Maastrichtian−basal Paleocene charophyte biozonation and its calibration to the Global Polarity Time Scale in the southern Pyrenees (Catalonia, Spain)

Abstract

A new charophyte biozonation for the non-marine Maastrichtian−lowermost Paleocene deposits in the South-Eastern Pyrenean Vallcebre Basin is proposed and calibrated to the Global Polarity Time Scale (GPTS) using magnetostratigraphic data. Planktonic foraminifera associated with charophyte assemblages provide maximum ages for correlation between non-marine and marine biostratigraphic zonations. The new charophyte biozonation is intended to be useful for terrigenous floodplain facies (red beds) with poorly developed lacustrine intervals and strong palaeoecological constraints for the development of charophytes. The taxonomy of charophytes was revisited and two new species were defined, Microchara nana Vicente and Martín-Closas and Peckichara serrata Vicente and Martín-Closas. Sedimentological analyses carried out in parallel with taphonomic observations allow us to infer the palaeoecological constraints of charophyte species. The new biozonation encompasses three biozones for the late Campanian−early Paleocene interval. The partial range biozone of Peckichara cancellata starts in chron C32r (∼73.91 Ma) according to previous studies, and extends its upper limit to chron C31r, with an age of ∼69.90 Ma in the Vallcebre Basin. The new Microchara punctata local biozone includes biozones of Septorella ultima (upper part), Microchara cristata and Peckichara sp. 1 (lower part) previously defined by Feist in Riveline et al. (1996). Some of these biozones were poorly characterized or were based on species with strong palaeoecological constraints. The lower Danian is characterized by the biozone of Peckichara toscarensis, replacing the previous biozone of Peckichara llobregatensis. The latter species was found to occur in the Maastrichtian.