Consolidation characteristics of offshore sediments in the Christiana, Santorini, and Kolumbo volcanic field, Greece (IODP Expedition 398)
- 1Kobe university, Kobe, Japan (takeru-yoshimoto@stu.kobe-u.ac.jp)
- 2University of California, Berkeley, USA
- 3Oregon State University, Corvallis, USA
- 4Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan
- 5University of Texas, Austin, USA
- 6Akita university, Akita, Japan
- 7Aristotle University of Thessaloniki, Thessaloniki, Greece
- 8Université Clermont Auvergne, Clermont-Ferrand, France
- 9GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
- 10Texas A&M University, College Station, USA
- *A full list of authors appears at the end of the abstract
An abnormal rapid accumulation of volcaniclastics is expected in sedimentary basins around submarine volcanoes. This phenomenon makes the sedimentary basin unstable because the drastic increase in overburden leads to generation of excess pore fluid pressure which prevent consolidation of sediments. Therefore, consolidation state of the sediments would be a crucial information for assessing the slope instability around volcanos.
IODP Expedition 398 cored marine sediments in the Christiana, Santorini, and Kolumbo (CSK) volcanic field in the Aegean Sea of Greece. In this study, we performed consolidation tests on mudstones and calcareous oozes just below the thick volcaniclastics in three basins (Anafi, Anydros, and Christiana Basin) oriented roughly NE-SW including Santorini caldera. Consolidation trends (void ratio vs. applied stress) show clear yield stress which indicate maximum consolidation stress of sediments. Some of ooze-dominated mudstones show the effects of cementation in their consolidation trends.
In the IODP site U1590 (Anydros Basin) and U1592 (Anafi Basin), consolidation yield stress of sediments was ~2 MPa lower than the overburden. It implies that the excess pore fluid pressure generates in the sediments and prevents the normal consolidation. The Anydros and Anafi basins represented underconsolidation state at 300-400 mbsf and ~300 mbsf, respectively. Both underconsolidated intervals are covered by >200 m thick volcaniclastics derived from the Santorini and the Kolumbo volcanos. Therefore, rapid sediment-supply (0.8-1.0 m/ky) from the submarine volcanos apparently makes the surrounding sedimentary basins unstable.
On the other hand, IODP site U1591 (i.e., Christiana Basin) and U1599 (i.e., Anafi Basin) represents the normal-consolidation state and the consolidation yield stress balances the overburden. There is relatively thin cover of volcaniclastics (~100 m) above the non-volcanic sediments and the sedimentation rate is moderate (0.1-0.4 m/ky).
In this presentation, we are going to compare the consolidation characteristics of three basins and discuss their spatial-temporal variation in relation to the sedimentation rate and physical properties of sediments.
Alexis Bernard, Carole Berthod, Hehe Chen, Acacia Clark, Susan DeBari, Tatiana I. Fernandez Perez, Ralf Gertisser, Christian Hübscher, Raymond M. Johnston, Christopher Jones, K. Batuk Joshi, Gunther Kletetschka, Xiaohui Li, Molly McCanta, Antony Morris, Katharina Pank, Ally Peccia, Jonas Preine, Masako Tominaga, Paraskevi Nomikou, Paraskevi N. Polymenakou
How to cite: Yoshimoto, T., Manga, M., Beethe, S., McIntosh, I., Woodhouse, A., Chiyonobu, S., Koukousioura, O., Druitt, T., Kutterolf, S., and Ronge, T. and the IODP Exp. 398 Scientists: Consolidation characteristics of offshore sediments in the Christiana, Santorini, and Kolumbo volcanic field, Greece (IODP Expedition 398), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6392, https://doi.org/10.5194/egusphere-egu24-6392, 2024.
