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Földtani Közlöny145. köt. 1. sz. (2015.)


  • Hidasi Tibor ,
    Varga Andrea ,
    Pál-Molnár Elemér :

    Abstract: Facies interpretation of volcanic rocks is of critical importance for the reconstruction of eruptive processes, particularly in ancient and sometimes strongly altered successions with a limited outcrop. However, this is often a difficult task since some pyroclastic rocks such as high-grade ignimbrites and felsic lavas may develop similar textures during emplacement, cooling and post-depositional alteration. In this study the samples of the ”Vulkanitok, etalon kollekció” thin-section collection (’Volcanic rocks, reference collection”, Mecsekérc Ltd) were examined, representing the rocks of the Permian Gyűrűfű Rhyolite Formation and their resedimented clasts from the Cserdi Conglomerate Formation (in southern Transdanubia, Mecsek Mountains, Hungary). This area represents a felsic igneous province in the post-collisional Variscan foreland; here the Gyűrűfű Rhyolite has been interpreted traditionally as a rather monotonous complex of lava flows. The most conspicuous feature of the studied samples is the apparent porphyritic texture com - prising abundant, but unevenly distributed, mostly broken quartz and feldspar phenocrysts and opaque pseudomorphs after biotite. An important indicator of the volcaniclastic origin is, however, the presence of relict, coarsely porphyritic pumice lapilli which have been flattened during compaction. Examination of a thin-section provides clear evidence of recrystallised shards in the matrix, showing strongly-altered vitriclastic textures. Some shards have recognisable rod and bubble-wall shapes, but those at the edges of quartz and feldspar crystals are strongly deformed and indicate welding compaction. The formerly glassy shards show remnants of an axiolitic devitrification texture. In the relict pumice clasts, the internal vesicular microstructure has been destroyed. The brown rims of pumice clasts show axiolitic and spherulitic devitrification. Their central parts consist of a mosaic of fine-grained quartz. Axiolitic devitrification develops during primary cooling and crystallisation of hot volcanic glass, and is a good indicator of the primary emplacement of volcani - clastic deposits. In the framework of the Cserdi Conglomerate samples, volcanic rock fragments with felsitic and altered vitriclastic textures are dominant. The data acquired for this study show that previously identified lavas are best interpreted as ignimbrites and that, as a result, the importance of explosive volcanism has been underestimated in the western part of the Mecsek Mts. This research has been supported by the Hungarian Scientific Research Found (OTKA; No. PD 83511) and by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences (AV).

    Keywords: Gyűrűfű Rhyolite, Permian, pyroclastic deposit, volcanic shard, fiamme, devitrification, spherulite

  • Győrfy Éva :

    Abstract: The goal of the thesis of the present study is to characterize the Mid-Miocene conglomerate/breccia of the Dráva Basin and to determine the source area of its dolomite, calcite and metamorphite clasts by using local borehole data (A– I, A–1, –2, –3, –4, –5, B–1).

    The local basin is a part of the Dráva Basin both in terms of geological and structural geological build-up; therefore it is made up of similar rocks. The stratigraphy evident from wells in the area indicates that the basement is made up of predominantly Palaeozoic metamorphic rocks and, subordinately, Triassic dolomite and limestone overlain uncon - formably by Miocene conglomerate/breccia.

    Syn-rift faults were responsible for the way in which the basin developed. In the post-rift phase, reverse faults came into being. The carbonate rock fragments can be placed in the Triassic, based on their textural attributes. The potential source area of dolomites is assumed to be in the south–south-west; this is proven by the roundness and variability in size of dolomite clasts in a N–NE direction. In this direction the size of the clasts is reduced while their roundness is increased. Further proof could also be that, with the exception of local boreholes, the carbonate rocks (mainly dolomites) appear only in C–2, B–1 and Tar M–1 boreholes. These carbonate rocks are known as bedrocks only in the Víz–4/b and F–1 boreholes; however, they probably appear in other parts of the area. Based on the size and roundness of dolomite and limestone clasts and the lack of dolomite and limestone pebbles in the N–NE part of the territory, the source area of the pebbles can be excluded as coming from this direction.

