Τίτλος:
Carbonatitic dykes during Pangaea transtension (Pelagonian Zone, Greece)
Γλώσσες Τεκμηρίου:
Αγγλικά
Περίληψη:
Carbonatitic dykes surrounded by K-Na-fenites were discovered in the Pelagonian Zone in Greece. Their carbonate portions have an isotopic mantle signature of δ13C and δ18O ranging from −5.18 to −5.56 (‰ vs. VPDB) and from 10.68 to 11.59 (‰ vs. VSMOW) respectively, whereas their mafic silicate portions have high Nb, Ta and ɛNd values, typical of alkaline basalts. Textural relationships hint at a cogenetic intrusion of silicate and carbonate liquids that according to antithetic REE profiles segregated at shallow depths (<0.6 GPa) from a parental melt sourced deeper in the mantle. Fenites bear similar REE abundances to mafic rocks but with high Rb-Ba and low Nb-Ta values. SHRIMP II U-Pb analyses of magmatic zircon cores (δ18O = 7.21–7.51) from a carbonate-bearing syenitic amphibolite yielded a Permian intrusion age at 278 ± 2 Ma, considerably older than a Cretaceous (118 ± 4 Ma) greenschist overprint obtained from metamorphic zircon rims (δ18O = 6.78–7.02). From 300 to 175 Ma the ɛNd of the Pelagonian magmatism rose irregularly to more primitive values attesting to a higher increment of asthenosphere-derived melts. In this context, the carbonatite formed within a transtensional regime of an intra-Pangaea dextral transform fault that signalled the forthcoming penetrating breakoff of the supercontinent, manifested in the Permo-Triassic. © 2018 The Authors
Συγγραφείς:
Schenker, F.L.
Burg, J.-P.
Kostopoulos, D.
Baumgartner, L.P.
Bouvier, A.-S.
Περιοδικό:
LITHOS - AMSTERDAM
Λέξεις-κλειδιά:
carbonatite; dike; fenite; Hercynian orogeny; magmatism; Pangaea; Permian; rare earth element; Tethys, Greece; Pelagonia
DOI:
10.1016/j.lithos.2018.01.011
