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  1. What is the flux-frequency distribution for ridge-crest hydrothermal activity (heat, fluid, chemistry)?

  2. To what depth and to what crustal age does significant ridge-flank hydrothermal circulation extend, and what is the influence of this flow on crustal evolution and ocean chemistry?

  3. What are the roles of fluids in the earthquake cycle?

  4. What role does fluid flow play in gas hydrate accumulation and how important are hydrates to climate change, slope stability, and energy resources?

  5. What are the extent and consequences of interactions between terrestrial ground water and marine systems (fluxes, diagenesis, biology, slope stability, canyon formation)?

  6. How much of a role does the microbial community play in subsurface chemical and physical transformations?

These, and a host of other exciting questions, remain mostly conjectural as there have been few quantitative microbiological studies specifically addressing these geological and geochemical problems. We therefore recommend that a small series of highly-focused studies be carefully prepared and executed, within several distinct seafloor environments, as soon as possible. The initial experiments should provide first-order information that will allow an assessment as to whether a significant initiative, and concentration of resources, is justified for more complete, long-term exploration of subseafloor microbial communities.

COMMON THEMES IN INFRASTRUCTURE

The main goal of the workshop meeting was to identify the important scientific questions that would be driving research in marine geology and geophysics in the next 10 to 20 years. However, it was not possible to discuss the science that we wish to accomplish without mentioning the new equipment or changes in the funding infrastructure that would either facilitate or enable researchers to address these questions. Some of these needs are pointed out directly in the thematic group reports, but others are so overarching that it made more sense to call them out in this separate section.

Common Use Equipment

Marine geology and geophysics is an observationally based science and will continue to rely on ocean-going observational capabilities. A significant amount of the technology used in MG&G studies is needed by a wide spectrum of the community (e.g., high resolution seismics for paleoceanographic, geohazard, and sediment processes studies; equipment to sample fluids and sediments; moored arrays for long-term observations for fluid and ridge crest processes; geophysical imaging equipment for studies of lithospheric and mantle dynamics, etc.).

The present funding model for much of the "common use equipment" has resulted in a gradual degradation of many MG&G capabilities. It is not unusual for equipment systems to be maintained as part of a specific ship operation. In some cases, systems are supported as independent cost centers. In either case, a use hiatus results in system degradation, loss of technician expertise, and ultimately a complete loss of the system capability. This problem affects "standard" shipboard equipment as well as portable equipment.

We recommend a community-wide effort to come to a consensus about (1) what instrumentation is broadly needed; (2) how it should be maintained and managed in a way that is appropriate for each facility; (3) how to build in appropriate funding feedbacks so that outdated or poorly managed equipment pools are discontinued and new instrumentation can be added; and (4) what funding structure best supports this equipment. While there will be some short-term costs associated with development of a reliable instrument pool that will be available to the community, in the long run, a cost-effective solution to the problem of deteriorating and unreliable facilities is essential to the health of marine geosciences.

The list of equipment that might be candidates for a shared pool is large: MCS equipment, ocean bottom seismometers, new-generation magnetometers and gravimeters, coring and sampling devices, autonomous underwater vehicles, tethered vehicles, submersibles, etc. We discuss below just a few of these capabilities that we believe are good candidates for placing in a common-use facilities pool.

Navigation

There is a general need for a community-supported facility to (1) position ships, water column instruments, and seafloor instruments in a relative reference frame with a precision of several meters; (2) position ships and instruments in an absolute reference frame with a similar accuracy; and (3) have this information available on the bridge and within scientific facilities in real time. This capability has significant implications for work across the full range of geological environments and scientific problems. Traditionally, precise navigation in a relative frame has been accomplished with a combination of seafloor transponders shipboard and relay transponders, and shipboard computer hardware and software (long-baseline navigation), all of which must be provided and integrated with the shipboard environment by a project investigator, team member, or consultant. Differential or P-code GPS similarly has not been routinely available, although this situation is changing aboard the larger UNOLS ships. Experience has proven that many scientific programs are difficult or impossible to complete without precise navigational capabilities. In addition, the captains and mates of ships of all sizes are much better able to locate and hold target positions (for both ships and instruments) when they get direct graphical feedback of relative and absolute locations. This capability should be made broadly availability within the MG&G community, and support capabilities



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