Romer R, Beier C, Haase K, Eberts A, Hübscher C (2021)
Publication Type: Journal article
Publication year: 2021
Book Volume: 40
Article Number: e2020TC006663
Journal Issue: 7
The Dom João de Castro seamount in the Hirondelle Basin (Azores) is a central volcano on the ultraslow diverging Terceira Rift axis. The combination of structural and geochemical data provides insights into the evolution of central volcanoes in oceanic rift systems above the Azores melting anomaly. The orientation of fault scarps and volcanic structures at D. João de Castro and the adjacent Castro fissure zone indicate that the regional SW-NE extending stress field dominates the morphology of the NW Hirondelle Basin. The regional tectonic stress field controls the crustal melt pathways and leads to dike emplacement along fissure zones and the prevalent eruption of mafic lavas. The occurrence of mafic to felsic lavas at D. João de Castro gives evidence for both a deep and a shallow crustal melt reservoir generating a subordinate local stress field at the seamount. New Sr-Nd-Pb isotope data along with incompatible trace element ratios indicate that D. João de Castro and the Castro Ridges originated from similarly heterogeneous mantle source but did not form simultaneously. Our new model implies that central volcanoes along the Terceira Rift form by the growth of volcanic ridges and transitioned into circular edifices after magmatic systems generate local changes in the regional lithospheric stress field. The geometry of D. João de Castro and other magmatic systems along the Terceira Rift combined with the alkaline nature of the erupted lavas, and the large lithosphere thickness indicates that young oceanic rifts are more similar to continental rifts rather than mid-ocean ridges.
Romer, R., Beier, C., Haase, K., Eberts, A., & Hübscher, C. (2021). The Evolution of Central Volcanoes in Ultraslow Rift Systems: Constraints From D. João de Castro Seamount, Azores. Tectonics, 40(7). https://dx.doi.org/10.1029/2020TC006663
Romer, René, et al. "The Evolution of Central Volcanoes in Ultraslow Rift Systems: Constraints From D. João de Castro Seamount, Azores." Tectonics 40.7 (2021).