The Evolution of Central Volcanoes in Ultraslow Rift Systems : Constraints From D. Joao de Castro Seamount, Azores

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Romer , R H W , Beier , C , Haase , K M , Eberts , A & Hübscher , C 2021 , ' The Evolution of Central Volcanoes in Ultraslow Rift Systems : Constraints From D. Joao de Castro Seamount, Azores ' , Tectonics , vol. 40 , no. 7 , ARTN e2020TC006663 , pp. e2020TC006663 . https://doi.org/10.1029/2020TC006663

Title: The Evolution of Central Volcanoes in Ultraslow Rift Systems : Constraints From D. Joao de Castro Seamount, Azores
Author: Romer, Rene H. W.; Beier, C.; Haase, Karsten M.; Eberts, A.; Hübscher, Christian
Contributor organization: Department of Geosciences and Geography
Helsinki Institute of Sustainability Science (HELSUS)
Petrology and Geochemistry
Date: 2021-07
Language: eng
Number of pages: 26
Belongs to series: Tectonics
ISSN: 0278-7407
DOI: https://doi.org/10.1029/2020TC006663
URI: http://hdl.handle.net/10138/333100
Abstract: The Dom Joao 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. Joao 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. Joao 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. Joao 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. Joao 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.
Subject: Azores
BENEATH
ISOTOPE
MAGMATIC EVOLUTION
MANTLE HETEROGENEITY
MID-ATLANTIC RIDGE
NE ATLANTIC
OCEANIC-CRUST
SAO-MIGUEL ISLAND
TECTONICS
TERCEIRA RIFT
Terceira Rift
central volcano
intraplate volcanism
melt transport
rifting
1171 Geosciences
Peer reviewed: Yes
Usage restriction: openAccess
Self-archived version: acceptedVersion


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