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| Titel |
Depositional age and palaeoclimatic signal, Upper Cretaceous continental deposits, Haţeg basin, South Carpathians: isotopic and lithostratigraphic evidences |
| VerfasserIn |
Ana-Voica Bojar, Stanislaw Halas, Hans-Peter Bojar, Dan Grigorescu  , Stefan Vasile |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048746
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| Zusammenfassung |
| In the Haţeg basin, South Carpathians, two different continental Formations of Maastrichtian age occur: the Densuş–Ciula and the S-npetru Formations. The Maastrichtian age of the middle Densuş–Ciula member and the S-npetru Formation is constrained by freshwater gastropod assemblages and palinology (Antonescu et al., 1983; Grigorescu, 2010). Aditionally, the age base on calcareous nannofossils, of the youngest Cretaceous marine deposits that are overlaid by the Densus-Ciula and, respectively Sanpetru Formations, is Late-Campanian-Early Maastrichtian (Grigorescu and Melinte, 2001; Melinte-Dobrinescu, 2010). Palaeomagnetic studies were carried out for the Sibişel Formation. For the Densuş–Ciula Formation, the palaeomagnetic signal displays no consistent results (Panaiotu and Panaiotu, 2010). Bojar et al. (2010a) found high amounts of magnetic titanohematite (up to 40%) with tabular crystallographic forms in the heavy mineral fraction of the Densuş–Ciula Formation, which disturbed the primary magnetic signal. The preservation of this mineral, which is most probably of volcanic origin, was favored by the general dry and oxic conditions at the time of deposition. For the Haţeg basin, the seasonally dry to sub-humid conditions prevailed during the sedimentation of Densuş-Ciula Formation and the lower part of the deposits occurring on Sibişel Valley. These conditions were put in evidence by mineralogical and isotopic investigations of palaeosol and fossil remains (Bojar et al., 2005; Bojar et al., 2009; Bojar et al., 2010 b). Recent palinological investigations (Lindfors et al., 2010) from a site situated near Valioara, in the Densuş-Ciula Formation, also support seasonally dry conditions during the formation of the deposits.
In order to constrain the age of the Densuş-Ciula Formation and correlate it with the S-npetru Formation, we separated and dated by K-Ar method biotites and amphibols from the volcanoclastic deposits. The mineralogy and lithology of the samples were done using X-ray diffraction and semi-quantitative determinations. Further correlations and interpretations are based on the new data presented in this study and previously published palaeomagetic and biostratigraphy.
References
Antonescu, E., Lupu, D., Lupu, M., 1983. Correlation palinologique du Crétacé terminal du sud-est des Monts Metaliferi et des Depressions de Haţeg et de Rusca Montană. Annales de l'Institut de Géologie et Géophysique 59: 71–77.
Bojar A-V, Bojar H-P, Ottner F, Grigorescu D, 2010 a. Heavy mineral distributions of Maastrichtian deposits from the Haţeg basin, South Carpathians: tectonic and palaeogeographic implications. Palaeogeography, Palaeoclimatology, Palaeoecology 293: 319–328.
Bojar, A-V, Csiki, Z, Grigorescu, D, 2010 b. Stable isotope distribution in Maastrichtian vertebrates and paleosols from the Haţeg Basin, South Carpathians. Palaeogeography, Palaeoclimatology, Palaeoecology 293: 329–342.
Bojar, A-V, Grigorescu, D, Ottner, F, Csiki, Z, 2005. Paleoenvironmental interpretation of dinosaur- and mammal-bearing continental Maastrichtian deposits, Haţeg basin, Romania. Geological Quarterly 49: 205–222.
Bojar A-V, Ottner F, Bojar H-P, Grigorescu D, Persoiu A, 2009. Stable isotope and mineralogical investigations on clays from Late Cretaceous sequences, Haţeg Basin, Romania. Applied Clay Sciences 45: 155–163.
Grigorescu D, 2010 a. The Latest Cretaceous fauna with dinosaurs and mammals from the Haţeg Basin — A historical overview. Palaeogeography, Palaeoclimatology, Palaeoecology 293: 271-282.
Grigorescu D, Melinte M, 2001. The stratigraphy of the Upper Cretaceous marine sediments from the NW Haţeg area (South Carpathians, Romania). Acta Palaeontologica Romaniae 3: 153–160.
Lindfors, SM, Csiki Z, Grigorescu D, Friis, EM, 2010. Preliminary account of plant mesofossils from the Maastrichtian Budurone microvertebrate site of the Haţeg Basin, Romania. Palaeogeography, Palaeoclimatology, Palaeoecology 293: 353-359.
Melinte-Dobrinescu, M.C. 2010. Lithology and biostratigraphy of Upper Cretaceous marine deposits from the Hateg region (Romania): palaeoenvironmental implications. Palaeogeography, Palaeoclimatology, Palaeoecology 293: 283-294. |
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