HR: 0830h
AN: GP11D-0285 [PDF]
TI: MAGNETIC PROPERTIES OF THE FOUM-ZGUID DYKE (SOUTH MOROCCO)
AU: Silva, P M
EM: pmfsilva@fc.ul.pt
AF: CGUL, FCUL, Campo Grande, Ed C8, Lisboa, 1749-016
Portugal
AU: Silva, P M
EM: pmfsilva@fc.ul.pt
AF: ISEL, Rua Conselheiro EmĦdio Navarro, 1, Lisboa, 1950-062
Portugal
AU: * Miranda, J M
EM: jmiranda@fc.ul.pt
AF: CGUL, FCUL, Campo Grande, Ed C8, Lisboa, 1749-016
Portugal
AU: Marques, F O
EM: fmarques@fc.ul.pt
AF: CGUL, FCUL, Campo Grande, Ed C8, Lisboa, 1749-016
Portugal
AU: Henry, B
EM: bhenry@ipgp.fr
AF: IPGP, 4 Av. de Neptune, Saint-Maur, Paris, 94107
France
AU: Mateus, A
EM: amateus@fc.ul.pt
AF: CREMINER, FCUL, Campo Grande, Ed C6, Lisboa, 1749-016
Portugal
AU: Lourenco, N
EM: nlouren@fc.ul.pt
AF: CGUL, FCUL, Campo Grande, Ed C8, Lisboa, 1749-016
Portugal
AB:
This work focuses on the study of magma flow and propagation, using rock magnetic methods on a group of cross sections of the
Foum-Zguid Jurassic dyke in Southern Morocco. Thermomagnetic analysis show that Ti-poor titanomagnetite is the main magnetic
carrier and petrographic analysis shows that the main Ti phase (ilmenite) can be either as exsolution within magnetite (core
of the dyke) or as isolated grains (dyke rim). Bulk magnetic properties display distinct behavior according to distance to
the dyke rim; grain size of the main magnetic carrier decreases towards the core of the dyke, while the natural remanent
magnetization and the bulk magnetic susceptibility increase. Only the magnetic susceptibility ellipsoid close to the dyke
rim corresponds to that usually found in thin dykes, with the magnetic foliation parallel to dyke borders. Maximum principal
axis is in most cases either parallel or perpendicular to the intersection between the planes of magnetic foliation and dyke
wall. Moreover, when this axis is perpendicular to the intersection it is associated with a more oblate magnetic
susceptibility ellipsoid shape, indicating the presence of complex magnetic fabrics. Magnetic properties show that flow
structures related with dyke propagation are only preserved close to the fast cooled dyke rims.
DE: 1518 Magnetic fabrics and anisotropy
DE: 1519 Magnetic mineralogy and petrology
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting