T223 Influence of Volcanism on the Evolution of Cretaceous and Paleogene Marine Ecosystems and Climate

Tuesday, 27 September 2016
1:30 PM - 5:30 PM
Room 505

VOLCANO-CLIMATE INTERACTIONS DURING THE PALEOCENE-EOCENE THERMAL MAXIMUM: ASSESSING THE IMPACT OF THE NORTH ATLANTIC IGNEOUS PROVINCE FROM THE FUR FORMATION, DENMARK

Paper number: T223-8
Program: Technical Sessions
Time: 3:20 PM – 3:40 PM

Authors

Abstract

The Paleocene-Eocene Thermal Maximum (PETM) was an extreme (5-6 °C) and rapid (<20 kyr) global warming event at ~56 Ma that persisted for ~170 kyr. This episode coincided with a major pulse of magmatism from the North Atlantic Igneous Province (NAIP), suggesting that emplacement of the NAIP could have released sufficient carbon through degassing and/or contact metamorphism to instigate the observed carbon isotope excursion. The island of Fur in Denmark is an excellently preserved terrestrial exposure of shallow marine sediments deposited during and after the PETM. Within this diatomitic clay sequence are over 180 distinct volcanic ash layers that originated from NAIP volcanic centers in east Greenland and northwest UK, indicating that they were formed during very large volcanic eruptions. The Fur Formation also contains a rich fossil assemblage, including fish, crustaceans, turtles, insects, terrestrial birds, and land plants.

Here we present the results of three stratigraphic logs through the Fur Formation, spanning the initiation of the PETM to completely post-PETM conditions (~300 kyr). We use high precision U-Pb dating of magmatic zircons found in tephra layers to estimate the mean deposition rate at Fur and to improve the timing and duration of the PETM. Detailed chemostratigraphic logs of δ13C (TOC) and δ15N values are used to place the PETM and later carbon isotope excursions within this improved absolute timeframe. Measurements of Hg concentrations within the sediments are used to assess the overall activity of the NAIP at this time. Comparisons of δ13C values between this study and other PETM sections suggests that part of the post-PETM sequence may be missing from Fur, either because of glaciotectonism or a depositional hiatus. There is a positive correlation between the largest tephra layers (#-33 and #+19) and the largest perturbations to the carbon isotopes, suggesting that a causal relationship is plausible, although there may be a local depositional effect on organic carbon preservation to consider. These results indicate that the Fur Formation is of key importance for furthering our understanding of the relationship between NAIP volcanism and Eocene hyperthermal events.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-282658

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