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The Pannonian Basin of Hungary is Europe's largest inter-mountain basin, where an evolution in drainage development patterns during the Quaternary was caused by changes in sediment flux to the basin, the dynamics of basin morphology development and the uplift history of the Apuseni Mountains source area, all directly or indirectly related to the tectonic systems operating in the region. Micro-mineralogical data of detrital heavy minerals from modern rivers and two key boreholes covering a time span from the present back to 2.6 Ma have been grouped by statistical analysis into two main clusters and some sub-clusters. The samples within the same cluster have a similar composition, and originated from the same source area. Based on the similar palaeogeographical setting of the potential source areas during the Quaternary, it has been possible to extrapolate the present transport directions of the rivers with a well-known catchment area geology and the heavy mineral composition to Pleistocene borehole data. The changes in transport directions were clearly sharp and related to significant changes in the uplift history of the Apuseni Mountains catchment area. During the Pliocene and Early Pleistocene the compressional stress field operating in the East Carpathians region resulted in the thrust-driven uplift of the Apuseni Mountains and the formation of a syn-sedimentary trap at the western margin of the source area, which captured the sediments of short, transverse rivers. During this period the drainage of the study area was characterized by axial drainage parallel to this trap, and sediments were transported from the northeast, also shown by micro-mineralogical data of detrital heavy minerals. At about 1.95 Ma this trap stopped being active due to the release of the compressional stress field and the isostatic uplift of the Apuseni Mountains, together with the adjoining basin area. This resulted in the filling of the thrust-bounded trap, and the development of transverse drainage, which was shown by characteristic SE transport directions, based on micro-mineralogical data in the study area, and also by an increase of sediment flux. The axial capturing shifted further to the west, developing a configuration approaching to the present river course pattern. By analogy with the Himalayan foreland and retro-arc basins of the Cordilleran-Andean ranges, it was demonstrated that tectonic activity exerts a strong control on the drainage pattern through its influence on variations in sediment supply. Jones et al. 1999; N4dor et al. 2000). Limited vegetation favoured catchment erosion during glacial periods and, as a consequence, increased sediment supply to the rivers resulting in aggradation. More temperate and humid interglacials lead to extended vegetation, a reduction in sediment supply and a vertical incision of the rivers,

Abstract:The study of the evolution of the river network in the Great Hungarian Plain has been based on sedimentological, neotectonical, morphological investigations, heavy mineral analysis and complementary OSL dating. The study area extends from the Körös sub-basin into the Ér and Berettyó river valleys which are situated northeast from the subsiding basin and northwest from the uplifting Apuseni Mountains. The OSL ages provide evidence that a large river run in the Ér-valley at least from 46±4 to 39±4 ka. It deposited garnet and magnetite-ilmenite-rich sediments, similar to the recent Berettyó, Ér and SebesKörös rivers and less intensive the modern Tisza river. These sediments originated from the nearly located metamorphic and Neogene volcanic rocks and contain some reworked older clastic sedimentary rocks from the northern part of the Apuseni Mountains. These OSL ages fit the active tectonic phase of the Érmellék depression. Loess is 49-47, 44, 39 and 25 ka old and aeolian sands 10 to 9 ka were dated. Their heavy mineral composition and that of fluvial sands is similar.

