The neogene-quaternary evolution of the karst landscape of the Veszprém plateau based on the study of Meggyespuszta paleodoline, Hungary

Abstract

IzvlečekUDK 551.435.8(439) Attila János Trájer, Tamás Hammer, Lilla Mlinárik, Ákos Bede-Fazekas & Judit Padisák:: Neogensko-kvartalni razvoj kraškega površja planote Veszprém na osnovi raziskav paleovrtače Meggyespuszta, Madžarska Na osnovi novih stratigrafskih in morfoloških raziskav orišemo geološki razvoj in funkcijo paleovrtače Meggyespuszta. Metode vključujejo geomorfološko modeliranje ter geološko kartiranje in obdelavo podatkov vrtin. Razvoj topografije vrtače delimo v tri faze: 1) začetno obdobje zakrasevanja v zgodnjem in srednjem neogenu, 2) pozno neogensko in zgodnje kvartarno polnjenje z rdečo glino in dolomitnim meljem, 3) pokrivanje paleovrtače s puhlico in z njo povezano prstjo v kvartarju. Erozijske doline so se oblikovale v pliocenu in zgodnjem pleistocenu, holocenski erozijski jarki pa le v severnem in vzhodnem delu vrtače. Prerazporeditev smeri odtekanja deževnice je verjetno posledica tanjšanja puhlice v smeri sever-jug zaradi vlažnejšega holocenskega podnebja. Glede na prisotnost oksidiranih sedimentov, odsotnost šote in drugih jezerskih sedimentov ter majhno vsebnost vode v sedimentih nad matično kamnino, sklepamo, da je Meggyespuszta ena največjih aktivnih vrtač v Transdonavskem hribovju. Ključne besede: paleovrtača, paleokras, Transdonavsko hribovje, Transdonavski tip krasa.1 University of Pannonia, Department of Limnology, veszprém, Egyetem utca 10, veszprém, Egyetem utca The development and the geological activity of the Meggyespuszta paleodoline in Hungary were reconsidered in the light of new findings and review of complex stratigraphic and morphological results. Methods included geomorphological modeling, field geological re-surveys of the data from the existing boreholes and study of the sediments of a newly drilled borehole. Three main phases of the topography evolution were determined: (1) a presumably Early-Middle Neogene primer karstification period, (2) a Late Neogene-Early quaternary partial charging with typical terrestrial red clay and dolomite silt sediments, (3) and the covering of the paleodoline with loess and loess-based soil cover during the quaternary. while the south erosion valley was formed likely during Pliocene-Early Pleistocene period, the young, Holocene gullies were found only in the North and East part of the paleodoline. The rearrangement of rainwater course directions could be the consequence of the thinning of the loess sediment from North to South due to the wetter climatic conditions of the Holocene. Based on the oxidized filling sediments, the lack of peat or other lacustrine deposits and the low water content of the sediments above the bedrock, it was concluded that Meggyespuszta paleodoline is one of the largest still active sinkhole in the Transdanubian Range.

Investigation of the vulnerability of a partly covered karst feature in Veszprém, Hungary

“…In the southern part, dolomite/limestone debris can be found which probably is the witness of an earlier erosion phase, when the relief was higher and the climate more humid and warmer than in the present era. The geomorphological evolution of the paleodoline had previously been studied and three main phases of the landscape evolution were described (Trájer et al 2015). While in the surrounding area, the erosion cleared previously deposited Neogene and partly the Quaternary sediments, we concluded that the paleodoline as a "time capsule" preserved the major environmental changes of the past in the studied area (Trájer et al 2015) (Table 1).…”

“…The studied paleodoline has a wide but asymmetrical water catchment area (Trájer et al 2015) which is not unusual in karstic areas since the water catchment boundaries in karst regions are often fragmented (Bonacci 2004). It was found that pollution affects mainly the south part of the paleodoline.…”

“…However, it is plausible that neither the deposition of the dolomite flour nor the sedimentation of the loess was continuous and an erosion discordance between the two filling sediments can be hypothesized. Trájer et al (2015) found that the paleodolinefilling dolomite flour can the product of erosion under the Mediterranean/warm temperate climate of the Pliocene or the early Pleistocene eras and the loess was deposited only in the late Pleistocene area, plausibly during the last glacial period.…”

“…In this area, the major phases of karstification occurred in the Early Cretaceous, the Latest Tertiary (Neogene), and the Pleistocene periods (Jakucs 1977). However, the Meggyespuszta paleodoline plausibly was formed during the Miocene epoch; there are some signs of a more recent cryptokarstification activity (Trájer et al 2015). The coordinates of the center of Meggyespuszta paleodoline are N47.06111 and E17.93611 in decimal.…”

“…The Meggyespuszta paleodoline is a partly fossilized karstic depression of the Transdanubian Central Range (Trájer et al 2015); Fig. 1).…”