Acta Geologica Hungarica最新文献

{"title":"New age data on the low-temperature regional metamorphism of Mt. Medvednica (Croatia)","authors":"K. Judik, K. Balogh, D. Tibljaš, P. Árkai","doi":"10.1556/AGEOL.49.2006.3.2","DOIUrl":"https://doi.org/10.1556/AGEOL.49.2006.3.2","url":null,"abstract":"K-Ar age data of illite-K-white mica-rich, <2 µm grain size fraction samples were determined on various lithotypes of the Paleozoic-Mesozoic, very low- to low-grade metamorphic complex, the Jurassic ophiolitic melange and the Cretaceous-Paleocene sedimentary sequence of Mt. Medvednica, Croatia. K-Ar ages of the high-temperature anchizonal-epizonal Paleozoic-Mesozoic complex scatter around ca. 110 Ma for slates, phyllites and marbles with phyllite intercalations, while they are significantly younger (ca. 80 Ma) for metavolcanoclastic rocks that are devoid of detrital K-white mica. Beside the Cretaceous (Alpine) K-Ar radiometric age data, no evidence of a possibly older, Variscan metamorphic event was detected. In the Jurassic ophiolitic melange and the Cretaceous-Paleocene sequence the obtained mixed isotopic age data do not provide reliable estimates for the age of the diagenetic alterations. In the Paleozoic and Mesozoic formations from the Bukk, Szendro and Uppony Mts. (NE Hungary) and in the Paleozoic ...","PeriodicalId":107929,"journal":{"name":"Acta Geologica Hungarica","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121161064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tectonic evolution of the polydeformed Sa'al Belt, South Sinai, Egypt","authors":"A. Hegazi","doi":"10.1556/AGEOL.49.2006.3.5","DOIUrl":"https://doi.org/10.1556/AGEOL.49.2006.3.5","url":null,"abstract":"The Sa’al Belt comprises a variety of Late Proterozoic island-arc assemblages of metasediments and metavolcanics. The metavolcanics are calc-alkaline to sub-alkaline rocks with minor tholeiitic tendency, whereas the metasediments are originally sediments that were shed from active volcanic islands. The belt is polydeformed and regionally metamorphosed up to the greenschist facies, with late and post-tectonic granitoid intrusions. Tectonically the Sa’al Belt evolved through multiple phases of ductile and brittle deformation. The ductile deformation is manifested in three folding generations and shear zones whereas the brittle deformation is represented by thrusting and faulting. The first folding generation (F1) is represented by intrafolial and drag folds that are apparently coeval with thrusting, and show vergence more or less parallel to that of thrusts. Thrusting took place in a convergent environment within and along the contact between different metavolcanics and metasediments. The highest principal stress is horizontal, oriented N50°W, and the relative transport direction is to SE toward the foreland. A second fold generation (F2) overprinted the first folding with widely-spread kink folds and kink bands. All criteria indicate the prevalence of a NW–SE-oriented simple shear regime that was associated with slip essentially parallel to banding. The third folding generation (F3) has a slip nature and has overprinted both F1 and F2, producing sub-vertical NW–SEtrending S 3 -surfaces, meaning that the highest principal stress orientation rotated towards NE–SW. Dynamic analysis of the fabrics within the extensive subvertical E–W-trending ductile shear zones indicates that they are produced by a subhorizontal highest principal stress oriented S47°E. Moreover, shear sense indicators display a simple shear with dextral sense of movement. Two conjugate shear planes are the main elements of the brittle deformation. The first is a leftlateral strike-slip fault set trending N to NNE, and the second a right-lateral strike-slip fault set trending NW. These conjugate shear planes were formed with subhorizontal highest principal stress oriented N25°W.","PeriodicalId":107929,"journal":{"name":"Acta Geologica Hungarica","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126441965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Middle Toarcian Ammonitina from the Gerecse Mts, Hungary","authors":"B. Géczy, I. Szente","doi":"10.1556/AGEOL.49.2006.3.3","DOIUrl":"https://doi.org/10.1556/AGEOL.49.2006.3.3","url":null,"abstract":"In the Gerecse Mts, Jurassic successions built of sedimentary rocks characteristic of the peri-Mediterranean region are found. The lower part of the Toarcian stage, largely representing the \"Ammonitico Rosso marl\" facies, contains very diverse and abundant ammonite faunas. Bed-by-bed sampling of four sections carried out during the late seventies and early eighties of the last century has resulted in the collection of more than 15 000 specimens, the bulk of them belonging to the orders Phylloceratina and Lytoceratina. Due to the presence of very rare index forms of the suborder Ammonitina, the successions could be fitted into the zonal scheme established for the NW European Toarcian. The aim of the present paper is to provide information on the stratigraphic distribution of