Circum-Tethyan carbonate platform evolution during the Palaeogene: the Prebetic platform as a test for climatically controlled facies shifts

Authors: STEFAN HÖNTZSCH, CHRISTIAN SCHEIBNER, JOHANNES P BROCK, JOCHEN KUSS

Abstract: The distribution of selected shallow-benthic biota at circum-Tethyan carbonate platforms demonstrates an excellent proxy for the impact of latitudinally controlled cooling and variations in the trophic resources during the Palaeogene. In this study, we link and compare the spatial distribution and abundance of larger benthic foraminifera and hermatypic corals of Tethyan carbonate successions with new records from the Prebetic platform in SE Spain. The succession of the Prebetic platform is dominated by larger benthic foraminifera and coralline red algae throughout the Eocene, whereas corals were not recorded until the Late Eocene. Similar biotic trends were reported from 10 selected circum-Tethyan carbonate platforms. High-resolution carbon isotopes indicate a decoupling from the global carbon cycle during the latest Eocene and Early Oligocene. Thus, a possible scenario is demonstrated by the increasing restriction of the Prebetic shelf due to the continuing convergence of the Betic domain towards Iberia during the Early Oligocene. Based on previous studies, we refined earlier established Palaeogene platform stages, which reflect the evolution of shallow-benthic communities during the transition from global greenhouse to icehouse conditions. Global cooling led to the recovery of coral communities in the northern Tethyan realm during the Bartonian (stage IV). A prominent cooling event at the Bartonian-Priabonian boundary, associated with the demise of many symbiont-bearing larger foraminifera, caused the proliferation of coral reefs in the northern Tethys and the recovery of corals in the southern Tethys (stage V). The massive temperature drop related to the Oi-1 glaciation represented the base of platform stage VI (Early Oligocene-?). After a transient platform crisis during the lowermost Oligocene, coral reefs spread throughout the Tethys and proliferated with newly emerged larger benthic foraminifera.

Keywords: Prebetic platform, Palaeogene platform stages, Tethys, larger benthic foraminifera, coral reefs, carbon isotopes, palaeoclimate, Spain

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