Global and regional assessment of Neogene climate and palaeoceanography using dinoflagellate cysts

• Main Author: Boyd, Jamie Lorna
• Format: Thesis
• Language: English
• Published: University of Leeds 2016
• Subjects: Sea ice
• Online Access: https://etheses.whiterose.ac.uk/16324/; https://etheses.whiterose.ac.uk/16324/1/Boyd%20-%20PHD%20Thesis%20Feb%202017.pdf

The Neogene Period (23.03–2.59 Ma) has been referred to as ‘the making of the Modern world’, which eventually, via a relatively consistent cooling trend, culminated in the present day climate conditions on Earth. Researching the Neogene provides important information for understanding how modern patterns of atmospheric and oceanic circulation developed, and how sensitive they are to environmental change. Climate and environmental parameter proxies are used to investigate past changes, and dinoflagellate cysts have great potential as their distribution can be limited by temperature, salinity, nutrient availability and sea ice cover. This project aims to use dinoflagellate cysts to study the evolution of the oceans over the Neogene and to further develop the potential of the climate proxy. This is achieved by collating all of the previously published literature on Neogene dinoflagellate cysts into a database and analysing the data on global and regional scales. This study allows for the first global synthesis, using dinoflagellate cysts, of changes that took place during the Neogene. It was found that, on a global scale, the distribution of Neogene dinoflagellate cysts was strongly controlled by temperature and can be correlated to the previously established cooling trend of the Neogene. However, short term climate changes superimposed on the overall cooling trend of the Neogene, cannot be observed. Changes to marine gateways have been shown to affect the composition of dinoflagellate cyst assemblages regionally, and caused allopatric speciation. New primary data from Cyprus demonstrates an increase in diversity in the Pliocene, which differs to the regional diversity. This reveals the importance of the difference between local and regional signals, and why it is important to understand, and to thoroughly explore, the datasets used in a global compilation.