr, Ni, Zn, Zr, Cu, Co and Sc. The total REE content is 49 mg/kg with strong light rare-earth elements (LREE) abundance. The Ce/Ce* and Eu/Eu* ratios are very close to 1 (0.98 and 1.02 respectively) and the (La/Yb) N ratio is very low (1.48). The weathering of the bedrock leads to the differentiation of coarse saprolite, fine saprolite, loamy clayey horizon and humiferous horizon.

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Aqueous and Sedimentary Geochemistry of the Rare Earth Elements

Cited by 169 publications

References 64 publications

Al2O3-REE correlations in sedimentary rocks.

Al2O3-REE correlations in sedimentary rocks.

Gem-quality chrysoprase from Haneti-Itiso area, Central Tanzania

Geochemical Features of the Weathered Materials Developed on Gabbro in a Semi-Arid Zone, Northern Cameroon

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