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Workreport 2017-27



Overburden Database and Stratigraphy Model at Olkiluoto Island and Nearby Sea Area


Mönkkönen, H., Somervuori, P., Ranta-aho, S., Pehkonen-Ollila, A-R.



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An overburden stratigraphy model has been created over Olkiluoto Island and nearby sea area.

The modelled area is approximately 35.7 km2 large and includes terrestrial and marine area. The approach to create the stratigraphy model was to first model the overburden thickness and elevation of the bedrock surface and then to model the thicknesses of each Quaternary deposit layer.

The available data of bedrock surface, overburden thickness and stratigraphy have been collected and stored to separate database. The data are collected from different sources and are based on a number of types of data in consequence that the quality and applicability of data sets vary. Therefore the data have been classified into reliability classes, which are used as preference order if data points nearby give conflicting information of bedrock surface. Sediment and soil types have been reclassified according to classification system used in biosphere assessment. Also stratigraphy data have been divided to priority classes according to data reliability. Data from 33650 observations of bedrock surface or overburden thickness have been stored to database in addition to interpreted outcrop areas.

The average overburden thickness in Olkiluoto Island is 2.18 m and it varies usually between 1.5–3 m. Generally overburden is thicker in the western part of Olkiluoto Island where model thickness is 14 m at most. At marine area the average overburden thickness is 2.9 m. If the outcrops are excluded the average overburden thickness in marine area is 4 m.


Bedrock surface, overburden thickness, stratigraphy, overburden database.


WR 2017-27_web (pdf) (13.2 MB)


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