Date of Award


Degree Type


Degree Name

Master of Science (MS)


Earth Sciences


Jeffrey A. Karson


Eyjafjörður, Iceland, Strike-slip Faults

Subject Categories

Earth Sciences


Strike-slip faults along mid-ocean ridge and subaerial spreading centers are generally thought to be restricted to transform boundaries connecting rift segments. Faults that are parallel to spreading centers are generally assumed to be normal faults associated with tectonic extension. However, clear evidence of north-south (rift-parallel), strike-slip displacements occur widely around the southern portion of Eyjafjörður, northern Iceland about 50 km west of the actively spreading Northern Rift Zone. The area is south of the southernmost strand (Dalvík Lineament) of the NW-SE-trending, dextral-slip, Tjörnes Fracture Zone (where N-S, sinistral, strike-slip “bookshelf” faulting occurs). Faults in the Eyjafjörður area cut 8.5-10 Ma basaltic crust, parallel to spreading-related dikes, and commonly cut preexisting dike margins. Fault rocks range from fault breccia to gouge. Riedel shears and other kinematic indicators provide unambiguous evidence of shear sense. Most faults show evidence of sinistral, strike-slip movement; less common normal and oblique-slip faults also are present. Cross-cutting relations among the different types of faults are inconsistent thus they are interpreted as being related to a single deformation event. Fault slip-line kinematic analysis yields solutions indicating an overall oblique-slip system with sinistral sense of shear. These results may be interpreted as previously unrecognized transform-fault bookshelf faulting or slip accommodating block rotation associated with northward propagation of the Northern Rift Zone.


Open Access



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.