HR: 1330h
AN: B12A-0763    [PDF]
TI: Plate Tectonic Modulation of Microbial Productivity in the Deep Ocean-A Keck-supported Proto-NEPTUNE Experiment
AU: * Delaney, J R
EM: jdelaney@u.washington.edu
AF: University of Washington, School of Oceanography Box 357940, Seattle, WA 98195 United States
AU: Keck Team, .
AF: University of Washington, School of Oceanography Box 357940, Seattle, WA 98195 United States
AB: Deformation and volcanic activity in a plate tectonic framework must result in fluid, and therefore nutrient, fluxes within the upper oceanic crust, and between the oceanic crust and the deep ocean. These fluxes support microbial activity of many types, but the linkages are difficult to define and the magnitude of the overall process is extremely difficult to characterize and quantify because of the episodic behavior of the processes involved. Solving this problem requires long-term commitment of instrumental arrays designed to simultaneously identify and measure interactions between the seafloor and the overlying ocean. Although largely operating in a plate tectonically dominated regime on earth, similar geo-biochemical processes may be active on any number of planets at some time following accretion. Understanding the interactions here on earth may inform exploration for life on other bodies in our solar system and beyond. As an initial step toward exploring these linked phenomena, three adjacent plate boundaries along the northern edge of the Juan de Fuca Plate, were instrumented in the summer of 2003 with support from the Keck Foundation and the NSF. The intent is to initiate a proto-NEPTUNE suite of experiments designed to define the basic relationships involved microbial productivity resulting from plate boundary deformation. Although deployed in an autonomous mode now, the instruments and the approaches involved will transition to the Regional Cabled Observatory planned for the NE Pacific within five years. The principal focus of this initial deployment was on a vigorously active ridge crest hydrothermal system overlying a known magma chamber. In the summer of 2003, a permanent installation of 8 seismometers, 7 seven-short period instruments and one broad band sensor, was completed at the northern end of the Juan de Fuca Ridge on the Endeavour Segment. The seismic array is complemented by a suite of temperature, fluid flow, and pressure measuring devices, as well as time-series fluid sampling systems, located in three of the five known hydrothermal vent fields. A well-defined mud volcano located along surface trace of the adjacent Nootka Transform fault, and seepage along a major carbonate-cemented active fault zone located near the toe of the nearby subduction complex were also instrumented with flow monitors and fluid sampling devices. Preliminary seismic data, baseline fluid chemistry, and selected microbial activity were characterized as an initial stage of the experiment.
UR: http://www.neptune.washington.edu/keck
DE: 0400 Biogeosciences
DE: 3015 Heat flow (benthic) and hydrothermal processes
DE: 3035 Midocean ridge processes
SC: Biogeosciences [B]
MN: 2003 Fall Meeting