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New InterRidge WG: Global Partitioning of Hydrothermal Activity

InterRidge Office mac at ext.jussieu.fr
Mon Dec 29 08:14:23 EST 1997

No. 36 of the 1997 Series of E-mail Announcements from the InterRidge Office
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New InterRidge Working Group: Global Partitioning of Hydrothermal Activity
Chair: Chris German (SOC, UK)

Dear Colleagues,

It is now recognised that hydrothermal circulation is more widely
distributed around the world's ridge-crests than had been previously
thought.  For physicists and geochemists this is of importance when
determining global hydrothermal fluxes which, to-date, may only be
cosntrained to within an order of magnitude.  Additionally, for relatively
short residence time chemical species which are not well-mixed throughout
the world's oceans, it is important to improve our understanding of how
their hydrothermal input is partitioned between the world's deep ocean
basins.  For marine biologists it is important to understand how different
biogeographic provinces have developed as a key to improving our
understanding on the nature and rates of evolutionary processes.  Also,
given the diversity of species, new to science, which have already been
found at the various vent-sites discovered so far, it seems clear that we
have not yet witnessed the full global biodiversity of these extreme
submarine environments.

Following discussions by the InterRidge steering committee and an open
InterRidge meeting at the American Geophysical Union's Fall Meeting,
on Dec.11 1997, we propose to establish a new InterRidge Working Group aimed
at targetting, and coordinating international collaboration in new areas of
the global ridge-crest which, to date, remain unexplored for hydrothermal
activity.  Clearly, it is neither practical, nor desirable, to attempt
systematic hydrothermal mapping of the entire global ridge-crest.  Rather,
we propose to adopt an intelligent approach to targetting new areas for
research, informed by both geophysical and geological input (e.g. selecting
areas with pre-existing swath bathymetry but also identifying key tectonic
provinces or petrologic domains) as well as being steered by vent
biogeographers' input as to key areas in which discovery of new species
might be most informative concerning global distributions of vent-specific
species through time.

We already have a simple and testable model which predicts that frequency
of venting should be directly related to heat-flux/spreading-rate.
However, it is already clear that this model needs further verification and
detailed revision, not only along slow and fast spreading ridges but also
in back-arc basin spreading centres.  Additionally, the question of how
hydrothermal fluxes at a given ridge location are partitioned between vents
and more diffuse and cooler fluxes needs further investigation, in a variety
of spreading environments.  We welcome any further input that individuals
may be able to contribute - either because they were unable to attend the
open discussion at AGU, or because they have had further time to reflect
since that meeting.  We seek contributions from suitably experienced
geophysicists, petrologists and vent biologists as well as the hydrothermal
researchers who, we envisage, will form an integral part of this working

Please send your contributions to Cara Wilson at the InterRidge
Office in Paris before the end of January 1998.  Cara and I will compile any
additional input received, and, over the timescale, we will invite
participation in an opening membership of the WG (approx. 10 people).  In
keeping with InterRidge objectives, invitations to join the working group
will be made to ensure that the group reflects a suitable blend of both
interdisciplinary and international expertise.  The aim will be to convene
a first meeting of the Working Group itself, as early as possible in
1998, to prepare a preliminary project plan for the working group, which it
is hoped would be able to identify a series of key target areas for future
new research as well as establishing a mechanism for coordinating more
efficient add-on hydrothermal upgrades to already funded geophysical and
geological cruises.

I shall look forward to hearing from you in the New Year.

Best wishes,  Chris

Chris German, SOC
Partitioning WG Chair    

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