Fluid expulsion related to mud extrusion off Costa Rica—A window to the subducting slab

Hensen, Christian; Wallmann, Klaus; Schmidt, Mark; Ranero, César R.; Suess, Erwin

doi:10.1130/g20119.1

Cited by 240 publications

(294 citation statements)

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“…These include clay mineral dehydration reactions, particularly the smectite-to-illite transition that occurs at approximately 1.5 km depth [24], differential-stress-induced smectite dehydration [25], and the opal-A to opal-CT transformation [26]. Evidence for migration of low salinity water is found along the Peruvian margin [27], along the décollement at the Costa Rica margin [28,29], and the Barbados margin [30].…”

Section: Resultsmentioning

confidence: 99%

A hydrothermal seep on the Costa Rica margin: middle ground in a continuum of reducing ecosystems

et al. 2012

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Upon their initial discovery, hydrothermal vents and methane seeps were considered to be related but distinct ecosystems, with different distributions, geomorphology, temperatures, geochemical properties and mostly different species. However, subsequently discovered vents and seep systems have blurred this distinction. Here, we report on a composite, hydrothermal seep ecosystem at a subducting seamount on the convergent Costa Rica margin that represents an intermediate between vent and seep ecosystems. Diffuse flow of shimmering, warm fluids with high methane concentrations supports a mixture of microbes, animal species, assemblages and trophic pathways with vent and seep affinities. Their coexistence reinforces the continuity of reducing environments and exemplifies a setting conducive to interactive evolution of vent and seep biota.

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Section: Resultsmentioning

confidence: 99%

A hydrothermal seep on the Costa Rica margin: middle ground in a continuum of reducing ecosystems

et al. 2012

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Section: Volatiles and Fluidsmentioning

confidence: 99%

“…Widespread mounds, some tens of meters high and a few hundred meters wide, have been monitored with current meters and hydrographic stations (Flüh et al, 2004). Outcropping carbonates on top and at the flanks indicate that these mounds are formed by authigenic precipitation at sites with abundant signs of fluid flow (Bohrmann et al, 2002;Hensen et al, 2004).…”

Section: Site Survey Datamentioning

confidence: 99%

“…Mud volcanoes and mud diapirs have also been found, particularly across the middle slope, and are associated with a high density of chemosynthetic vents. The chemistry of the pore fluids sampled at these midslope features is indicative of clay dehydration reactions at depth (Shipley et al, 1992;Bohrmann et al, 2002;Grevemeyer et al, 2004;Hensen et al, 2004;Sahling et al, 2008).Along the décollement and the upper prism fault zone, coring and sampling during Ocean Drilling Program (ODP) Legs 170 and 205 offshore the Nicoya Peninsula revealed freshened pore waters containing elevated Ca, Li, and C 3 -C 6 hydrocarbon concentrations and low K concentrations (Kimura, Silver, Blum, et al, 1997;Silver et al, 2000;Chan and Kastner, 2000;Morris, Villinger, Klaus, et al, 2003;Kastner et al, 2006). These fluids contrast with pore fluids from below the décollement and between the décollement and upper fault zone that have near-seawater chemistry (Kimura, Silver, Blum, et al, 1997;Morris, Villinger, Klaus, et al, 2003).…”

