The Tectonic Evolution of the Tjornes Fracture Zone, Offshore Northern Iceland-ridge Jumps and Rift Propagation

• Main Authors: Detrick, R S, Brandsdottir, B, Driscoll, Neal W, Richter, B, Mayer, Larry A., Fornari, D J, Calder, Brian R., Kent, G. M.
• Format: Text
• Language: unknown
• Published: University of New Hampshire Scholars' Repository 2003
• Subjects: Geophysics and Seismology; Oceanography and Atmospheric Sciences and Meteorology; Tectonics and Structure; Sav’; Kolbeinsey; Kolbeinsey Ridge; Iceland; Flatey
• Online Access: https://scholars.unh.edu/ccom/564; http://abstractsearch.agu.org/meetings/2003/FM/T21E-03.html

The Tjornes Fracture Zone (TFZ) links the rift zones in northern Iceland with the Kolbeinsey Ridge north of Iceland. The TFZ was initiated during the Miocene (7-9 Ma), following an eastward jump of the spreading axis in northern Iceland. A roughly 150 km long (EW) and 50 km wide (NS) deformation zone has since developed which includes both right-lateral, strike-slip faults and three N-S trending extensional grabens (from west to east the Eyjafj\"{o}rdur, Skj\'{a}lfandi and \"{O}xarfj"{o}rdur basins) which are filled with a 0.5-4 km thick sedimentary sequence. There are two WNW-striking bands of seismicity in the TFZ, a northern band known as the Gr\'{\i}msey lineament and a southern band associated with the WNW-trending H\'{u}sav\'{\i}k-Flatey fault (HFF). Over the past three field seasons we have mapped a large portion of TFZ utilizing multibeam echo sounders (both EM300 and a Reson 8101 shallow water system), collected high-resolution multichannel seismics and Chirp sonar, and obtained bottom photographs. The HFF can be traced offshore from H\'{u}sav\'{\i}k village across Skj\'{a}lfandi Bay as two WNW-trending, south-facing fault scarps and northwest of Flatey Island into the southern Eyjafj\"{o}rdur basin as a WNW-trending, north-facing scarp. In Skj\'{a}lfandi Bay several smaller WNW-trending faults are located sub-parallel of the main HFF. Offshore Flateyjarskagi, west of Flatey Island, a zone of intense deformation has been mapped, including clear evidence of right-lateral strike-slip faulting. The sediment-filled basins north of the HFF are bounded by numerous NS-trending faults, some of which extend to the seafloor, suggesting they are actively extending. The very subtle expression of the HFF in eastern Skj\'{a}lfandi Bay, and the more prominent but simple expression of recent (post-glacial) faulting along the western HFF near Flatey Island are consistent with historical and recent seismicity which is concentrated on the H\'{u}sav\'{\i}k fault system on the Tj\"{o}rnes peninsula, along the western HFF ...