Possible Trigger Mechanisms for the Paleocene-Eocene Thermal Maximum

Overview

The purpose of our experiment was to use the information and core samples we had to impact the ongoing discussion of what caused the Paleocene-Eocene Thermal Maximum (PETM) that happened around 55 million years ago.The Paleocene-Eocene Thermal Maximum was an abrupt global warming event that occurred over the course of approximately 20,000 years, with a recovery period lasting as long as 200,000 years. It was marked by an increase in sea surface temperatures (SST) of approximately 5℃ in the tropics and greater in Arctic regions. This time period is seen in sedimentary records through an excursion in carbon isotopes of approximately -3‰ , and a widespread dissolution of calcium carbonate. During this time period, there was a significant decrease in overall benthic foraminifera abundance and size. Analysis of sediment cores in New Jersey, Virginia, and Maryland show the kaolinite-rich clay deposits during this time period, known as the Marlboro Clay, which indicates an increase in temperature and precipitation. Multiple theories exist to explain the anomalies, including theories of an impact and volcanic sill intrusions in the North Atlantic Igneous Province. The experiment was conducted in three main steps: core cleaning and disaggregation, foraminifera picking, and mica picking. The cores that we were given were in large solid pieces and in order to pick mica and foraminifera, they needed to be broken down. The foraminifera were from a >63 micron fraction and we used a paintbrush to pick them out of the core samples and into a picking tray. The picked foraminifera were then imaged, weighed and sent to a mass spectrometer. Similar to the foraminifera, the mica were picked in the same way and were irradiated and measured for age with the Ar method to identify their source area. The benthic foraminifera indicated a sudden decrease in delta-C13 of 4‰, precisely at the start of the Marlboro Clay, which agrees with the bulk carbonate isotopes both in magnitude and duration. Additionally, the recovery of the excursion overlaps with the termination of the Marlboro Clay layer. .

Competition history

• AJAS 2018 Category not listed

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