2024-03-29T09:01:35Zhttps://riubu.ubu.es/oai/requestoai:riubu.ubu.es:10259/61172021-12-16T14:04:54Zcom_10259.4_2560com_10259_5086com_10259_2604col_10259.4_2561
An Integrated Paleomagnetic, Multimethod- Paleointensity, and Radiometric Study on Cretaceous and Paleogene Lavas From the Lesser Caucasus: Geomagnetic and Tectonic Implications
Calvo Rathert, Manuel
Bógalo Román, Mª Felicidad
Morales, J.
Goguitchaichvili, Avto
Lebedev, Vladimir A.
Vashakidze, George T.
García Redondo, Natalia
Herrero, E.
Caucasus
Cretaceous
K-Ar dating
Paleointensity
Paleomagnetism
Rock magnetism
Sixteen rhyolitic and dacitic Cretaceous and Paleocene-Eocene lavas from the Lesser Caucasus have been subjected to paleomagnetic and multimethod paleointensity experiments to analyze the variations of the Earth's magnetic field. Paleointensity experiments were performed with two methods. Thellier-type experiments with the IZZI method on 65 specimens (nine flows) yielded 15 successful determinations and experiments with the multispecimen method on 14 samples (seven flows) yielded two successful determinations. The joint analysis of the results obtained with both methods produced a mean FuK = (19.9 ± 3.7) µT for upper Cretaceous and FPg = (20.7 ± 3.3) µT for Paleogene sites. Low virtual axial dipole moments for the Cretaceous (3.4 × 1022 Am2) and Paleogene (3.5 × 1022 Am2) samples support the idea of a lower average dipole moment during periods of stable polarity of the Earth magnetic field. Mean flow paleomagnetic directions did not match expected upper Cretaceous to Paleogene directions calculated from the European Apparent Polar Wander Path. While inclination results roughly agreed with expected values, a group of sites showed nearly North-South paleodeclinations (D = 1.1° ± 14.2°), and another group displayed eastward deviated paleodeclinations (D = 72.9° ± 26.6°). These results suggest the occurrence of nearly vertical-axis rotations, probably as a result of continental collision since Oligocene. In addition to paleomagnetic and palaeointensity analyses, new K-Ar absolute age determinations have been performed on three of the studied sites, yielding Late Cretaceous ages (78.7 ± 1.7, 79.7 ± 1.6, and 83.4 ± 1.8 Ma (2σ)).
2021-11-08T11:30:47Z
2021-11-08T11:30:47Z
2021-11-08T11:30:47Z
2021-02
info:eu-repo/semantics/article
2169-9313
http://hdl.handle.net/10259/6117
10.1029/2020JB020019
eng
Journal of geophysical research. Solid earth. 2021, V. 126, n. 2, e2020JB020019
https://doi.org/10.1029/2020JB020019
info:eu-repo/semantics/openAccess
American Geophysical Union (AGU)