Pore water sulfate, alkalinity, and carbon isotope profiles in shallow sediment above marine gas hydrate systems: A numerical modeling perspective

Chatterjee, Sayantan; Dickens, Gerald R.; Bhatnagar, Gaurav; Chapman, Walter G.; Dugan, Brandon; Snyder, G. T.; Hirasaki, George J.

doi:10.1029/2011jb008290

Cited by 91 publications

(84 citation statements)

References 82 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It should be noted that at seafloor locations with significant upward advection of fluids, such as at seeps and vents, the aforementioned reactions occur, but the pore water profiles become more complicated to model (Berner, 1980;Torres et al, 2002;Chatterjee et al, 2011). This is because the advecting fluids typically have different chemistry than surrounding sediment (even if charged with CH 4 ) and because advection often involves multiphase fluid flow (free gas and liquid) that may be episodic.…”

Section: Pore Water Chemistry Above Methane-charged Sedimentmentioning

confidence: 99%

“…Because CH 4 is greatly depleted in 13 C, due to isotope fractionation during methanogenesis at depth (Whiticar, 1999;Paull et al, 2000), the conversion of CH 4 to HCO − 3 (Eq. 1) decreases the δ 13 C of DIC across the SMT (Torres et al, 2007;Holler et al, 2009;Chatterjee et al, 2011;Yoshinaga et al, 2014). However, the magnitude of this change in δ 13 C composition of 2934 C. M. Miller et al: East Siberian Sea, low methane concentrations DIC (δ 13 C-DIC) is complicated because excess 13 C-enriched HCO − 3 (formed during methanogenesis and subsequent reactions) can also rise from below (Snyder et al, 2007;Chatterjee et al, 2011).…”

Section: Pore Water Chemistry Above Methane-charged Sedimentmentioning

confidence: 99%

“…The consequent reaction with SO 2− 4 via AOM (Eq. 1) leads to a series of flux changes in dissolved components (addition or removal) and predictable variations in concentration profiles across an SMT (Alperin et al, 1988;Borowski et al, 1996;Niewohner et al, 1998;Ussler and Paull, 2008;Dickens and Snyder, 2009;Chatterjee et al, 2011). Furthermore, the depth of the SMT directly relates to the flux of CH 4 from below (Jørgensen et al, 1990;Dickens, 2001;D'Hondt et al, 2002;Figure 3.…”

Section: Pore Water Chemistry Above Methane-charged Sedimentmentioning

confidence: 99%

“…Therefore, because of the production of HS − and HCO − 3 , an inflection in Alk T occurs across the SMT (Luff and Wallmann, 2003;Dickens and Snyder, 2009;Jørgensen and Parkes, 2010;Chatterjee et al, 2011;Smith and Coffin, 2014;Ye et al, 2016).…”

Section: Pore Water Chemistry Above Methane-charged Sedimentmentioning

confidence: 99%

“…1) decreases the δ 13 C of DIC across the SMT (Torres et al, 2007;Holler et al, 2009;Chatterjee et al, 2011;Yoshinaga et al, 2014). However, the magnitude of this change in δ 13 C composition of 2934 C. M. Miller et al: East Siberian Sea, low methane concentrations DIC (δ 13 C-DIC) is complicated because excess 13 C-enriched HCO − 3 (formed during methanogenesis and subsequent reactions) can also rise from below (Snyder et al, 2007;Chatterjee et al, 2011). Dissolved Ba 2+ concentrations generally increase significantly just above the SMT.…”

Section: Pore Water Chemistry Above Methane-charged Sedimentmentioning

confidence: 99%

See 4 more Smart Citations

Pore water geochemistry along continental slopes north of the East Siberian Sea: inference of low methane concentrations

et al. 2017

Self Cite

View full text Add to dashboard Cite

Abstract. Continental slopes north of the East Siberian Sea potentially hold large amounts of methane (CH 4 ) in sediments as gas hydrate and free gas. Although release of this CH 4 to the ocean and atmosphere has become a topic of discussion, the region remains sparingly explored. Here we present pore water chemistry results from 32 sediment cores taken during Leg 2 of the 2014 joint Swedish-Russian-US Arctic Ocean Investigation of Climate-Cryosphere-Carbon Interactions (SWERUS-C3) expedition. The cores come from depth transects across the slope and rise extending between the Mendeleev and the Lomonosov ridges, north of Wrangel Island and the New Siberian Islands, respectively. Upward CH 4 flux towards the seafloor, as inferred from profiles of dissolved sulfate (SO 2− 4 ), alkalinity, and the δ 13 C of dissolved inorganic carbon (DIC), is negligible at all stations east of 143 • E longitude. In the upper 8 m of these cores, downward SO 2− 4 flux never exceeds 6.2 mol m −2 kyr −1 , the upward alkalinity flux never exceeds 6.8 mol m −2 kyr −1 , and δ 13 C composition of DIC (δ 13 C-DIC) only moderately decreases with depth (−3.6 ‰ m −1 on average). Moreover, upon addition of Zn acetate to pore water samples, ZnS did not precipitate, indicating a lack of dissolved H 2 S. Phosphate, ammonium, and metal profiles reveal that metal oxide reduction by organic carbon dominates the geochemical environment and supports very low organic carbon turnover rates. A single core on the Lomonosov Ridge differs, as diffusive fluxes for SO 2− 4 and alkalinity were 13.9 and 11.3 mol m −2 kyr −1 , respectively, the δ 13 C-DIC gradient was 5.6 ‰ m −1 , and Mn 2+ reduction terminated within 1.3 m of the seafloor. These are among the first pore water results generated from this vast climatically sensitive region, and they imply that abundant CH 4 , including gas hydrates, do not characterize the East Siberian Sea slope or rise along the investigated depth transects. This contradicts previous modeling and discussions, which due to the lack of data are almost entirely based on assumption.

