The degradation of monazite: Implications for the mobility of rare-earth and actinide elements during low-temperature alteration

Read, David; Andreoli, M. A. G.; Knoper, Michael; Williams, C. T.; Jarvis, Neil V.

doi:10.1127/0935-1221/2002/0014-0487

Cited by 45 publications

(28 citation statements)

References 25 publications

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“…Summary of waste forms for HLW from reprocessing of commercial spent fuel and special purpose formulations for Pu and actinides. Ringwood et al, 1988 and references therein), or as specialist materials for the encapsulation of actinides and fission products that would arise from the possible separation of HLW into various fractions, or for Pu from dismantled nuclear weapons or other industrial processes. Although some waste forms are conceived as single-phase ceramics such as the pyrochlore-based materials designed in~1997 for the US Plutonium Immobilization Project (e.g.…”

Section: Waste Forms Drive Natural Analogue Studiesmentioning

confidence: 99%

“…In Synroc-C, for example, zirconolite is designed to be the primary host phase for actinides, perovskite is the host phase for Sr and hollandite is the host phase for Cs. Synroc in its various forms is perhaps the most studied ceramic waste form to date, with numerous reports and publications on the processing conditions, crystal chemistry, element partitioning, aqueous durability and radiation damage effects (Ringwood et al, 1988;Smith et al, 1992;Vance, 1994;Lumpkin, 2001Lumpkin, , 2006Begg, 2003).…”

Section: Waste Forms Drive Natural Analogue Studiesmentioning

confidence: 99%

“…Furthermore, in monazite the Ln elemental distributions also vary as a result of the different conditions and reaction mechanisms. In a study of monazite from the Steenkampskraal mine, South Africa, Read et al (2002) have shown that the heavy Ln and Y are released and precipitated locally as secondary phosphate minerals, U is released to the fluid phase, while the light Ln elements are retained in altered monazite. Mathieu et al (2001) studied monazite from Lower Proterozoic sandstones of the Franceville basin, Gabon, reporting the alteration of monazite to a Th-silicate phase in the presence of a diagenetic brine, resulting in loss of light Ln elements and U to the fluid phase.…”

Section: Geochemical Behaviourmentioning

confidence: 99%

“…However, some scientists have questioned the use of glass from the perspective of aqueous durability, especially at elevated temperature, and the potential for higher dissolution rates in geological repositories, resulting in the release of radionuclides into the environment (e.g. McCarthy, 1977;Ringwood, 1978). Focussed research activities on alternative materials to borosilicate glass began to appear~40 years ago and have continued to evolve over time.…”

Section: Introductionmentioning

confidence: 99%

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The role of Th-U minerals in assessing the performance of nuclear waste forms

et al. 2014

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Materials designed for nuclear waste disposal include a range of ceramics, glass ceramics and glass waste forms. Those with crystalline phases have provided the momentum for studies of minerals as a means to understand aspects of waste-form crystal chemistry, behaviour in aqueous systems and radiation damage over geological periods of time. Although the utility of natural analogue studies varies, depending upon the degree of analogy to the proposed geological repository and other factors such as chemical composition, the available data suggest that Th-U host phases such as brannerite, monazite, pyrochlore, zircon and zirconolite are resistant generally to dissolution in aqueous fluids at low temperatures. Geochemical durability may or may not extend to hydrothermal systems depending on the specifics of fluid composition, temperature and pressure. At elevated temperatures, for example, davidite may break down to new phase assemblages including titanite, ilmenite and rutile. Perovskite is generally less resistant to dissolution at low temperatures and breaks down to TiO2, releasing A-site cations to the aqueous fluid. Studies of radiation damage indicate that the oxide and silicate phases become amorphous as a result of the gradual accumulation of alpha-recoil collision cascades. Monazite tends to remain crystalline on geological time scales, a very attractive property that potentially eliminates major changes in physical properties such as density and volume, thereby reducing the potential for cracking, which is a major concern for zircon. In spite of recent success in describing the behaviour of Th-U minerals in geological systems, considerable work remains in order to understand the P-T-X conditions during alteration and T-t history of the host rocks. ABSTRACTMaterials designed for nuclear waste disposal include a range of ceramics, glass ceramics and glass waste forms. Those with crystalline phases have provided the momentum for studies of minerals as a means to understand aspects of waste-form crystal chemistry, behaviour in aqueous systems and radiation damage over geological periods of time. Although the utility of natural analogue studies varies, depending upon the degree of analogy to the proposed geological repository and other factors such as chemical composition, the available data suggest that Th-U host phases such as brannerite, monazite, pyrochlore, zircon and zirconolite are resistant generally to dissolution in aqueous fluids at low temperatures. Geochemical durability may or may not extend to hydrothermal systems depending on the specifics of fluid composition, temperature and pressure. At elevated temperatures, for example, davidite may break down to new phase assemblages including titanite, ilmenite and rutile. Perovskite is generally less resistant to dissolution at low temperatures and breaks down to TiO 2 , releasing A-site cations to the aqueous fluid. Studies of radiation damage indicate that the oxide and silicate phases become amorphous as a result of the gradual accumulation of...