    The first type of metamorphite (consisting of Al-silicate) might have emerged from a NW direction on the basis of its textural characterization (i.e in the So–3 and perhaps Szta–2 boreholes). The nearby source area is underpinned and reinforced by the relatively angular appearance of the metamorphite. The determination of the source area of the second type of metamorphite is complicated; this is due to its well-rounded shape and the fact that it is exclusively composed of quartz, feldspar and mica.

    Keywords: Dráva Basin, Miocene, dolomite, limestone and metamorphite clasts, roundness analyst, palaeogeography, transport direction

  • Macovei Gheorghe ,
    Kovács-Pálffy Péter ,
    Kónya Péter :

    Összefoglalás: Az Avas-medence a Pannon-tó önálló öbleként működött a környező neogén vulkáni hegyekkel körülvéve. A kristályos aljzatra paleogén és neogén üledékek települtek. A késő-miocénban az éghajlat, valamint a tó vízszintjének válatakozása következtében mocsári erdők fejlődtek ki (Byttneriophyllum és Alnus). Így mocsarak, tőzeglápok alakultak ki, melyek jellemző növényzete a Glyptostrobus europaeus, Byttneriophyllum tiliifolium és Alnus cecropiaefolia, amelyek széntelepeket képeztek. Az Avas-medence szenei jó minőségű lignitek, melyek fűtőértéke átlagban 22 100 kJ/kg.

    Tárgyszavak: Románia, Avas-medence, késő-miocén, mocsári erdők, szénképződés, lignit

    Abstract: The present paper contains a significant amount of data concerning the geology, genesis and physical and chemical features of lignite in the Oaş Depression (North-western Transylvania, Romania). The present-day circular Oaş Depression is bordered by Neogene eruptive complexes; however, it is most likely that initially it functioned as a gulf of Lake Pannon. It was open to the west, north-west and most probably to the east as well. The age of the lignite-bearing unit is Late Miocene. Due to climate changes and lake level fluctuations during the Late Miocene, the sedimentary basin was occupied repeatedly by mires of forest swamp. Genetically, coal accumulated from the swampy forest vegetation which developed in certain areas. The presence of the swampy forest is proved by Glyptostrobus europaeus, Byttneriophyllum tiliifolium, and Alnus cecropiaefolia. In the Oaş Depression the lignite has excellent quality . The physical and chemical characteristics show an average caloric value of 22,100 kJ/kg.

    Keywords: Romania, Oaş Depression, Late Miocene, swamp forest, coal generation, lignite

    Rezumat: Depresiunea sedimentară a Oaşului a funcţionat ca un golf al Lacului Pannonian, având o formă circulară determinată de limita cu eruptivul neogen înconjurător. Depozitele sedimentare dispuse peste un soclu cristalin aparţin paleogenului şi miocenului. Miocenul superior este dezvoltat în facies pannonic şi cuprinde resturi vegetale fosile, reprezentând flora miocen-superioară. Pentru flora miocenă sunt caracteristice biotopurile de pădure mlăştinoasă (în special Byttneriophyllum şi Alnus). Schimbările de climă, precum şi fluctuaţiile nivelului apei din lac din miocenul superior unele sectoare din bazinul de sedimentare s-au transformat într-o turbărie. Prezenţa în aceste turbării a vegetaţiei de pădure mlăştinoasă (Glyptostrobus europaeus, Byttneriophyllum tiliifolium, Alnus cecropiaefolia) este răspunzătoare de formarea depozitelor de cărbune. Cărbunii din Depresiunea Oaşului sunt ligniţi de calitate superioară, caracteristicile fizico-chimice indică o putere calorifică medie de 22 100 kJ/kg.

