Gravity modelling and petrophysical data from western Norway

Abstract

Gravity data have been interpreted with a view to determining the depth extent of the Devonian Hornelen Basin. We find that the Hornelen Basin has a maximum depth of 3-4 km (below sea level). Uncertainity in the modelling originates in the low density contrast between the Devonian sedimentary rocks and the crystalline basement rocks. There is a rather close correlation between surface geology and gravity maps, which provides constraints on the gravity modelling. Summary statistics of petrophysical property data are reported. The magnetic susceptibility data show that, on a regional scale, most magnetic anomaly sources will be felsic gneisses and metavolcanic Caledonian rocks. The low Q-values indicates the dominance of induced magnetization in these rocks.