Interpretación tectónica de la remagnetización terciaria del segmento Sur de la Sierra Madre Oriental Mexicana

Resumo

A total amount of 22 Mesozoic sedimentary sites have been sampled in southern Sierra MadreOriental (SMO), México. Stepwise demagnetization analyses have been carried out in Jurassic toCretaceous carbonates ("Group7 ") and Late Triassic to Early Jurassic mudstones and sandstones("Croup 2"). Both groups showed a common Characteristic Remanence Magnetization (ChRM),always of reversed polarity despite the different lithologies and ages, which is considered asynchronous remagnetization. These 22 sites were grouped in 7 localities in order to perform statistical fold tests with their paleomagnetic directions for tectonic purposes. Fold test results showsa pre-, post- and sin- tectonic ChRM acquisition, implying that the remagnetization is simultaneous with the Early Tertiary shortening period of the southern SMO Laramide Orogeny. Very similarChRM paleolatitudes were found in between localities, and they are also in agreement with theexpected paleoinclination obtained from the 50 Ma paleomagnetic poles of North America's Apparent Polar Wander Path (Besse and Courtillot; 2002). Paleomagnetic poles of the studied localitieslies in an equal paleolatitud minor circle evidencing the existence of great post-Paleocene anticlockwise differential vertical axis rotations, which increases eastwardly up to 43s.