Catastrophic mass extinction and assemblage evolution in planktic foraminifera across the Cretaceous/Paleogene (K/Pg) boundary at Bidart (SW France)

Last occurrence of Abathomphalus mayaroensis (Bolli) foraminiferid index of the Cretaceous–Paleogene boundary: the calcareous nannofossil proof

“…Gardin 2002;Keller et al 2007), characterizes the earliest Danian. Comparative studies by Gallala et al (2009;fig. 6) showed that the Danian planktonic foraminiferal assemblages from different sections may consist of up to 28 % of Cretaceous survivor or disaster species, on average.…”

“…Berggren et al 1995;Ogg & Hinnov 2012), was recently replaced with the planktonic foraminiferal Hedbergella holmdelensis Subzone forming the lower subzone of the G. cretacea Zone. The H. holmdelensis Subzone is also an acme biozone, similarly to the whole G. cretacea Zone (Arenilllas et al 2004Gallala et al 2009 (Keller & Abramovich 2009). A shift in ecological setting, especially the increase in environmental stress inferred by climate changes, led to its absence in some basins (see Keller & Abramovich 2009).…”

“…Similarly, the Lower Paleocene foraminiferid assemblages also comprise reworked and survivor taxa (Huber 1996;Gallala et al 2009;Slimani & Toufiq 2013). Moreover, the post-extinction Paleogene recovery of planktonic foraminiferids was polyphasic and began thousands of years after the terminal event (Coxall et al 2006;Gallala et al 2009;Schulte et al 2010).…”

“…Similarly, the Lower Paleocene foraminiferid assemblages also comprise reworked and survivor taxa (Huber 1996;Gallala et al 2009;Slimani & Toufiq 2013). Moreover, the post-extinction Paleogene recovery of planktonic foraminiferids was polyphasic and began thousands of years after the terminal event (Coxall et al 2006;Gallala et al 2009;Schulte et al 2010). The increase in abundance (bloom) of survivor or disaster opportunistic taxa, such as the planktonic foraminiferids Guembelitria cretacea, Hedbergella holmdelensis, or H. monmouthensis (Pardo & Keller 2008;Slimani & Toufiq 2013), and the calcareous nannoplankton Braarudosphaera spp.…”

“…The G. cretacea Zone is an acme biozone characterized by abundant occurrence of the Maastrichtian survivor or disaster species that bloomed after the K/Pg boundary event (e.g. Smit & Romein 1985;Canudo et al 1991;Arenillas et al 2006;Molina et al 2006;Gallala et al 2009;Ogg & Hinnov 2012) and by an abrupt increase in abundance of G. cretacea just above the K/Pg boundary. Its lowest interval, called the P0 Zone (e.g.…”