Spatial occurrences of selected sandstone bodies in the De Geerdalen Formation, Svalbard, and their relation to depositional facies
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Three different localities in the De Geerdalen Formation, Svalbard have been studied with theaim of investigating sandstone bodies and their relation to the depositional environment. Thesandstone bodies of the De Geerdalen Formation are the expected reservoir target for the Longyearbyen CO2 Lab, and it has therefore been of interest to improve the understanding of sandstone body distribution. Lidar data has been a main tool in lateral and geometric data acquisition. Detailed sedimentological logging and facies analysis were the basis on which the geometric information was to be evaluated. The spatial information has contributed to making the interpretation of the depositional environment more certain than it would have been without. Various depositional elements interpreted from their facies architecture and their geometry, reflect a setting of deltaic nature affected by river-, wave- and tidal processes. In all localities there is an upward shallowing and upward coarsening trend. The southeastern localities at Edgeøya (Klinkhamaren, Slåen and Siegelfjellet), reflect a proximal environment, of a fluvially dominated delta front. Further west, at Botneheia, Central Spitsbergen, the deposits are more reworked and show signs of tide and wave modulation. As deltaic signals are present, the environment is interpreted as a wave influenced distal shelf/prodelta. Prediction of sandstone distribution can be done with some control on the depositional environment. In a fluvially dominated delta setting, voluminous, but discrete sandstone bodies occur. However, good connectivity can be present, as distributary channel belts tend to have a sheet like distribution, yielding thin continuous sandstone units. On a wave dominated prodelta shelf the sandstone bodies tend to be thin, but laterally extensive.