Resumen de Messinian evaporites in the Mesaoria Basin, North Cyprus: facies and environmental interpretations
This study focuses on the depositional environments of the Messinian evaporites exposed in the Mesaoria Basin of Northern Cyprus, which has been considered as a marginal gypsum deposit formed in the upper evaporites. The evaporite unit is divided into several kinds of gypsum facies, such as nodular gypsum (F.1), non-bedded selenite (F.2), bedded selenite (F.3), laminated–interbedded grass-like selenite (F.4), gypsarenite with selenite banks (F.5), gypsum megabreccia (F.6), and non-selenitic laminated gypsum (F.7). Among these, nodular gypsum (F.1) and gypsarenite with thick-bedded selenite banks facies (F.5) occurred on the evaporative shoal, modified by seasonal lowstand–highstand cycles with multiple drying and flooding episodes. Selenite facies (F.2-4) was deposited in a wide range of shallow-subaqueous environments, such as marine-fed salinas divided into deep (perennial), moderately deep and shallow (ephemeral) pans resulted from fluctuations of the pycnocline level in the saline pans. In particular, the shallow pans were temporarily influenced by sheet flood or runoff fresh water, leading to the deposition of the grass-like selenite (F.4) with fresh/brackish water limestone (e.g., İskele section). The Gypsum megabreccia (F.6) is a mass flow deposit or consists of blocks emplaced by gravity in the deeper basin. This depositional period was indicated by large-scale slope failure and basin margin erosion that was triggered by synsedimentary tectonics towards the end of the Messinian episode. Non-selenitic laminated gypsum beds (F.7) are composed of alternations of resedimented/detrital fine gypsum with (current structures), chemical gypsum cumulates, carbonates and diatomaceous muds (with sulfur nodules). Halite-anhydrite couplets were only inferred in a borehole drilled in Yeri village south of Lefkosa (Nicosia). In contrast to the basin margin erosion between Messinian gypsum and Pliocene marine sediments, the halite-anhydrite grades upwards into the Latest Messinian/Early Pliocene-shelly gray mudstone and peats, presumably indicating Lago-Mare-type deposits. The various kinds of gypsum facies studied here have average values of stable isotopes (δ 87/86Sr = 070896, δ18O = 13.5, and δ 34S = 24.6) which fall into the isotopic range of Messinian marine evaporites.
