Re-examination of the palynological content of the Lower Cretaceous deposits of Angeac (Charente, south-west France)
Résumé
Further to the work published by Néraudeau et al. (2012), palynological matter recovered from the lignitic bone bed of Angeac (Charente, SW France) has been re-examined, an additional sample having been processed in order to provide more evidence of its age, the previous determination being regarded as controversial (Benoit et al., in press). The samples come from four sedimentological units (An2–An5), which together yielded an assemblage of 31 species, taxonomically dominated by verrucate spores, including Concavissimisporites montuosus, Concavissimisporites verrucosus, Trilobosporites apiverrucatus, Trilobosporites canadensis, Verrucosisporites major, and other taxa. The criteria for their identification commonly being regarded as problematic, a PCA has been carried out on 60 well-enough preserved specimens from the most productive unit An2, taking into account eight morphological variables. The results show one group consisting of specimens referred to Trilobosporites, and a second larger group comprising Concavissimisporites, Verrucosisporites, and various morphologically intermediate forms, thus underscoring the subjectivity of their generic and specific attributions. A few bisaccate pollen grains, including Vitreisporites pallidus, have been recovered, but the gymnospermous pollen spectrum is clearly dominated by the cheirolepidiaceous genus Classopollis, representing 60% of the total assemblage. This dominance, coupled with the great abundance of Trilobosporites and Concavissimisporites, along with the presence of other spores typical of Lower Cretaceous deposits, such as Aequitriradites spinulosus, renders this assemblage most similar to those of the Hastings Group of southern England, and the Bückeberg Formation in north-western Germany. The time of deposition is therefore more likely to be Berriasian–Valanginian than Hauterivian–Barremian, as previously stated (Néraudeau et al., 2012; Allain et al., 2014).
Benoit, R-A., Néraudeau, D., Martín-Closas, C.,. A review of the Upper Jurassic-Lower Cretaceous charophytes from the northern Aquitain Basin. Cretaceous Research, in press.
Allain, R., Vullo, R., Le Loeuff, J., Tournepiche, J.F., 2014. European ornithomimosaurs (Dinosauria, Theropoda): an undetected record. Geologica Acta 12(2), 127-135.
Néraudeau, D., Allain, R., Ballèvre, M., Batten, D.J., Buffetaut, E., Colin, J.P., Dabard, M.P., Daviero-Gomez, V., El Albani, A., Gomez, B., Grosheny, D., Le Loeuff, J., Leprince, A., Martín-Closas, C., Masure, E., Mazin, J.-M., Philippe, M., Pouech, J., Tong, H., Tournepiche, J.F., Vullo, R., 2012. The Hauterivian–Barremian lignitic bone bed of Angeac (Charente, south-west France): stratigraphical, palaeobiological and palaeogeographical implications. Cretaceous Research 37, 1–14.