U–Pb zircon ages for post-Variscan volcanism in the Ligurian Alps(Northern Italy)
Giorgio Dallagiovanna
Laura Gaggero
Matteo Maino
Silvio Seno
Massimo Tiepolo
10.6084/m9.figshare.3454565.v1
https://geolsoc.figshare.com/articles/journal_contribution/U_Pb_zircon_ages_for_post-Variscan_volcanism_in_the_Ligurian_Alps_Northern_Italy_/3454565
<p>Ages of Permian volcanic rocks from the Ligurian Briançonnais domain (Western Italian Alps) have been determined by laser
ablation inductively coupled plasma mass spectrometry U–Pb dating of zircon. Three major volcanic units yielded zircons that
were dated: calc-alkaline rhyolites (285.6 ± 2.6 Ma), andesites (with inherited cores yielded ages <em>c</em>. 476 Ma and older) and voluminous rhyodacites–rhyolites (272.7 ± 2.2 Ma). Following an amagmatic, sediment-starved time gap
of <em>c</em>. 14 Ma, alkaline volcanic activity is recorded, at the top of the sequence, by K-alkaline rhyolites dated at 258.5 ± 2.8
Ma. The Ligurian segment of the Southern Variscan belt records transtensional and then extensional tectonics associated with
the volcanic activity. The switch from calc-alkaline to alkaline activity corresponds to the transition from a post-orogenic
to an anorogenic setting in the Southern Variscides; it may represent progressive and increasing delamination of the continental
lithosphere, accompanied by partial melting of the lithospheric mantle.
</p>
2016-06-21 12:12:37
Southern Variscan belt records transtensional
ages c
Ligurian segment
rhyolite
Southern Variscides
14 Ma
Alps
476 Ma
zircon
laser ablation inductively
Ligurian Brian çonnais domain
lithospheric mantle
extensional tectonics
Geology