Cenozoic larger foraminifera and palaeonvironmental reconstruction from the Prebetic Domain (SE Spain)

The Cenozoic shallow marine deposits of the External Prebetic of Alicante (SE Iberian Peninsula) shows a rich association of benthic foraminifera, dominated by hyaline walled macroforaminifera such as myogypsinids, lepidocyclinids and nummulitids. This study analyses the microbiofacies and systematics of benthic foraminifera at genus and species level in the stratigraphic sections of "El Barranc dels Molins", in the surroundings of the locality of Ibi, and in the Natural Park of "El Carrascal de la Font Roja", nearby the city of Alcoi. The aim of this work is to develop a biostratigraphic study complemented by a sequential stratigraphic analysis and a palaeoenvironmental and depositional interpretation.

The section of Ibi includes benthic foraminifera characteristic of the Upper Eocene and the Oligocene, corresponding to SB zones 19 to 23 (Priabonian-Chattian). The Upper Eocene assemblage includes: Borelis vonderschmitti, Orbitolites aff. armoricensis, Nummulites fabianii, Nummulites sp., Discocyclina sp., Asterocyclina sp., Silvestriella tetraedra, Asterigerina rotula, Fabiania cassis, Halkyardia maxima, Chapmanina gassinensis and Acervulina linearis. The Oligonene species identified are: Pennarchaias glynnjonesi, Peneroplis thomasi, P. flabeliformis, Sorites sp., Sivasina egribucakensis, Borelis pygmaeus, B. inflata, Amphistegina bohdanowiczi, A. mammilla, Risananeiza pustulosa, Heterostegina assilinoides, Cycloclypeus carpenter and C. mediterraneus.

This work extends the stratigraphic distribution of Archaias sp. and Sorites sp. to the Chattian (SBZ 23) in the Tethys. It also confirms the extension of the range of Cycloclypeus mediterraneus and Amphistegina mammilla, and the presence of large-sized Victoriella conoidea (more than 3 mm in length) in the Upper Chattian of the Prebetic Domain.

In both localities, the identification of larger foraminifera and other fossil fauna, such as scleractinian corals, indicate a low-latitude shallow marine environment, at a depth of less than 40 metres. The vertical repetition of microbiofacies observed throughout the studied record is consistent with inner carbonate platform environments outgoing aggrading. This high-stand aggrading system was punctuated by low-stand regressive pulses that ended with the subaerial exposure of the inner platform, as indicated by the presence of several Microcodium horizons.