Late Chattian platform carbonates with benthic foraminifera and coralline algae from the SE Iberian plate

Abstract

The carbonate system studied represents an under-investigated sedimentary record formed in the western end of the Tethys during the Chattian relatively warm climate regime. These platform carbonates are examined with respect to rock fabrics, biostratigraphy, biostratinomy, paleoecology, and sequence stratigraphy. Dominant carbonate producers include scleractinian corals and echinoids, but the most prolific were symbiontbearing benthic foraminifera and coralline algae. The presence of Miogypsinoides complanatus and Miogypsinoides formosensis indicates a late Chattian age (Shallow Benthic Zone 23). The depositional profile is consistent with a homoclinal ramp. The absence of a barrier margin and thus, of a lagoon, facilitated the transport and re-working of biogenic components throughout the platform. As a result, facies are rather homogeneous corresponding to a rudstone mainly formed by benthic foraminifera and coralline algae, which passes basinwards to deeper ramp to hemipelagic deposits rich in echinoids and planktonic foraminifera. Within this dominant facies, only subtle and gradual lateral variations on the relative abundance or absence of certain skeletal components or species are recognized, comprising two end members. A proximal biofacies of benthic foraminifera and coralline algae including corals in growth position, fragments of green algae, and seagrass dwellers where Eulepidina, Nummulites, and Operculina are absent, and a distal biofacies where corals, green algae, and seagrass dwellers are not present, but Eulepidina, Nummulites and Operculina are common. Carbonate deposition was controlled by long-term relative sea-level fluctuations including a Rupelian?-late Chattian transgression, a late Chattian regression, which ended in subaerial exposure of proximal ramp carbonates, and a latest Chattian to early Miocene transgression. The Chattian carbonate platform was finally drowned around the Oligocene/Miocene transition.