Becker, E. (1999). Biostratigraphy based on Orbitolinids in the Lower Cretaceous (Hauterivian - Barremian) of the Spanish Pyrenees (Organya section, Prov. Lerida). Revue de Paléobiologie. 18(2): 359-489.

337796

Becker, E.

1999

18(2): 359-489

Publication

A Lower Cretaceous carbonate platform (Hauterivian - Barremian) within the Southern Pyrenees was subdivided biostratigraphically by means of foraminifera, mainly Orbitolinids. The rock sequence examined is located in the gorge of Organya (Spanish Pyrenees, Prov. Lerida). Due to its richness in microfossils in connection with considerable sedimentary thicknesses (690 m) and good exposure, it provides excellent conditions for detailed biostratigraphic work. Especially the genus Valserina SCHROEDER, 1968 delivers excellent biostratigraphic markers. Thus, further samples were taken at the type locality 'Rocher des Hirondelles' (Ain, SE-France) of Valserina primitiva, V. broennimanni and V. charollaisi in order to compare the different specimens from Organya with material from the type locality. The basis of this study is a detailed description of the different species which occur in the rock sequence of Organya. Altogether 23 species of large foraminifera were described in detail. Systematic work on the Orbitolinids delivered 19 different species, among them 4 which were previously unknown, and 2 transitional forms. Based on a broad discussion of the stratigraphic distribution of the various species, the studied sequence of the Hauterivian and Lower Barremian carbonate platform of Organya was divided into 8 foraminifera zones. The Lower Hauterivian is characterised by a previously unknown, small benthic foraminifera, Montsalevia? sp. 1. The Upper Hauterivian - Lower Barremian is characterised by the Orbitolinids Orbitolinopsis? flandrini, Orbitolinopsis subkiliani, Praedictyorbitolina simplex n. sp., Valserina primitive, Valserina broennimanni, Palorbitolina turbinata and Paleodictyoconus actinostoma. Comparison with other profiles of the same stratigraphic interval in SE-France and Switzerland gave evidence of the wide regional significance of the zones V. primitiva, V. broennimanni and P. turbinata. The foraminifera fauna shows a hiatus between the partly siliciclastic succession characterised by Montsalevia? sp. 1 (Hostal Nou Formation after BERASTEGUI et al., 1990) and the overlying platform carbonates, which are rich in Orbitolinids (Prada Formation after BERASTEGUI et al., 1990). But contrary to current views, this hiatus covers the stratigraphic interval of the middle Lower Hauterivian to the basal Upper Hauterivian at the most. By comparison with hemipelagic rock sequences in SE-France and Switzerland (mainly Subalpine Chains and Jura) the foraminifera zones of Organya were correlated with the ammonite biozones of the Lower Cretaceous of Southern Europe.

RIS (EndNote, Reference Manager, ProCite, RefWorks)
BibTex (BibDesk, LaTeX)

[Back to search]