The response of calcareous nannofossils to carbon cycle perturbations during the early Eocene

Abstract

This thesis examines the geological past to understand potential consequences of climate change, focusing on the early Eocene (56–49 Ma), a period of extreme warmth and elevated CO2. Marine sediments from International Ocean Drilling Program 378, recovered south of New Zealand, provide a record of these events. The first part of the study constructed a high-resolution age model to track warming events and revealed diachroneity in calcareous nannofossil datums, suggesting this may be a feature of early Paleogene high-latitude sites. The second part analyzes the impact of warming on nannoplankton, finding a response to transient warming events, with significant changes occurring prior to the Early Eocene Climatic Optimum. The third part presents evidence of enhanced silica content in South Pacific sediments during hyperthermals, supporting the idea of a global cooling mechanism involving silicate weathering and marine productivity.