Very-low-grade phyllosilicates in the Aravis massif (Haute-Savoie, France) and the di-trioctahedral substitution in chlorite
| Autor: | B. Dubacq, G. Bonnet, M. Warembourg, B. Baptiste |
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| Jazyk: | angličtina |
| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | European Journal of Mineralogy, Vol 35, Pp 831-844 (2023) |
| Druh dokumentu: | article |
| ISSN: | 0935-1221 1617-4011 |
| DOI: | 10.5194/ejm-35-831-2023 |
| Popis: | Very-low-grade mineral veins investigated in the impure limestone massif of the Aravis (Haute-Savoie, France) yielded a rich mineral assemblage typified by dolomite, calcite, quartz, illitic mica, fluorite and three types of chlorite. The vein network extends over more than 5 km and was probably emplaced around peak burial of the limestone (∼7 km depth, 190 ∘C). The mineralogy has been investigated with electron microscopy, mass spectrometry and X-ray diffraction, with emphasis on chlorite types. The first chlorite type is a chamosite often interlayered with illitic mica. The second type is a Mg-rich, Al-depleted cookeite. The third type is a Li-rich sudoite. Presence of the three chlorite types shows limited solubility between di-trioctahedral chlorite phase components (sudoite and cookeite) and with tri-trioctahedral chlorite (chamosite). Departure of the Li-rich sudoite and Mg-rich cookeite from the ideal end-member compositions suggests solid solutions towards a Li-sudoite component. The associated illitic mica does not contain Li in significant proportion but shows pyrophyllitic and di-trioctahedral substitution, without a Tschermak component. These results call for systematic studies of the Li content of chlorite and for better modelling of di-trioctahedral substitution in chlorite and mica. |
| Databáze: | Directory of Open Access Journals |
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