Apparent Polar Wander Path for Adria udextended by new Jurassic paleomagnetic results from its stable core: tectonic implicationsud

摘要

As a continuation of a systematic paleomagnetic research in the northern part of stable Adria, which provided a well-defined apparent polar wander (APW) path for the Cretaceous-Eocene, we present new paleomagnetic results for the Jurassic. These new data were obtained from 15 geographically distributed localities from the Trento platform (eastern Southern Alps) using standard paleomagnetic approach. The Lower Jurassic shallow water carbonates are not considered for tectonic interpretation, due to inconsistent inclinations. The Middle and Upper Jurassic Rosso Ammonitico provided excellent kinematic constraints.udWith the new Jurassic results, an APW is now defined for Adria for the 167-40Ma interval. It is well constrained for timing of important changes, like the speed and the sense of rotations. This APW suggests that the CW rotation and southward shift changed to the opposite at 155.1±5.3Ma, signifying a dramatic change in the life of the Neo-Tethys, from opening to closing. The latter is manifested in fast CCW rotation and northward movement of Adria up to 102.9±2.4Ma and moderate displacements in the same manner in post-103 Ma times. Combined data sets from stable Istria and the foreland of the Southern Alps point to an approximately 15° CW rotation with respect to Africa at the end of the Cretaceous, and an about 25° in the CCW sense, after the Eocene.