Britholite, monazite, REE carbonates, and calcite: Products of hydrothermal alteration of allanite and apatite in A-type granite from Stupné, Western Carpathians, Slovakia

Uher, Pavel; Ondrejka, Martin; Bačík, Peter; Broska, Igor; Konečný, Petr

doi:10.1016/j.lithos.2015.09.005

Cited by 38 publications

(28 citation statements)

References 73 publications

(102 reference statements)

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“…However, only minor amounts of REE-rich fluorapatite formed in the experiments, whereas fluorcalciobritholite or Y-rich fluorcalciobritholite were the main products due to high Y + REE bulk content. In nature, these phases are relatively uncommon, and have been reported in post-magmatic assemblages including britholite-(Y), fluorbritholite-(Y), fluorcalciobritholite, secondary monazite, and REE carbonate minerals formed during low-temperature alteration of primary magmatic fluorapatite and allanite-(Ce) in A-type granites from the Western Carpathians in Slovakia (Uher et al 2015). Britholites also occur in various alkaline rocks such as alkali granites (Lyalina et al 2014), pegmatites associated with peralkaline granites (Pekov et al 2011), nepheline syenites (Liferovich and Mitchell 2006;Dumańska-Słowik et al 2012), and carbonatites (Ahijado et al 2005;Doroshkevich et al 2009).…”

Section: Interpretation Of the Experimental Results: Runs With Xenotimentioning

confidence: 99%

Experimental constraints on the relative stabilities of the two systems monazite-(Ce) – allanite-(Ce) – fluorapatite and xenotime-(Y) – (Y,HREE)-rich epidote – (Y,HREE)-rich fluorapatite, in high Ca and Na-Ca environments under P-T conditions of 200–1000 MPa and 450–750 °C

et al. 2016

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The relative stabilities of phases within the two systems monazite-(Ce)fluorapatiteallanite-(Ce) and xenotime-(Y)-(Y,HREE)-rich fluorapatite-(Y,HREE)-rich epidote have been tested experimentally as a function of pressure and temperature in systems roughly replicating granitic to pelitic composition with high and moderate bulk CaO/Na 2 O ratios over a wide range of P-T conditions from 200 to 1000 MPa and 450 to 750°C via four sets of experiments. These included (1) monazite-(Ce), labradorite, sanidine, biotite, muscovite, SiO 2 , CaF 2 , and 2 M Ca(OH) 2 ; (2) monazite-(Ce), albite, sanidine, biotite, muscovite, SiO 2 , CaF 2 , Na 2 Si 2 O 5 , and H 2 O; (3) xenotime-(Y), labradorite, sanidine, biotite, muscovite, garnet, SiO 2 , CaF 2 , and 2 M Ca(OH) 2 ; and (4) xenotime-(Y), albite, sanidine, biotite, muscovite, garnet, SiO 2 , CaF 2 , Na 2 Si 2 O 5 , and H 2 O. Monazite-(Ce) breakdown was documented in experimental sets (1) and (2). In experimental set (1), the Ca high activity (estimated bulk CaO/Na 2 O ratio of 13.3) promoted the formation of REE-rich epidote, allanite-(Ce), REE-rich fluorapatite, and fluorcalciobritholite at the expense of monazite-(Ce). In contrast, a bulk CaO/ Na 2 O ratio of~1.0 in runs in set (2) prevented the formation of REE-rich epidote and allanite-(Ce). The reacted monazite-(Ce) was partially replaced by REE-rich fluorapatite-fluorcalciobritholite in all runs, REE-rich steacyite in experiments at 450°C, 200-1000 MPa, and 550°C, 200-600 MPa, and minor cheralite in runs at 650-750°C, 200-1000 MPa. The experimental results support previous natural observations and thermodynamic modeling of phase equilibria, which demonstrate that an increased CaO bulk content expands the stability field of allanite-(Ce) relative to monazite-(Ce) at higher temperatures indicating that the relative stabilities of monazite-(Ce) and allanite-(Ce) depend on the bulk CaO/ Na 2 O ratio. The experiments also provide new insights into the re-equilibration of monazite-(Ce) via fluid-aided coupled dissolution-reprecipitation, which affects the Th-U-Pb system in runs at 450°C, 200-1000 MPa, and 550°C, 200-600 MPa. A lack of compositional alteration in the Th, U, and Pb in monazite-(Ce) at 550°C, 800-1000 MPa, and in experiments at 650-750°C, 200-1000 MPa indicates the limited influence of fluid-mediated alteration on volume diffusion under high P-T conditions. Experimental sets (3) and (4) resulted in xenotime-(Y) breakdown and partial replacement by (Y,REE)rich fluorapatite to Y-rich fluorcalciobritholite. Additionally, (Y,HREE)-rich epidote formed at the expense of xenotime-(Y) in three runs with 2 M Ca(OH) 2 fluid, at 550°C, 800 MPa; 650°C, 800 MPa; and 650°C, 1000 MPa similar to the experiments involving monazite-(Ce). These results confirm that replacement of xenotime-(Y) by (Y,HREE)-Editorial handling: L. Nasdala

