Abstract

It is widely accepted that the Troodos massif of Cyprus is a fragment of oceanic lithosphere formed at a constructive margin beneath a small marginal sea some 85 m.y. ago. The Arakapas fault belt is an elongate east-west fracture zone where an intensely brecciated basement of ocean crust is overlain by a variety of mafic volcanic rocks and clastic sediments. While constructive margin processes were still active elsewhere on the massif, the Arakapas fault belt existed as a trough with a rugged bathymetry formed of numerous fracture zones between which were relatively undeformed blocks. The north-south–trending dikes of the main massif swing progressively westward into an east-west alignment as the fault is approached. This deviation could be due to horizontal drag along the fault, but dike injection into a sygmoidal stress field prior to the development of the fault is considered. Onto the rugged bathymetry, in which fault scarps and associated scree deposits are still identifiable, mafic lavas were extruded, and a variety of sediments, produced by the submarine erosion of bathymetric highs within and on the flank of the trough, were deposited. Some of the volcanic rocks within the fault belt are more primitive than those of the main massif, and this is interpreted as owing to a higher percentage of melt in the underlying mantle and easier egress for the basaltic magmas. The metamorphic imprint indicates that the thermal gradient in the fault zone was steeper than elsewhere on the massif and that quantities of circulating sea water were greater. Later, once this part of the fault zone had moved well outside the constructive margin offset, serpentinite masses were emplaced and normal and reverse faulting occurred. Structural, petrochemical, and sedimentary features combine to suggest that the Arakapas fault belt is a fossil transform fault.

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