Postdoctoral Fellowship: EAR-PF: The generation and interaction of magmatic sills and dikes in extensional settings

The transport of magma is a fundamental process in volcanic eruptions, crustal extension and the creation of new crust on earth. Dikes and sills are magma-driven fractures that often record past evidence of this process. Over the past two decades, observations of magma transport in the crust have highlighted the need to better understand how magmatic and tectonic processes interact to emplace dikes and sills on earth. In this study, PI Scholz will conduct a combination of numerical and analog modeling to address the fundamental dynamics of the transition from dike to sill and from sill to dike in extensional tectonic settings, like the Reykjanes Peninsula in Iceland. These models will lend insight into how and where magma is stored before volcanic eruptions and into the triggering mechanisms of dikes. A better understanding of these factors is at the core of forecasting the timing of volcanic eruptions and, consequently, volcanic risk mitigation efforts. Furthermore, the project will incorporate hands-on opportunities to engage local K-12 audiences through existing outreach avenues at LDEO and mentor an undergraduate student researcher in the lab. This project will address two key questions. Does the change in stress associated with dike opening influence magma flow into sills and dikes during plate spreading and extension? Are dikes at spreading centers and continental rifts more likely to be triggered by earthquakes driven by lithospheric extension or by magma overpressure caused by pulses of magma rising from below? PI Scholz aims to demonstrate that the stress field associated with dike opening could induce sill formation using analog gelatin tank experiments that reflect the structure of spreading centers. The results from these analog experiments will be combined with numerical models for repeated dike and sill injections to understand how intrusions impact the local stress field and, consequently, the depth of sill formation during extension. To address the second question, PI Scholz will extend an existing geodynamic model for extensional margins to explore the relative importance of earthquakes and the buildup of magmatic overpressure on the initiation of dike events. By integrating these model results with existing geophysical datasets, this work will produce a novel model for the frequency of dike events in extensional settings. 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.