An onshore bathyal record of tectonics and climate cycles at the onset of the Early-Middle Pleistocene Transition in the eastern Mediterranean
Résumé
Early Pleistocene (Calabrian) clays of the Lindos Bay Formation have been uplifted and are exposed today on the eastern coast of Rhodes (Hellenic forearc, Greece). The hemipelagic origin of these sediments and the excellent preservation of the microfossils they contain, make the Lindos Bay Formation a unique element in the eastern Mediterranean, which has the potential to constitute a paleoclimate referential framework of the region for the Early-Middle Pleistocene Transition (EMPT). In this context, 98 samples were collected in the type locality section of the Lindos Bay Formation. Stable isotope (δ18O, δ13C) analyses were carried out on benthic (Uvigerina peregrina) and planktonic (Globigerina bulloides) foraminifera for the interval between ∼1100 ka and ∼858 ka. We identify and continuously reconstruct the climate cycles that occurred between Marine Isotope Stages (MIS) 32 and 21. Counts of planktonic foraminifera were further carried out and allow connecting the conditions occurring locally in the surface waters with the glacial-interglacial cycles during the onset of the EMPT. While (sub)tropical taxa dominate the assemblages, glacials were associated with short-term (<∼10 kyr) influxes of temperate to subpolar species suggesting cooling and/or increasing productivity in the surface waters correlating with the deposition of sapropels in the eastern Mediterranean deep sea. Finally, planktonic/benthic foraminiferal ratios show that the section deposited at upper bathyal depths between ∼450 m and ∼150 m. During the late Early Pleistocene, the eastern coast of Rhodes has locally undergone repeated, transient and possibly very rapid vertical motions which are overprinted on a regional tectonically-forced regressive trend.
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