The GSSP for the base of the Santonian Stage is defined at 94.4 m in the eastern border of the “Cantera de Margas” quarry, Olazagutia (Navarra, N. Spain: 42º 52' 05.3" N, 2º 11' 40" W) and marked by the first occurrence of the inoceramid bivalve Platyceramus undulatoplicatus.
The Olazagutia section is located in a working quarry to the south of Olazagutia, Navarra, Spain. Its geographical location is 42º 52' 05.3" N, 2º 11' 40" W; Lambert Coordinates 919, 722, 1:25000 topographic sheet no. 113-4 Olazagutia.
The section along the disused eastern side of the Cantera de Margas quarry exposes ca. 160 m of marls and marly limestones and extends from the middle Coniacian to the middle Santonian. The lower, more marly part is referred to the La Barranca Member of the El Zadorra Formation; the higher part to the Olazagutia Formation.
First occurrence of the inoceramid bivalve Platyceramus undulatoplicatus.
First occurrence of the planktonic foraminifer Sigalia carpatica, which is 7 m below the primary marker.
Six peaks in the carbon stable isotope curve can be recognized between the Kingsdown Event 17.2 m below and the Bedwell Event 12.35 m above the GSSP.
Lamolda, M. A., Paul, C. R. C., Peryt, D., Pons, J. M., 2014. The Global Boundary Stratotype and Section Point (GSSP) for the base of the Santonian Stage, “Cantera de Margas”, Olazagutia, northern Spain. Episodes 37/1, p. 2 - 13.