Emplacement mechanisms and the role of mass wasting in the Gulf of Corinth

This Moratorium Award proposal aims to provide a greater understanding of the emplacement mechanisms of mass failure deposits, in both macro- and micro-scale resolution, recovered within cores from Hole M0079A from IODP Expedition 381, "Corinth Active Rift Development". The project will aid in addressing one of the primary objectives of the Expedition, that of understanding surface processes in active rifts and the relative impacts of tectonics and climate on sediment flux. It will also contribute towards the secondary objective of improving our understanding of seismic, landslide and tsunami hazards within the Corinth Rift area. To achieve these goals it is crucial to understand previous mass failure events throughout the evolution of the rift basin for both syn-rift sediment infill and landslide frequency analysis in relation to regional geohazards. Furthermore, this study will contribute to evaluating the potential risks of subaqueous mass flows on seabed infrastructure (e.g. cables, pipelines, seabed installations) by increasing our understanding of their mode of emplacement and how this might affect debris flow run-out distances, and the impacts of these potentially destructive deposits upon near-surface sediments. There are two phases to the proposed research:

1) "The role of mass wasting in the evolution of a young active rift system: examples from the Gulf of Corinth". This research line involves the interpretation of high-resolution line scan images of split cores to understand the sedimentological and structural styles of deformation occurring during mass wasting. Cores recovered during drilling in the Gulf of Corinth preserved thick (metre-scale) debrite and slump deposits, with evidence of different styles of transport and emplacement. By interpreting these line scan images of split cores, we can identify key features of each mass movement deposit, such as styles of brittle and plastic soft-sediment deformation, evidence of syn-sedimentary intra-basinal erosion (rip-up clasts) and reworking of pre-existing sediments, and evidence of liquefaction and homogenisation during mass movement, as well as basal shearing within both the mass flow/debrite and underlying sediments. The results will be interpreted in terms of the dominant emplacement styles of these mass movement deposits (e.g. slumping vs debris flow) and their implications for the deposition of the syn-rift sediments.

2) "Macro- and Micro-scale evidence of mass movement emplacement mechanisms in the Gulf of Corinth". This part of the project focuses on the detailed micro-scale analysis of the slumps and debrites (using Micro-CT scan images and thin section analysis) and will provide critical insights into the emplacement mechanisms and processes (e.g. ductile shearing, brittle failure, liquefaction, hydrofracturing) occurring during the detachment, transport and emplacement of these mass movement deposits. The focus will be on investigating the changes in the style of deformation during mass transport and relating these to the dominant emplacement mechanism (e.g. basal shearing, hydroplaning) and their impacts upon the underlying sediments. The results of this study have implications for understanding the factors controlling not only mass flow emplacement, but also the run out distances of these deposits and their potential for impacting upon seafloor infrastructure (e.g. pipelines, cables).

The proposed research would use multiple datasets to produce (a minimum of) two academic articles for publication in peer-reviewed journals.

For further details, please see the attachment "Description of Proposed Research".

The following groups will benefit from this research, in the following ways:

- Academic community: The academic community will benefit from this research, particularly those in the fields of marine geohazards and sedimentology, as we aim to increase our understanding of the emplacement mechanisms of large-scale debris flows. The project will create an extremely high-resolution dataset documenting the internal structure and physical properties of these debrite deposits. New insights will be gained into the factors controlling basal deformation and thereby the forward motion and runout distances of debris flows when in motion. This research will promote greater understanding of the processes occurring beneath mass flows, and ultimately their runout distances (which has significant implications when assessing slope failures as marine geohazards). This research is of global significance, feeding our fundamental knowledge of subaqueous mass flows in addition to syn-rift sediment accumulation, and is therefore applicable to both the fields of marine geohazards and petroleum geosciences. We will also make the digital dataset (Micro-CT scans and thin section photos) available through PANGEA for other academics to access once results have been published (see attachment "Project Data Management" for more details).

- Offshore industry: Offshore infrastructure planning will be impacted as many of the factors and processes considered to be critical in the dynamics of subaqueous mass flows are equally valid in rift or non-rift settings. Indeed, mass wasting events in a marine environment provide a significant hazard to offshore infrastructure (pipelines, cables, structural foundations for wind turbines and O&G platforms), and understanding landslide runout distances relating to emplacement mechanisms is crucial for any geohazard assessment for marine developments. These stakeholders will benefit directly from the dissemination of new research findings (through peer-reviewed publications) relating to the emplacement mechanisms of subaqueous mass flows. As well as new insights into the emplacement mechanisms of subaqueous mass flows, our research will aid in delivering a new understanding of the way these sediments deform during landslide initiation and development. This information is critical in the development of methodologies to mitigate against geological hazards related to submarine landslides.

- IODP: Will benefit from the dissemination of scientific findings directly linked to an IODP-funded expedition. We are confident that there will be a minimum of two scientific, peer-reviewed publications as a result of this research, which will be submitted to high-impact journals. In addition, research results will be presented at international conferences, further benefiting IODP as their support for the project will be well publicized.