Footprints of ice: Ice loading and its effects on sedimentary basins and the carbon cycle
Final Report Abstract
Due to low ground and ice-sheet base temperatures during glacial stages, temperatures in the subsurface are effectively lowered down to a depth of around 3-4 km at the present day. In places that experienced ice sheet coverage, this influence of Pleistocene glaciations should be considered in estimating subsurface temperatures. Permafrost formed during parts of the Late Pleistocene in parts of western Europe reaching during the Last Glacial Maximum in the northern Netherlands a thickness of up to 200 m. The development of permafrost is mainly controlled by the presence and duration of low ground temperatures. In areas covered by thick ice sheets during the Pleistocene, subsurface rocks experienced strong overpressures caused by additional, rapid loading. These overpressures rapidly decrease in permeable, well-connected, shallow sedimentary layers, while they tend to persist in deeply buried sedimentary layers with permeability barriers (e.g., fine-grained, clay-rich sediments, salt). Thus, deep sedimentary layers that are sensitive to overpressure generation might still be overpressured at the present day. Rock properties such as permeability and porosity of sedimentary layers are lowered due to mechanical compaction, in particular, in the most shallow part of the subsurface. The reduction of porosities and permeabilities mainly takes place during the first ice advance and is, therefore, caused by the first additional load the subsurface experiences from ice sheets. A leakage of hydrocarbons, sourced by deeply buried organic-rich layers, was calculated from sedimentary layers in the subsurface to the seafloor or the surface with the retreat of ice sheets. This indicates a cyclic release of carbon-bearing fluids from the subsurface to the surface during the Pleistocene, particularly at the end of each glacial stage.
Publications
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(2021, September 19-24). Influence of Quaternary glaciations on subsurface temperatures and pressures in NE onshore Netherlands. GeoKarlsruhe 2021 Sustainable Earth - from processes to resources, Karlsruhe, Germany
Amberg, S., Sachse, V., Littke, R., & Back, S.
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(2022). Influence of Quaternary glaciations on subsurface temperatures, pore pressures, rock properties and petroleum systems in the onshore northeastern Netherlands. Netherlands Journal of Geosciences, 101
Amberg, S., Sachse, V., Littke, R., & Back, S.
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(2022). Numerical 3D modeling of burial and temperature history, source rock maturity, and hydrocarbon generation in the onshore northeastern Netherlands. International Journal of Earth Sciences, 111(3), 1033-1055
Amberg, S., Back, S., Sachse, V., & Littke, R.
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(2022). Reconstructing 3D subsurface salt flow. Solid Earth, 1-21
Back, S., Amberg, S., Sachse, V., & Littke, R.
