Using field data to constrain a numerical kinematic model for ridge-transform deformation in the Troodos ophiolite, Cyprus

Abstract

The Troodos ophiolite in Cyprus provides a unique opportunity to examine spatially varying patterns of deformation near a ridge-transform intersection. We focus on the paleo–inside corner defined by the E-W–striking, dextral Arakapas transform fault and the N-S–striking Solea graben. Rocks within the inside corner are primarily sheeted dikes and gabbros. The strikes of dikes vary with proximity to the Arakapas fault, changing from NW- to N- to E-striking with increasing proximity to the fault. We report new paleomagnetic results from 24 stations in the gabbroic rocks. When augmented with data from several previous studies, the combined paleomagnetic data set indicates that vertical-axis rotations increase from 5° to 90° with distance from the Solea graben. Rotations are also largest near the transform fault. We develop numerical kinematic models for deformation within the inside corner based on these field data. First, we fit an interpolation function to the two-dimensional field of vertical-axis rotations. This field is then used to undeform dikes, assuming that dikes were either part of rigid blocks or passive markers within a continuum. We find that dikes return to a consistent NW to NNW strike throughout much of the inside corner. This initial orientation is not ridge-parallel and therefore different from most common assumptions of dike behavior in Cyprus. However, the orientation is consistent with predictions from dynamic models of heterogeneous stress directions that develop near ridge-transform intersections.