Open AccessPalaeomagnetic Evidence For Local and Regional Post‐Eocene Rotations In Northern Mexico
Author(s) -
Nowicki M. J.,
Hall S. A.,
Evans I.
Publication year - 1993
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1993.tb01466.x
Subject(s) - geology , clockwise , paleomagnetism , paleontology , cretaceous , remanence , paleogene , ridge , rotation (mathematics) , geometry , magnetization , physics , mathematics , quantum mechanics , magnetic field
Summary 122 oriented core samples were collected from folded Lower Cretaceous units at four localities in the Sierra Madre Oriental Mountains near Torreon, northeast Mexico. Palaeomagnetic analyses of these samples identify a stable synfolding remanence at three localities that was acquired during the Laramide Orogeny (Eocene). the fourth locality exhibited a post‐folding or late‐synfolding remanence. Each locality has undergone a regional rotation and at least three localities have undergone local rotations since remanence acquisition. By examining the relationships between the apparent polar wander paths for North America and Mexico, pole positions generated by this study and observed structural trends, it has been possible to evaluate the different contributions of local versus regional rotations and to calculate a least‐locally‐rotated Eocene pole position for the Torreon region. This pole (Lat. = 69.9deg;N, Long. = 172.8deg;E, n = 27, k = 30, α 95 = 5.2deg;) agrees well with a published Mexican Eocene pole position for a locality located 450km north‐northwest of the present study area. On the basis of this information, we conclude that a large fragment of northern Mexico has undergone a 10deg;‐15deg; post‐Eocene counterclockwise rotation with respect to the rest of North America, in agreement with the model proposed by Urrutia‐Fucugauchi (1981).