Popis: |
The Western Limassol Forest Complex (WLFC), Cyprus, forms an anomalous ophioliteterrain in the south of the Troodos Massif. Detailed studies have revealed magmatic and structural histories that differ markedly from the Penrose-type ophiolite of the Troodos Massif to the north. In the WLFC, a tectonised harzburgite of upper mantle origin has been intruded by multiple ultramafic and gabbroic plutons and swarms of mainly NE-SW trending dykes. The entire complex has been sheared along E-W trending serpentinite shear zones, the orientation of which indicate sinistral displacement. The various styles of deformation from ductile to brittle, and the progressive cooling history of the Intrusive plutons and dykes indicate a history of about 4km of uplift for the host upper mantle lithologies, while in a sea floor setting. The geochemistry of the intrusive plutons and dykes is similar to the lavas that crop out around the periphery of the WLFC, and Indicate derivation from a depleted upper mantle source. Geochemical comparison with the Troodos massif basalts suggests a tectonic history involving rapid extension across the WLFC and adiabatic melting of the upper mantle producing boninitic magmas. The regional setting for the WLFC suggests a model of formation involving the development of a transtensional transform fault zone and an extensional relay zone that off-set to the south, sinistral transform movement along the Arakapas fault belt. Comparison of the WLFC with a transpressional palaeo-transform fault preserved in the Antalya complex of Turkey suggests that the Neo-Tethyan spreading system (within which the Troodos massifformed) was experiencing an anticlockwise rotational torque during the final stages of oceanic crustal formation. |