Plio-Pleistocene Dust Traps on Paleokarst Surfaces: A Case Study From the Carpathian Basin

János Kovács,Péter Szabó,Klemens Seelos,József Dezső,Nadia Gammoudi,Gábor Újvári,György Varga

doi:10.3389/feart.2020.00189

Abstract

Plio-Pleistocene silt/clay-rich deposits and paleo-karst fissure sediments from sites of the northern and southern parts of the Carpathian Basin were investigated. These materials were supposed to be mixed during transport before being captured in karstified fissures. Evidence that the eolian fissure sediments of Plio-Pleistocene age in the older Triassic–Cretaceous limestones are derived from eolian silt and clay includes compositional and textural matches, especially decreasing grain-size trends observed downwards from the paleo-surface of the former landscape. Various environmental factors could be recognized by the statistical evaluation of grain-size distribution curves of fissure fillings sediments, such as the effects of eolian transport, parent rock type, weathering, and other sediment transport processes. Grain-size distribution curves with a single maximum in the silt size range are typical for the overlying siltstone debris, for the redeposited loess and red paleosol underlying the loess. Red clay fissure fillings yield bimodal grain-size distribution curves with maxima both in the clay and silt fractions. The research reported in this paper identifies for the first time the presence of eolian deposits in karst fissures of the Carpathian Basin and investigates the characteristics and origin.

Highlights

Granulometry based on laser diffraction is a fundamental technique widely used in eolian sediment research (Tsoar and Pye, 1987)
The quartz grains are from proximal, the silt/clay particles are from more distal sources
Multi-proxy formal analyses provide deeper insight into red paleosol genesis and material provenance situated in karstified fissures in Mesozoic limestones

Summary

Introduction

Granulometry based on laser diffraction is a fundamental technique widely used in eolian sediment research (Tsoar and Pye, 1987). Substantial accumulations of silty wind-blown dust require a source of silt and clay particles, transport media (prevalent winds of adequate energy), climate, and sediment traps (Tsoar and Pye, 1987; Evans and Reed, 2007; Kok et al, 2012; Újvári et al, 2016). A recent dust provenance study based on clay mineralogy, Sr-Nd isotopes and zircon U-Pb ages by Újvári et al (2012) suggest that “the Danube loess in the Carpathian Basin was derived from two major sources: alluvial fans of the Danube River and local rocks exposed in the surrounding mountains of specific loess sites.”. This research aimed at better understanding the origin of Upper Pliocene and Pleistocene allochthonous fissure deposits in Triassic and Cretaceous limestones in the Carpathian Basin (Kovács et al, 2017). These fissure deposits can be linked to the overlying silty (loessic) deposits, with long-distance (Alpine realm, Western Europe, Carpathian foreland) or short-distance (Carpathian Basin) source areas (Újvári et al, 2010, 2012; Kovács et al, 2013; Markovicet al., 2015; Obreht et al, 2019)

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