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| Titel |
Heat and Volume Fluxes at the Turtle Pits Vent Site, southern Mid Atlantic Ridge |
| VerfasserIn |
Janna Köhler, Maren Walter, Christian Mertens, Jürgen Sültenfuß, Monika Rhein |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250035323
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| Zusammenfassung |
| The Turtle Pits vent site consists of eight known high temperature vents and several
diffuse vent sites which are distributed over three hydrothermal fields: Turtle Pits,
Comfortless Cove, and Red Lion. These vent fields are located in a north-south
orientated rift valley at the Mid-Atlantic Ridge (MAR) near 5-S. The total volume
and heat emissions of the entire Turtle Pits site have been calculated with three
different approaches using data collected during a Meteor cruise in May 2006 and a
L′Atalante cruise in January 2008. The data sets consist of vertical profiles and towed
transects of temperature, salinity, and turbidity, as well as direct velocity measurements
with a lowered acoustic Doppler current profiler (LADCP) and water samples for
Helium isotope analysis. Vent fluid samples for noble gas analysis where taken with
ROVs.
Since the vent fluid is highly enriched in primordial 3He this noble gas can be used
as a conservative tracer for vent fluid. The geographical setting of the vent site
confines the particle plume to the rift valley since the depth of the valley exceeds the
rise height of the plume. Therefore the fluxes of heat and volume can be estimated
from the horizontal helium transport in the valley in combination with a mean 3He
endmember concentration determined from the water samples taken with the ROVs.
The comparison of the 3He concentrations measured south of the hydrothermal
vents with the 3He signal north of the hydrothermal vents suggests a rather strong
northward flow. This is confirmed by the tide corrected velocities observed with
the LADCP during the Meteor cruise. The northward volume transport has been
calculated using the local bathymetry and tide corrected velocities from the Meteor
cruise. In combination with the 3He concentrations and the average 3He endmember
concentration a flux of 1000 Â l/s is estimated, which corresponds to a heat flux of
1400 MW.
The measured temperature anomalies within the plume combined with the known
background stratification and the mean flow velocity within the valley yield an estimate of the
total flux of the hydrothermal vents which is significantly lower.
Similar results have been calculated using the rise height of the particle plume estimated
from the measured temperature anomalies in combination with the background
stratification.
In contrast to the flux calculated from the 3He concentrations the fluxes calculated from
the temperature anomaly and the plume rise height only take the emissions from hot vents
into account and exclude emissions from diffuse vent sites. |
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