2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 122-16
Presentation Time: 12:45 PM

ROCK MAGNETIC DATA FROM THE OUTSIDE CORNER OF A RIDGE-TRANSFORM SYSTEM, TROODOS OPHIOLITE, CYPRUS


WAGNER, Chelsea A., ALEXANDER, Sarah O. and TITUS, Sarah, Dept. of Geology, Carleton College, 1 North College St, Northfield, MN 55057, chls.wgnr@gmail.com

The Troodos ophiolite in Cyprus preserves a NS-striking ridge system (Solea graben), and an EW-striking dextral paleotransform fault (Arakapas fault). Where these two orthogonal structures meet, we have the opportunity to examine deformation near a ridge-transform intersection exposed in the mid-crustal units of the ophiolite.

Many studies in Cyprus have focused on the inside corner of the ridge-transform system. This region displays a dramatic clockwise rotation of the sheeted dike strikes, from NS-striking away from the fault to nearly EW-striking near the transform. Paleomagnetic data demonstrate that rocks experienced clockwise vertical-axis rotations that increase in magnitude near the transform fault. Thus, the swing in dike orientations is not an original seafloor feature. Anisotropy of magnetic susceptibility (AMS) results from gabbros show a magnetic lineation direction that is NW-trending for many stations in the inside corner; however, these sites have not been corrected for the inferred paleomagnetic rotations.

We examine deformation from the less-studied outside corner of the ridge-transform system. The current strike of sheeted dikes is ~NS, although there are subtle variations in the region. We present new rock magnetic data from 26 sites primarily within the sheeted dike complex. Our paleomagnetic results suggest two possible initial orientations for the dikes. In one solution, dikes strike NW and were rotated to their present-day orientations about SE-plunging rotation axes. In the other solution, dikes were initially NE-striking, and have been rotated about NW-plunging axes. While gentle tilting about sub-horizontal axes is consistent with outside corner deformation, it is difficult to determine which solution is more likely. Our AMS results do not help distinguish between solutions; there are no clear patterns for the in situ data or for the rotated results. Our results indicate that deformation can be complicated even within an outside corner.