Magnetostratigraphic significance of Middle Cretaceous limestones exposed at La Boca and Santa Rosa Canyons, northeastern Mexico
Abstract
Short reverse polarity intervals within the Cretaceous Normal Polarity Superchron which are recorded in the Aptian-Albian of southern Europe are tested in coeval rocks of two stratigraphic sections in northeastern Mexico. The thermally demagnetized northeastern Mexican rocks at both sections exhibit two post-folding, secondary magnetizations consisting of a recent normal polarity overprint and a magnetization acquired during an interval of reverse polarity. Samples from the Santa Rosa Canyon also exhibit a pre-folding magnetization with a direction that is consistent with the Early Cretaceous field direction at this locality, although the mean declination indicates significant clockwise rotation of $\sim$69$\sp\circ.$ Based on foraminiferal zonation constraining the age of the rocks between Late Barremian and Early Albian, and assuming that the pre-folding remanence is primary, the lowermost and uppermost short reverse polarity intervals are interpreted as the MO$\rm \sb{r}$-chron and the ISEA, respectively and the two others short reverse polarity intervals are here considered to be unknown.
Subject Area
Geophysics|Geology|Paleontology
Recommended Citation
Poetisi, Ewald, "Magnetostratigraphic significance of Middle Cretaceous limestones exposed at La Boca and Santa Rosa Canyons, northeastern Mexico" (1996). ProQuest ETD Collection for FIU. AAI1379022.
https://digitalcommons.fiu.edu/dissertations/AAI1379022