Geoff Wheat uses chemical tracers to understand processes that influence the cycle of elements in the oceans. Much of this work focuses on the transport of fluids through the oceanic crust in a range of settings including hydrothermal systems on mid-ocean ridges and flanks and seepage sites along zones of subduction and in coastal environments. Studies typically include sampling and analyzing fluids and solids, developing transport-reaction models, and relating results to biogeochemical cycles and crustal evolution. Wheat has participated on 79 ocean expeditions of which 49 included a submersible or ROV component. On 26 of these cruises Wheat was either the Chief Scientist or one of two Co-Chief Scientists. Wheat also has participated on two legs of the Ocean Drilling Program and seven expeditions of the Integrated (International) Ocean Drilling (Discovery) Program (IODP).

Abstract:

The Mariana forearc is home to tens of active serpentinite mud volcanoes, which are the largest mud volcanoes on Earth, some spanning 50 km in diameter and kilometers high. These mud volcanoes form at the intersection of faults in a non-accretionary forearc prism. Such faults permit fluids, muds, clasts, and rocks to be transported from the subduction channel to the seafloor. Because these active serpentinite mud volcanoes are located at different distances from the trench, they are supplied by material that originates at a range of depths, temperatures, and pressures within the subduction channel. Thus, serpentinite mud volcanoes are windows into the subduction channel, allowing us to characterize physical, thermal, chemical, and microbial processes within a subduction channel. 

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