Gravity‐Driven Deposits in an Active Margin (Ionian Sea) Over the Last 330,000 Years

Abstract

In the Ionian Sea, the subduction of the Nubia plate underneath the Eurasia plate leads to an important sediment remobilization on the Calabrian Arc and the Mediterranean Ridge. These events are often associated with earthquakes and tsunamis. In this study, we analyze gravity‐driven deposits in order to establish their recurrence time on the Calabrian Arc and the western Mediterranean Ridge. Four gravity cores collected on ridges and slope basins of accretionary prisms record turbidites, megaturbidites, slumping and micro‐faults over the last 330,000 years. These turbidites were dated by correlation with a hemipelagic core with a multi‐proxy approach: radiometric dating, δ18O, b* colour curve, sapropels and tephrochronology. The origin of the gravity‐driven deposits was studied with a sedimentary approach: grain‐size, lithology, thin section, geochemistry of volcanic glass. The results suggest three periods of presence/absence of gravity‐driven deposits: a first on the western lobe of the Calabrian Arc between 330,000 and 250,000 years, a second between 120,000 years and present day on the eastern lobe of the Calabrian Arc and over the last 60,000 years on the western lobe, and a third on the Mediterranean Ridge over the last 37,000 years. Return times for gravity‐driven deposits are around 1,000 years during the most important record periods. The turbidite activity also highlights the presence of volcaniclastic turbidites that seems to be link to the Etna changing morphology over the last 320,000 years.

Deciphering Co‐Seismic Sedimentary Processes in the Mediterranean Sea Using Elemental, Organic Carbon, and Isotopic Data

“…Given these limitations, the study of turbidites is a powerful tool for reconstructing the long‐term earthquake history of tectonically active continental margins (Goldfinger et al., 2014 and references therein), and could potentially extend the earthquake records further back in time than historical catalogs, encompassing several seismic cycles. This approach was applied to the Calabrian Arc, one of the most seismically active region in the Mediterranean Sea, where frequent earthquakes and associated tsunamis represent the most common triggering mechanism for massive sediment remobilization in the deep basins (Kastens, 1984; Köng, Zaragosi, Schneider, Garlan, Bachèlery, San Pedro, & 2017; Köng, Zaragosi, Schneider, Garlan, Bachèlery, San Pedro, et al., 2016; Polonia, Nelson, et al., 2017; Polonia, Panieri, et al., 2013; Polonia, Romano, et al., 2015; San Pedro et al., 2017).…”

“…further back in time than historical catalogs, encompassing several seismic cycles. This approach was applied to the Calabrian Arc, one of the most seismically active region in the Mediterranean Sea, where frequent earthquakes and associated tsunamis represent the most common triggering mechanism for massive sediment remobilization in the deep basins (Kastens, 1984;Köng, Zaragosi, Schneider, Garlan, Bachèlery, San Pedro, & 2017;Köng, Zaragosi, Schneider, Garlan, Bachèlery, San Pedro, et al, 2016;Polonia, Nelson, et al, 2017;Polonia, Romano, et al, 2015;San Pedro et al, 2017).…”

Land-sea correlations in the Eastern Mediterranean region over the past c. 800 kyr based on macro- and cryptotephras from ODP Site 964 (Ionian Basin)

“…5b, 7d, e and A7), it must represent an older eruptive event in the CVZ. This is evidenced by its stratigraphic position more than 0.5 m below sapropel S9 (Köng et al, 2017), which is equivalent to sapropel SAP7 at ODP Site 964 (Lourens, 2004), while tephra 964A-2H-5-59b is embedded within the respective sapropel at Site 964A (Fig. A1).…”

Biogeochemical Cycles and Aerosols Over the Last Million Years

“…Two important developments have been down recently concerning sapropel modeling: much longer simulation and much higher spatial resolution. Superimposed to precession cycles, since one million years the 100ky glacial-interglacial cycle has also affected sapropel occurrence (Köng et al, 2017). Recent modeling studies (Grimm et al, 2015) aimed to simulate the S1 from its onset.…”