The Ocean Floor

The Cluster works towards providing quantitative estimates of fluxes of carbon and other elements and developing modeling frameworks that integrate multidisciplinary observations into a global synthesis of the carbon cycle. The processes examined so far range from organic-matter accumulation in ocean-floor sediments to emissions of various compounds at hydrothermal vents and cold seeps to element fluxes controlled by tectonics. Following the flux of organic matter into the sedimented ocean floor, we revealed the impact of microbial processes on carbon fluxes and the composition of organic matter.

Hydrothermal systems are reactive interfaces between the ocean floor and the water column, with the fluxes across this interface impacting budgets of nutrients and various carbon species in the ocean. Current estimates of hydrothermal fluxes across the ocean floor are crude and have barely been improved in the last three decades. We have taken first major steps towards improving this situation by compiling the chemical and isotopic compositions of >6000 fluid samples from all types of geological settings in the oceans. This database will enable, for the first time, the estimation of hydrothermal fluxes resolved for different basement compositions, spreading rates, and sediment thicknesses.

We have developed fully coupled models that enable the simulation of mantle melting, magma emplacement, lithospheric deformation, and hydrothermal circulation, which now allow simulating basin-scale processes and examining the role of variable spreading rate and sea-level. The implementation of hydrothermal flow in these models is key to the ongoing progress in bringing water-rock reactions and chemical fluxes into these simulations.