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Pitch Lake Project, a Natural Asphalt Lake in Trinidad and Tobago
Pitch Lake of Trinidad and Tobago is the largest of the three natural
asphalt lakes that exist on Earth. This asphalt lake is a large oval-shaped
reservoir composed of an oil, clay and muddy water mixture. Methanogenesis
seems to be a dominant metabolic pathway based on (1) DNA sequencing results,
(2) in situ measurements, and (3) carbon isotope analyses of the chemical
composition of the petroleum. We suggest that the driving mechanism for
Pitch Lake and the nearby mud volcanoes is the same. Organic material including
bitumen near the oil reservoir is transported upward by the low density
of supercritical water as a liquefied particulate mass. Because of adiabatic
and conductive cooling some of the transported fluids will condense out,
but the internal conduit of the slurry remains at supercritical water temperatures
and is insulated against conductive cooling by sheaths of condensed bitumen
and clay. Eventually the material emerges at the surface of the asphalt
lake. We propose that the mechanism for the mud volcanoes is essentially
the same, only that the source is not located close to an oil reservoir
but rather is comprised of marine sediments. Hydrocarbon lakes have been
confirmed to exist on Titan and the presence of mud volcanoes has been
proposed and modeled for Titan, thus Pitch Lake represents a unique opportunity
as an analog site to study dynamic processes on Titan. The gained insights
will prove invaluable for future missions to the Saturnian system such
as TANDEM currently considered by the European Space Agency.
Standing water on hardened natural asphalt
Sampling is tough at Pitch Lake
International Team of Investigators