Footprints of ice

 

Footprints of ice: Ice loading and its effects on sedimentary basins and the carbon cycle

Knowing the ice loading effects on sedimentary basins is a key to understand the paleo temperatures affecting petroleum reservoirs and possible source rocks in certain depths as well as paleo pore overpressures and paleo porosity leading to explosive leakage of carbon bearing fluids and thus rapid escape to the atmosphere or the water column of the oceans. To understand and quantify the organic carbon cycle in terms of storage, migration and leakage within sedimentary basins, it is thus indispensable to know the performance of these properties under ice load and unload.

Unsolved questions remain the impact of temperature variabilities through ice-related loading and unloading on reservoir, seal and source rocks, potentially leading to petroleum leakage. Furthermore, the influence of ice on the performance of petrophysical properties (porosity, permeability, pressure) which directly seem to be coupled to ice fluctuation is not investigated. Basin history simulations suggest that in most sedimentary basins the bulk of the generated fluids are lost migrating upwards into the water column of the oceans and into the atmosphere on continents. Thus, numerical modeling has become an important analytical tool to study sedimentary systems on large scales and over large time spans taking into account petrophysical properties (such as permeability, porosity and gas adsorption capacity) as well as geochemical properties that are controlled by the origin and type of the sedimentary organic matter.

However, few basin history simulations took into account the glaciational and interglaciational phases. This proposed study will focus on the impact of Quaternary ice loads on the carbon cycle inside sedimentary basins in Germany (Northern Germany and Ruhr area), the Netherlands and Arctic Norway. These areas are very well suited, because on the one hand they contain sedimentary rocks rich in organic carbon. On the other hand, ice shields covered these areas several times during major glaciations in the past million years.

The proposed investigations will focus on (1) the specification of geochemical and geophysical parameters relevant for the carbon cycle during glaciations. (2) The impact of thickness and duration of ice loads on different types of sediments. (3) Potential carbon migration and leakage pathways related to glaciation processes, and (4) degree of reversibility of petrophysical (permeability, pressure, porosity) and geochemical parameters after retreat of the ice loads.

The results of this study are expected to provide new and more detailed insights on the effects of ice loads on the carbon cycle within sedimentary basins and its interaction with surface and atmospheric carbon. Based on this approach, the flux of carbon-bearing fluids released to the surface and the atmosphere can be quantified and the impact of ice load and retreat on the carbon cycle will be much better understood. This is important to know in the context of the expected global warming and related ice shield melting.

Contact: Sebastian Amberg

Funding: DFG project 403093957