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Section: Interpretation Of the Experimental Results: Runs With Xenotimentioning

confidence: 99%

Experimental constraints on the relative stabilities of the two systems monazite-(Ce) – allanite-(Ce) – fluorapatite and xenotime-(Y) – (Y,HREE)-rich epidote – (Y,HREE)-rich fluorapatite, in high Ca and Na-Ca environments under P-T conditions of 200–1000 MPa and 450–750 °C

et al. 2016

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“…The fluids also degrade calcite and titanite in some places. Breakdown of allanite I to the REE carbonate minerals requires fluid containing F, CO 2 and H 2 O, and this process has been described at many sites, (e.g., Berger et al 2008;Budzyń et al 2010;Uher et al 2015). These examples suggest that primary magmatic allanite can be unstable during relatively low-temperature, metamorphic-hydrothermal alteration by fluids rich in F, CO 2 and H 2 O.…”

Section: Allanite Breakdown and Formation Of Ree Carbonatesmentioning

confidence: 99%

Fluid-driven destabilization of REE-bearing accessory minerals in the granitic orthogneisses of North Veporic basement (Western Carpathians, Slovakia)

et al. 2016

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A variety of rare earth elements-bearing (REE) accessory mineral breakdowns were identified in granitic orthogneisses from the pre-Alpine basement in the Veporic Unit, Central Western Carpathians, Slovakia. The Ordovician granitic rocks were subjected to Variscan metamorphic-anatectic overprint in amphibolite facies. Chemical U-Th-Pb dating of monazite-(Ce) and xenotime-(Y) reveal their primary magmatic Lower to Middle Ordovician age (monazite: 472 ± 4 to 468 ± 6 Ma and xenotime: 471 ± 13 Ma) and/or metamorphic-anatectic Variscan (Carboniferous, Visean) age (monazite: 345 ± 3 Ma). Younger fluid-rock interactions caused breakdown of primary magmatic and/or metamorphic-anatectic monazite-(Ce), xenotime-(Y), fluorapatite and allanite-(Ce). Fluid-induced breakdown of xenotime-(Y) produced numerous tiny uraninite inclusions within the altered xenotime-(Y) domains. The monazite-(Ce) breakdown produced secondary egg-shaped coronal structures of different stages with welldeveloped concentric mineral zones. Secondary sulphatian monazite-(Ce) (up to 0.15 apfu S) occasionally formed along fluorapatite fissures. Localized fluorapatite and monazite-(Ce) recrystallization resulted in a very fine-grained, nonstoichiometric mixture of REE-Y-Fe-Th-Ca-P-Si phases. Finally, allanite-(Ce) decomposed to secondary REE carbonate minerals (members of the bastnäsite and synchysite groups) and calcite in some places. Although the xenotime alteration and formation of uraninite inclusions is believed to be the result of dissolution-reprecipitation between early magmatic xenotime and late-magmatic granitic fluids, the monazite, apatite and allanite breakdowns were driven by metamorphic hydrothermal fluids. While earlier impact of postmagmatic fluids originated probably from Permian acidic volcanic and microgranitic veins crosscutting the orthogneisses, another fluid-rock interaction event most likely occurred during Late Cretaceous metamorphism in the Veporic basement and covering rocks. This stage indicates carbon-bearing fluids precipitating the carbonate minerals.

