Evento-Estratigrafía con foraminíferos en el tránsito Cretácico-Terciario de Aïn-Settara (Tunicia) y Coxquihui (México)

Resumen

Foraminiferal quantitative studies were performed in Cretaceous/Tertiary (KJT) boundary sediments from the shallow, outer platform Am Settara section (Tunisia) and the lower bathyal Coxquihui section (Mexico). Comparative studies allowed us to establish three main evolutionary stages in the first 100 k.y. after the K/T boundary. In contrast to the stability of the Upper Cretaceous assemblages, the genera Cuembelitria and Cibicidoides bloomed during the lower part of the G. cretacea Biozone (Stage 1). During Stage 2 (upper G. cretacea and lower Pv. eugubina Biozones), foraminiferal communities are dominated by planktic Parvularugoglobigerina and Globoconusa, whereas a slight recovery of infaunal groups is recorded among benthic foraminifera. Finally, foraminiferal assemblages during Stage 3 (upper P. eugubina and P. pseudobulloides Biozones) are dominated by the planktic Chiloguembelina and Woodringina, and the benthic Nuttallides, Nuttallinella and Anomalinoides. These three stages are related to the evolutionary patterns and long-term environmental turnover after the K/T boundary catastrophic event, and may be useful in correlation and in recognizing hiatuses across the K-T transition.