Collaborative Research: Unraveling the timing of intrusion and episodicity of intrusions under a distributed volcanic field

About This Grant

Distributed volcanic fields (DVFs) have many volcanic vents distributed over broad regions that are often close to population centers and important infrastructure. The chance of a volcanic eruption in a DVF in the western U.S. is about 1 in 1,000 per year, which is at least as likely as any individual volcanoes in the Cascade Range. Since these eruptions are hazardous, it is important to learn about how long they last (years? decades?) and how much area is affected by them. To answer these questions, the project team will examine exposed intrusions of the San Rafael Volcanic Field (SRVF, Utah). This 4-million-year-old DVF is eroded to about 1 km depth and now exposed at the Earth’s surface. Precise dates from these magmatic intrusions will help constrain how often underground magma bodies form and change. In doing so, this work informs models for how volcanic systems develop and cause eruptions. This work will also help clarify the link between movement of magma in the subsurface and volcanic structures and hazards at the surface. New ages, paleomagnetic data, and conceptual models will expand knowledge about the evolution of DVFs in the western United States. This project will also provide training for undergraduate and graduate students. Rock samples from this project will be used in courses for hands-on activities. Methods, models and data, will be shared with the community through portals, public databases, and publications. Images from thin sections of rocks will be added to a free digital collection of geological sample images, along with resources for teaching and research. High-precision 40Ar/39Ar dates, paleomagnetic data, and geological mapping and magnetometry surveys will be carried out to (1) constrain the absolute and relative ages of intrusive episodes, therefore calculating the number and rate of intrusive events, (2) locate and estimate the number and size of individual intrusive bodies, adding to an existing lidar-based 3D model of sills, dikes, conduits at the SRVF, and (3) integrate results in a statistical age model to calculate recurrence rates of intrusions. With such data, the episodicity of shallow intrusions beneath a distributed volcanic field will be quantified. The project’s findings will provide fundamental information to propose a 4D model of a basaltic plumbing system in an intraplate setting related to the growth of a DVF at the surface, with the goal of generalizing concepts to explain observations made at the surface in Quaternary volcanic fields. The data gathering and modeling activities proposed in the workplan offer a unique opportunity to discover the frequency and magnitudes of intrusions that feed DVF eruptions, thus providing a crucial link between subsurface intrusions and the resulting volcanic hazards at the surface, with aims to inform monitoring and forecasting efforts at intraplate DVF and elsewhere. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.