An integrated sedimentological and magnetostratigraphic study of the Pissouri Basin: constraints on the uplift history of Cyprus?
British Sedimentological Research Group Annual Meeting, (2006.)Abstract
An integrated sedimentological, structural and magnetostratigraphic study sheds light on the Late Pliocene-Holocene uplift history of the Troodos Massif, southern Cyprus. Plio-Quaternary marine to non-marine sedimentary rocks in the Pissouri Basin, southwest Cyprus, provide an excellent record of syn-tectonic uplift.
The discrete NNW-SSE-trending extensional Pissouri basin was initiated during the Early Miocene, related to changes in regional stress patterns related to subduction and/or continental collision to the south. A possible cause of extension was relative "roll-back" of the subducting/colliding plate to the south.
The Pissouri Basin experienced a transition from deep-water pelagic sediments of the Maastrichtian - L. Oligocene Lefkara Formation, to more varied shallower water, mixed carbonate and terrigenous sediments of the L. Oligocene - E. Miocene Pakhna Formation. By the latest Miocene (Messinian) the Basin existed as a shallow, fault-bounded, silled depression semi-isolated from the Mediterranean Sea to the south. A range of pre-evaporitic to evaporitic facies accumulated, including minor amounts of microbial carbonate, overlain by fine to coarse-grained and redeposited gypsum. Facies analysis indicates several periods of tectonic instability during the Messinian, associated with sediment redeposition and slumping. During the latest Miocene, small fan-deltas prograded from the fault-active basin margins into ephemeral lakes overlain by palaeosols (‘Lago Mare’ facies). The sea flooded back at the end of the Messinian, followed by deposition of marginal fan-deltas, which pass basinwards into shelf-depth marls (Nicosia Formation). These sediments are intercalated with terrigenous siltstone/sandstone turbidites, previously interpreted as the bottomsets and foresets of large marine fan-deltas. Large, intercalated lenses of bioclastic calcarenites and ophiolite-derived sandstones are interpreted as conduits for marginal shelf and terrigenous material. Soft-sediment deformation and slump structures (e.g. overturned and recumbent ductile folds) characterise the margins of these channels. The orientation of the channelling and slumping indicates a generally southward palaeo-slope towards the deep Mediterranean Sea. Higher within the Plio-Pleistocene succession, stacked micro-Gilbert-type fan-deltas (<1.77 Ma) are interbedded with Terra Rosa-type palaeosols that are interpreted as prograding fan-delta topsets.
To determine timing of the uplift we have generated a magnetostratigraphy for the basin by palaeomagnetically analysing each unit of the Plio-Pleistocene basin-fill. Our results indicate that rapid uplift began in the latest Pliocene (c. 1.77 Ma), coincident with the large-scale progradation of the Gilbert-type fan-deltas. This timing of uplift is compatible with earlier results from elsewhere around the Troodos Massif (‘Mesaoria Basin’). The regional driving force of the uplift has been seen as the collision of the Eratosthenes Seamount with the Cyprus active margin to the south of Cyprus.