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Mud Volcanoes (mud + volcano)

Distribution by Scientific Domains

Earth and Environmental Science	70%

Selected Abstracts

Mud volcanoes of Italy

GEOLOGICAL JOURNAL, Issue 1 2004
Giovanni Martinelli
Abstract The locations and information about the sizes of 61 mud volcanoes on the Italian mainland and Sicily, plus an area of mud diapirism in the Italian Adriatic Sea, are presented. Data about the emission products are also provided. The majority of these mud volcanoes are found where thick sedimentary sequences occur within a zone of tectonic compression associated with local plate tectonic activity: the movement of the Adriatic microplate between the converging African and Eurasian plates. The principal gas emitted by these mud volcanoes is methane, which probably originates from deep within the sediments. Other mud volcanoes, associated with igneous volcanism, produce mainly carbon dioxide. The mud diapirs in the Adriatic Sea are thought to form as a result of the mobilization of shallow gassy sediments. It has been shown that radon emissions from mud volcanoes are indicators of forthcoming earthquake events. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Prokaryotic diversity and metabolically active microbial populations in sediments from an active mud volcano in the Gulf of Mexico

ENVIRONMENTAL MICROBIOLOGY, Issue 10 2006
Robert J. Martinez
Summary In this study, ribosomes and genomic DNA were extracted from three sediment depths (0,2, 6,8 and 10,12 cm) to determine the vertical changes in the microbial community composition and identify metabolically active microbial populations in sediments obtained from an active seafloor mud volcano site in the northern Gulf of Mexico. Domain-specific Bacteria and Archaea 16S polymerase chain reaction primers were used to amplify 16S rDNA gene sequences from extracted DNA. Complementary 16S ribosomal DNA (crDNA) was obtained from rRNA extracted from each sediment depth that had been subjected to reverse transcription polymerase chain reaction amplification. Twelve different 16S clone libraries, representing the three sediment depths, were constructed and a total of 154 rDNA (DNA-derived) and 142 crDNA (RNA-derived) Bacteria clones and 134 rDNA and 146 crDNA Archaea clones obtained. Analyses of the 576 clones revealed distinct differences in the composition and patterns of metabolically active microbial phylotypes relative to sediment depth. For example, ,- Proteobacteria rDNA clones dominated the 0,2 cm clone library whereas ,-Proteobacteria dominated the 0,2 cm crDNA library suggesting , to be among the most active in situ populations detected at 0,2 cm. Some microbial lineages, although detected at a frequency as high as 9% or greater in the total DNA library (i.e. Actinobacteria, ,- Proteobacteria), were markedly absent from the RNA-derived libraries suggesting a lack of in situ activity at any depth in the mud volcano sediments. This study is one of the first to report the composition of the microbial assemblages and physiologically active members of archaeal and bacterial populations extant in a Gulf of Mexico submarine mud volcano. [source]

Microbiological investigation of methane- and hydrocarbon-discharging mud volcanoes in the Carpathian Mountains, Romania

ENVIRONMENTAL MICROBIOLOGY, Issue 4 2006
Karine Alain
Summary Paclele Mici is a terrestrial mud volcano field located in the Carpathian Mountains (Romania), where thermal alteration of sedimentary organic compounds leads to methane, higher hydrocarbons and other petroleum compounds that are continuously released into the environment. The hydrocarbons represent potential substrates for microorganisms. We studied lipid biomarkers, stable isotope ratios, the effect of substrate (methane, other organic compounds) addition and 16S rRNA genes to gain insights into the hitherto unknown microbial community at this site. Quantitative real-time polymerase chain reaction analysis demonstrated that bacteria were much more abundant than archaea. Phylogenetic analyses of 16S rDNA clone sequences indicated the presence of bacterial and archaeal lineages generally associated with the methane cycle (methanogens, aerobic and anaerobic methanotrophs), the sulfur cycle (sulfate reducers), and groups linked to the anaerobic degradation of alkanes or aromatic hydrocarbons. The presence of sulfate reducers, methanogens and methanotrophs in this habitat was also confirmed by concurrent surveys of lipid biomarkers and their isotopic signatures. Incubation experiments with several common and complex substrates revealed the potential of the indigenous microbial community for sulfate reduction, methanogenesis and aerobic methanotrophy. Additionally, consistently to the detection of methane-oxidizing archaea (ANME) and 13C-depleted archaeal lipids, a weak but significant activity of anaerobic methane oxidation was measured by radiotracer techniques and in vitro. This survey is the first to report the presence and activity of ANME in a terrestrial environment. [source]

