Tectonic modulation of caldera volcanism on the South Aegean Volcanic Arc

Metcalfe, Abigail, Druitt, Tim, Pank, Katharina, Kutterolf, Steffen, Preine, Jonas, Beethe, Sarah, Schmitt, Axel, Hübscher, Christian, Nomikou, Paraskevi, Ronge, Thomas A., Berthod, Carole, Chen, Hehe, Chiyonobu, Shun, Clark, Acacia, DeBari, Susan, Gertisser, Ralf, Johnston, Raymond, Koukousioura, Olga, Manga, Michael, McCanta, Molly, McIntosh, Iona, Peccia, Ally, Tominaga, Masako, Yamamoto, Yuzuru, Woodhouse, Adam, Bernard, Alexis, Perez, Tatiana Fernandez, Jones, Christopher K., Joshi, Kumar Batuk, Kletetschka, Günther, Morris, Antony, Polymenakou, Paraskevi, Li, Xiaohui, Papanikolaou, Dimitrios, Pyle, David and Sternai, Pietro 2025. Tectonic modulation of caldera volcanism on the South Aegean Volcanic Arc. Earth and Planetary Science Letters 671 , 119633. 10.1016/j.epsl.2025.119633

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Abstract

Many highly hazardous, caldera-forming explosive eruptions occur in extensional tectonic regimes, but the role of lithospheric rifting in modulating caldera volcanism remains enigmatic. IODP Expedition 398 deep-drilled the volcano-sedimentary infills of submarine half-grabens around Santorini caldera on the continental South Aegean Volcanic Arc. Here we use the volcanic tephra archives to produce a high-resolution eruptive chronostratigraphy for Santorini, to ground-truth seismic stratigraphy, and to extract an integrated timeline of volcano-tectonic couplings. The rift basins contain several submarine volcaniclastic megabeds from the caldera-forming eruptions of Santorini and one from the Kos caldera. The thickest megabed succession is < 250,000 yrs old and lies on a seismic reflection onlap surface that records a phase of rapid rifting. Sedimentation lagged behind subsidence during this rifting phase, creating bathymetric troughs. Integrating submarine core-seismic and onland datasets, we propose that rifting may have driven the transition of Santorini from a prolonged state of effusive and minor explosive activity (∼550 – 250 ka) typical of arc stratovolcanoes to one of repeated caldera-forming eruptions (<250 ka). Rapid rifting may have amplified the normal internal dynamics of the magmatic system in three ways, driving the volcano into a sustained, highly explosive state: (1) an increase in the supply of mantle-derived basalt, (2) enhanced shearing, permeability, and melt percolation in the transcrustal magmatic system, and (3) the development of horizontally extensive magma reservoirs. Broadly simultaneous transitions into caldera-forming activity of the widely separated Santorini and Kos Volcanoes suggest that the two magmatic systems are linked by plate-scale lithospheric stresses.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Earth and Environmental Sciences
Publisher:	Elsevier
ISSN:	0012-821X
Date of First Compliant Deposit:	29 October 2025
Date of Acceptance:	6 September 2025
Last Modified:	29 Oct 2025 15:00
URI:	https://orca.cardiff.ac.uk/id/eprint/181976

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