HR: 14:45h
AN: GP73A-04    [Abstracts]
TI: Magnetic signature and fabric of serpentinized mantle rocks in the Betic-Rif Arc and tectonic implications
AU: * Martin-Hernandez, F
EM: fatima@fis.ucm.es
AF: Dep. Geophysics, Fac. Physics, Universidad Complutense, Av. Complutense s/n, Madrid, 28040, Spain
AU: Ferre, E C
EM: eferre@mail.science.siu.edu
AF: Dep. Geology, Southern Illinois University, Mailcode 4324 Carbondale, Carbondale, IL 62901, United States
AU: Belley, F
EM: fanfan24@siu.edu
AF: Dep. Geology, Southern Illinois University, Mailcode 4324 Carbondale, Carbondale, IL 62901, United States
AU: Ruiz-Martinez, V
EM: vcarlos@fis.ucm.es
AF: Dep. Geophysics, Fac. Physics, Universidad Complutense, Av. Complutense s/n, Madrid, 28040, Spain
AU: Garrido, C J
EM: carlosg@ugr.es
AF: Dep. Mineralogy and Petrology, Faculty of Science, Granada University, Fuentenueva s/n, Granada, 18002, Spain
AU: Osete, M
EM: mlosete@fis.ucm.es
AF: Dep. Geophysics, Fac. Physics, Universidad Complutense, Av. Complutense s/n, Madrid, 28040, Spain
AB: Serpentinized peridotites from the Betic-Rif Arc constitute the largest exposure of subcontinental mantle. Exhumation of these large peridotitic bodies is still controversial and therefore extensive structural studies as well as paleomagnetic studies have been carried out. However, the origin of the magnetic susceptibility and magnetic remanence as well as the timing of NRM acquisition have not been established yet. A comprehensive rock magnetic study combined with a low-field AMS study on a collection of samples along the arc have been carried out. These include thermomagnetic curves, hysteresis parameters, IRM acquisition and subsequent back field curves and mathematical modelling of the derived coercivity spectra and FORC diagrams. The results show the presence of two distinct magnetic populations of very different coercivity, one most likely associated with small magnetite inclusions in olivine, pyroxene etc, crystals and the other being a soft component associated with the serpentinization process, taken place at two stages of the exumation/emplacement. AMS has been determined at all sites and separation of magnetic subfabrics by high-field methods was carried out in selected samples. The results show a magnetic lineation that outlines the trace of the arc although it is systematically different from the magnetic lineation in the field. The magnetic foliation is also shallower than the structural foliation being the first dominated by the serpentinization.
DE: 1518 Magnetic fabrics and anisotropy
DE: 1519 Magnetic mineralogy and petrology
DE: 1525 Paleomagnetism applied to tectonics: regional, global
DE: 1540 Rock and mineral magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2009 Joint Assembly