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“…The britholite group contains relatively common accessory minerals that are considered to be among the main carriers of the rare-earth elements (REE) in certain igneous rocks. The minerals have been identified in felsic magmatic rocks, and in metasomatites and pegmatites associated with subalkali and alkali granites, alkali and nepheline syenites, alkali volcanics, and carbonatites [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. It has been suggested that britholites in most occurrences crystallized at the late-to post-magmatic (pegmatite and hydrothermal) stages.…”

Section: Introductionmentioning

confidence: 99%

“…The britholite group belongs to the apatite supergroup and currently includes (with the exception of the tritomite species) britholite-(Ce), britholite-(Y), fluorbritholite-(Ce), fluorbritholite-(Y), and fluorcalciobritholite [25]. In the literature, the potential phases "calciobritholite" [8,16] and IMA valid "britholite-(La)" [15] have also been mentioned. The group includes minerals with the general chemical formula IX M1 2 VII M2 3 ( IV TO 4 ) 3 X where M = Ca 2− , Ce 3− , La 3− , Y 3− ; T = P 5− , Si 4− ; X = F − , (OH) − , Cl − .…”

Section: Introductionmentioning

confidence: 99%

“…The chemical compositions of these minerals are highly variable with different REE/Ca, P/Si and F/OH ratios depending mainly on the chemistry of the environment of formation and reflect complex isomorphic solid solutions among the britholite end-members. Several species may crystallize in a single rock due to different genetic processes (e.g., in UK Paleogene granites [8], the Stupne granite, Slovakia [16], and the Sakharjok nepheline syenite, Kola Peninsula, NW Russia [21,26].…”

Section: Introductionmentioning

confidence: 99%

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Britholite Group Minerals from REE-Rich Lithologies of Keivy Alkali Granite—Nepheline Syenite Complex, Kola Peninsula, NW Russia

et al. 2019

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The Keivy alkali granite-nepheline syenite complex, Kola Peninsula, NW Russia, contains numerous associated Zr-REE-Y-Nb occurrences and deposits, formed by a complex sequence of magmatic, late-magmatic, and post-magmatic (including pegmatitic, hydrothermal, and metasomatic) processes. The REE-rich lithologies have abundant (some of economic importance) and diverse britholite group minerals. The REE and actinides distribution in host rocks indicates that the emanating fluids were alkaline, with significant amounts of F and CO2. From chemical studies (REE and F variations) of the britholites the possible fluid compositions in different lithologies are proposed. Fluorbritholite-(Y) and britholite-(Y) from products of alkali granite (mineralized granite, pegmatite, quartzolite) formed under relatively high F activity in fluids with low CO2/H2O ratio. The highest F and moderate CO2 contents are characteristic of fluid from a mineralized nepheline syenite, resulting in crystallization of fluorbritholite-(Ce). Britholite group minerals (mainly fluorcalciobritholite and ‘calciobritholite’) from a nepheline syenite pegmatite formed from a fluid with composition changing from low F and high CO2 to moderate F and CO2. An extremely high F content is revealed for metasomatizing fluids emanating from alkali granitic magma and which affected the basic country rocks. The dominant substitution scheme for Keivy britholites is REE3+ + Si4+ = Ca2+ + P5+, showing the full range of ‘britholite’ and ‘calciobritholite’ compositions up to theoretical apatite.

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Britholite, monazite, REE carbonates, and calcite: Products of hydrothermal alteration of allanite and apatite in A-type granite from Stupné, Western Carpathians, Slovakia

Cited by 38 publications

References 73 publications

Experimental constraints on the relative stabilities of the two systems monazite-(Ce) – allanite-(Ce) – fluorapatite and xenotime-(Y) – (Y,HREE)-rich epidote – (Y,HREE)-rich fluorapatite, in high Ca and Na-Ca environments under P-T conditions of 200–1000 MPa and 450–750 °C

Experimental constraints on the relative stabilities of the two systems monazite-(Ce) – allanite-(Ce) – fluorapatite and xenotime-(Y) – (Y,HREE)-rich epidote – (Y,HREE)-rich fluorapatite, in high Ca and Na-Ca environments under P-T conditions of 200–1000 MPa and 450–750 °C

Fluid-driven destabilization of REE-bearing accessory minerals in the granitic orthogneisses of North Veporic basement (Western Carpathians, Slovakia)

Britholite Group Minerals from REE-Rich Lithologies of Keivy Alkali Granite—Nepheline Syenite Complex, Kola Peninsula, NW Russia

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