A U-Pb zircon age (479 +/- 5 Ma) from the uppermost layers of the Ollo de Sapo Formation near Viveiro (NW Spain): implications for the duration of rifting-related Cambro-Ordovician volcanism in Iberia

作者：Lopez Sanchez M A^*; Iriondo A; Marcos A; Martinez F J

来源：Geological Magazine, 2015, 152(2): 341-350.

DOI：10.1017/S0016756814000272

• Cambro-Ordovician volcanism
• Ollo de Sapo Formation
• Iberian Massif
• northern Gondwana break-up
• U-Pb SHRIMP-RG zircon dating

The uppermost metavolcanic layer of the Cambro-Ordovician Ollo de Sapo Formation, the largest accumulation of pre-Variscan igneous rocks in the Iberian Peninsula, have been dated in its northernmost part using U-Pb SHRIMP-RG zircon age techniques at 479.0 +/- 4.7 Ma. The age obtained is the youngest age found so far in the metavolcanic facies of Ollo de Sapo Formation and represents the cessation of the rifting-related Cambro-Ordovician Ollo de Sapo volcanism at the northernmost tip of the Iberian Peninsula. Our results show that the Cambro-Ordovician volcanism in the NW of the Iberian Peninsula is not as short-lived as previously thought and confirm the correlation between the Cambro-Ordovician volcanic sequences that crop out in the Central Iberian Zone and the French Southern Armorican Massif. Finally, our study suggests that the cessation of the Cambro-Ordovician volcanism along the Ibero-Armorican Arc was synchronic or, less probably, slightly diachronic with younger ages towards the north (in present-day geographical coordinates).

• 出版日期2015-3