STRUCTURE AND DYNAMICS OF ENDOGENIC RELIEF OF THE TJÖRNES TRANSFORM ZONE (NORTHERN ICELAND)

Abstract

The Tjörnes Transform Zone connects the Kolbeinsey spreading ridge and the Northern rift zone of Iceland. It includes two overlapping rift segments resulting from the rift zones propagating. Nowadays it includes several morphostructures that vary in their organization and dynamics, such as magmatic and amagmatic rifts, oblique fault zones, or tectonic-volcanic rises. They often overlap with each other promoting the development of block morphostructures of different scale. Using the morphometric analysis of present-day fault scraps we revealed the areas of different recent tectonic activity and faulting intensity, and explained geodynamic reasons of these differences. For instance, the most active morphostructures are spreading and rift segments of the western branch of the transform zone. The eastern branch has significantly weaker tectonic activity which is mainly due to the intensive volcanic processes. Nowadays the eastern branch of the transform zone continues its development that is expressed through the formation of block rises between the overlapping rift segments. The western branch has less complicated structure and gradually fading tectonic-magmatic activity. We also showed the functional changes of amagmatic rifts: at the early stages of transform zone development, they probably evolved as a continuation of adjacent spreading centers. Meanwhile now they have their own independent extension centers. All explored morphostructures influence each other in the process of overlapping that significantly impacts the endogenic relief formation, especially faulting, at different sections of the morphostructures.