The Bazar Ophiolite of NW Iberia: a relic of the Iapetus–Tornquist Ocean in the Variscan suture

Abstract

The Bazar Ophiolite, one of the ophiolitic units involved in the
Variscan suture of NW Iberia, is mainly formed by metagabbroic
high T amphibolites with N-MORB affinity. The ophiolite
appears accreted under an arc-derived upper terrane affected
by intermediate-P granulite facies metamorphism dated at 496–
484 Ma. U-Th-Pb geochronology and Lu-Yb-Hf isotope geochemistry
of zircons allow recognizing two growth stages. The
first occurred during crystallization of the gabbroic protolith
and has been dated at 495 ± 2 Ma, whereas the second one,
interpreted as dating the high T metamorphism, yielded an age
of 475 ± 2 Ma. The chronology of the Bazar Ophiolite and its
accretionary history suggest that this unit is a relic of the
Cambrian ocean located to the North of Gondwana, the
Iapetus–Tornquist Ocean, accreted to a dissected arc during
or before the early stages in the opening of the Rheic Ocean.