Age and evolution of the Serbian Lake System: integrated results from Middle Miocene Lake Popovac

Abstract

During the Early to Middle Miocene, a complex interplay of climate variability, sea level change, and Alpine tectonics resulted in the development of a series of long-lived lakes in the Dinarides and Serbian regions. While recent dating studies improved understanding of the Dinaride Lake System (DLS) evolution, independent age constraints are still lacking for the Serbian Lake System (SLS). Here, we present the results of an integrated study combining biostratigraphy, magnetostratigraphy, and 40Ar/39Ar radioisotopic dating of the sedimentary succession of ancient Lake Popovac to improve the chronostratigraphic framework and paleoenvironmental understanding of the SLS. Our biostratigraphic analyses of the mollusks and ostracods show endemic marker taxa for the Middle Miocene bioprovince of the SLS, such as Prososthenia fuchsi PAVLOVIC, ?Mediocypris sp., and ?Dinarocythere sp. Magnetostratigraphy revealed only one normal polarity interval, with a single reversed sample on top and, combined with an 40Ar/39ArAr weighted mean crystallization age of 14.40 ± 0.01 Ma, we correlate the studied Lake Popovac succession to Chron C5ADn, with a maximum extent from 14.61-14.16 Ma. Cyclostratigraphic analysis based on magnetic susceptibility and natural gamma radiation field logs suggest insolation forcing of the succession with an upward decrease in sedimentation rate from 25 to 12 cm/kyr. While the majority of the DLS originated during the Miocene Climatic Optimum (MCO) at ~ 17 Ma and disappeared before ~ 15 Ma, the development of the SLS started around 14.5 Ma in the Langhian. Regionally overlying Serravallian marine sediments of the Central Para - tethys imply that the Serbian Lake cycle must have ended before 13.8 Ma. Initiation of SLS deposition in the study area coincided with a peak of syn-rift extension in the Pannonian back-arc basin, which apparently also affected the Peri-Pannonian realm as far south as the study area in the Morava depression.