Durbachites – source of uranium for the deposits in the eastern Moldanubian Zone
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| Year of publication | 2023 |
| Type | Appeared in Conference without Proceedings |
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| Description | The unusual trace element chemistry of the low-T hydrothermal vein-type deposits (high Zr, Nb, Ti, ?REE) and their close spatial association with HFSE- and U–Th REE-rich durbachite intrusions in the Moldanubian Zone of the Bohemian Massif most likely point towards their mutual genetic relation. The massive mobilization of U together with HFSE and REE in durbachites is well-documented by EMP imaging (Fig. 1) and analyses of their main U-bearing phases – pristine magmatic Uraninite, Thorite, Zircon, Allanite and rare Monazite (Kubeš et al. 2021, 2022). We propose that radiation damage of major refractory minerals likely enhanced permeability due to their volume expansion, which facilitated fluid-mineral interaction and thus promoted HFSE and REE leaching from their source. Accordingly, enhanced HFSE mobility in circulating hydrothermal fluids is reflected by presence of Zr–Th–U–Si phase that typically fills abundant microfracture intimately surrounding metamict zircon (Fig. 1). Thus, the extreme HFSE and REE mobilization linked to the extensive dissolution of major U-bearing phases in durbachites provide the most likely explanation for the unusual chemistry of Moldanubian U-deposits. Taking into account a much larger original extent of the highly alkaline (ultra)potassic intrusions, the original U content of this intrusion was estimated on minimum 28 mil t of U. |
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