Geological arguments against a Late Cretaceous(?) age for the freshwater limestone bodies in the Köves Valley, (Vértes Hills, Hungary)

Földtani érvek a vértesi Köves-völgy karbonátos forráskúpjainak késő-kréta(?) kora ellen

Fodor, László

Kercsmár, Zsolt

Sásdi, László

Harangi, Szabolcs

Magyarhoni Földtani Társulat / Hungarian Geological Society

2020-04-14

In a recent paper SIKLÓSY et al. (2006) — following PEREGI &KORPÁS (2002) and SIKLÓSY (2003) — described calcite bodies inthe Vértes Hills, Hungary. The geochemical character of thesebodies is supposed to be similar to those related to the LateCretaceous(?) lamprophyre magmatism, known in the Transdanubian Range (HORVÁTH et al. 1985a, SZABÓ et al. 1993, GYALOG& HORVÁTH, 2004). The geochemical tracers would enable a LateCretaceous(?) age to be confirmed for both the calcite dykes, andsome of the travertine cones. In our short paper we list geologicalobservations and arguments which support the Cretaceous – earlyPalaeogene age of the red calcite dykes, but which contradictgiving the same age to the circular freshwater limestone.The red, brownish red calcite dykes are exposed on a subhorizontal denudation surface; the latter was formed in the courseof several episodes of subtropical denudation during the LateCretaceous to Middle Eocene (Figures 1, 2). Clasts of these dykescan be found in the basal conglomerate or limestone layers ofMiddle Eocene (Bartonain) age (KERCSMÁR 1995, 2004). Thesedykes are similar to those described in other parts of theTransdanubian Range, and they can be presumed to be related toLate Cretaceous lamphrophyre magmatism (SZABÓ et al. 1993,DEMÉNY et al. 1997, GYALOG & HORVÁTH 2004). It is to be notedthat in all except one case, the formation of the dykes cannot bebetter estimated than as having occured in the Albian to MiddleEocene period.On the other hand, the freshwater limestone bodies occur onthe slopes of the Quaternary (Pliocene?) Köves Valley (Figure 3).If these bodies had formed in the Late Cretaceous the valleys wouldhave existed already at that time. However, the Köves Valleyterminates in the Kápolnapuszta depression, which started to formonly in the Late Miocene (FODOR et al. 2004). The age of the valley(and thus the travertine cone inside) could hardly be older than LateMiocene.We also question the possibility that the travertine cone wouldhave been precipitated in subsurface caves; no formationmechanism of the caves (e.g. hydrothermal/descending coldwater), no driving force for water circulation, and no otherexamples of appropriately sized caves have been discussed ordemonstrated.Finally, we comment on the conclusions drawn from theappearance of accessory minerals, such as monacite, xenotime,zircon and rutile in the travertine cones; these minerals are alsocited as proofs of the connection with Cretaceous magmatic rocks.These minerals are often angular in shape (SIKLÓSY et al. 2006,Table IV/2, 4) and can hardly be low-temperature hydrothermal inorigin. It is probable (but not discussed in detail) that minerals werederived from denudation processes (e.g. wind or slope wash) andincorporated into the precipitating calcite on the surface, at themoment of water discharge.

A tanulmány kritika alá veszi SIKLÓSY et al. 2006-ban megjelent cikkét, amely a Vértes hegységi Köves-völgy környezetébenmegjelenő kalcit és édesvízi mészkőtestekről szól. Egyetértünk aszerzők, valamint PEREGI & KORPÁS (2002) korában kifejtettálláspontjával, vagyis az édesvízi mészkőtestek forráskúp eredetével. Ugyanakkor földtani érvek, és a testek geomorfológiaihelyzete alapján nem fogadjuk el a testek késő-kréta(?) korbesorolását: véleményünk szerint azok leginkább a pliocén(?)–kvarterfolyamán keletkeztek. A forráskúp, más vörös kalcittelérek és akéső-kréta lamprofíros magmatizmus feltételezett geokémiairokonságának bizonyítékai a cikkben nem meggyőzőek, mertvéleményünk szerint a korrelációban fontos járulékos elegyrészeknem kogenetikusak a forráskúpmészkővel.

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https://ojs3.mtak.hu/index.php/foldtanikozlony/article/view/2835

Földtani Közlöny; Vol. 138 No. 2 (2008); 181-188

Földtani Közlöny; Évf. 138 szám 2 (2008); 181-188

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https://ojs3.mtak.hu/index.php/foldtanikozlony/article/view/2835/2091

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