Pliocene–Pleistocene sedimentary development of the syntectonic Polis graben, NW Cyprus: evidence from facies analysis, nannofossil biochronology and strontium isotope dating

Abstract

The recently uplifted and exposed Pliocene and Pleistocene sedimentary infill of the neotectonic Polis graben provides an excellent opportunity to understand extensional basin development in a marine setting. Fieldwork, facies analysis and dating using nannofossils and strontium isotopes reveal how the sedimentary conditions evolved during infill of the Polis graben during Pliocene and Pleistocene time, and allow a composite succession for the depocentre to be determined for the first time. Six lithofacies are recognized in the northern Polis graben, allowing evolving palaeoenvironments to be inferred. By the end of Miocene time (Messinian) a major c. N–S-trending graben was established; extensional faulting continued during the Pliocene–Pleistocene until recent time. Post-Messinian salinity crisis deposition began with deposition of hemipelagic muds (c. 5.08–2.76 Ma), equivalent to the Nicosia Formation. This was followed by upwards incoming of repeated normal-graded bioclastic carbonates (couplets) (c. 2.76–1.6 Ma), which are interpreted as age-equivalents of the Athalassa Formation elsewhere in Cyprus. The upwards sudden facies change is explained by tectonically controlled shallowing which enabled neritic carbonate production on the basin margins. The appearance of basement-derived material (e.g. ophiolitic extrusive detritus) in the highest stratigraphic levels of the basin fill in the north (c. 1.7–1.6 Ma) reflects onset of rapid surface uplift focused on the Troodos ophiolitic massif. Overall, the syntectonic basin infill appears to document a two-stage, pulsed uplift related to early-stage collision of the African and Eurasian plates in the easternmost Mediterranean region.

The Uplift of the Troodos Massif, Cyprus

“…Final cooling commencing at 6 ± 2 Ma is in line with a late Miocene phase of N‐S shortening reported by several workers (e.g., Calon et al, ; McCallum & Robertson, ; Stow et al, ), and also E‐W extension forming the sedimentary basins (Balmer et al, ).…”

“…Subsidence accelerated in the early Pleistocene (Robertson, ). In most parts of Cyprus, there was a short period of shallow marine sedimentation in the Pleistocene; otherwise, the Pleistocene was entirely non marine, except for coastal fringing areas (Balmer et al, ).…”

Provenance and magmatic-tectonic setting of Campanian-aged volcaniclastic sandstones of the Kannaviou Formation in western Cyprus: Evidence for a South-Neotethyan continental margin volcanic arc

“…The post-depositional geological development needs to be taken into account to understand the sedimentary development of the Kannaviou Formation. In particular, western Cyprus was affected by extension along a c. north-south axis during late Miocene to recent, related to formation of the Polis graben (Robertson, 1977c;Robertson, 1995, 2000;Balmer et al, 2019).…”

“…3, 4e). The formation was later transected by c. northwest-southeast-trending steep extensional faults related to the Polis graben during late Miocene-Pliocene Robertson, 1995, 2000;Balmer et al, 2019) (see Supplementary material). The present-day exposure is locally influenced by landsliding, triggered by the Pleistocene uplift of Cyprus and related earthquakes (Mercier et al, 1973;Robertson, 1977c;Poole and Robertson, 1998;Morag et al, 2016).…”

Pliocene–Pleistocene sedimentary and geomorphologic development of the Vasilikos river catchment, S Cyprus, in relation to uplift of the Troodos ophiolite and climate-related changes

“…Although the Troodos Massif has risen as a relatively coherent entity, this has been modified by neotectonic faulting in some areas. The most notable of these is the Polis graben of west Cyprus, which has continued to be highly active during Late Miocene to Recent time (Robertson, 1977a;Payne & Robertson, 1995;Balmer et al 2018). In addition, coastal SE Cyprus is cut by numerous high-angle c. E-W faults that are related to regional strike-slip faulting (Soulas, 2002;JP Soulas & Geoter Consortium, unpub.…”