Age constraints on Late Paleozoic evolution of continental crust from electron microprobe dating of monazite in the Peloritani Mountains (southern Italy): another example of resetting of monazite ages in high-grade rocks |
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Authors: | Peter Appel Rosolino Cirrincione Patrizia Fiannacca Antonino Pezzino |
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Institution: | 1.Institut für Geowissenschaften,Universit?t Kiel,Kiel,Germany;2.Dipartimento di Scienze Geologiche,Catania University,Catania,Italy |
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Abstract: | In situ monazite microprobe dating has been performed, for the first time, on trondhjemite and amphibolite facies metasediments
from the Peloritani Mountains in order to obtain information about the age of metamorphism and intrusive magmatism within
this still poorly known sector of the Hercynian Belt. All samples show single-stage monazite growth of Hercynian age. One
migmatite and one biotitic paragneiss yielded monazite ages of 311 ± 4 and 298 ± 6 Ma, respectively. These ages fit with previous
age determinations in similar rocks from southern Calabria, indicating a thermal metamorphic peak at about 300 Ma, at the
same time as widespread granitoid magmatism. The older of the two ages might represent a slightly earlier event, possibly
associated with the emplacement of an adjacent trondhjemite pluton, previously dated by SHRIMP at 314 Ma. No evidence for
pre-Hercynian events and only a little indication for some monazite crystallization starting from ca. 360 Ma were obtained
from monazite dating of the metasediments, suggesting either a single-stage metamorphic evolution or a significant resetting
of the monazite isotope system during the main Hercynian event (ca. 300 Ma). Rare monazite from a trondhjemite sample yields
evidence for a late-Hercynian age of about 275 Ma. This age is interpreted as representing a post-magmatic stage of metasomatic
monazite crystallization, which significantly postdates the emplacement of the original magmatic body. |
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