Collaborative Research: NSF GEO-NERC: The Cracking of a Craton: Understanding Volatile Release during Continental Breakup

The oldest and most stable parts of the Earth’s continents are called cratons. When continents break-up, or rift, these stable crustal areas split apart and allow magma to rise from Earth’s deep interior. This forms new crust. When this happens, reservoirs of economically valuable volatile elements like helium and hydrogen get stuck underneath the craton, forming a reservoir. Geologically important volatiles like carbon dioxide also get stuck, but how and why this happens is not well understood. When cratons eventually break apart, these gases are released to the atmosphere and have potentially significant impacts. The goal of this work is to determine the processes that control how volatiles are made and stall, how they move through the crust, and how they are released at the surface. This team will focus on the Tanzania Craton. Graduate students will be trained in field and laboratory techniques, data interpretation and application of these techniques as they relate to economically valuable gases.

This project is a comprehensive study of the volatile gases that are being emitted from gas and water seeps along the flanks of the Tanzanian craton - a region where the stable continental craton is actively being “cracked” by rifting and simultaneously heated by plume-induced volcanism. The overall aims are to understand: 1) the mechanisms by which gases have been produced and stored in stable cratons over >109-year timescales, and 2) how they are liberated and transported to the surface during cratonic breakup. The study primarily focuses on helium (He) and nitrogen (N2) and their isotopic characteristics, which are the main constituents of cratonic gas accumulation, but other noble gases (Ne, Ar, Kr, Xe) and their isotopes, CO2, CH4 (as well as their isotopes) and H2 in seeps will also be measured. Field-and lab-generated gas chemistry results will be used to form an integrated model of gas formation and transport along the flanks of the Tanzania craton. Volatile fluxes will be calculated to understand the extent of gas release when a cratonic region is disrupted by rifting and volcanism. Constraining how volatiles are accumulated and released during steady-state rifting and magmatic conditions will allow characterization of cratonic volatile inventories and fluxes. This information will provide valuable context to researchers studying the effects of gases abruptly released from the stable craton to the atmosphere as well as the formation of economically valuable gas reservoirs of helium and hydrogen.

This award was made possible through the NSF/GEO-UKRI/NERC lead agency opportunity.

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.

Award Number: 2618910
Principal Investigator: Tobias Fischer
Funds Obligated: $211,902
State: CA