Distribution of Trace Elements Controlled by Sector and Growth Zonings in Zircon from Feldspathic Pegmatites (Ilmen Mountains, the Southern Urals)

Левашова, Е. В.; Скублов, С. Г.; Popov, V.A.

doi:10.3390/geosciences11010007

Cited by 9 publications

(2 citation statements)

References 53 publications

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“…The Hf content, the level of which, on the contrary, increases from the crystal central zone to its margin zone, may indicate a relatively slow cooling during crystallization [43]. This is also characteristic of zircon from the feldspar pegmatite of the Ilmensky mountains [39,44].…”

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confidence: 99%

Distribution of trace elements controlled by sector and growth zonings in zircon from a miaskite pegmatite of the Vishnegorsky massif, the Southern Urals

Левашова

Popov

Levashov

et al. 2022

PMI

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Data on the content and distribution of trace and rare-earth elements (SIMS method) in sectors and growth zones of a large zircon crystal from miaskite pegmatites of the Vishnegogorsky massif are presented. The morphology of the zircon crystal is a combination of a dipyramid {111} and prism {010}. It has been established that the growth sector of dipyramid {111} is characterized by almost one order of magnitude higher contents of Y, Nb, REE, Th; higher Th/U and Eu/Eu* values; REE distribution spectra are flatter compared to prism {010} growth sector. A regular decrease in the content of trace and rare-earth elements in the direction from the central zone to the marginal zone of crystal growth was revealed. A smooth regression of zircon crystallization temperature of zircon from 960 °C in the central zone to 740 °C in the marginal zone of the dipyramid sector and 700-650 °C in the prism sector has been revealed, which may be a reflection of thermal evolution of the crystallization process. It is assumed that crystallization of the central zone of zircon occurred at early stages from a relatively trace-еlement-rich melt. The crystallization was completed at lower temperatures, probably, simultaneously with the formation of REE-concentrating minerals, which resulted in natural decrease of content of trace and rare-earth elements in the melt and, consequently, in zircon crystallizing from it.

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Section: Introductionmentioning

confidence: 99%

Distribution of trace elements controlled by sector and growth zonings in zircon from a miaskite pegmatite of the Vishnegorsky massif, the Southern Urals

Левашова

Popov

Levashov

et al. 2022

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“…Indicators of changes in growth conditions and post-growth processes remain in the zoning of diamond crystals, including after the imposition of secondary inhomogeneities [12,13]. Most other deep-seated minerals, except for zircon [14][15][16], are homogenized during long-term natural annealing and show no growth zoning [13,17,18]. Changing environmental conditions are often studied by the zoning of the chemical composition or micro impurities [19][20][21].…”

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Thermal history of diamond from Arkhangelskaya and Karpinsky-I kimberlite pipes

Васильев

Kriulina

Azhari

2022

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This work studies and compares the main morphological, structural, and mineralogical features of 350 diamond crystals from the Karpinsky-I and 300 crystals of the Arkhangelskaya kimberlite pipes. The share of crystals of octahedral habit together with individual crystals of transitional forms with sheaf-like and splintery striation is higher in the Arkhangelskaya pipe and makes 15 %. The share of cuboids and tetrahexahedroids is higher in the Karpinsky-I pipe and stands at 14 %. The share of dodecahedroids in the Arkhangelskaya and Karpinsky-I pipes are 60 % and 50 %, respectively. The indicator role of the nitrogen-vacancy N3 center active in absorption and luminescence is shown. Crystals with the N3 absorption system have predominantly octahedral habit or dissolution forms derived from the octahedra. Their thermal history is the most complex. Absorption bands of the lowest-temperature hydrogen-containing defects (3050, 3144, 3154, 3188, 3310 cm−1, 1388, 1407, 1432, 1456, 1465, 1503, 1551, 1563 cm−1), are typical for crystals without N3 system, where in the absorption spectra nitrogen is in the form of low-temperature A and C defects. The above mentioned bands are registered in the spectra of 16 % and 42 % of crystals from the Arkhangelskaya and Karpinsky-I pipes, respectively. The diamond of the studied deposits is unique in the minimum temperature (duration) of natural annealing. Based on a set of features, three populations of crystals were distinguished, differing in growth conditions, post-growth, and thermal histories. The established regularities prove the multi-stage formation of diamond deposits in the north of the East European Platform and significant differences from the diamonds of the Western Cisurals. The results suggest the possibility of the existence of primary deposits dominated by diamonds from one of the identified populations.

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Mineral chemistry aspects of radioactive mineralization associated with Zr-, Nb-, and REE-bearing minerals from felsic dikes at Abu Hawis, North Eastern Desert, Egypt

Gawad

2022

Arab J Geosci

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The exposed rocks in Abu Hawis area, North Eastern Desert (NED), Egypt, consist of tonalite-granodiorite and monzogranite, dissected by post-granite felsic (microgranite and rhyolite) and mafic (basaltic-andesite) dikes. The investigated radioactive minerals and Zr-, Nb-, and REE-bearing minerals were restricted to felsic dikes having E–W and NE–SW trends. Uraninite, uranothorite, and thorite occur as the main radioactive minerals in microgranite dikes, while thorite is represent in rhyolite dikes. Y2O3 and HREE are recorded in zircon crystals from rhyolite dikes whereas HREEs in zircon grains from microgranite dikes are below detection limit. Zircon crystals from microgranite dikes contain high values of HfO2 with up to 9.08 wt % owing to the effect of hydrothermal activity. Columbite from microgranite dikes has Ta/(Ta + Nb) and Mn/(Mn + Fe) ratios ranging between 0.0052–0.0164 and 0.0549–0.7010, respectively, which point to manganocolumbite composition, except for two spots that show a ferrocolumbite composition. Fergusonite is recorded in microgranite dikes, with average values of Nb2O5, Y2O3, and HREE2O3 reaching 50.3, 22.93, and 17.68 wt%, respectively. Monazite is recorded in both microgranite and rhyolite dikes, with marked enrichment of ThO2, which reaches up to 12.52 wt% in the first one, while the total ΣLREE2O3 reached up to 68.5 wt% in the latter. Parisite and chevkinite are confined to rhyolite dikes with clear enrichment in LREE with averages ranging between 53.53 and 43.75 wt% ΣLREE2O3, respectively.

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Distribution of Trace Elements Controlled by Sector and Growth Zonings in Zircon from Feldspathic Pegmatites (Ilmen Mountains, the Southern Urals)

Cited by 9 publications

References 53 publications

Distribution of trace elements controlled by sector and growth zonings in zircon from a miaskite pegmatite of the Vishnegorsky massif, the Southern Urals

Distribution of trace elements controlled by sector and growth zonings in zircon from a miaskite pegmatite of the Vishnegorsky massif, the Southern Urals

Thermal history of diamond from Arkhangelskaya and Karpinsky-I kimberlite pipes

Mineral chemistry aspects of radioactive mineralization associated with Zr-, Nb-, and REE-bearing minerals from felsic dikes at Abu Hawis, North Eastern Desert, Egypt

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