Oligocene through Palaeogene/Neogene boundary foraminifera of the northern Mesohellenic Basin (Macedonia, Greece): biostratigraphy and palaeoecologic implications

Abstract

Foraminifera of the Oligocene and early Miocene siliciclastic units from the northern part of the Mesohellenic Basin (Macedonia, northern Greece) provide good biostratigraphic potential. Taxa identified from a number of sections cropping out in the study area indicate that these deposits fan in Zones P20 (upper part), P21, P22 and most of Zone N4 of Blow's zonal scheme. The occurrence within the lowest part of the Pendalofos Formation of abundant Globigerinoides primordius, together with other earliest Miocene planktonics, defines the base of the Miocene. Although a remarkable planktonic foraminiferal turnover occurred close to the Palaeogene/Neogene boundary, the benthic populations do not show any clear change, except in relation to palaeoecologic conditioning. Analysis of benthic foraminifera led to the definition of a palaeodepth curve indicating that the deposition during the late Oligocene and early Miocene occurred in a middle to upper (mostly) bathyal and outer neritic conditions. The distribution of selected benthic foraminifera is compared with sedimentologically derived depositional environments. The correlation between the major global unconformities predicted by the Exxon coastal onlap chart and the Mesohellenic succession is based on the joint use of biochronologic and biostratigraphic/palaeoecologic tools.