HR: 11:30h
AN: P12A-05    [Abstracts]
TI: Low and high temperature susceptibility data of the Chicxulub Yax-1 drill core: link to magnetic carriers.
AU: * Elbra, T
EM: tiiu.elbra@helsinki.fi
AF: Division of Geophysics, University of Helsinki, PO Box 64 (Gustaf Hallstromin katu 2), Helsinki, 00014 Finland
AU: Pesonen, L J
EM: lauri.pesonen@helsinki.fi
AF: Division of Geophysics, University of Helsinki, PO Box 64 (Gustaf Hallstromin katu 2), Helsinki, 00014 Finland
AU: Rebolledo-Vieyra, M
EM: marior@cicy.mx
AF: Centro de Investigaci¢n Cient¡fica de Yucat n, A.C., Canc£n, Quintana Roo, M‚xico,
AB: Temperature variations of weak-field magnetic susceptibility of Yax-1 drill core of the Chicxulub impact structure were examined in order to characterize magnetic minerals carrying the induced and remanent magnetization. Measurements were carried out at the Solid Earth Geophysics Laboratory, University of Helsinki, using KLY-3 kappabridge coupled with CS-3 temperature control. The applied temperature ranged from -192 °C to room temperature (low temperature treatment) and from ambient temperature to 700 °C (high temperature treatment). Both air and argon environments were used at high temperatures. Preliminary results show that in the impact samples there is a distinct change in the slope of the susceptibility vs. temperature curve at 450 °C. This possibly corresponds to titanomagnetite with relatively low Ti content. In some samples the data show also presence of nearly pure magnetite and/or pyrrhotite. Fe-Ti-oxides has been observed in impact rocks also before (Pilkington et al. 2004). Paleomagnetic data have previously (Elbra et al. 2004) shown that there are often two polarities present in same impact samples. Current data reveal also two magnetic carriers. We are now looking whether the polarity observations can be linked to these magnetic carriers. References Elbra, T., Pesonen, L.J., Kenkmann, T., Smit, J., 2004. A new preliminary paleomagnetic and petrophysical data of the Yaxcopoil drillcore, Chicxulub impact, Mexico. Geophysical Research Abstracts, EGU General Assembly, Nice, France. Volume 6. ISSN: 1029-7006. Pilkington, M., Ames, D. E.,Hildebrand A. R., 2004. Magnetic mineralogy of the Yaxcopoil-1 core, Chicxulub. Meteoritics & Planetary Science 39, Nr 6, 831-841
DE: 1519 Magnetic mineralogy and petrology
DE: 1535 Reversals (process, timescale, magnetostratigraphy)
DE: 1540 Rock and mineral magnetism
DE: 5134 Thermal properties
DE: 8125 Evolution of the Earth
SC: Planetary Sciences [P]
MN: 2005 Joint Assembly