Does the Ollo de Sapo magmatic event support Furongian‒Tremadocian mantle plume activity fringing NW Gondwana?

ABSTRACT

We propose that the 495-470 Ma Ollo de Sapo magmatism in the Iberian Massif was the result of a mantle plume event in the Furongian-Early Ordovician. This plume was located beneath the northwestern margin of Gondwana and caused rapid and extensive melting of Ediacaran arc-related crustal rocks and their derived sediments. Mafic magmas due to plume partial melting underplated the crust and were emplaced at mid-lower crustal levels (~15km), and provided the heat for crustal melting. Manifestations of the plume include (i) pronounced magnetic anomalies in the region which match the distribution of Ollo de Sapo rocks, (ii) the Toledanian unconformity (and gap), which is attributed to thermal doming, and (iii) the significant thickness variations in Lower to Middle Ordovician sedimentary successions in adjacent areas. In a more regional context, we infer that the plume was one of a cluster of plumes impacting the Gondwana periphery and that it contributed to the birth and development of the Rheic Ocean throughout Gondwana margin breakup.

KEYWORDS:

• Ordovician plume
• Ollo de Sapo magmatism
• Toledanian unconformity
• magnetic anomalies
• Gondwana

Acknowledgments

JMC acknowledges the hospitality of the Earth Science Department of the Saint Francis Xavier University (Antigonish, NS, Canada) during a 2022-2023 one-year sabbatical. We acknowledge the comments and suggestions of C. Rodríguez and an anonymous reviewer that have improved our manuscript. We appreciate their time and effort. We also thank to the editor, Robert J. Stern, for his consideration of our research and editorial assistance.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work is a contribution to PID2021-122467NB-C22 and PID2021-125585NB-I00 projects from the Ministerio de Ciencia, Innovación y Universidades/Agencia Estatal de Investigación/Fondo Europeo de Desarrollo Regional (FEDER), EU. JBM acknowledges the continuing support of NSERC, Canada.