Structural analysis of the Húsavík-Flatey Transform Fault and its relationships with the rift system in Northern Iceland

Abstract

The Húsavík-Flatey Fault (HFF), partially exposed on land in the Tjörnes Peninsula, is a major dextral transform fault of the Tjörnes Fracture Zone which accommodates the movement between the North Volcanic Zone of Iceland and the Kolbeinsey Ridge. We present a revisited structural pattern of the HFF in this area, based on the mapping of tectonic features using satellite images, aerial photography, and field structural analysis. We show that the HFF comprises several WNW-trending fault segments that localise both strike-slip and normal movements, agreeing with a transtensional deformation pattern. Two different types of transform-rift connections were recognised: (1) the progressive bending of a WNW-ESE transform fault segment that merges into a N-S rift structure and further north (2) a typical triple junction between another WNW-trending transform fault segment and a N-S normal fault of the rift. Furthermore, two immature WNW-ESE-trending faults, with poorly expressed fault traces, have been observed in the northern part of the HFF. These observations are consistent with the successive formation of transform fault segments from south to north due to the northward development of the HFF together with the rift structures.