Stratigraphy, facies and geodynamic settings of Jurassic formations in the Buekk Mountains, North Hungary: its relations with the other areas of the Neotethyan realm

• Published in: Geological magazine Vol. 150; no. 1; pp. 18 - 49
• Main Authors: Haas, Janos, Pelikan, Pal, GOeROeG, AGNES, JoZSA, SANDOR, OZSVART, PETER
• Format: Journal Article
• Language: English
• Published: 01.01.2013
• Subjects: Foraminifera; Radiolaria; Hungary
• ISSN: 0016-7568; 1469-5081
• DOI: 10.1017/S0016756812000246

Jurassic melange complexes related to the subduction of the Neotethys Ocean occur in the Buekk Mountains, North Hungary. This paper characterizes the sedimentary sequence of basin and slope facies that occur in the southwestern part of the Buekk Mountains, placing special emphasis on the redeposited sedimentary rocks (olistostromes, olistoliths: Monosbel Group) in order to obtain information on the provenance of the clasts, and the mode and time of their redeposition. The series of formations studied shows a general coarsening-upwards trend. Based on radiolarians and foraminifera, the Monosbel Group formed in Early to Late Bathonian time. The lower part of the complex is typified by a predominance of pelagic carbonates, shale and radiolarite with andesitic volcaniclastic intercalations. The higher part of the succession is characterized by polymictic olistostromes. Large olistoliths that are predominantly blocks of Bathonian shallow marine limestone (Buekkzserc Limestone) appear in the upper part of the sequence. Based on the biostratigraphic and sedimentological data, results of analyses of the redeposited clasts and taking into consideration the concepts of the development of the western Neotethys domain, the evolutionary stages of the sedimentary basins were defined. The onset of the compressional stage led to initiation of nappe stacking that led to the formation of polymict olistostromes and then to the redeposition of large blocks derived from out-of-sequence nappes of the former platform foreland.