Summary
The Gohta High is located in the southwestern Barents Sea and part of the Loppa High. It is characterized by relatively shallow depth to the crystalline basement (<4-5 km) and a prominent magnetic anomaly of ~850 nT. The origin of the structural high and the strong magnetic signature is not fully understood yet. This report focuses on the origin and nature of the magnetic source(s) that gives rise to the atypical Gohta magnetic anomaly. 2D forward modelling along seismic lines NBR10-230110 (Finnmark Platform to Vestbakken Volcanic Province) and NBR-07-137451 (Senja Ridge to eastern Nordkapp Basin) was carried out to develop and test concepts focusing on the depth to basement, the dimensions of different terranes and their relevant physical properties. The final concept was implemented in a 3D model in order to verify the developed ideas under consideration of full 3D geometries and possible edge effects. The developed 2D and 3D integrated models are consistent in explaining the origin of the Gohta magnetic high by an upper-crustal body with average density of 2800-2850 kg.m-3 and high magnetic susceptibilities of ~0.04-0.08 SI. This body is assumed to be part of or lying on top of a thick Precambrian continental crustal block. Analogues as the Seiland Volcanic Province (Finnmark) and West Troms Basement Complex suggest the presence of Caledonian nappes and the involvement of old Neoarchaean to Palaeoproterozoic terranes. Even though the structure and evolution of the Gohta High and its surroundings was better derived by this study, it also revealed that the complex basement structure of the Loppa High is still not fully understood and needs further investigation.
