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Istituto di Geoscienze e Georisorse     
Villa I. Datability of Quaternary volcanic rocks: an 40Ar/39Ar perspective on age conflicts in lavas from the Alban Hills, Italy. In: European Journal of Mineralogy, vol. 4 (2) pp. 369 - 383. Schweizerbart, 1992.
 
 
Abstract
(English)
High-resolution ⁴⁰Ar/⁹Ar dating experiments on four leucites from lavas and scoriae of the Alban Hills, recently reported to have ⁰Th/⁸U ages between 7 and 25 ka, fail to confirm these young age assignments. Plateau and isochron ages are concordant and consistent with the previously known history of the volcano : 355, 283, 250, and 30-40 ka. A historic Vesuvius lava flow, analysed as a control sample, correctly yields a < 19 ka age, corresponding to a saddle minimum. From the consistency of the ⁴⁰Ar/⁹Ar data it is concluded that these rocks do not fulfill the requirements for ⁰Th/⁸U dating, probably because they interacted with the LILE-enriched fluids known to have affected the entire Roman Volcanic Province. Sample N-2 is shown to have undergone enrichment both in ⁴⁰Ar and ⁸⁷Sr. Major amounts of magma were not produced during the Holocene in the Alban Hills; the city of Rome is not exposed to an increased volcanic risk.
URL: http://www.schweizerbart.de/j/ejm/
Subject ⁴⁰Ar/⁹Ar dating
⁰Th/⁸U dating
age discordance
fluid-rock interaction
Quaternary chronology
Italy
Alban Hills


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