Uranium-bearing francolites present in organic-rich limestones of NW Greece: a preliminary study using synchrotron radiation and fission track techniques

Tzifas, Ioannis; Glasmacher, Ulrich A.; Μisaelides, P.; Γοδελίτσας, Α.; Gamaletsos, P.; Goettlicher, J.; Godoy, Daniel Françoso de

doi:10.1007/s10967-016-4973-4

Cited by 6 publications

(2 citation statements)

References 46 publications

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“…REE deposits related to carbonatitic magmatism as well as ion-adsorption type deposits, are presently the most popular resources under production [15,16]. Therefore, research on new REE deposit types is becoming increasingly pertinent, with emphasis particularly on the viability of bauxites, phosphates, placers and clay deposits as promising REE resources [17][18][19][20][21][22]. It should be pointed out that although measured REE contents might appear economically attractive across a breadth of alternative deposit types, the feasibility of many of these may be hindered due to limitations with respect to current methodologies in metallurgical extraction.…”

Section: Rare Earth Element (Ree) Applications and Global Demandmentioning

confidence: 99%

The Potential for REE and Associated Critical Metals in Coastal Sand (Placer) Deposits of Greece: A Review

2019

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The rare earth elements (REEs) are characterized by the European Union (EU) as critical raw materials with a significant risk of supply because of their broad utility in both traditional and emerging technological applications. The growing demand for REE has caused a flurry in the search for new REE deposits in Europe and elsewhere in the world, and is also linked to rising exploitation efforts in a variety of geological settings. To this end, Greece appears to be a promising candidate to become a leading EU country in terms of REE by virtue of its natural endowment in sedimentary heavy mineral deposits (placers) along its long coastline. The present review focuses on the distribution, abundance, and bulk geochemistry of REEs and other critical metals (Ta, Nb, Co) associated with placer deposits of Greece, and specifically with geologically young heavy mineral sand accumulations developed proximal to felsic plutonic source rocks. These deposits are also enriched in the actinides uranium (U) and thorium (Th), as both of these metals are typically associated with REE-rich minerals such as xenotime, monazite, thorite, allanite, and zircon. Previous studies have employed a variety of analytical techniques down to nano-meter scale with the aim to elucidate the mineralogy and distribution of REE and associated actinides in Greek beach placers. In view of this mineralogically-intensive background, the present review focuses chiefly on bulk geochemical characteristics of the same deposits and the variations thereof between two major geographical regions (northern Greece, southern Aegean) and across individual placer occurrences within them. In this framework, we present comprehensive compositional comparisons between the different deposits, highlighting the geological sub-environments wherein they occur, their distinctive sources and geochemical signatures, and their potential economic significance in terms of REE and other critical metal enrichments where applicable.

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Section: Rare Earth Element (Ree) Applications and Global Demandmentioning

confidence: 99%

The Potential for REE and Associated Critical Metals in Coastal Sand (Placer) Deposits of Greece: A Review

2019

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“…Tzifas et al. () flagged the potential for FT dating of francolite, but to date no LTT data have been reported. This study investigates A‐apatite genesis and thermal history using AFT, AHe and ZHe dating from Cambrian strata and underlying crystalline basement in the Nahal Shehoret and Eilat area, southern Israel, bordering the DST (Figure ).…”

Section: Introductionmentioning

confidence: 99%

Low‐temperature thermochronology of francolite: Insights into timing of Dead Sea Transform motion

et al. 2019

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Cambrian siliciclastic sequences along the Dead Sea Transform (DST) margin in southern Israel and southern Jordan host both detrital fluorapatite [D‐apatite] and U‐rich authigenic carbonate‐fluorapatite (francolite) [A‐apatite]. D‐apatite and underlying Neoproterozoic basement apatite yield fission‐track (FT) data reflecting Palaeozoic–Mesozoic sedimentary cycles and epeirogenic events, and dispersed (U–Th–Sm)/He (AHe) ages. A‐apatite, which may partially or completely replace D‐apatite, yields an early Miocene FT age suggesting formation by fracturing, hydrothermal fluid ascent and intra‐strata recrystallisation, linked to early DST motion. The DST, separating the African and Arabian plates, records ~105 km of sinistral strike‐slip displacement, but became more transtensional post‐5 Ma. Helium diffusion measurements on A‐apatite are consistent with thermally activated volume diffusion, indicating Tc ~52 to 56 ± 10°C (cooling rate 10°C/Ma). A‐apatite AHe data record Pliocene cooling (~35 to 40°C) during the transtensional phase of movement. This suggests that timing of important milestones in DST motion can be discerned using A‐apatite low‐temperature thermochronology data alone.

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Tracking of uranium and thorium natural distribution in the chemical fractions of the Nile Valley and the Red Sea phosphorites, Egypt

Aita,

Abdel-Azeem,

Abu Khoziem

et al. 2024

Carbonates Evaporites

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The present study aims to elucidate the possible sources of uranium and thorium content in the Campanian–Maastrichtian phosphorites from the Duwi Formation in the Nile Valley and Red Sea by conducting facies analysis and sequential leaching method. Nile Valley samples were collected from the El-Sibaiya East area, while those of the Red Sea were collected from two locations: Hamadat and Zug El Bahar. The petrographic investigation revealed that the Sibaiya East phosphorites exhibit peloidal bioclastic phospharenite–phospharudite microfacies, while Hamadat and Zug El Bahar phosphorites display peloidal bioclastic phosphalutite and silicified peloidal bioclastic phospharenite microfacies, respectively. Besides, U–Th bearing accessory minerals, such as zircon and monazite occur in Sibaiya East phosphorites. Thorium is present in Zug El Bahar phosphorites as minute accumulations associating apatite and quartz. Moreover, uranium is found with vanadium and iron as fine patches in the Sibaiya East phosphorite, and as small disseminations associated with Ca and Si in the Hamadat phosphorite. The X-ray diffraction shows that the investigated phosphorites are essentially built up of hydroxyl apatite Ca5(PO4)3(OH) and quartz SiO2. To accurately evaluate the bioavailability and mobility of uranium and thorium in the investigated phosphorites, it was necessary to identify the overall concentration and the various chemical forms of these elements by a five-step sequential leaching technique. The results indicate that Th and U are more abundant in the Red Sea phosphorites than in the Nile Valley phosphorites. Furthermore, Th is not bio-available and it is mostly found in the residue as Th-bearing minerals. Uranium, unlike Th is bio-available and fractionates among all fractions, indicating that U accumulation is the result of various diagenetic processes.

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Uranium-bearing francolites present in organic-rich limestones of NW Greece: a preliminary study using synchrotron radiation and fission track techniques

Cited by 6 publications

References 46 publications

The Potential for REE and Associated Critical Metals in Coastal Sand (Placer) Deposits of Greece: A Review

The Potential for REE and Associated Critical Metals in Coastal Sand (Placer) Deposits of Greece: A Review

Low‐temperature thermochronology of francolite: Insights into timing of Dead Sea Transform motion

Tracking of uranium and thorium natural distribution in the chemical fractions of the Nile Valley and the Red Sea phosphorites, Egypt

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