NSF Award
2413598
Gas hydrate is an ice-like substance that contains mostly water and methane gas, requiring moderate pressure and low temperature to form and is often found in deep-water sediments and polar regions. Following depressurization or increasing temperature, hydrates melt into water and methane, which can lead to ocean acidification and the addition of greenhouse gases to the atmosphere. Polar hydrates are particularly unstable after ice-sheet retreat due to increased temperature and loss of pressure from the ice overburden. New heat flow and sediment core data from the Ross Sea, Antarctica collected during an RVIB Nathaniel B. Palmer research cruise tentatively scheduled for February-April 2025 will provide the basis for future ice sheet and hydrate modeling to investigate the mechanisms that control the rate at which the hydrate stability zone has adjusted to the retreat of the Antarctic Ice Sheet since the Last Glacial Maximum. Results will provide information on the amount of methane released in the past and potentially into the future, a significant contribution towards broader international initiatives to investigate carbon fluxes in Antarctica. <br/><br/>This project will collect key datasets for investigating potential instabilities of the Ross Sea gas hydrate system. Warming, uplift, and depressurization from post-glacial rebound are predicted to lead to hydrate destabilization in polar regions, making these hydrates particularly vulnerable to change. Bottom simulating reflections (BSRs) in seismic data, marking the base of hydrate stability, can be used to constrain sub-seafloor temperatures. In the Ross Sea, in an area near the Terror Rift, there is a significant discrepancy between BSR-derived temperatures and those from seafloor heat probes from the 1980s, indicating the hydrate system may be out of equilibrium and still be adjusting following ice-sheet retreat. Alternatively, vertical migration of deep-sourced thermogenic natural gas may result in a more stable hydrate than one formed from pure microbially formed methane. This project will collect key observations that will aid in distinguishing between these mechanisms. Heat flow data, collected along geochemical coring transects and co-located with seismic data will provide necessary constraints to discern between BSR- and seafloor-derived temperatures. Additional sediment cores will be collected to determine the timing and rate of past ice-sheet retreat. These data form the basis for reconstructing the evolution of the Ross Sea gas hydrate system from the Last Glacial Maximum to the present, providing constraints on methane flux from dissociating hydrate in the past and therefore informing the future. The project will also offer undergraduate and graduate students hands-on experience in marine heat flow studies, and, more broadly, Antarctic science.<br/><br/>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.
