Flow-Dynamic-Fan: FLOW-process related deposits: a new tool to better assess the morphoDYNAMIC of deep-water submarine FAN environments

Funded by the Austrian Science Fund (FWF) (2021-2023; FWF Project Nr. M 3065)

PI (Lise-Meitner Fellow): Dr. Pauline Cornard

Host: Univ-Prof. Dr. Michael Strasser

Wider research context:
Submarine fans (SFs) are a major sink of atmospheric carbon dioxide and contain some of the highest concentrations of microplastics. In view of environmental and human health issues, predicting SF geometry and associated flow-processes has become a priority for Earth scientists. To predict SF architecture, most researchers use facies models such as the Bouma sequence (Bouma 1962), the Lowe model (Lowe 1982), or the Mutti model (Mutti 1992). However, a majority of SFs cannot be adequately described using these models. An exciting new approach to predict SF morphodynamic is to evaluate the importance of flow criticality and especially supercritical flow because they represent the most powerful flows in deep-marine environments.

Research questions:
This project aims to evaluate supercritical-flow deposits (SFDs), as a potential new tool to assess both ancient and modern SF morphodynamics. To this end, two challenges are identified:
(1) How common are SFDs and what are the parameters controlling their distribution in deep-water SF environments?
(2) How to fill the gap between field-based observations of SFDs in ancient deep-water SFs and interpretation of SFDs in currently active deep-water SFs?

Approach:
To respond to these challenges, three objectives are targeted based on a multidisciplinary approach, involving outcrops, seafloor/subsurface data, and laboratory experiments.
(1) To address challenge 1, facies classification related to SFDs developed by Cornard & Pickering (2019; in press) will be tested and SFD distribution will be analysed on textbook deep-marine outcrops with contrasting settings: the Annot Formation (France; weak tectonic control), and the Gosau Group (Austria; strong tectonic control). These analyses will also help to appraise the influence of tectonic on SF morphodynamics.
(2) To respond to challenge 2, micro-CT analysis will be undertaken to study micro-fabrics of SFDs observed in outcrops to develop micro-fabric proxies to identifying SFDs in the cores from the Kumano Basin (KB; offshore SW Japan).
(3) On a larger scale, challenge 2 will be addressed by a comparison of seismic-scale outcrops with high-resolution bathymetry and reflection seismic datasets acquired from Pleistocene-to-modern SF systems in the well-studied KB.

Level of originality:
By applying my original concept on the textbook outcrops of the Annot Formation, where many authors have proposed their sedimentological models, I will be among the first to re-evaluate these outcrops in terms of flow criticality.
While there is a lot of recent information on the tectono-stratigraphic evolution and sediment provenance of the KB, I will be the first to consider its deep-marine sedimentary system in terms of flow dynamic.
Another novel approach is to use micro-CT which has a resolution two order of magnitude higher than medical-CT scan, to develop micro-fabric proxies towards inferring flow criticality from deposits in outcrop and core samples.

Collaborators:

Michael Strasser and Hugo Ortner (Department of Geology, University of Innsbruck, Austria)

Kevin Pickering (University College London, U.K.)

Greg Moore (University of Hawaii, U.S.A.)

Gerald Degenhart (Universitätsklink für Radiologie, Medizinische Universität Innsbruck)