Calpionellid biostratigraphy, U-Pb geochronology and microfacies of the Upper Jurassic-Lower Cretaceous Pimienta Formation (Tamazunchale, San Luis Potosí, central-eastern Mexico)

Resumen

Detailed sampling of a
stratigraphic section corresponding to the La Pimienta Formation in
the state of San Luis Potosí allows the determination of the upper
Tithonian Crassicollaria Zone (Remanei, Brevis and Colomi Subzones).
The presence of Praetintinnopsella andrusovi Borza and
chitinoidellids in the Crassicollaria Zone, was interpreted as the
result of sedimentary reworking as due to fact that these taxa have
not been reported in such a high stratigraphic position. Nonetheless
additional work is needed in order to establish a clear
relationship. The U-Pb date for a bentonite bed that underlies rocks
of the Elliptica Subzone is 139.1 ± 2.6 Ma (late Berriasian-early
Valanginian). These new data suggest a different age range for the
Elliptica Subzone in Mexico as compared with coeval sections in the
Mediterranean Tethys