    Cuvinte cheie: România, Depresiunea Oaş, miocen superior, păduri mlăştinoase, geneza cărbunilor, ligniţi

  • Kercsmár Zsolt ,
    Thiele Ádám :

    Abstract: In the region of Inner Somogy, Late Pleistocene – Early Holocene fluvial freshwater marshes were created by active neotectonic deformations. Bog iron ore deposits were formed in these freshwater marshes due to the precipitation of Fe(III) minerals; this occurred during the microbial and chemical oxidation of fluids containing Fe(II), while they were streaming beneath the surface. The bog iron ore deposits can be grouped into three types based on their genetics: (i) microbial bog iron ore lenses made by Fe(II)-oxidizing microorganisms in the back shallows of the southern part of Nagyberek (this is now an uplifted area); (ii) limonitic indications formed by chemical oxidation on the margins of back marshes filled up with sandy sediments and on the uplifted areas; and (iii) in the area which uplifted from the Early Holocene microbial bog iron ore lenses were redeposited by creeks and later developed as redeposited bog iron ore layers. Bog iron ores from the microbial bog iron ore lenses and from the redeposited bog iron ore layers were smelted intensively during the period of Avar settlement of Hungary and also later, during the age of the Conquest and after. This was due to the abundance and high quality of the ores. However, the bog iron ores of Somogy had a high phosphorus content, and so the phosphoric iron extracted by the smelting of these ores had poor mechanical properties. However, due to the presence of calcium carbonate in the area, the phosphorus content of the iron blooms could be decreased.

    Keywords: bog iron ores, Pleistocene, Inner Somogy, morphology, archaeometallurgy, geochemistry, genetics, phosphorus

    Összefoglalás: Belső-Somogyban, a késő-pleisztocén–óholocén folyóvízi–ártéri környezet kialakulását és megváltozását aktív tektonikai deformáció okozta és kísérte. A Nagyberek déli peremén megjelenő ártéri mocsarakban és lápokban a magas oldott Fe(II) tartalmú felszíni és felszín alatti vizekből, kémiai és biogén oxidációval vas-hidroxid ásványokból álló gyepvasérc telepek keletkeztek. A ma fellelhető gyepvasérc telepek genetikailag három csoportba oszthatók. A Nagy - berek déli nyúlványának megfelelő, mára kiemeltebb területen, lápi környezetben, vasbaktériumok életműködése követ - keztében gyepvasérc lencsék váltak ki. A homokos üledékkel feltöltődő láp peremén, illetve a kiemeltebb része ken, talajosodáshoz köthető kémiai oxidációval limonitos indikációk keletkeztek. A kora-holocéntől kezdve megemelke dő területen, a felszín közeli biogén gyepvasérc lencséit patakok tárták fel és halmozták át, ezzel másodlagos, torlatos, áthal - mozott gyepvasérc rétegeket hozva létre.

    A biogén gyepvasérc lencsékben és az áthalmozott gyepvasérc rétegekben található érc, megfelelő geokémiai össze - tétele és mennyisége miatt, a területen folyó intenzív avar és honfoglalás kori vaskohászat ércbázisául szolgált. Bár a gyakran mészkiválásos szinttel kísért belső-somogyi gyepvasércek foszfortartalma magas volt, így kohósításukkal általában rossz mechanikai tulajdonságokkal rendelkező, nagy foszfortartalmú vasanyagot lehetett előállítani, a területen gyakran előforduló kalcium-karbonát kiválásnak köszönhetően a vasbucák foszfortartalma csökkenthető volt.

