Reconstructing paleoenvironments in the paleogene: microfossils on the paleocontinental coastal plain

Abstract

Since 66.05 million years ago (i.e., the start of the Paleogene; 66.05-23 Myr), the Earth has undergone significant development. As such, the latest Paleocene to Eocene (~56-37 Myr) greenhouse world is the focus of this dissertation. The overall warming trend of the latest Paleocene to early Eocene was punctuated by prominent warming events, called hyperthermals. These transient episodes of warming were marked by negative carbon isotope excursions (CIEs) recorded in both the marine in terrestrial setting, and were linked to the injection of isotopically light carbon into the Earth’s mobile carbon reservoirs. The most prominent of these events is known as the Paleocene Eocene Thermal Maximum (PETM; ~56 Ma), an event associated with abrupt warming, ocean acidification, and has been compared to modern climate change. From the middle Eocene onwards (~48 Ma), global deep waters and high-latitude temperatures cooled, eventually leading to the onset of continental-sized Antarctic glaciation at the Eocene-Oligocene Transition (EOT; 34-33.5 Ma). This greenhouse-to-icehouse event, which is marked by a noteable increase in δ¹⁸O, is due to either a decline in atmospheric CO₂ and/or changes in oceanic circulation (gateway openings).

The following dissertation focuses on three periods from the timeline described above. The first chapter investigates the evidence of widespread wildfires linked to an extraterrestrial impact at the Paleocene-Eocene boundary. The second chapter examines the faunal response associated with early Eocene hyperthermal events on the New Jersey paleocontinental margin. The third and final chapter considers the role of glacioeustasy in a greenhouse world.