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Absolute Pacific Plate Motions and the Evolution of the Hawaii-Emperor Seamount Chain

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The plate tectonics hypothesis remains a fundamental paradigm in the Earth sciences. One avenue of research focuses on absolute plate motions (APM), seeking to determine models that may place lithospheric motions in a geodynamic framework. Traditionally, APM models are inferred from seamount chain geometry and age progressions. A classic example is the association of the Hawaii-Emperor Bend with a prominent change in motion of the Pacific plate at 50 Ma. Yet, the discovery of significant paleolatitude anomalies along the Emperor Ridge has shifted modeling efforts from a fixed hotspot reference frame to ones defined by moving hotspots. Incorporating plume drift has made modeling more challenging as direct observations of plume drift are lacking. Predictions from mantle convection models that broadly satisfy observed paleolatitudes have so far been the only approach to derive APM over moving hotspots. Nevertheless, uncertainties in mantle rheology, temperature, and initial conditions make such models nonunique and not precise. Furthermore, the Pacific plate is particularly difficult to model due to a limited set of seamount ages and an absence of continental crust from which reliable paleolatitude observations could be made, necessitating oceanic drilling of seamounts. Unlike stable terrestrial locales, volcanic seamounts undergo a rapid dynamic evolution over a geologically short period, and it remains unclear if this evolution and subsequent decay could induce tilting of the platform which might bias paleo-inclinations observed today.

This seminar will discuss recent developments in understanding the origin of the Hawaii-Emperor Bend and its significance for APM studies. I will examine the evidence for plate and plume motions and review the paleomagnetic, geometric, and chronologic observations from the Pacific basin. My ongoing Leverhulme Visiting Professorship at the University of Oxford involves modeling of the dynamic evolution of the Hawaii-Emperor seamount chain and building a temporal model to mimic the construction and decay of the entire chain. The model will be used to load a suitable rheologic model for the lithosphere and allow us to examine predictions of spatial and temporal variations of flexural deformation, implications for seamount tilt and the potential for bias in paleomagnetic inclinations obtained from oceanic drill holes. In addition, it will hopefully provide new insight into the evolution of one of the most ubiquitous landforms on Earth: seamounts

This talk is part of the Bullard Laboratories Wednesday Seminars series.

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