The Gerecse Hills, which represent the northwesternmost part of the Mesozoic-Palaeogene Transdanubian Range, are surrounded by an Upper Miocene -Pliocene (Pannonian) lacustrine to fluvial sedimentary cover to the west and to the north: namely, towards the Danube -Kisalföld Basin of Slovakia and Hungary. The oldest reports on fossil molluscs from these sediments were published almost 150 years ago. A systematic mapping of the area by geologists of the Geological and Geophysical Institute of Hungary during the last decades revealed a number of natural and artificial outcrops of fossiliferous Lake Pannon sediments. The present study is based on the molluscs collected from these outcrops, and the sedimentological description and interpretation of the embedding sequences.The Upper Miocene deposits near the Gerecse Hills comprise one transgressive-regressive cycle. In the brickyard claypits of Tata, located in the western foreland of the Gerecse Hills, the transgressive limb is represented by the Szák Formation. This formation starts with a thin transgressive lag and consists of homogeneous, bioturbated, bluish-grey clay and argillaceous marl, deposited from suspension in quiet offshore conditions. Characteristic mollusc species include large dreissenids (Congeria czjzeki, C. partschi, C. ungulacaprae), a wide variety of cockles (Lymnocardium tegulatum, L. triangulatocostatum, L. majeri, L. apertum, L. aff. brunnense, L. aff. rogenhoferi, "Pontalmyra" otiophora, Paradacna sp.), and deep-water-adapted pulmonate snails (Valenciennius reussi, Radix kobelti, Gyraulus sp.). This fauna lived in a nutrient-rich and well-oxygenated deep sublittoral environment, at a water depth of several tens of metres.Probably the same transgressive event is reflected in the Vályus-kút outcrop (Tardos), in the central part of the hills at 375 m above sea level, where a small patch of Lake Pannon sediments escaped subsequent erosion. In this sequence, lignite-bearing black clay and variegated clays with freshwater and terrestrial molluscs (Theodoxus radmanesti, Melanopsis sturi sturi, M. sturi tortispina, Planorbidae sp., Unionidae sp., Valvata oecsensis, V. obtusaeformis, Oxychilus procellarius) are overlain by clay and silt with Congeria czjzeki, Lymnocardium majeri, and other brackish species. This superposition indicates flooding of paludal areas, deepening, and the development of an intense connection with the sublittoral offshore environment of Lake Pannon.A third -and highly atypical -type of lower contact of Pannonian sediments was discovered in one of the northern valleys of the Gerecse Hills (Iván-halála Valley, Dunaszentmiklós). A poorly-sorted conglomerate consisting of cobbleand boulder-sized clasts with a sandy-clayey matrix overlies directly a Cretaceous sandstone. Imbrication of the clasts indicates a N to S transport direction i.e. from the open lake towards the dry land. The matrix contains abundant mollusc fauna, including articulated valves of Congeria aff. simulans turgida, Dreissenomya (Sinucongeria) arcuata, Pa...

A Zsámbéki-medence földtani térképezése során részletesen felvettük a Strázsa-hegy kőfejtője által feltárt kainozoos rétegsort, valamint elvégeztük az őslénytani, rétegtani és tektonikai adatok elemzését. A középső-triász dolomitra viszonylag vékony és hézagos középső–felső-miocén rétegsor települ, amelynek alsó szakaszát felső-badeni, középső szakaszát szarmata finomszemcsés sziliciklasztitok (kőzetliszt–középszemcsés homok) és karbonátok alkotják. Az e fölött üledékhézaggal települő édesvízi mészkő a Zsámbéki-medence felső-miocén (pannóniai) rétegsorának bázisképződménye. A Zsámbéki-medencében általános elterjedésű pannóniai üldékek a Strázsa-hegyen lepusztultak, az algás édesvízi mészkőre közvetlenül pleisztocén alluviális-proluviális rétegsor települ. A szedimentológiai jellegek és az ősmaradványok elemzése alapján rekonstruált neogén üledékképződési környezet több vonatkozásban is egyéni jellegeket mutat. A késő-badeni során kezdetben csökkent sótartalmú, partmenti védett lagúnában zajlott az üledékképződés a Vértessomló–Nagykovácsi-zóna mentén kiemelkedő paleomorfológiai hát (sziget vagy félsziget) mögött, amelybe jelentős mennyiségű finomszemcsés törmelék áramlott. Ezzel egy időben a sziget déli oldalán sziklás abráziós part rekonstruálható. A lagúnába a késő-badeni során édesvízi hozzáfolyás zajlott, ami a szarmata során elzáródott, végül a késő-miocén elejére tavi környezet jött létre. A Strázsa-hegyen keresztülhaladó Ny–K-i csapású Vértessomló–Nagykovácsi-zóna neogén–kvarter szerkezetfejlődésén belül több szerkezeti fázist sikerült azonosítani. Ezek közül a legidősebb a triász dolomit kismértékű rátolódása a középső-miocén rétegsorra, amely a késő-badeni sziliciklasztos rétegsor leülepedésével egyidős lehet. A tektonikai zóna szarmata aktivitására utal a rétegsor szélsőségesen vékony kifejlődése és diszkordáns települése. A következő szerkezeti fázist a pannóniai édesvízi mészkövön észlelt oldalirányú vetőkarcok jelzik, ez a fázis megfeleltethető a Gerecse D11-es transzpressziós szerkezeti fázisának. A szerkezeti zóna legfiatalabb deformációja során zajlott kiemelkedés a pannon rétegsor lepusztulását eredményezte, amely a pliocén–kora-pleisztocénre tehető.