The Structure and Dynamics of the Endogenic Relief of the Tjörnes Transform Zone, North Iceland

The Tjörnes Transform Zone (transform zone) joins the Kolbeinsey Ridge and the Northern Rift Zone of Iceland. It consists of two overlapping rift segments, which formed as a result of propagation of rift zones. It currently includes a series of morphostructures of various structures and dynamics such as magmatic and amagmatic rifts, normal–strike-slip fault zones, and tectono-volcanic uplifts, which often overlap each other, which leads to the formation of various scales of block morphostructures. Using morphometric analysis of the present-day normal fault scarps, we revealed areas with different current tectonic activity and intensity of faulting, as well as explaining the geodynamic causes of these differences. For example, the spreading and rift areas of the western branch of the transform zone are most tectonically active in contrast to its eastern branch, which is related to the presence of intense volcanic activity. The eastern branch continues to form resulting in the formation of block uplifts in the overlapped rift segments. The western branch has a simpler structure and its tectono-magmatic activity currently is attenuating. The changes in functioning of amagmatic rifts are shown: during the early stages of the evolution of the transform zone, the rifts probably evolved as a continuation of adjacent spreading centers, whereas now they have independent extension centers. All the studied morphostructures significantly affect each other during overlapping of extension axes, which influences the character of endogenic relief formation, especially faulting at different areas of these morphostructures.