Hydrologic responses to earthquakes and a general metric

GEOFLUIDS (ELECTRONIC), Issue 1-2 2010
CHI-YUEN WANG
Geofluids (2010) 10, 206,216 Abstract Hydrologic responses to earthquakes, including liquefaction, changes in stream and spring discharge, changes in the properties of groundwater such as geochemistry, temperature and turbidity, changes in the water level in wells, and the eruption of mud volcanoes, have been documented for thousands of years. Except for some water-level changes in the near field which can be explained by poroelastic responses to static stress changes, most hydrologic responses, both within and beyond the near field, can only be explained by the dynamic responses associated with seismic waves. For these responses, the seismic energy density e may be used as a general metric to relate and compare the various hydrologic responses. We show that liquefaction, eruption of mud volcanoes and increases in streamflow are bounded by e , 10,1 J m,3; temperature changes in hot springs are bounded by e , 10,2 J m,3; most sustained groundwater changes are bounded by e , 10,3 J m,3; geysers and triggered seismicity may respond to seismic energy density as small as 10,3 and 10,4 J m,3, respectively. Comparing the threshold energy densities with published laboratory measurements, we show that undrained consolidation induced by dynamic stresses can explain liquefaction only in the near field, but not beyond the near field. We propose that in the intermediate field and far field, most responses are triggered by changes in permeability that in turn are a response to the cyclic deformation and oscillatory fluid flow. Published laboratory measurements confirm that changes in flow and time-varying stresses can change permeability, inducing both increases and decreases. Field measurements in wells also indicate that permeability can be changed by earthquakes in the intermediate field and far field. Further work, in particular field monitoring and measurements, are needed to assess the generality of permeability changes in explaining far-field hydrologic responses to earthquakes. [source]

Transfer of hydrocarbons from natural seeps to the water column and atmosphere

GEOFLUIDS (ELECTRONIC), Issue 2 2002
I. R. MacDonald
Abstract Results from surface geochemical prospecting, seismic exploration and satellite remote sensing have documented oil and gas seeps in marine basins around the world. Seeps are a dynamic component of the carbon cycle and can be important indicators for economically significant hydrocarbon deposits. The northern Gulf of Mexico contains hundreds of active seeps that can be studied experimentally with the use of submarines and Remotely Operated Vehicles (ROV). Hydrocarbon flux through surface sediments profoundly alters benthic ecology and seafloor geology at seeps. In water depths of 500,2000 m, rapid gas flux results in shallow, metastable deposits of gas hydrate, which reduce sediment porosity and affect seepage rates. This paper details the processes that occur during the final, brief transition , as oil and gas escape from the seafloor, rise through the water and dissolve, are consumed by microbial processes, or disperse into the atmosphere. The geology of the upper sediment column determines whether discharge is rapid and episodic, as occurs in mud volcanoes, or more gradual and steady, as occurs where the seep orifice is plugged with gas hydrate. In both cases, seep oil and gas appear to rise through the water in close proximity instead of separating. Chemical alteration of the oil is relatively minor during transit through the water column, but once at the sea surface its more volatile components rapidly evaporate. Gas bubbles rapidly dissolve as they rise, although observations suggest that oil coatings on the bubbles inhibit dissolution. At the sea surface, the floating oil forms slicks, detectable by remote sensing, whose origins are laterally within ,1000 m of the seafloor vent. This contradicts the much larger distance predicted if oil drops rise through a 500 m water column at an expected rate of ,0.01 m s,1 while subjected to lateral currents of ,0.2 m s,1 or greater. It indicates that oil rises with the gas bubbles at speeds of ,0.15 m s,1 all the way to the surface. [source]

Mud volcanoes of Italy

Fluid dynamics and subsurface sediment mobilization processes: an overview from Southeast Caribbean

BASIN RESEARCH, Issue 4 2010
Éric Deville
ABSTRACT This paper discusses the origin and the dynamics of subsurface sediment mobilization processes in tectonically mobile regions and shale-rich environment. This is illustrated by the example of Trinidad and the south of the Barbados prism. In this area of the southeast Caribbean, geophysical acquisitions have spectacularly shown the widespread development of sediment mobilization features in the interference area between the southern part of the Barbados prism and the active turbidite system of the Orinoco. Numerous mud volcanoes are especially developed along ramp anticline crests through hydraulic fracture systems. The area also exhibits trends of structures that correspond to massive uplifts of well-preserved turbidite and hemipelagic sediments that cut up the surrounding sediments. Some of these structures are complicated by the development of collapse structures, calderas and superimposed mud volcanoes. The mobilized sediments expelled by the mud volcanoes are not only liquefied argillaceous but also fine sandy material from deep horizons, and various shallower formations pierced by the mud conduits. Both in the Barbados prism and in Trinidad, the expelled mud is rich in thin, angular and mechanically damaged quartz grains, which are probably cataclastic flows issued from sheared and collapsed deep sandy reservoirs. The exotic clasts and breccias result mostly from hydraulic fracturing. In Trinidad, the gas phase is mainly deep thermogenic methane associated with hydrocarbon generation at depth. Subsurface sediment mobilization notably differs from salt mobilization by the role taken by the fluid dynamics that control overpressured shale mobilization and induce sediment liquefaction. A reaction chain of several deformation processes develops around the conduits. Massive sedimentary uplift corresponds to large movements of stratified solid levels, possibly due to the tectonic inversion of pre-existing mud volcano systems. All these phenomena are controlled by the development of overpressure at depth. No evidence for piercing shale diapirs has been observed in the area studied. [source]