The thickest and the most complete loess sequence in the Carpathian basin: the borehole Udvari-2A

Abstract

Abstract The key geological borehole Udvari-2A is located in Hungary at the Tolna Hegyhat Hills, in the central part of the Carpathian basin. Its detailed interpretation yielded valuable information on the stratigraphy and the post-Pannonian continental sedimentation regime of this territory. Stratigraphic data provided by the borehole facilitated the drawing up of a more precise picture on the post-Pannonian paleoenvironment and history of the evolution of the area. The borehole cut a thick series of the post-Pannonian Tengelic formation and the overlying, presumably complete sequence of the continental loess sediments of this region. The magnetostratigraphic correlation indicates that the 97 m thick loess sequence in the borehole Udvari-2A is the thickest and most complete so far recorded in Hungary and the deposition of loess started approximately at 1.1 Ma. In this sequence each of the four separable sedimentary periods of the loess are represented by distinct sediments. A theoretical stratigraphic column is also outlined to describe the Paks Loess Formation using data from the SE Transdanubia, defining and characterizing its lithological units. Since the formation is widely known, it was possible to correlate the most complete loess sequence in the Carpathian basin with the Marine Isotope Stages, and this opens up new opportunities for global correlation.