Minerals Report - International Seabed Authority

that same summer. A more typical experience, previously, had been that
researchers would waste valuable time at new vent-sites diving blindly across
the seafloor in search of the actual site of venting.
5. Resource Evaluation
Once a new hydrothermal site has been located, as described above,
the problem of evaluation of that deposit’s resource potential must
commence. In many cases, this will typically be initiated through
investigation by either tethered or manned deep-ocean vehicles. For example,
a deep-towed camera system may be used to complete a thorough gridded
over-flight survey to provide a 100% coverage image determining the full
extent of the sulphides deposit (at least in 2-D). Alternately either a manned
submersible or a tethered ROV (remotely operated vehicle) may be lowered to
the seabed to conduct both detailed sampling and mapping of the seafloor
exposures of the sulphides deposit. Any further characterization of the 3dimensional
nature and/or extent of such a structure can also be conducted,
albeit at considerable cost.
In the future, it is to be anticipated that full-ocean depth AUV’s
(Autonomous Underwater Vehicles) will also be able to complete this work
extremely efficiently. Such systems could be equipped with in situ optical and
chemical instruments to first map out the 3-dimensional distribution of a
neutrally-buoyant plume to locate fresh vent-sites, to conduct detailed
imaging of the seafloor using a combination of digital photography and/or coregistered
hi-resolution side-scan sonar and multi-beam bathymetry, and
perhaps also to use high-resolution 3-component magnetometer
measurements to determine constraints on the subsurface structure/extent of
the located massive sulphides body.
In the meantime, simple analysis of plume characteristics of any new
hydrothermal field may also provide important and inexpensive first-order
information concerning the nature of the hydrothermal fluids erupting at
depth that, in turn, exhibit a pronounced influence upon the particles
collected from hydrothermal plumes overlying an extensive section of the
northern East Pacific Rise. Feely et al. [22] used the simple measure of (Iron)
Fe: (Sulphur) S: (Copper) Cu to accurately predict the relative proportions of
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