Motion in the north Iceland volcanic rift zone accommodated by bookshelf faulting

Green, Robert G. and White, Robert S. and Greenfield, Tim (2013) Motion in the north Iceland volcanic rift zone accommodated by bookshelf faulting. Nature Geoscience, 7 (1). pp. 29-33. ISSN 1752-0894 DOI 10.1038/ngeo2012

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Official URL: http://dx.doi.org/10.1038/ngeo2012

Abstract

Along mid-ocean ridges the extending crust is segmented1 on length scales of 10–1,000 km. Where rift segments are offset from one another, motion between segments is accommodated by transform faults that are oriented orthogonally to the main rift axis. Where segments overlap, non-transform offsets with a variety of geometries2 accommodate shear motions. Here we use micro-seismic data to analyse the geometries of faults at two overlapping rift segments exposed on land in north Iceland. Between the rift segments, we identify a series of faults that are aligned sub-parallel to the orientation of the main rift. These faults slip through left-lateral strike-slip motion. Yet, movement between the overlapping rift segments is through right-lateral motion. Together, these motions induce a clockwise rotation of the faults and intervening crustal blocks in a motion that is consistent with a bookshelf-faulting mechanism, named after its resemblance to a tilting row of books on a shelf3. The faults probably reactivated existing crustal weaknesses, such as dyke intrusions, that were originally oriented parallel to the main rift and have since rotated about 15° clockwise. Reactivation of pre-existing, rift-parallel weaknesses contrasts with typical mid-ocean ridge transform faults and is an important illustration of a non-transform offset accommodating shear motion between overlapping rift segments.

Item Type: Article
Additional Information: This paper is Open Access
Uncontrolled Keywords: 2013AREP; IA66; Part III,
Subjects: 02 - Geodynamics, Geophysics and Tectonics
06 - Part-III Projects
Divisions: 06 - Part-III Projects
Journal or Publication Title: Nature Geoscience
Volume: 7
Page Range: pp. 29-33
Identification Number: 10.1038/ngeo2012
Depositing User: Sarah Humbert
Date Deposited: 25 Feb 2014 11:03
Last Modified: 17 Feb 2017 13:11
URI: http://eprints.esc.cam.ac.uk/id/eprint/2972

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