Deformation styles adjacent to transform faults: evidence from the Troodos ophiolite, Cyprus

Abstract

Abstract In the southeast part of the Troodos ophiolite much of the tectonic fabric is demonstrably associated with its formation at a spreading ridge adjacent to the Southern Troodos Transform Fault. A combined palaeomagnetic and structural study has revealed many features of its genesis. Palaeomagnetism can be used to identify original dyke intrusion directions and any subsequent block rotations. The region can be subdivided into two distinct sub-areas on the basis of their dyke orientations. In the southeast corner of the ophiolite, dykes had an original northwest strike, and have suffered only simple tilting about strike-parallel normal faults to assume their present orientation. In contrast, further west, dykes now striking northeast or east have been rotated on average 100° clockwise on sets of strike-slip faults, from an original northwest strike. A model for the structural processes active at ridge-transform intersections is suggested. Normal faulting dominates at the outside corner, where there is no slip across the transform. At the inside corner, oblique normal/strike-slip faulting is prevalent. Within this context, the eastern area of the ophiolite developed at the outside corner, and the area further west, at the inside corner. A ridge-jump boundary has been preserved between the areas, where a new ridge, which subsequently formed the eastern area, cut the older, western area.