An Integrated Paleomagnetic, Multimethod‐Paleointensity, and Radiometric Study on Cretaceous and Paleogene Lavas From the Lesser Caucasus: Geomagnetic and Tectonic Implications

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)). Plain Language Summary Paleomagnetic and paleointensity experiments allow the retrieval of the intensity and direction of the magnetic field of the Earth (EMF) in the geological past, so that this kind of data can inform us about how the EMF has changed with time. Furthermore, paleomagnetic directions can also inform us about what kind of tectonic movements the studied regions have experienced. If the experimental results obtained do not agree with known expected directions, this can be an indication of tectonic movements in the study area. In the present study, we have analyzed rocks with ages between ∼50 and 85 million years. Analysis of their paleointensity suggests that the strength of the EMF at that time could have been lower than half its present‐day value. The study of the magnetization directions recorded in these rocks tells us