Magnetostratigraphy and radio-isotope dating of upper Miocene-lower Pliocene sedimentary successions of the Black Sea Basin (Taman Peninsula, Russia)

Abstract

We present a new chronology for the upper Miocene to Pliocene deposits of the Black Sea basin based on highresolution magnetostratigraphic data coupled with 40Ar/39Ar dating from the 475 m long Zheleznyi Rog section on the Taman Peninsula (Russia). This section comprises the stratigraphic interval of the Khersonian to Kimmerian regional stages of the Eastern Paratethys. Our magnetostratigraphic record is based on biogenic and early-diagenetic greigite components and yields a magnetostratigraphic sequence of 8 polarity zones. A volcaniclastic ash layer at the upper part of the Khersonian is radio-isotopically dated at 8.69±0.18 Ma. The age of the Khersonian–Meotian transition arrives at 8.6 or 8.2 Ma, which is significantly younger than earlier estimates. The new age has important consequences for the Hipparion-datum in the Eastern Paratethys, and implies that all Vallesian fossil sites are younger than 11.2 Ma. The Meotian stage has a total duration of 2.2 to maximum 2.6 Myr, and is marked by multiple erosional events. The end of the Paratethys Sea is dated at 5.5 Ma, when the Black Sea becomes isolated from the Caspian Sea, the Dacian basin and the Mediterranean.