Abstract

The map pattern of the Troodos ophiolite in Cyprus is an expression of a simple, elongate anticlinal structure. The cross-sectional form of the anticline can be described by a sinusoidal dip model. On the northern flank of the anticline, the thickness of various units, number of gossans, etc., were measured along profiles, at 2.5 km intervals normal to strike, using existing maps supplemented by new observations. Profiles are approximately perpendicular to the spreading direction during crustal construction, and uncertainties in unit thickness are smaller than the range of unit thicknesses.Data on the profiles were analyzed quantitatively by harmonic analysis using the Fourier transform method. The harmonic analysis discloses cyclic variation in the thickness of major units, number of gossans, etc., that provides a link with the regular spacing of five groups of Cu–Fe–Zn orebodies. Groups of orebodies occur preferentially where sheeted dikes are at a shallow crustal depth, sheet and massive flows and dikes are common in the extrusives, the sediment–extrusive interface is at a relatively low elevation, and gossans and umbers are well developed. This association has the potential for providing an exploration tool in Cyprus and elsewhere. It can be accounted for in terms of the regular arrival in the crust of batches of mantle-derived magma. Arrival of a batch of magma in the crust would have been followed by voluminous sea-floor eruptions (which often formed sheet or massive rather than pillowed flows), rapid extension and subsidence, and enhanced hydrothermal circulation, a combination of circumstances leading to an increased probability of formation and preservation of orebodies.The thickness variations provide context for the few measured thickness values for in situ oceanic crust. The wide range in thickness values for the Cyprus ophiolite and the elevation of the sediment–extrusive interface suggest that the ophiolitic ocean crust was probably formed in a low-spreading-rate environment.

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