Effects of glaciations on sedimentary basins

Many of the Earth's sedimentary basins are affected by glaciations. Repeated glaciations over the last millions of years had great influence on the physical conditions in sedimentary basins and on basin structuring. This paper presents some of the major effects that glaciations have on sedimentary basins including examples of quantifications of their significance. Ice sheets are capable of eroding, transporting and depositing huge amount of sediments. The shape of ice sheets changes over time, and in general the erosion will have concentric pattern forms due to the low ice velocity under the center of the continental glaciers, and the more rapid basal ice velocity near the margins. Glaciations add a degree of difficulty to petroleum exploration. Erosion leads to cooling, which implies that the source rocks will be at a higher degree of maturation than expected from their present depth. The temperature effects of the glacial cycles will add to the erosion effect. A sedimentary basin covered by glacier ice during the last ice age is not in thermal equilibrium, maybe as far as 10-15 degrees C from equilibrium at 2 km depth. Among the most important effects are also movements of the solid Earth caused by glacier loading and lateral movements of sediments. The driving factor of these movements is isostasy. Sedimentary basins near the former ice margin can be tilted as much as 4 m/km which might significantly alter pathways of hydrocarbon migration. The modeled examples are from Northern Europe, but the conclusions are valid for sedimentary basins beyond this area.