My research investigates carbon cycling in subseafloor hydrothermal systems. In particular, I am interested in studying fluid-rock interactions that can transform carbon compounds in these settings. CO2 in fluids emanating from hydrothermal vents is primarily derived from the degassing of magma at depth as new crust forms along mid-ocean ridges. The dissolved gas circulates through hot, permeable crust and reacts with its host rock under elevated temperatures and pressures. Yet, the fate of CO2 and its role in cycling carbon between the lithosphere and ocean depend greatly on the local physical and geochemical environments. For instance, CO2 can react with mafic and ultramafic rocks to precipitate carbonate minerals in a process known as mineral carbonation, or it can be reduced to form simple organic molecules such as methane.
My work aims to examine the conditions under which these different reaction pathways can occur and to understand the linkages between them. Such work will not only help constrain carbon fluxes in deep-sea environments, but will also have important implications for microbial ecosystems that use reduced carbon compounds as an energy source. The abiotic production of methane may help sustain a deep biosphere in regions of hydrothermal activity. Additionally, it may represent a potential mechanism for forming prebiotic compounds on an early Earth.
I am currently conducting experiments with Frieder Klein and Jeff Seewald in the Marine Chemistry and Geochemistry Department to simulate the reaction of CO2-rich fluids with the oceanic lithosphere in peridotite-hosted hydrothermal systems. Abyssal peridotites have been proposed as likely substrates for both carbonate formation and hydrocarbon production during subseafloor hydrothermal flow. Some of the questions I will investigate include: What range of environmental conditions can support mineral carbonation vs. abiotic organic synthesis? What hydrothermal settings can we expect to favor these different reactions? What does the extent of each reaction tell us about the potential of the oceanic crust to act as a source or sink for carbon? Insights gained into these questions will ultimately help us constrain carbon cycling on a global scale.
*Niya is funded through DOEI's Ocean Ridge Initiative
Last updated: August 27, 2014