engleski

The mechanism accounting for the geometry of offshore External Dinarides

The outcroping parts of offshore External Dinarides are the Adriatic islands stretching from the Kvarner islands in the NW to the Southern Adriatic islands in the SW. The chain of the islands as well as the thrust front between the External Dinarides and stable Adria have arcuated shape which is a feature easily interpreted as due to oroclinal bending. A systematic paleomagnetic research of Cretaceous, dominantly shallow water limestones provided a substantial data set for Cres, Ist and several surrounding islets, Dugi Otok, Brač, Hvar, Korčula, Mljet and Vis islands (Márton et al. 2014, 2022). The best quality results from these islands are covering the Albian-Santonian time interval. They document, with exceptionally precise paleomagnetic data, the lack of relative vertical axis rotation between the islands, i.e. clearly contradict the oroclinal bending as a possible mechanism accounting for the observed geometry. However, observations of the superposition of the products of Late Cretaceous (E-W compression), Late Eocene (NE-SW compression) and Neotectonic (N-S compression) strain field from Brač island (Marinčić 1997) provide a key to the arcuated shape. The structures belonging to the first are dominant in the northernmost, those related to the second, in the northern and the third in the Central and southern Adriatic island. The field measurements of the strikes of the beds sampled for the paleomagnetic studies are in line with this model. Moreover, the Albian-Santonian paleomagnetic vectors from the Adriatic islands are perfectly aligned with those for the outcroping areas (stable foreland of the Southern Alps and stable Istria), pointing to the absence of significant vertical axis rotation between them.

Cretaceous, Paleomagnetic studies, Limestones, Adriatic Islands Rotation

nije evidentirano