show abstract

Section: Pore Water Chemistry Above Methane-charged Sedimentmentioning

confidence: 99%

Section: Pore Water Chemistry Above Methane-charged Sedimentmentioning

confidence: 99%

Section: Pore Water Chemistry Above Methane-charged Sedimentmentioning

confidence: 99%

Section: Pore Water Chemistry Above Methane-charged Sedimentmentioning

confidence: 99%

Section: Pore Water Chemistry Above Methane-charged Sedimentmentioning

confidence: 99%

See 3 more Smart Citations

Pore water geochemistry along continental slopes north of the East Siberian Sea: inference of low methane concentrations

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

The impact of lithologic heterogeneity and focused fluid flow upon gas hydrate distribution in marine sediments

et al. 2014

Self Cite

View full text Add to dashboard Cite

Gas hydrate and free gas accumulation in heterogeneous marine sediment is simulated using a two-dimensional (2-D) numerical model that accounts for mass transfer over geological timescales. The model extends a previously documented one-dimensional (1-D) model such that lateral variations in permeability (k) become important. Various simulations quantitatively demonstrate how focused fluid flow through high-permeability zones affects local hydrate accumulation and saturation. Simulations that approximate a vertical fracture network isolated in a lower permeability shale (k fracture >> k shale ) show that focused fluid flow through the gas hydrate stability zone (GHSZ) produces higher saturations of gas hydrate (25-70%) and free gas (30-60%) within the fracture network compared to surrounding shale. Simulations with a dipping, high-permeability sand layer also result in elevated saturations of gas hydrate (60%) and free gas (40%) within the sand because of focused fluid flow through the GHSZ. Increased fluid flux, a deep methane source, or both together increase the effect of flow focusing upon hydrate and free gas distribution and enhance hydrate and free gas concentrations along the high-permeability zones. Permeability anisotropy, with a vertical to horizontal permeability ratio on the order of 10 À2, enhances transport of methane-charged fluid to high-permeability conduits. As a result, gas hydrate concentrations are enhanced within these high-permeability zones. The dip angle of these high-permeability structures affects hydrate distribution because the vertical component of fluid flux dominates focusing effects. Hydrate and free gas saturations can be characterized by a local Peclet number (localized, vertical, focused, and advective flux relative to diffusion) relative to the methane solubility gradient, somewhat analogous to such characterization in 1-D systems. Even in lithologically complex systems, local hydrate and free gas saturations might be characterized by basic parameters (local flux and diffusivity).

show abstract

Brucite chimney formation and carbonate alteration at theShinkaiSeepField, a serpentinite‐hosted vent system in thesouthernMariana forearc

Okumura

Ohara

Stern

et al. 2016

Geochem. Geophys. Geosyst.

View full text Add to dashboard Cite

Brucite-carbonate chimneys were discovered from the deepest known ($5700 m depth) serpentinite-hosted ecosystem-the Shinkai Seep Field (SSF) in the southern Mariana forearc. Textural observations and geochemical analysis reveal three types (I-III) of chimneys formed by the precipitation and dissolution of constitutive minerals. Type I chimneys are bright white to light yellow, have a spiky crystalline and wrinkled surface with microbial mat and contain more brucite; these formed as a result of rapid precipitation under high fluid discharge conditions. Type II chimneys exhibit white to dull brown coloration, tuberous textures like vascular bundles, and are covered with grayish microbial mats and dense colonies of Phyllochaetopterus. This type of chimney is characterized by inner brucite-rich and outer carbonate rich zones and is thought to have precipitated from lower fluid discharge conditions than type I chimneys. Type III chimneys are ivory colored, have surface depressions and lack living microbial mats or animals. This type of chimney mainly consists of carbonate, and is in a dissolution stage. Stable carbon isotope compositions of carbonates in the two types (I and II) of active chimneys are extremely 13 C-enriched (up to 124.1&), which may reflect biological 12 C consumption under extremely low dissolved inorganic carbon concentrations in alkaline fluids. Type III chimneys have 13 C compositions indicating re-equilibration with seawater.Our findings demonstrate for the first time that carbonate chimneys can form below the carbonate compensation depth and provide new insights about linked geologic, hydrologic, and biological processes of the global deep-sea serpentinite-hosted vent systems.

show abstract

Pore water sulfate, alkalinity, and carbon isotope profiles in shallow sediment above marine gas hydrate systems: A numerical modeling perspective

Cited by 91 publications

References 82 publications

Pore water geochemistry along continental slopes north of the East Siberian Sea: inference of low methane concentrations

Pore water geochemistry along continental slopes north of the East Siberian Sea: inference of low methane concentrations

The impact of lithologic heterogeneity and focused fluid flow upon gas hydrate distribution in marine sediments

Brucite chimney formation and carbonate alteration at theShinkaiSeepField, a serpentinite‐hosted vent system in thesouthernMariana forearc

Contact Info

Product

Resources

About