A 56 ka eruptive history of Sartori mud volcano in the Calabrian accretionary prism, Mediterranean Sea

Abstract

Mud volcanoes (MVs) are geological structures that episodically eject mud breccias composed of fluids and solids from the Earth's interior. MVs are predominantly associated to converging plate boundaries such as the African-European collision zone in the Mediterranean Sea. Although many investigations have been conducted on the global distribution, morphology and current activity of MVs, studies on the eruptive history and episodic activity of MVs are limited. This study presents a comprehensive analysis of the chronology of mud eruptions from the submarine Sartori MV located in the Calabrian Accretionary Prism in the central Mediterranean Sea at a water depth of about 1900 m. Seafloor bathymetry and backscatter mapping combined with multi-proxy sediment analysis of 16 sediment cores collected in the area of the MV indicate mud breccia deposits from six distinct eruptive phases. Radiocarbon ages of planktonic foraminifera, ages of interbedded tephra layers, identification of the Holocene sapropel marker horizon S1, and correlation with calculated sedimentation rates of hemipelagic sediments revealed that these six phases occurred during the last ∼56 ka. The mudflow deposits of the individual mud eruption phases differ slightly in their bulk organic carbon and nitrogen content, suggesting that the mud breccia composition varied between each eruptive phase. The duration of the quiescent phases between each eruption varied from ∼1.4 ka to ∼12.2 ka. The backscatter data from the seafloor indicate that only the mudflows that were mobilized between ∼56 and 22 ka cover the surroundings of Sartori MV over a wide area. Mudflows generated during more recent eruptive phases remained confined to the central area and the immediate vicinity of the MV, suggesting that MV activity was attenuated during the post-glacial sea level rise and Holocene sea level highstand. Eruptive phases of Sartori MV did not coincide with the eruptions of magmatic volcanoes in the region, and a correlation with earthquake events is also not evident due to the sparse documentation of (pre-)historical events. Internal processes such as pressure release from over-pressured mud chambers are believed to be important drivers of the episodic activity of Sartori MV. This study documents the episodic activity of a MV, and shows the interplay between internal driving processes and external influencing factors over geological time.