Methane Flux and Authigenic Carbonate in Shallow Sediments Overlying Methane Hydrate Bearing Strata in Alaminos Canyon, Gulf of Mexico

In June 2007 sediment cores were collected in Alaminos Canyon, Gulf of Mexico across a series of seismic data profiles indicating rapid transitions between the presence of methane hydrates and vertical gas flux. Vertical profiles of dissolved sulfate, chloride, calcium, magnesium, and dissolved inorganic carbon (DIC) concentrations in porewaters, headspace methane, and solid phase carbonate concentrations were measured at each core location to investigate the cycling of methane-derived carbon in shallow sediments overlying the hydrate bearing strata. When integrated with stable carbon isotope ratios of DIC, geochemical results suggest a significant fraction of the methane flux at this site is cycled into the inorganic carbon pool. The incorporation of methane-derived carbon into dissolved and solid inorganic carbon phases represents a significant sink in local carbon cycling and plays a role in regulating the flux of methane to the overlying water column at Alaminos Canyon. Targeted, high-resolution geochemical characterization of the biogeochemical cycling of methane-derived carbon in shallow sediments overlying hydrate bearing strata like those in Alaminos Canyon is critical to quantifying methane flux and estimating methane hydrate distributions in gas hydrate bearing marine sediments.

[1]  S. Boehme,et al.  A MASS BALANCE OF 13C AND 12C IN AN ORGANIC-RICH METHANE-PRODUCING MARINE SEDIMENT , 1996 .

[2]  Erik Cordes,et al.  Cold seeps of the deep Gulf of Mexico: Community structure and biogeographic comparisons to Atlantic equatorial belt seep communities , 2007 .

[3]  P. Weimer,et al.  The Perdido Fold Belt, Northwestern Deep Gulf of Mexico, Part 2: Seismic Stratigraphy and Petroleum Systems , 1999 .

[4]  J. Greinert,et al.  Authigenic carbonates from the Cascadia subduction zone and their relation to gas hydrate stability , 1998 .

[5]  C. Paull,et al.  Geochemical constraints on the distribution of gas hydrates in the Gulf of Mexico , 2005 .

[6]  C. Paull,et al.  Rates of anaerobic oxidation of methane and authigenic carbonate mineralization in methane-rich deep-sea sediments inferred from models and geochemical profiles , 2008 .

[7]  P. Weimer,et al.  The Perdido fold belt, northwestern deep Gulf of Mexico; Part 1, Structural geometry, evolution and regional implications , 1999 .

[8]  G. Dickens,et al.  Pore water sulfate, alkalinity, and carbon isotope profiles in shallow sediment above marine gas hydrate systems: A numerical modeling perspective , 2011 .

[9]  M. Muir.  Physical Chemistry , 1888, Nature.

[10]  J. Greinert,et al.  Gas Hydrate‐Associated Carbonates and Methane‐Venting at Hydrate Ridge: Classification, Distribution, and Origin of Authigenic Lithologies , 2001 .

[11]  R. Sassen,et al.  Quantifying carbon sources in the formation of authigenic carbonates at gas hydrate sites in the Gulf of Mexico , 2004 .

[12]  D. Schrag,et al.  Rates of methanogenesis and methanotrophy in deep‐sea sediments , 2005 .

[13]  W. Borowski,et al.  30. ZONATION OF AUTHIGENIC CARBONATES WITHIN GAS HYDRATE-BEARING SEDIMENTARY SECTIONS ON THE BLAKE RIDGE: OFFSHORE SOUTHEASTERN NORTH AMERICA 1 , 2000 .

[14]  Carolyn A. Koh,et al.  Clathrate hydrates of natural gases , 1990 .

[15]  Henry Elderfield,et al.  Diagenesis and interstitial-water chemistry at the Peruvian continental margin; major constituents and strontium isotopes , 1990 .

[16]  F. Anselmetti,et al.  Proceedings of the Ocean Drilling Program. Initial Reports , 2002 .

[17]  Richard B. Coffin,et al.  Contribution of Vertical Methane Flux to Shallow Sediment Carbon Pools across Porangahau Ridge, New Zealand , 2014 .

[18]  Bo Barker Jørgensen,et al.  Diffusion coefficients of sulfate and methane in marine sediments: Influence of porosity , 1993 .

