Fluorine-hydroxyl exchange in apatite and biotite: A potential igneous geothermometer

Stormer, John C.; Carmichael, I. S. E.

doi:10.1007/bf00373455

Cited by 111 publications

(32 citation statements)

References 9 publications

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“…Several workers note that, while biotite is susceptible to latestage exchange in the hydroxyl site involving low temperature aqueous fluids, apatite appears to resist this process (Stormer and Carmichael, 1971;Nash, 1976). It appears that while chlor-apatite will exchange and possibly reach equilibrium with a F-rich solution, as may have been the case with the granite-gneiss, fluor-apatite will not react with a C1-rich solution.…”

Section: Nature Of the Fluidmentioning

confidence: 99%

Metasomatism in the North Qôroq centre, South Greenland: apatite chemistry and rare-earth element transport

Rae

Coulson²,

Chambers³

1996

Mineral. mag.

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The North Q6roq syenite centre forms part of the Gardar Province of South Greenland. Extensive metasomatism, associated with the evolution of syenitic magmas, has resulted in redistribution of the rareearth elements (REE), originally concentrated by magmatic processes, in both the syenites and surrounding granite-gneiss and quartzite country rocks. An important host for REE is apatite which can occur irl significant quantities. Metasomatic apatites show complex, concentric, but irregular patterns of zonation, clearly seen using CL and BSE imaging. This zonation is related to successive pulses of metasomatising fluids. Electron microprobe analysis confirms the presence of significant quantities of REE in the apatites. The dominantcation exchange mechanism proposed is Ca + P ~--~ REE + Si . In contrast to apatites from the nearby Ilfmaussaq intrusion, there is no significant Na present in the structure and exchange reactions involving Na + and REE 3+ for Ca 2+ have not occurred. Apatites from the quartzite are fluor-apatites, while those from the granite-gneiss are more Cl-rich. These differences reflect the fact that granite-gneiss apatites are original and modified by metasomatism, whereas, those in the quartzite are metasomatic in origin. REE were probably transported as carbonate, fluoride or fluor-carbonate complexes, and reflect the activity of a F-rich, CO~ -rich fluid phase.

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Section: Nature Of the Fluidmentioning

confidence: 99%

Metasomatism in the North Qôroq centre, South Greenland: apatite chemistry and rare-earth element transport

Rae

Coulson²,

Chambers³

1996

Mineral. mag.

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“…Chlorine exhibits antithetic behavior to fluorine and is relatively enriched in the least differentiated rocks of individual plutonic associations. Stormer and Carmichael (1971) evaluated the distribution of fluorine and hydroxyl between apatite and coexisting biotite as a geothermometer using the following exchange reaction: The necessary free energy data for the reaction was estimated from simple hydroxides and fluorides. Subsequently, Ludington (1978) refined the geothermometer with additional data on Fe-Mg substitution in mica, thermodynamic data on apatite endmembers (Duff 1971), and revised data on F-OH exchange in biotite.…”

Section: Halogensmentioning

confidence: 99%

Phosphate Minerals in Terrestrial Igneous and Metamorphic Rocks

Nash

1984

Photosphate Minerals

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“…We detected higher amounts of fluorine in the monazite (average 0.88 ± 0.10 wt %) ( Table 2, Figure 4A-C), an element commonly found in apatite [40][41][42]. We found no clear relationship between the amount of F and any cations, perhaps due to its substitution in the anion site or interstitial sites in the monazite structure, creating a degree of disorder.…”

Section: Llallagua Monazite Epmamentioning

confidence: 74%

Speculations Linking Monazite Compositions to Origin: Llallagua Tin Ore Deposit (Bolivia)

Catlos

Miller

2017

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Monazite [(Ce,Th)PO 4 ] from the Llallagua tin ore deposit in Bolivia is characterized by low radiogenic element contents. Previously reported field evidence and mineral associations suggest the mineral formed via direct precipitation from hydrothermal fluids. Monazite compositions thus may provide insight into characteristics of the fluids from which it formed. Chemical compositions of three Llallagua monazite grains were obtained using Electron Probe Microanalysis (EPMA, n = 64) and laser ablation mass spectrometry (LA-ICP-MS, n = 56). The mineral has higher amounts of U (123 ± 17 ppm) than Th (39 ± 20 ppm) (LA-ICP-MS, ±1σ). Grains have the highest amounts of fluorine ever reported for monazite (0.88 ± 0.10 wt %, EPMA, ±1σ), and F-rich fluids are effective mobilizers of rare earth elements (REEs), Y, and Th. The monazite has high Eu contents and positive Eu anomalies, consistent with formation in a highly-reducing back-arc environment. We speculate that F, Ca, Si and REE may have been supplied via dissolution of pre-existing fluorapatite. Llallagua monazite oscillatory zoning is controlled by an interplay of low (P + Ca + Si + Y) and high atomic number (REE) elements. We suggest monazite compositions provide insight into fluid geochemistry, mineral reactions, and tectonic settings of ore deposits that contain the mineral.

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Fluorine-hydroxyl exchange in apatite and biotite: A potential igneous geothermometer

Cited by 111 publications

References 9 publications

Metasomatism in the North Qôroq centre, South Greenland: apatite chemistry and rare-earth element transport

Metasomatism in the North Qôroq centre, South Greenland: apatite chemistry and rare-earth element transport

Phosphate Minerals in Terrestrial Igneous and Metamorphic Rocks

Speculations Linking Monazite Compositions to Origin: Llallagua Tin Ore Deposit (Bolivia)

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