Concordant thermoluminescence and 238U–230Th ages for a trachytic dome (Grand Sarcoui) from the Chaîne des Puys (French Massif Central)
2003; Elsevier BV; Volume: 23; Issue: 5-6 Linguagem: Inglês
10.1016/j.quascirev.2003.06.002
ISSN1873-457X
AutoresDidier Miallier, Maud Condomines, T. Pilleyre, S. Sanzelle, J Guittet,
Tópico(s)Mineralogy and Gemology Studies
ResumoThis paper presents the results of thermoluminescence (TL) and 238U–230Th datings of a trachytic dome from the Chaı̂ne des Puys in the French Massif Central, the Grand Sarcoui dome. TL dating was performed on quartz xenocrysts extracted from the phreatomagmatic tephra that initiated the eruptions. Red TL and blue TL give consistent results with an average age of 12.6±3 ka (2σ). A 238U–230Th isochron age is calculated using data obtained on groundmass and zircon: this corresponds to a crystallization age of 12.8±1.4 ka (2σ). The excellent agreement between the ages derived from both methods indicate that the interval between zircon crystallization in the magma chamber and eruption was probably very short (a few centuries at most). This and other geochemical arguments suggest that the differentiation (through fractional crystallization accompanied by crustal contamination) of the trachytic magmas of the Chaı̂ne des Puys took place rather quickly in small and separate shallow reservoirs, only a few km apart. The eruption of trachytic magma was restricted to a period between 13 and 9 ka, near the end of eruptive activity in the central part of the Chaı̂ne des Puys.
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