Geochemical fingerprints of paleo-environmental changes and paleo-pollution in the sedimentary archives of the Roman harbor of Ephesus (Turkey)

English Abstract:

At the end of the 1^st c. BC, Ephesus became the Roman capital of Asia Minor and the most important commercial, religious, and cultural center of the area. To shed light on the paleo-environmental evolution of the harbor, including potential anthropogenic fluxes, we measured major and trace element concentrations, including heavy metals, Pb isotope compositions, and ¹⁴C ages of ancient harbor sediments from a 12 m long sediment core drilled in the Roman basin of Ephesus. Using these data together with sedimentological data, grain size distribution analysis, and Principal Component and Factor Analyses, we reconstituted the paleo-environment of the harbor basin.

We ascribe observed shifts in the geochemical and sedimentological parameters to the deltaic progradation of the Cayster River (Küçük Menderes) towards the west. A single major disruptive event located at 550 cm core depth (1^st BC/AD) significantly affected the ventilation of the harbor water body resulting is oxygen deficit (anoxia). It appears that either passage of the river mouth to the west of the harbor basin or avulsion of the river towards the north was responsible for this abrupt environmental change.

While concentrations of metallic trace elements are well correlated with the oxygenation conditions of the harbor water body throughout the core, the Pb isotope compositions of leachates and residual fractions attest to possible anthropogenic influx in only the uppermost part of the core. The geologically and geochemically informed parameters T_mod-µ-к (derived from the time-integrated measured Pb isotope compositions) are exogenous to the Eastern Mediterranean basement (Pb age-depth model >200 Ma). Searching our European and Circum-Mediterranean Pb isotope database (>6800 samples) we find that Pb ores used at Ephesus during the late Middle Ages came from Western Europe (France, Germany, England) consistent with archeological and historical data indicating that at that time the main active European mines were those of Germany and England.