The age of the Sarmatian-Pannonian transition in the Transylvanian Basin (Central Paratethys) |
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Authors: | Iuliana Vasiliev Arjan de Leeuw Wout Krijgsman Marius Stoica |
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Affiliation: | a Paleomagnetic Laboratory ‘Fort Hoofddijk’, Budapestlaan 17, 3584 CD, Utrecht, The Netherlandsb Department of Geology, ‘Babe?-Bolyai’ University, Kog?lniceanu St. 1, 400084 Cluj-Napoca, Romaniac Department of Isotope Geochemistry, Faculty of Earth and Life Sciences, Vrije University, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlandsd Department of Palaeontology, Faculty of Geology and Geophysics, University of Bucharest, B?lcescu Bd. 1, Bucharest, 010041, Romaniae National Institute of Marine Geology and Geoecology, GeoEcoMar, Dimitrie Onciul Street 23-25, Bucharest, 70318, Romania |
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Abstract: | A marked paleoenvironmental change took place at the beginning of the late Miocene in the Central Paratethys, with dominantly marine Sarmatian successions grading rapidly into mainly brackish Pannonian deposits. A long and excellently exposed section comprising the Sarmatian-Pannonian transition has been investigated at Oarba de Mure? in the Transylvanian basin (Romania). In this paper, we focus on both radiometric and magnetostratigraphic dating to provide a chronology for the Sarmatian-Pannonian transition in Transylvania. Two volcaniclastic layers, located approximately 40 m below the Sarmatian-Pannonian transition, yield excellent 40Ar/39Ar ages. The weighted mean plateau age for biotite and sanidine separates provided isotopic ages of 11.62 ± 0.12 Ma and 11.65 ± 0.13 Ma. This implies deposition during the magnetic chron C5r.2r, which is in agreement with the magnetostratigraphic results of the Oarba de Mure? composite section. Rock magnetic analyses indicate greigite as the main magnetic carrier, with characteristics very similar to the magnetosomal greigite found in the Carpathian foredeep. The newly obtained chronology at Oarba de Mure? constrains the age of the Sarmatian-Pannonian transition in the Transylvanian basin to 11.3 ± 0.1 Ma, slightly younger than the 11.61 Ma postulated in the Styrian and Vienna Basins. |
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Keywords: | Central Paratethys Sarmatian Pannonian Magnetostratigraphy 40Ar/39Ar dating |
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