Relationship between environmental conditions and magnetic properties of Norwegian black shales
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As part of a project to describe organic rich black shales from the Upper Jurassic from the Hekkingen Formation on the Norwegian shelf, cores 7430/10-U-01 North from the Nordkapp Basin (NE Barents Sea) and 7018/05-U-01 offshore Tromsø were investigated. The investigation was done by detailed sedimentological description, where the cores were investigated by facies description, and measurement of high resolution magnetic bulk susceptibility. The latter was done by measuring at intervals of 2 cm for core 7430/10-U-01 and 10 cm for core 7018/05-U-01. This small sampling interval is used to detect small variations. These two results are then combined to determine the relationship between the sedimentological characteristics and any variation or trend in the bulk magnetic susceptibility readings.The results show that the Hekkingen Formation shows cyclicity of 28-30 kyr, 34-35 kyr and possibly 59-71 kyr in core 7018/05-U-01, 21.1-24.2 kyr, 28.9 kyr, 43.2 kyr and 66.3-99.9 kyr in core 7430/10-U-01. The connections between depositional environment and the magnetic properties can be seen in the amplitude spectrum, as they are created at intervals with similar lithology, and at the boundary between the different intervals, there is a change in composition of the core. In core 7018/05-U-01, the first spectrum is created for a shell-dominated interval, the second for an interval with few to no shell fragments, and the last for below the boundary between the upper Krill Member and lower Alge Member. For the 7430/10-U-01 core it is difficult to see the connection between the sedimentology and the magnetic signal.