Insights into the Middle-Late Miocene palaeoceanographic development of Cyprus (E. Mediterranean) from a new δ¹⁸O and δ¹³C stable isotope composite record

Abstract. The Middle to Late Miocene was a time of significant global climate change. In the eastern Mediterranean region, these climatic changes coincided with important tectonic events, which resulted in changes in the organisation of oceanic gateways, altering oceanic circulation patterns. The Miocene Climatic Optimum is regarded as the most recent CO₂-driven warming event in Earth’s climate history and has been proposed as an analogue for future climate change. We present a c. 12 Ma record of oxygen and carbon stable isotopes from the Island of Cyprus to help constrain the nature and extent of Miocene palaeoceanographic changes in the eastern Mediterranean region. Cyprus includes Neogene deep-sea pelagic sedimentary rocks which are suitable for stable isotope studies. Our composite geochemical record integrates data from the Lower-Upper Miocene succession at Kottaphi Hill along the northern margin of the Troodos ophiolite, and the Upper Miocene succession at Lapatza Hill to the south of the Kyrenia Range. Calcareous nannofossil biostratigraphy reveals that the composite record spans the Miocene Climatic Optimum's onset to the beginning of the Messinian Salinity Crisis. The new stable isotopic record reveals a complex interplay between global climate change and regional-to-local tectonic changes. In the earlier part of the record, global climate change dominated; however, by the end of the Late Miocene, tectonic events culminated in isolation of the Mediterranean basins, resulting in a deviation from the global open-ocean trends. Strontium isotope analysis was used primarily to help constrain the age of the Miocene successions sampled but also implies changes in the connectivity of eastern Mediterranean basins during the Late Miocene. This research provides a useful reference for oceanographic changes during the Miocene of the Eastern Mediterranean compared to the global oceans.