Grand Challenges in Sedimentology.

Grand Challenges (and Great Opportunities) in Sedimentology, Stratigraphy, and Diagenesis Research.

2018

David M. Hodgson, Anne Bernhardt, Michael A. Clare, Anne-Christine Da Silva, Julie C. Fosdick, Barbara Mauz, Ivar Midtkandal, Amanda Owen and Brian W. Romans

Front. Earth Sci. 6:173. doi: 10.3389/feart.2018.0017

This paper concerns the major role of sedimentology (research on sediments) in and for our society and the grand challenges sedimentologists would have to tackle. Sedimentary rocks cover about 75 % of the Earth’s surface and interactions between human society and sediments are multiples.

Climate change is of course one of the main challenge for humanity. Understanding past climate change has to be done through the study of old sedimentary records, which can help us to apprehend the future. It is clear that sea level is going to increase in the future with global warming. Sedimentary record shows us many and clear sea level changes which can help us to better understand how these variations impact coastal topography and human population. It is essential when we know that only a few decimeters of sea-level rise can inundate large areas of coastal lowlands, particularly at river deltas which host seven times the global mean population density.

Ongoing anthropogenic activities, and associated accelerated changes in global climate and Earth system processes, would lead to numerous natural hazards (storms, flood, tsunamis, etc.). These risks can influence sediment fluxes between continent and ocean which would impact pollution dispersal and ultimately clean drinking water and fisheries. To understand the dispersal of pollutants we need to understand a lot of sedimentological phenomenon, such as the impact of submarine landslides, the impact of storms on river flooding, relationship between coastal zones and rivers and so on. All these phenomenon should be studied in the past, in sedimentary archives which are the most pertinent in order to better understand and predict future risks facing society.

The carbon sequestration (or “negative emissions”), will likely be a required component of broader climate-change mitigation to reduce the excess atmospheric CO2 in the Anthropocene Earth system. Carbon can be removed from the atmosphere and captured into sedimentary rocks. In order to do so, we need to understand which one of these sedimentary rocks would be the best carbon traps, but also what would be the impact of this CO2 on these rocks to assess feasibility and longevity of CO2 sequestration projects.

It is also essential to understand the way fauna and flora and sediments interacts. These interactions can have an impact on topography, soil development and coastal zones. The marine biosphere is also a major control on the cohesion of sediments and plants strongly influence soil development.

Sedimentologists are trying to build a full picture of sedimentary systems, meaning understanding the source, erosional processes, transport of sediments and deposition. Understanding sediment flux from source to depositional zones would help us to understand how external factor (climate change, hearthquakes, etc) affect Earth surface at different time scale, from year to millions of years. Understanding rates and durations are essential in order to understand the how climatic changes will affect us. It is then essential to understand past climate changes and to improve the time resolution for these events (via cyclostratigraphy for example).