Day 5, Locality 2

Excerpt from CGE-7, pp 117 to 120.  Stop 5.1 Sedimentary and volcanic rocks of the Dhiarizos Group.

The geological foundations of southwest Cyprus are possibly the most complex on the island.  Here there are a great variety of lithologies, interesting geological relationships and excellent exposures.  The basement geology of this region is made up of rocks of the Cretaceous Troodos terrane and the Triassic-Cretaceous Mamonia terrane, which were brought together by plate-tectonic processes in the Upper Cretaceous during closure of part of the Neotethyan Ocean.  Erosional windows through the Maastrichtian and younger sedimentary cover rocks expose the suture zone between these two terranes.  It is marked by outcrops of serpentinite and it forms an arcuate belt almost 30km wide that runs east-west in the southwest part of the island and bends around to become north-south on the Akamas Peninsula.  These serpentinites are derived from the Troodos terrane and they form part of a series of displaced rock masses that resulted from the collision between the Mamonia margin and Troodos microplate.  The partial subduction of the Mamonia margin beneath the Troodos microplate caused the build-up of a prism of accreted thrust slices at the subduction zone, in which Mamonia and Troodos rocks were tectonically mixed in an intricate fashion.

The spectacular view to the west reveals large blocks of pale limestone rising out of the inviting blue sea.  The largest block on the far promontory is Petra tou Romiou (the Rock of Romios).  Thus, this rock is named not after Aphrodite, the goddess of love who is alleged to have ascended from the waves at the rock, but rather the Byzantine folk hero Romios, who used this and other large blocks and boulders to hurl at pirates.  More importantly, from the viewpoint it is clear that the limestones are closely associated with dark rocks in the foreground, which are Upper Triassic volcaniclastic sandstones, tuffs, pillow lavas and lava breccias in a matrix of thin-bedded dark-red radiolarian cherts and mud­stones.  This close link between the limestones and volcanic rocks is ubiquitous throughout the Mamonia terrane and lends support to the idea that the limestones represent what were once small carbonate reefs on volcanic islands and seamounts associated with oceanic crust that formed during the early stages of the opening of the Tethyan Ocean basin.

It is worth casting an eye over the slopes on the land­ward side of the road.  These are dominated by chalks, marly chalks and marls of the Lefkara and Pakhna Formations, which are clearly unstable and failing in places because of movement concentrated within marl and within the clay-rich lithologies in the underlying Mamonia rocks and Kannaviou Formation, upon which the carbonate rocks rest unconformably.  This unconformity marks the end of significant regional tectonism in the geological evolution of the island and the onset of a tectonically quiescent period in much of southern Cyprus.