The Vogar Fissure Swarm, Reykjanes Peninsula, Iceland: Aseismic Kinematics of an Oblique Rift Zone

• Main Author: Runnals, Keegan Timothy
• Format: Text
• Language: unknown
• Published: SCARAB 2011
• Subjects: Iceland; Rift Boundary; Fissure Swarm; Kinematics; Geology; Mid-Atlantic Ridge; Reykjanes
• Online Access: https://scarab.bates.edu/honorstheses/6; https://scarab.bates.edu/cgi/viewcontent.cgi?article=1004&context=honorstheses

Exposure of the Mid-Atlantic ridge in Iceland offers a unique place to study hotspot-ridge interactions along an oblique rift zone. The Reykjanes Peninsula is a left lateral shear zone characterized by a series of NE striking en echelon fissure swarms oblique to the rift axis, and N-S trending dextral strike slip faults. This study focuses on the Vogar fissure swarm in southwest Iceland, in order to better constrain the mode of deformation within it. Movement of the faults and fissures that make up the fissure swarm is thought to either be related to seismic events along the ridge, or occur aseismically due to dike injections during eruptive episodes. GPS measurements and field based mapping were employed to examine a 7x3 km cross section of the fissure swarm in order to constrain its kinematics. The faults tend to terminate at the contact of a historical fissure lava and an ~12,000 year old shield lava. Cooling properties of the historical lava flow and overflown pre-existing faults were concluded to contribute to its present day structure. The faults’ termination at the historical lava supports the theory that movement along the faults occurs primarily aseismically during eruptive episodes. With this assumption a hypothetical cross section was created of the Vogar fissure swarm extending to the base of the crust, relating the normal faults at the surface to dikes at depth. The continued activity along the Reykjanes Peninsula suggests that it is still a very active spreading center, making it important to constrain the types of deformation that characterize it.