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Section: Waste Forms Drive Natural Analogue Studiesmentioning

confidence: 99%

Section: Waste Forms Drive Natural Analogue Studiesmentioning

confidence: 99%

Section: Geochemical Behaviourmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The role of Th-U minerals in assessing the performance of nuclear waste forms

et al. 2014

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“…Since the late 1980s, detailed mapping in central and southern Namaqualand brought to light other clusters of intrusive rocks with many of the lithological, geochemical, emplacement age, and structural features distinctive of the Koperberg Suite near Springbok (Figure 1; Andreoli et al, 1986;Hamman et al, 1996;Read et al, 2002). This southern region experienced upper granulite facies conditions characterized by the stability of such rare minerals like osumilite, as well as spinel + quartz (P >5 kbars, T ~860 to 1000°C; Mouri et al, 2003;Robb et al, 1999).…”

Section: Tectonic Terranes Are Shown In Variable Shade Double Dottmentioning

confidence: 99%

Petrogenesis of Cu-Ni Sulphide Ores From O'OKIEP and Kliprand, Namaqualand, South Africa: Constraints From Chalcophile Metal Contents

Maier¹,

Andreoli²,

Groves³

et al. 2012

South African Journal of Geology

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In situ geochemistry of middle Ordovician dolomites of the upper Mississippi valley

Callen

Herrmann

2018

The Depositional Record

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The dolomitization and diagenetic history of Ordovician carbonates of southern Wisconsin is complex. Previous studies attributed dolomitization to various diagenetic factors and environments. In this study, high‐resolution, in situ laser ablation inductively coupled mass spectrometry analysis of rare earth element patterns of dolomite was used to assess the diagenetic fluids responsible for dolomitization of the Ordovician Decorah Formation. Integrated geochemical data and petrographic evidence suggest that the dolostones are formed in two different diagenetic realms: shallow burial and hydrothermal. Shallow burial dolomites exhibit three distinct rare earth element patterns. Dolomite from the middle portion of the Guttenberg Member exhibits light rare earth element enrichment consistent with early burial dolomitization. Dolomites of the Carimona, Specht's Ferry and Lower Guttenberg members are often burrow associated and exhibit medium rare earth element enrichment associated with Fe‐oxide desorption in anoxic porewaters. Leaching of Mg from co‐occurring volcanic ash during alteration is a probable source that contributed to the dolomitization. Extensively dolomitized samples in the upper Guttenberg and Ion Member exhibit evidence of hydrothermal dolomitization. The relationship of these heavily dolomitized samples to interbedded limestones provides evidence for a recently proposed hydrothermal dolomitization model invoking pressure solution of calcite and precipitation of dolomite. These early burial and hydrothermal depositional models are consistent with models proposed for overlying and underlying Ordovician dolostones.

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The degradation of monazite: Implications for the mobility of rare-earth and actinide elements during low-temperature alteration

Cited by 45 publications

References 25 publications

The role of Th-U minerals in assessing the performance of nuclear waste forms

The role of Th-U minerals in assessing the performance of nuclear waste forms

Petrogenesis of Cu-Ni Sulphide Ores From O'OKIEP and Kliprand, Namaqualand, South Africa: Constraints From Chalcophile Metal Contents

In situ geochemistry of middle Ordovician dolomites of the upper Mississippi valley

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