Ammonitina in the Bifrons and Gradata Zones as well as to present a subzonal subdivision of these beds.","PeriodicalId":107929,"journal":{"name":"Acta Geologica Hungarica","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134183633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochronology of the metamorphic basement, Transdanubian part of the Tisza Mega-Unit","authors":"G. Lelkes-Felvári, W. Frank","doi":"10.1556/AGEOL.49.2006.3.1","DOIUrl":"https://doi.org/10.1556/AGEOL.49.2006.3.1","url":null,"abstract":"The results of seven new 40 Ar/ 39 Ar analyses and two K/Ar analyses of mineral separates of metamorphic rocks from the Transdanubian part (west of the Danube River) of the Tisza Mega-Unit is presented, and a review of the geochronological data available in the literature is given. Investigated rocks come from boreholes and include amphibolite facies rocks, mainly containing garnet, staurolite, kyanite, andalusite and sillimanite as index minerals. The investigated area covers 120 × 85 km in Transdanubia, including all tectonic units distinguished by previous authors. The 40 Ar/ 39 Ar spectra of the muscovites yielded fairly well-established plateau ages ranging from 307 Ma-312 Ma in all units. Similar muscovite Ar/Ar cooling ages of ca 310 Ma were obtained from other parts of Tisza Mega-unit east of the Danube, e.g. from the kyanite-sillimanite-bearing metapelites of the Villany-Bihar Subunit (Great Plain; Lelkes-Felvari et al. 2003).","PeriodicalId":107929,"journal":{"name":"Acta Geologica Hungarica","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133772179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diversity changes of the Brachiopods in the Northern Caucasus: a brief overview","authors":"D. Ruban","doi":"10.1556/AGEOL.49.2006.1.4","DOIUrl":"https://doi.org/10.1556/AGEOL.49.2006.1.4","url":null,"abstract":"The diversity of the brachiopods in the Northern Caucasus significantly fluctuated throughout the Paleozoic-Mesozoic. Weak diversifications occurred in the Middle Cambrian, Late Silurian - Early Devonian, and Late Devonian - Early Carboniferous. Since the Late Permian brachiopod assemblages became quite diverse. The maximum number of species was reached in the Rhaetian. The Permian/ Triassic mass extinction and enigmatic Ladinian crisis, on the other hand, led to regional brachiopod demises. In the Jurassic - Early Cretaceous interval the diversity of brachiopods generally decreased. The strongest drops of species numbers occurred in the Toarcian and Berriasian following the Pliensbachian-Toarcian and end-Jurassic global mass extinctions, and in the Kimmeridgian due to the regional salinity crisis. It is evident that some of the regional brachiopod diversifications coincided with the development of rimmed shelves.","PeriodicalId":107929,"journal":{"name":"Acta Geologica Hungarica","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123087036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"K-rich rocks and their relation to mineralization in the Mátra Mountains (North Hungary)","authors":"B. Nagy","doi":"10.1556/AGEOL.49.2006.1.2","DOIUrl":"https://doi.org/10.1556/AGEOL.49.2006.1.2","url":null,"abstract":"At the end of the 1960s scientists of the Geological Institute of the Hungarian Geological Survey described K-enrichments in different rock types exposed at surface in the Western and Central Matra Mts. At that time these K-rich rocks were not studied in detail. In the framework of a research project we indicated that the main K-bearing minerals are sanidine and orthoclase. The average K2O content of the different potassium-rich rock types reached 9.16%, whereas their K-content is 7.6%. In contrast to previous opinions no direct mineral paragenetic relationship could be established between hydrothermal ore mineralization and the formation of the K-rich rock types. K/Ar data obtained on K-rich rocks indicate that the K-rich rock types are older than the ore mineralization.","PeriodicalId":107929,"journal":{"name":"Acta Geologica Hungarica","volume":"123 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114568842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleoenvironmental evaluation of the Tata Travertine Complex (Hungary), based on stable isotopic and petrographic studies","authors":"S. Kele, L. Korpás, A. Demény, P. Kovács-Pálffy, B. Bajnóczi, Z. Medzihradszky","doi":"10.1556/AGEOL.49.2006.1.1","DOIUrl":"https://doi.org/10.1556/AGEOL.49.2006.1.1","url":null,"abstract":"In the area of the town of Tata (Hungary) there are several Quaternary travertine outcrops, of which the Porhanyo Quarry is the best-exposed one. The travertine of the Porhanyo Quarry can be vertically divided into six units. Algal and other phytoclastic and phytohermal grainstone, boundstone and floatstone are the dominant microfacies. On the walls of the quarry carbonate vents and cones were detected; these forms are indicators of former spring activity at the bottom of a shallow lake. The lake, fed by thermal springs, was formed in a siliciclastic