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Expedition 344 summary

Li¹,

Malinverno²,

Torres³

et al. 2013

Proceedings of the IODP

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Expedition 344 summaryProc. IODP | Volume 344 2 from velocity-strengthening to velocity-weakening friction, and shear becomes localized. The onset of seismogenic behavior is correlated with the intersection of the 100°-150°C isotherm and the subduction thrust (Hyndman et al., 1997;Oleskevich et al., 1999). With increasing depth down the subduction thrust, the frictional characteristics undergo a second transition either due to the juxtaposition with the forearc mantle or because the rocks are heated to 350°-450°C and can no longer store elastic stresses needed for rupture. Transitional regions between the three zones have conditional stability and can host rupture but are generally not thought to be regions where large earthquakes initiate.Although this three-zone two-dimensional view of the subduction thrust provides a reasonable framework, it is simplistic. Rupture models for large subduction earthquakes suggest significant fault plane heterogeneity in slip and moment release that in three dimensions is characterized as patchiness (Bilek and Lay, 2002). Additionally, we now know the transition zone from stable to unstable sliding is not simple but hosts a range of fault behaviors that includes creep events, strain transients, slow and silent earthquakes, and low-frequency earthquakes (Peng and Gomberg, 2010;Beroza and Ide, 2011;Ide, 2012).Fundamentally unknown are the processes that change fault behavior from stable sliding to stick-slip behavior. Understanding these processes is important for understanding earthquakes, the mechanics of slip, and rupture dynamics. For a fault to undergo unstable slip, fault rocks must have the ability to store elastic strain, be velocity weakening, and have sufficient stiffness. Hypotheses for mechanisms leading to the transition between stable and unstable slip invoke temperature, pressure, and strain-activated processes that lead to downdip changes in the mechanical properties of rocks. These transitions are also sensitive to fault zone composition, lithology, fabric, and fluid pressures.The composition of the material in the fault zone and its contrast with the surrounding wall rock play a key role in rock frictional behavior. The frictional state of the incoming sediment changes progressively with increasing temperature and pressure as it travels downdip. Important lithologic factors influencing friction are composition, fabric, texture, and cementation of rocks, as well as fluid pore pressure (Bernabé et al., 1992;Moore and Saffer, 2001;Beeler, 2007;Marone and Saffer, 2007;Collettini et al., 2009). For example, fault rocks with high phyllosilicate content are generally weaker than rocks with low phyllosilicate content (Ikari et al., 2011). Sediment properties including porosity, permeability, consolidation state, and alteration history also exert a strong influence on fault zone behavior. At erosive margins, where the plate boundary cuts into the overriding plate, the composition and strength of the upper plate is also important (McCaffrey, 1993).Field observations and la...

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“…Organic carbon accumulation at continental margins can lead to the formation of large methane reservoirs through its biological or thermogenic breakdown (Judd et al, 2002;Schmidt et al, 2005;Hensen and Wallmann, 2005;Crutchley et al, 2014). Produced methane gas may be transported upwards in solution by molecular diffusion or by ascending fluids, mobilized by, for example, sediment compaction or clay mineral dehydration (Hensen et al, 2004;Tryon et al, 2010;Crutchley et al, 2014). When the fluids are highly enriched in hydrocarbon gases, gas hydrates may precipitate depending on the pressure-temperature conditions .…”

Section: Introductionmentioning

confidence: 99%

Efficiency and adaptability of the benthic methane filter at Quepos Slide cold seeps, offshore of Costa Rica

et al. 2015

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Abstract. Large amounts of methane are delivered by fluids through the erosive forearc of the convergent margin offshore of Costa Rica and lead to the formation of cold seeps at the sediment surface. Besides mud extrusion, numerous cold seeps are created by landslides induced by seamount subduction or fluid migration along major faults. Most of the dissolved methane migrating through the sediments of cold seeps is oxidized within the benthic microbial methane filter by anaerobic oxidation of methane (AOM). Measurements of AOM and sulfate reduction as well as numerical modeling of porewater profiles revealed a highly active and efficient benthic methane filter at the Quepos Slide site, a landslide on the continental slope between the Nicoya and Osa Peninsula. Integrated areal rates of AOM ranged from 12.9 ± 6.0 to 45.2 ± 11.5 mmol m −2 d −1 , with only 1 to 2.5 % of the upward methane flux being released into the water column.Additionally, two parallel sediment cores from Quepos Slide were used for in vitro experiments in a recently developed sediment-flow-through (SLOT) system to simulate an increased fluid and methane flux from the bottom of the sediment core. The benthic methane filter revealed a high adaptability whereby the methane oxidation efficiency responded to the increased fluid flow within ca. 170 d. To our knowledge, this study provides the first estimation of the natural biogeochemical response of seep sediments to changes in fluid flow.

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Fluid expulsion related to mud extrusion off Costa Rica—A window to the subducting slab

Cited by 240 publications

References 26 publications

A hydrothermal seep on the Costa Rica margin: middle ground in a continuum of reducing ecosystems

A hydrothermal seep on the Costa Rica margin: middle ground in a continuum of reducing ecosystems

Expedition 344 summary

Efficiency and adaptability of the benthic methane filter at Quepos Slide cold seeps, offshore of Costa Rica

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