TY - JOUR
T1 - Petrology and Sr-Nd-Hf isotope geochemistry of gabbro xenoliths from the Hyblean Plateau
T2 - A MARID reservoir beneath SE Sicily?
AU - Sapienza, Giovanna T.
AU - Griffin, William L.
AU - O'Reilly, Suzanne Y.
AU - Morten, Lauro
PY - 2009
Y1 - 2009
N2 - In situ trace-element and isotopic (87Sr/86Sr) data and whole-rock Sr-Nd-Hf data on 12 gabbro xenoliths from the Hyblean Plateau (south-eastern Sicily) illustrate the complex petrogenetic evolution of this lithospheric segment. The gabbros formed by precipitation of plagioclase + clinopyroxene from a HIMU-type alkaline melt, then were cryptically metasomatized by a low-Rb, high-87Sr/86Sr fluid, and finally infiltrated by an exotic, late Fe-Ti-rich melt with 87Sr/86Sr ∼ 0.7055, carrying high concentrations of Sr, Rb and HFSE. The geochemical and isotopic features of both the metasomatizing fluid and the Fe-Ti-rich melt are compatible with their common derivation by the progressive melting of an amphibole-phlogopite-ilmenite metasomatic domain (MARID-type?) that probably resided within the subcontinental lithospheric mantle. Therefore, both the astenosphere and the lithosphere underneath the Hyblean Plateau contributed to the petrogenesis of the gabbros. Sm-Nd dating yields an age of 253 ± 60 Ma for the cumulitic pile, roughly coinciding with a hydrothermal event recorded by crustal zircons in the area. We suggest that the Hyblean Plateau suffered a thermal event - probably related to lithospheric thinning and upwelling and melting of the asthenosphere - in Permo-Triassic time (the opening of the Ionian Basin?). The induced perturbation in the lithosphere caused consequent melting of some previously metasomatised portions.
AB - In situ trace-element and isotopic (87Sr/86Sr) data and whole-rock Sr-Nd-Hf data on 12 gabbro xenoliths from the Hyblean Plateau (south-eastern Sicily) illustrate the complex petrogenetic evolution of this lithospheric segment. The gabbros formed by precipitation of plagioclase + clinopyroxene from a HIMU-type alkaline melt, then were cryptically metasomatized by a low-Rb, high-87Sr/86Sr fluid, and finally infiltrated by an exotic, late Fe-Ti-rich melt with 87Sr/86Sr ∼ 0.7055, carrying high concentrations of Sr, Rb and HFSE. The geochemical and isotopic features of both the metasomatizing fluid and the Fe-Ti-rich melt are compatible with their common derivation by the progressive melting of an amphibole-phlogopite-ilmenite metasomatic domain (MARID-type?) that probably resided within the subcontinental lithospheric mantle. Therefore, both the astenosphere and the lithosphere underneath the Hyblean Plateau contributed to the petrogenesis of the gabbros. Sm-Nd dating yields an age of 253 ± 60 Ma for the cumulitic pile, roughly coinciding with a hydrothermal event recorded by crustal zircons in the area. We suggest that the Hyblean Plateau suffered a thermal event - probably related to lithospheric thinning and upwelling and melting of the asthenosphere - in Permo-Triassic time (the opening of the Ionian Basin?). The induced perturbation in the lithosphere caused consequent melting of some previously metasomatised portions.
UR - http://www.scopus.com/inward/record.url?scp=56349138999&partnerID=8YFLogxK
U2 - 10.1007/s00410-008-0317-x
DO - 10.1007/s00410-008-0317-x
M3 - Article
AN - SCOPUS:56349138999
SN - 0010-7999
VL - 157
SP - 1
EP - 22
JO - Contributions to Mineralogy and Petrology
JF - Contributions to Mineralogy and Petrology
IS - 1
ER -