[19]  David L. Valentine,et al.  Biogeochemistry and microbial ecology of methane oxidation in anoxic environments: a review , 2002, Antonie van Leeuwenhoek.

[20]  M. Reagan,et al.  Occurrence of gas hydrate in Oligocene Frio sand: Alaminos Canyon Block 818: Northern Gulf of Mexico , 2009 .

[21]  E. Burton.  Controls on marine carbonate cement mineralogy: review and reassessment , 1993 .

[22]  A. Boetius,et al.  Hydrate Ridge: A natural laboratory for the study of microbial life fueled by methane from near-surface gas hydrates. , 2004 .

[23]  D. Schrag,et al.  Anaerobic methane oxidation and the formation of dolomite , 2003 .

[24]  C. Paull,et al.  29. Methane-derived authigenic carbonates associated with gas hydrate decomposition and fluid venting above the Blake Ridge Diapir , 2000 .

[25]  H. Roberts,et al.  Free hydrocarbon gas, gas hydrate, and authigenic minerals in chemosynthetic communities of the northern Gulf of Mexico continental slope: relation to microbial processes , 2004 .

[26]  M. Ivanovb,et al.  Methane-related authigenic carbonates from the Black Sea : geochemical characterisation and relation to seeping fluids , 2004 .

[27]  Klaus Wallmann,et al.  Fluid flow, methane fluxes, carbonate precipitation and biogeochemical turnover in gas hydrate-bearing sediments at Hydrate Ridge, Cascadia Margin: numerical modeling and mass balances , 2003 .

[28]  G. Aloisi,et al.  Methane-related authigenic carbonates of eastern Mediterranean Sea mud volcanoes and their possible relation to gas hydrate destabilisation , 2000 .

[29]  W. Borowski,et al.  Factors affecting the diagenesis of Quaternary sediments at ODP Leg 172 sites in western North Atlantic: evidence from pore water and sediment geochemistry , 2001 .

[30]  K. Nauhaus,et al.  In vitro cell growth of marine archaeal-bacterial consortia during anaerobic oxidation of methane with sulfate. , 2007, Environmental microbiology.

[31]  T. Lorenson,et al.  The Global Occurrence of Natural Gas Hydrate , 2013 .

[32]  Walter S Borowski,et al.  8. MODEL, STABLE ISOTOPE, AND RADIOTRACER CHARACTERIZATION OF ANAEROBIC METHANE OXIDATION IN GAS HYDRATE-BEARING SEDIMENTS OF THE BLAKE RIDGE 1 , 2000 .

[33]  P. Hart,et al.  High-resolution seismic-reflection investigation of the northern Gulf of Mexico gas-hydrate-stability zone , 2002 .

[34]  J. Bernhard,et al.  Anaerobic diagenesis of silica and carbon in continental margin sediments : Discrete zones of TCO2 production , 2005 .

[35]  Antje Boetius,et al.  The anaerobic oxidation of methane and sulfate reduction in sediments from Gulf of Mexico cold seeps , 2004 .

[36]  W. Borowski,et al.  Global and local variations of interstitial sulfate gradients in deep-water, continental margin sediments: Sensitivity to underlying methane and gas hydrates , 1999 .

[37]  Dave Meyer,et al.  Emergence of the Lower Tertiary Wilcox trend in the deepwater Gulf of Mexico , 2005 .

[38]  Warren T. Wood,et al.  Analysis of methane and sulfate flux in methane-charged sediments from the Mississippi Canyon, Gulf of Mexico , 2008 .

[39]  R. Berner.  Sulfate reduction and the rate of deposition of marine sediments , 1978 .

[40]  K. Kvenvolden.  Gas hydrates—geological perspective and global change , 1993 .

[41]  G. Dickens,et al.  Pore water profiles and authigenic mineralization in shallow marine sediments above the methane-charged system on Umitaka Spur, Japan Sea , 2007 .

[42]  Wenyue Xu,et al.  Predicting the occurrence, distribution, and evolution of methane gas hydrate in porous marine sediments , 1999 .

[43]  J. Charlou,et al.  Physical and chemical characterization of gas hydrates and associated methane plumes in the Congo-Angola Basin , 2004 .

[44]  W. Borowski,et al.  Marine pore-water sulfate profiles indicate in situ methane flux from underlying gas hydrate , 1996 .

[45]  Robert A. Berner,et al.  An idealized model of dissolved sulfate distribution in recent sediments , 1964 .