Mamonia Complex, southwest Cyprus: Evolution and emplacement of a Mesozoic continental margin

The Mamonia Complex in southwest Cyprus comprises an assemblage of Upper Triassic to Lower Cretaceous sedimentary rocks, Upper Triassic mafic igneous rocks, and subordinate metamorphic rocks, which together lie adjacent to the southwest margin of the Troodos ophiolitic complex and its Upper Cretaceous sedimentary cover.

The sedimentary facies of the Mamonia Complex record the progressive development of a Mesozoic passive continental margin. Initial crustal subsidence associated with deltaic and turbiditic terrigenous clastic sedimentation was followed by continental rifting and then the genesis of marginal oceanic crust in Late Triassic time. Subsequent pelagic and hemipelagic deposition during Jurassic and Early Cretaceous time reflects passive continental margin subsidence. Shallow-water calcareous material derived from an adjacent carbonate platform, probably now located in southern Turkey, was deposited on the margin by gravity flows. After initial rifting, coarse terrigenous clastic input was minimal until a major influx of terrigenous material in Early Cretaceous time, possibly contemporaneous with an episode of renewed ocean-floor spreading in the area. Allowing for the 90° Tertiary rotation of Cyprus, the Mamonia rocks formed part of the northern margin of a small ocean basin during Jurassic and Cretaceous time. The Troodos Complex is likely to represent a younger surviving fragment of the same basin. By Late Cretaceous time, ocean-floor spreading had ended, followed in the Maastrichtian by disruption, folding, and emplacement of the Mamonia sedimentary sequences onto the Troodos ophiolitic rocks. The Mamonia sedimentary rocks are now arranged in subhorizontal sheets which, on the basis of fold vergence and facing directions, were emplaced toward the present northeast – that is, prior to paleorotation, toward the original southeast. The displaced sheets probably represent down-margin gravity slides. The evidence is compatible with both the Mamonia and Troodos Complexes having a local (“external”) origin in contrast to the currently favored “internalist” hypothesis involving long-distance transport.