Paleomagnetism and the K-Pg mass extinction - Courtney Sprain - 2021 MagIC Workshop (1/19/21)
Channel: Magnetics Information Consortium (MagIC)
Date: 2021-01-20

"Using paleomagnetism to understand the causes and consequences of the Cretaceous-Paleogene mass extinction" by Courtney Sprain, Department of Geological Science, University of Florida

Talk presented at the virtual 2021 MagIC Workshop (https://earthref.org/events/MAGIC/2021/) - Rock and Paleomagnetism through Time and Space. Jan 19th-21st, 2021.

Abstract:
Since the start of the Phanerozoic the proliferation of life on Earth has been interrupted by five major mass extinctions events. Generally, these extinction events share many common factors: they are geologically abrupt (timescales ~ Myr or less), they are associated with major shifts in climate (both warming and cooling), and four out of the five events correlate in time with the eruption of continental flood basalts (CFBs). But, to properly understand the causes of large-scale ecosystem collapse, and to what extent these extinction events can inform modern ecological crises, we have to move beyond broad generalizations and look into these extinction events in more detail. To do this, we need to understand how forcing mechanisms, such as meteor impacts or volcanism, manifest themselves into environmental change and how this environmental change results in large-scale ecosystem collapse. A key inhibitor to comprehending these major events in Earth history is poor chronology. An accurate timescale can inform us about rates of natural processes, can correlate rock sequences across distant localities and geological settings, and in turn can be used to help us understand the underlying mechanisms behind these major events. Over the past ten years, improved analytical techniques and new instrumentation have enabled amazing strides in high-precision geochronology, which has led to a large increase in the precision of geochronological ages (with achievable precisions 0.1 - 0.01%). This enhanced precision has allowed us to more closely investigate the causes of mass extinction events. 
However, high-precision geochronology is not enough. The timescales of forcing mechanisms responsible for mass extinctions are typically faster than what can be resolved using absolute geochronologic techniques, which can be further limited by the availability of the required materials for direct dating. An integration of multiple approaches is required to resolve events on these timescales, with paleomagnetism representing a powerful tool to complement direct age dating. This presentation will provide an overview of recent advances on combining absolute age data with paleomagnetic observations, with a focus on the Cretaceous-Paleogene extinction event (Fig. 1), specifically highlighting the ways in which we’ve used paleomagnetism to help us better understand the causes of mass extinction events. Traditional paleomagnetic techniques, such as magnetostratigraphy, continue to provide insights into the timing of geologic events. Here, we also highlight new techniques, such as quantitative secular variation analysis, that are helping to provide a high-resolution picture of the Cretaceous-Paleogene mass extinction.