NEW ADVANCES FOR PALEOMAGNETIC STUDIES OF SEDIMENT CORES USING U-CHANNELS

Accurate and detailed paleomagnetic data can be obtained from continuous measurements of U-channels extracted from sedimentary cores using a small-diameter pass-through magnetometer and high resolution signal-response pick-up coils. The spatial resolution is not significantly lower than that obtained by measuring standard paleomagnetic samples and features on the order of 3-5 cm can be confidently resolved. We propose a method to analyze the demagnetization data based on the angular dispersion of the directions between successive demagnetization steps and the downcore changes in the rate of intensity decrease. This technique allows us to distinguish very rapidly between intervals with well-identified characteristic magnetic components and zones characterized by a more complex behavior during demagnetization. It is also possible to directly measure the magnetic susceptibility, and to induce and measure most rock magnetic properties along the U-channels. Thus all parameters necessary for a complete paleomagnetic study of sediment cores can be confidently obtained directly from U-channels without extracting individual samples. Finally this equipment makes possible the measurement and complete demagnetization of up to 10 single samples at a time in less than one hour by using techniques similar to those developed for the U-channels.