This new paper examines the role of lithospheric melting during the late stage of rifing and presents a new model describing how the lithosphere might be destroyed during this event. You can read more here.

This project was funded by NSF through  Award # 1850606

Assessing the relationship between strain localization and magmatism during rift evolution

This NSF award focused on one of the most important concepts associated with plate tectonics: the unresolved details surrounding how continents break apart and oceans are created. Among the questions that have remained elusive is the mechanism by which large volume pulses of lava are created just prior to ocean formation.  These lava pulses can dominate the architecture of the offshore continental shelf after breakup, a critical region for hosting natural resources. Our study focused on the East African rift system because this region is actively splitting apart the continent of Africa, allowing us to probe processes currently in operation. We used the chemical composition of lavas erupted in the East African Rift to probe the conditions under which Earth’s mantle melted to form the magmas that eventually created the large volume lava pulses. Our research discovered two mechanisms that allowed magmas to form:

1) The tectonic plate upon which Africa is located experienced episodes of focused thinning. When the plate experienced such an episode, the mantle beneath it was able to rise into the space created, melt, and generate magmas.

2) Magma infiltrated the overlying plate and, through chromatography, changed the composition of the plate. This new composition made the plate more susceptible to melting. Magmas were generated upon minor thermobaric perturbation of the plate as continental breakup continued.

This is a critical new discovery as it is a new mechanism to explain how a thick continental plate can transition to a much thinner oceanic plate.  

This work has broader implications beyond the discipline. Our new discoveries about the mechanisms of magma generation during the terminal stage of rifting have application to understanding the structure and evolution of many passive rifted margins, such as the Eastern seaboard of the United States. Specifically, placing new constraints on the relationship between thinning of the plate and the formation of thick piles of lava, or identifying new magma-generation mechanisms disconnected from this plate thinning process, may impact interpretation of these rifted margins. 

Training and human resource development have been a central feature of the project. Three graduate students have been funded by the project and will enter the United States STEM workforce. The project permitted 12 undergraduate students to undertake research projects and receive training in modern geoscience methods. Students learned techniques such as: research study construction, hypothesis building, data collection and processing, data interpretation, and the presenting of findings in oral or written form at a local or national meeting. These experiences resulted in many students deciding to attend graduate school in STEM disciplines, building the pipeline for such talent in the United States. Additionally, the project supported the employment of undergraduate students working in the laboratory preparing samples and undertaking other practical tasks. Funds from the award help maintain the geoanalytical infrastructure at MSU – providing a resource in Central Michigan for the characterization of earth materials. Award funds furthermore expanded our analytical infrastructure by permitting the establishment of geologically-relevant isotopic separation facilities at MSU for the first time.

The communication of research findings is an ongoing process. Two graduate students and four undergraduate students continue studies on their projects commenced during the award. To date, we have presented our findings in seven journal articles, with one book chapter awaiting publication. Findings from the project have been disseminated in 14 presentations at national and international conferences. Additionally, undergraduate students supported by the project have presented their research findings at the University-wide MSU Research and Arts Fair.