Late Miocene to Early Pliocene depositional history of the intramontane Florina–Ptolemais–Servia Basin, NW Greece: Interplay between orbital forcing and tectonics

Upper Miocene and Lower Pliocene shallow lacustrine deposits from the Florina–Ptolemais–Servia Basin in northwest Greece show a distinct m-scale sedimentary cyclicity of alternating marls and lignites or clays, which were shown to be primarily related to precession-induced climate variations ([van Vugt, N., Steenbrink, J., Langereis, C.G., Hilgen, F.J., Meulenkamp, J.E., 1998. Magnetostratigraphy-based astronomical tuning of the early Pliocene lacustrine sediments of Ptolemais (NW Greece) and bed-to-bed correlation with the marine record. Earth Planet. Sci. Lett. 164 (3–4) 535–551; Steenbrink, J., Van Vugt, N., Hilgen, F.J., Wijbrans, J.R., Meulenkamp, J.E., 1999. Sedimentary cycles and volcanic ash beds in the lower Pliocene lacustrine succession of Ptolemais (NW Greece): Discrepancy between 40Ar/39Ar and astronomical ages. Palaeogeogr. Palaeoclimatol. Palaeoecol. 152, 283–303; Steenbrink, J., Van Vugt, N., Kloosterboer-van Hoeve, M.L., Hilgen, F.J., 2000. Refinement of the Messinian APTS from sedimentary cycle patterns in the lacustrine Lava section (Servia Basin, NW Greece). Earth Planet. Sci. Lett. 181 (3–4) 161–173]). Three additional sections and drill cores from the same basin are studied using a combination of cyclostratigraphy, magnetostratigraphy and 40Ar/39Ar dating. Together with the earlier studied sections, they provide a continuous succession that documents the depositional history of the intramontane Neogene basin fill. Sedimentation in the basin started at around 8 Ma ago with deposition of coarse-grained terrigenous-clastics in an alluvial environment. From ∼ 7.1 to ∼ 6.1 Ma ago, diatomaceous marls were deposited in a lacustrine environment, frequently interrupted by deposition of clays and local xylite-type lignite seams. Hereafter, deposition of alternating coarse- and fine-grained terrigenous-clastic alluvial sediments took place, followed by a gradual shift towards lacustrine sedimentation at around 5.5 Ma. Deposition of alternating fine-grained clastics (silts and clays) and biochemical sediments (carbonates, marls and thin lignites), with episodic periods of sub-aerial exposure continued until ∼ 5.23 Ma. From then onwards up to ∼ 3.9 Ma, regular alternating lignites and marls were formed in a shallow lacustrine environment. Precession-induced fluctuations of regional climate primarily defined the m-scale variations in lithology as observed in all members of succession, whereas the 100- and 400-kyr eccentricity cycle had a clear impact on larger-scale lithological alternations in parts of the succession as well. A marked similarity in the ages of fundamental changes in depositional environments between the Florina–Ptolemais–Servia Basin and the marine basins in the Mediterranean is observed, suggesting (but not necessarily implying) that they have a common, possibly tectonic origin.