RT Journal Article
T1 Increasing size and abundance of microbialites (oncoids) inconnection with the K/T boundary in non-marine environmentsin the South Central Pyrenees.
A1 Astibia Ayerra, Humberto
A1 López Martínez, María Nieves
A1 Elorza, José Javier
A1 Vicens, Enric
AB A layer rich in giant microbialites, developed within continental deposits of the Tremp Formation (South-Central Pyrenees) in the aftermath of the end-Cretaceous mass extinctions, is here reported for the first time. Its stratigraphic location just above the Latest Maastrichtian Reptile Sandstone unit, and a characteristic δ13C anomaly, are clear proofs linking this so-called “z” layer to the K/T boundary. The great abundance of microbialites, their outsized dimensions (oncoids with coating thickness up to 1.2m; average >50mm), and the great lateral continuity of the “z” layer in the study zone, support the hypothesis that these giant microbialites may represent disaster forms linked to the latest Mesozoic crisis. To our knowledge, this is the first time a record of this type is reported in continental realms. Other large continental oncoids and stromatolite constructions (e.g., in the Late Palaeogene deposits of the Pyrenees, Ebro basin, and Mallorca island) differ from those of the “z” layer in occurring in carbonate rocks and in having less lateral continuity, but they could also have been favoured by palaeoenvironmental crises, such as the global Eocene hyperthermals, Early Eocene Climatic Optimum, Middle Eocene Climatic Optimum, and the climatic cooling of the Eocene-Oligocene transition. It is thus possible that some layers of microbialites may record biotic crises in continental series, as they do in the marine record.
PB Instituto de Ciencias de la Tierra "Jaume Almera" (Barcelona)
SN 1695-6133
YR 2012
FD 2012
LK https://hdl.handle.net/20.500.14352/43398
UL https://hdl.handle.net/20.500.14352/43398
LA eng
NO Ministerio de Educación y Ciencia
NO Universidad Complutense de Madrid
NO Gobierno Vasco
DS Docta Complutense
RD 13 abr 2025