School of Geosciences Seminar Series - Colleen Dalton (EarthScope Distinguished Lecturer)
Dr. Colleen Dalton: Associate Professor, Department of Earth, Environmental and Planetary Sciences | Brown University
Dalton SMALL.jpgColleen Dalton is an Associate Professor in the Department of Earth, Environmental and Planetary Sciences at Brown University. Her research is focused on using seismic waves to image the Earth’s crust and mantle in order to determine the three-dimensional distribution of temperature, composition, partial melt, and volatile abundance. Colleen has developed new approaches that utilize seismic-wave amplitudes to image seismic attenuation. Her research also combines geophysical observations together with observations from other geoscience disciplines, such as geochemistry and mineral physics, to produce a more complete picture of the planet’s interior. She was awarded an NSF CAREER grant from the EarthScope program in 2016. Colleen received her B.S. in Geology/Physics-Math from Brown University and her Ph.D. in Geophysics from Harvard University. She was a postdoctoral fellow at the Lamont-Doherty Earth Observatory at Columbia University and an assistant professor in the Department of Earth Sciences at Boston University before joining the Brown faculty in 2014.
Presentation: The evolution of a continent as revealed by seismic-wave attenuation
The North American continent contains vastly diverse geology: volcanoes and mountains in the west, interior plains, and broad hills in the east. This topography reflects the episodes of continental collision, breakup, and modification that the land mass has experienced over billions of years. The movements of tectonic plates at Earth’s surface are inextricably linked to convection in Earth’s mantle. Understanding the connection between the Earth’s interior and surface is essential to addressing fundamental questions about how continents are created, how they evolve over time, and how they are destroyed.
In this talk I will discuss how the energy loss (attenuation) experienced by seismic waves can be used to image the properties of the crust and mantle beneath North America and, by extension, the evolution of the continent. While it is generally acknowledged that seismic attenuation has the potential to be a valuable source of information about the Earth’s interior, it is difficult to isolate attenuation from other wave-propagation phenomena, which has historically limited its use by researchers. The EarthScope USArray seismometers have recorded what is likely the best data set in existence to confront many of the challenges that typically plague investigations of surface-wave attenuation. I will also show how jointly interpreting models of seismic attenuation and velocity together with laboratory measurements of these quantities can constrain the variations in temperature, composition, partial melt, and water in the North American upper mantle.