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Schlagwörter:
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Zusammenfassung:
Mud volcanoes are frequently encountered geo-structures at active and passive
continental margins. In contrast to magmatic volcanoes, mud volcanoes are marine or
terrestrial, topographic elevations built from vertically rising fluidized mud or mud breccia.
Commonly, these structures have a crater, hummocky rime and caldera. Mud volcanism is
triggered by various geological processes which lead to a high pore fluid pressure at great
depth, sediment instabilities and a subsequent discharge of mud, fluids and gases such
as hydrocarbons (mostly the greenhouse gas methane). Although global estimates of methane
emissions from mud volcanoes vary over two orders of magnitude, mud volcanism could
be an important source for atmospheric methane. However, a substantial fraction of the
hydrocarbons are retained in the mud volcanoes surface sediments. Here, the upwelled
hydrocarbons fuel a variety of free-living and symbiotic, chemosynthetic communities that
oxidize these with electron acceptors such as oxygen or sulphate from the water column or the
atmosphere. The activity of the chemosynthetic communities is regulated by the availability
of either electron donors (hydrocarbons) or acceptors which, in return, is determined by
mass transport processes. Most important in this context are the magnitudes of upward
advection of electron donors and the influx of electron acceptors due to diffusion and
bioirrigation.
