HR: 1340h
AN: GP13A-0021    [Abstracts]
TI: The Advantage of Heavy Liquid Separates in Low-Temperature Magnetometry: Case Study of Pelagic Sediments from the Equatorial Atlantic
AU: Dekkers, M J
EM: dekkers@geo.uu.nl
AF: Paleomagnetic Laboratory 'Fort Hoofddijk', Utrecht University, Budapestlaan 17, 2584 CD, Utrecht Netherlands
AU: * Franke, C
EM: cfranke@uni-bremen.de
AF: Paleomagnetic Laboratory 'Fort Hoofddijk', Utrecht University, Budapestlaan 17, 2584 CD, Utrecht Netherlands
AU: * Franke, C
EM: cfranke@uni-bremen.de
AF: Department of Geosciences, University of Bremen, P.O.Box 330 440, Bremen, 28334 Germany
AU: Frederichs, T
EM: thofred@uni-bremen.de
AF: Department of Geosciences, University of Bremen, P.O.Box 330 440, Bremen, 28334 Germany
AB: The low concentration of magnetic minerals in bulk marine sediments often prevents detection of the low-temperature magnetic transitions indicative of certain ferri- and antiferromagnetic minerals. To raise magnetic concentrations, magnetic extraction is routinely applied, but the extracts cannot always be considered as representative of the entire magnetic inventory. Strongly magnetic material, such as magnetite and titanomagnetite is over represented in such extracts and therefore quantification is very difficult, if not impossible. Here, we show that heavy liquid separates using a hydrophile sodium polytungsten solution yield much more detailed and representative low-temperature remanence curves. Marine sediments from the Equatorial Atlantic were subjected to low-temperature cycling of zero field cooled (ZFC), field cooled (FC) and room temperature saturation isothermal remanent magnetization (RT-SIRM). This was done on bulk sediments, magnetic extracts and heavy liquid separates to demonstrate the advantage of the latter technique. Several magnetic mineral phases in the high- and low-coercivity ranges could be identified and quantified using the heavy liquid method. Low-temperature cycling of the RT-SIRM in particular seems to be most powerful to this end.
DE: 1512 Environmental magnetism
DE: 1519 Magnetic mineralogy and petrology
DE: 1540 Rock and mineral magnetism
DE: 1594 Instruments and techniques
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005