Improvements in long-core measurement techniques: applications in palaeomagnetism and palaeoceanography



We report on new developments in the long-core measurement techniques using u channels in connection with new small-access cryogenic magnetometers. With these new instruments, u-channel samples allow us to measure a wide range of magnetic parameters along entire-core length with a spatial resolution and accuracy virtually equivalent to that obtained using discrete cubic samples. An additional advantage is that the sediment disturbance when sampling is significantly less when using u channels.

We present comparisons of results from both continuous and discrete measurements and examine the effectiveness of minimal deconvolution using various techniques. Examples of continuous measurements of low-field susceptibility, NRM, ARM, IRM, Hrc from North Atlantic deep-sea cores show that it is possible to generate logs of combination of parameters related to rock-magnetic characteristics of the sediments useful in palaeoceanography. In particular, the continuous method allows us to rapidly detect core regions with fast changing magnetic parameters useful for correlation between cores and also for understanding changes in palaeo-environmental conditions.

The fast scan also allows us to detect regions of the core where the rock magnetic parameters are suitable (or not suitable) for palaeomagnetic studies related to changes in the geomagnetic field such as the relative changes in palaeointensity.