    Tárgyszavak: gyepvasérc, pleisztocén, Belső-Somogy, morfológia, archaeometallurgia, geokémia, genetika, foszfor

  • Botka Dániel ,
    Mészáros Lukács :

    Abstract: The detailed taxonomic and morphological description of the remains of a rodent — that is, the shrew Beremendia fissidens — from the Somssich Hill 2 locality is given in the present article. Comparison of this species with the material of the Osztramos 7 locality provided an opportunity to work out the exact differential diagnosis between B. fissidens and its relative, B. minor. There were 169 specimens, with a minimum number of 61 individual examples identified from the 50 excavated layers of the site. The relatively large number of specimens gave a chance to take exact measurements on the teeth of this species. The presence of the species in most of the layers indicates the occurrence of an open-water body in the surroundings of the site. Beremendia used a special ’nutrition strategy’ which contributed significantly to its survival in this ecotype. This strategy was one in which it could envenom its prey with its grooved lower incisors. The storing of the paralyzed victims allowed Beremendia to survive the unstable climatic periods.

    Keywords: Beremendia fissidens, Lower Pleistocene, Somssich Hill, Soricidae, Villány Hills

    Összefoglalás: A cikk a Somssich-hegy 2-es lelőhely Beremendia fissidens cickánymaradványainak részletes anatómiai és taxonó - miai leírását mutatja be. Az Osztramos 7-es lelőhely anyagával való összevetés lehetővé tette a pontos elkülönítő diagnózis kidolgozását a rokonfaj B. minortól. A lelőhelyen feltárt 50 rétegből 169 maradványt sikerült azonosítani, 61 minimum egyedszámmal. A nagy egyedszám lehetőséget biztosított a fogak méreteinek pontosabb meghatározására. A faj legtöbb rétegben azonosítható jelenléte a lelőhely közelében nyílt víztükör jelenlétére utal. Ebben az ökotópban a Beremendia különleges táplálkozási stratégiát folytatott, amely nagyban segítette túlélését. Hasított metszőfoga segítségével mérget juttathatott prédájába. A megbénított áldozatok raktározása lehetőséget nyújtott a kedvezőtlen időszakok átvészelésére.

    Tárgyszavak: alsó-pleisztocén, Beremendia fissidens, Somssich-hegy, Soricidae, Villányi-hegység

  • Kocsis T. Ádám ,
    Sághi Kristóf ,
    Pálfy József :

    Abstract: The ultimate goal of palaeontological research is to reveal the history of life on Earth. The rise of the discipline of palaeobiology since the 1970s has sometimes been called a ’revolution’, given that it places emphasis on the synoptic analysis of the entire fossil record.

    Since the new millennium, the Paleobiology Database (PaleoDB) has played a central role in this field of research. Rapid advances in computer technology and the spread of the internet have enabled an international community of palaeontologists to develop a database to hold all the information of the known fossil record. The continuously growing database currently contains approximately 1.2 million records of 300 thousand taxa from 53 thousand references. The data allow statistical treatment to be used in order to correct for known biases of the fossil record, employing subsampling methods for data standardization. Thus an increasingly more reliable view is emerging on: (i) the history of life, (ii) similarities and differences of the diversity of certain fossil groups and the global biota, (iii) mass extinction events and (iv) intervals of diversification.

    Biological patterns through time can now be analyzed and compared with time series of various palaeoenvironmental parameters, in order to search for cause-and-effect relationships between environmental and biotic changes. The present study looks at a broad range of modern PalaeoDB-based research through selected case studies. Hungary has been part of the PalaeoDB community since 2007 (when one of the authors of this paper joined as a member). The first goal was to contribute Hungarian fossil occurrence data. The next step dealt with data analysis and the first results co-authored by Hungarian researchers have been recently published. It is paramount that Hungarian fossil occurrences be published in a format amenable to data entry into the PalaeoDB. It is recommended that more Hungarian palaeontologists recognize the usefulness and significance of the PaleoDB and become active members by contributing new and previously published Hungarian data. It is desirable that a school of palaeobiological research grows in Hungary because this is a field where limited research funding does not prohibit cutting-edge research which can have an international impact. Analytical palaeobiology is one of the most progressive research areas in the field of palaeontology in the 21st century and data analysis from the PaleoDB will continue to play an outstanding role in revealing the history of life.

    Keywords: Paleobiology Database, diversity, extinction, origination

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