TABLE 2-2 Fluids and Life in the Oceanic Crust: Areas Where Observatories Are Very Useful to Investigate a Particular Scientific Problem and Where They Are Useful

Observatory science is VERY USEFUL to investigate the following:

  • The chemical and biological response to episodic volcanic and hydrothermal events;

  • The formation of event plumes;

  • Subsurface biosphere;

  • Marine food webs on the seafloor; and

  • The linkages between geological, biological, and chemical processes in ocean crust.

Observatory science is USEFUL to investigate the following:

  • Fluid flow on ridge flanks; and

  • Simultaneous environmental variability in ridge crest, flanks, and convergent margins.

To address the science where observatories are very useful, development or improvement of the following sensors is needed:

  • Chemical, biological, and flow-rate sensors that can operate at high temperatures for long-term deployment without servicing;

  • Fluid and biological samplers suitable for long-term deployment;

  • AUVs, drifters, and other instruments for use in rapid-event response;

  • Downhole sensors for use in boreholes;

  • Instruments for acoustic event detection (such as the SOund SUrveillance System [SOSUS]); and

  • Advanced capabilities for drilling into ocean crust.

injected into the crust. This research would include the response of seafloor biological communities at convergent margin seepage sites to abrupt changes in fluid and chemical fluxes caused by seismic activity. Similarly, the dynamics of gas hydrate formation and dissociation, especially in response to perturbations produced by tectonic cycles or global warming, is a problem of current interest that could be addressed by observatory science.

FUTURE DIRECTIONS AND MAJOR SCIENTIFIC PROBLEMS

Four different oceanic environments are important for research on fluids and life in the ocean crust: ridge crests, ridge flanks, convergent margins, and coastal areas on passive margins. The ridge-crest environment can be further subdivided into sedimented versus non-sedimented ridges, magma-rich versus



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