Michael J. Mottl

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Hydrothermal circulation within the sea floor, through lithosphere older than one million years (Myr), is responsible for 30% of the energy released from plate cooling, and for 70% of the global heat flow anomaly (the difference between observed thermal output and that predicted by conductive cooling models). Hydrothermal fluids remove significant amounts(More)
[1] One hundred seven thermal gradients were measured in shallow surface sediments using the submersible Alvin within a 0.5 km area on and around the 65-m-high, mostly sediment-covered Baby Bare outcrop located on the eastern flank of the Juan de Fuca Ridge. Heat flow values range from 0.35 W m , which is close to the average value (0.27 W m ) for the(More)
During the cycling of seawater through the earth's crust along the mid-ocean ridge system, geothermal energy is transferred into chemical energy in the form of reduced inorganic compounds. These compounds are derived from the reaction of seawater with crustal rocks at high temperatures and are emitted from warm (</=25 degrees C) and hot ( approximately 350(More)
During the Integrated Ocean Drilling Program (IODP) Expedition 331 at the Iheya North hydrothermal system in the Mid-Okinawa Trough by the D/V Chikyu, we conducted microbiological contamination tests of the drilling and coring operations. The contamination from the drilling mud fluids was assessed using both perfluorocarbon tracers (PFT) and fluorescent(More)
[1] We use the distributions of sediment physical properties and modeled basement overpressures to estimate the spatial distribution of fluid seepage through sediments over and around the ‘‘First Ridge,’’ a buried basement ridge on the eastern flank of Juan de Fuca Ridge. Fluid discharge rates differ by 1 order of magnitude because of differences in(More)
The hydrogen-isotope [deuterium/hydrogen (D/H)] ratio of Earth can be used to constrain the origin of its water. However, the most accessible reservoir, Earth's oceans, may no longer represent the original (primordial) D/H ratio, owing to changes caused by water cycling between the surface and the interior. Thus, a reservoir completely isolated from surface(More)
A sealed borehole observatory (CORK) was deployed on South Chamorro Seamount, an active serpentinite mud volcano in the Mariana forearc to explore subduction-related processes on a non-accretionary, convergent plate margin. Formation fluid was overpressured relative to ambient hydrostatic conditions. Fluid flowed from the borehole at ~0.2 L/s when the(More)
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