Some geophysical profiles in Østfold.

Abstract

Based on detailed observations three profiles are examined, the profiles running some 20 km west-east from Jeløya, Østfold fylke. The magnetic values are taken from maps published by NGU. Geological samples have been collected and the physical properties of the samples have been determined in the laboratory. By application of GIER-ALGOL programmes models have been studied. The known geological displacement which is estimated to about 1000 m between Jeløya and the main-land is not seen on the gravimetric picture in the northern profile, while the two southerly profiles give displacement values of 800-900 m. In the northern Jeløya a heavy body of thickness of about 800 m is calculated. A smaller basic body of 100 m thickness is located in the main-land on profile II. Granitic bodies of thickness from 350 to 2000 m are found in profiles II and III. The magnetic values suuport the interpretation in the Jeløya area, while we have no distinct magnetic anomalies in the main-land.