floodplain. The upwelling thermal water brought quartz and other detrital grains from the underlying Pannonian siliciclastic sediments to the surface, concentrating them in the vents. The three main phases of lacustrine evolution were interrupted first by a drying and flooding event, followed by a fluvial-eolian event and finally by eolian sedimentation. The oxygen isotope compositions of the vents differ from the values of vertical sections and slope samples...","PeriodicalId":107929,"journal":{"name":"Acta Geologica Hungarica","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127463982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleomagnetic evidence for a megabreccia horizon in the Upper Jurassic sequence of Eperkés Hill, Transdanubian Range, Hungary","authors":"P. Convert, E. Márton, J. Haas","doi":"10.1556/AGEOL.49.2006.1.3","DOIUrl":"https://doi.org/10.1556/AGEOL.49.2006.1.3","url":null,"abstract":"Eperkes Hill is a thoroughly studied classic exposure, yet its facies interpretation is still debated. The issue is whether Upper Triassic - lowermost Jurassic carbonates are regular beds or blocks embedded within the Kimmeridgian-Berriasian limestone. The answer to this question is important for the interpretation of the structural evolution and paleogeography of the Transdanubian Range area at the Jurassic-Cretaceous boundary; we decided therefore to contribute to the solution by applying paleomagnetism to the problem.  We tested several regular beds and suspected olistoliths from two artificial exposures. In order to check the consistency of the paleomagnetic signal on site level, we drilled three or more cores from each, and subjected them to standard paleomagnetic laboratory processing and evaluation.  We found that magnetic parameters were distinctly different for \"regular\" beds and for suspected olistoliths, but that the paleomagnetic signal was consistent within every site. However, between-site c...","PeriodicalId":107929,"journal":{"name":"Acta Geologica Hungarica","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116765677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative geochemical studies of obsidian samples from various localities","authors":"P. Rózsa, Gyula Szö?r, Z. Elekes, B. Gratuze, I. Uzonyi, Árpád Z. Kiss","doi":"10.1556/AGEOL.49.2006.1.5","DOIUrl":"https://doi.org/10.1556/AGEOL.49.2006.1.5","url":null,"abstract":"Obsidian samples from different localities of various geologic settings (Armenia, Hungary, Iceland, Mexico, Slovakia and Turkey) were analyzed by particle induced gamma-ray emission (PIGE) technique and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Samples from Mexico and Iceland show higher alkali and REE content as well as higher Nb and Ta abundances than the other samples. Discrimination diagrams show samples from Mexico and Iceland to belong to WPG. The position of the samples from the Tokaj Mts is also definite, and it corresponds to the expectation (VAG or VAG+syn-COLG fields). Using a Li-B diagram the obsidian samples can be distinguished according to their geographic distribution. By means of a Ce-Ti diagram, obsidian from the Tokaj Mts can be divided into three groups that may correspond to the archeometrical C2E, C2T and C1 groups. Phenocrysts in the obsidian samples from the Tokaj Mts, and the Aragats Mts (Armenia) were detected and analyzed by micro-PIXE (proton indu...","PeriodicalId":107929,"journal":{"name":"Acta Geologica Hungarica","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125091501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formations of Late Neogene and Pleistocene terrestrial sediments in the region of Mórágy Hill (Hungary)","authors":"L. Koloszár, István Marsi","doi":"10.1556/AGEOL.48.2005.3.5","DOIUrl":"https://doi.org/10.1556/AGEOL.48.2005.3.5","url":null,"abstract":"In the 1990s detailed geologic exploration in the eastern part of Moragy Hill (Hungary, southeastern Transdanubia) provided a great deal of new knowledge on stratigraphic features. Making use of and reinterpreting all available geologic data, our study gives an overview of the surface and subsurface extent of the Late Neogene and overlying Pleistocene beds, their stratigraphic position, thickness characteristics, as well as lithology, facies and age. We also cover in detail the stratigraphic position, accumulation type and age of the granite rubble, together with the Tengelic Red Clay Formation, previously unknown in the area. A theoretical section of the characteristics of the Paks Loess Formation is shown, based on the data of Moragy Hill and the Tolna Hegyhat Hills, defining and describing its lithological units. Using the large number of accurately evaluated borehole sections in the region it could be proved that the Hungarian loess stratigraphy elaborated by the specialists of the Geographic Research...","PeriodicalId":107929,"journal":{"name":"Acta Geologica Hungarica","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124326066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}