Multiple tectonic rotations and transform tectonism in an intraoceanic suture zone, SW Cyprus

Abstract

New palaeomagnetic data from the Late Cretaceous, Neotethyan Troodos ophiolite and related units in SW Cyprus provide compelling evidence that transform tectonism is recorded outside the main outcrop of the fossil Southern Troodos Transform Fault Zone (STTFZ). High-level intrusive and extrusive sequences were sampled along the SW margin of the Troodos massif and in ophiolitic slivers preserved along arcuate fault lineaments further to the south and west. These units show cross-cutting relationships with corresponding differences in remanent magnetisation directions, characteristic of syn-magmatic rotation in an active transform setting. Net tectonic rotation analyses allow decomposition of the total rotation at these sites into early and late components. Early transform-related rotations are consistently clockwise, in agreement with all other studies of rotations associated with the STTFZ further to the east. Late rotations and the net rotations derived at localities where cross-cutting relationships were not present are regarded as composite in origin. The composite rotation axes closely relate to the orientation of observed regional structures. In these circumstances, additional constraints are used to attempt geologically viable interpretations. The overall distribution of transform-related rotations (steeply and shallowly plunging rotation axes) and spreading axis-related rotations (sub-horizontal rotation axes) is comparable with that along the STTFZ and adjacent parts of the Troodos massif. This is most readily explained by simple along-strike extension of the primary spreading axis and transform fabrics into SW Cyprus, with minor late disruption by high-angle dextral shear zones and neotectonic graben systems.