HR: 16:50h
AN: GP24A-03    [Abstracts]
TI: Lower Tertiary Remagnetization in Mesozoic Rocks from Southern Sierra Madre Oriental of Mexico. Tectonic Implications.
AU: * Villalain, J J
EM: villa@ubu.es
AF: Universidad de Burgos, Departamento de Fisica, E.Politecnica Superior, Universidad de Burgos, Avda. Cantabria S/N, Burgos, 09006, Spain
AU: Ruiz, V C
EM: vcarlos@fis.ucm.es
AF: Universidad Complutense de Madrid, Departamento de Geofísica, Facultad de C.C. Físicas, Universidad Complutense de Madrid, Madrid, 28040, Spain
AU: Rey, D
EM: danirey@uvigo.es
AF: Universidade de Vigo, Dep. de Xeociencias Mariñas. Facultade de Ciencias do Mar Universidade de Vigo, Vigo, 36310, Spain
AU: Caballero, C
EM: cecilia@tonatiuh.igeofcu.unam.mx
AF: Instituto de Geofisica - UNAM, Instituto de Geofisica - UNAM, Ciudad Universitaria, Del. Coyoacan, Mexico, 04510, Mexico
AU: Soler, A M
EM: anesoler@tonatiuh.igeofcu.unam.mx
AF: Instituto de Geofisica - UNAM, Instituto de Geofisica - UNAM, Ciudad Universitaria, Del. Coyoacan, Mexico, 04510, Mexico
AU: Osete, M L
EM: mlosete@fis.ucm.es
AF: Universidad Complutense de Madrid, Departamento de Geofísica, Facultad de C.C. Físicas, Universidad Complutense de Madrid, Madrid, 28040, Spain
AU: Urrutia, J
EM: juf@tonatiuh.igeofcu.unam.mx
AF: Instituto de Geofisica - UNAM, Instituto de Geofisica - UNAM, Ciudad Universitaria, Del. Coyoacan, Mexico, 04510, Mexico
AB: 32 Mesozoic sedimentary sites (about 350 samples) have been sampled in southern Sierra Madre Oriental (SMO), México. Stepwise demagnetization analyses have been carried out in Jurassic to Cretaceous carbonates and Late Triassic to Early Jurassic mudstones and sandstones. Both groups of lithologies showed a common Characteristic Remanence Magnetization (ChRM), always of reversed polarity despite the different lithologies and ages, which is considered a synchronous remagnetization. These 32 sites were grouped in 10 localities in order to perform statistical fold tests with their paleomagnetic directions for tectonic purposes. Fold tests results show pre-, syn- and mostly post-tectonic ChRM acquisition, implying that the remagnetization is simultaneous with the Early Tertiary shortening period of the southern SMO Laramide Orogeny. In some Cretaceous limestone sites, a pre-folding high temperature component with mixed polarities has been also observed showing directions close to the post-folding remagnetization. Very similar ChRM paleolatitudes were found in between localities, and they are also in agreement with the expected paleoinclination obtained from the 50 Ma paleomagnetic poles of North America's Apparent Polar Wander Path (Besse & Courtillot, 2002). Paleomagnetic poles of the studied localities lies in an equal paleolatitud minor circle evidencing the existence of great post-Paleocene anticlockwise differential vertical axis rotations, which increases eastwardly up to 40°. In addition, rock magnetic analyses have been performed in order to study the origin of the remagnetization.
DE: 1525 Paleomagnetism applied to tectonics: regional, global
DE: 1527 Paleomagnetism applied to geologic processes
DE: 1533 Remagnetization
DE: 1540 Rock and mineral magnetism
DE: 8102 Continental contractional orogenic belts and inversion tectonics
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly