TY - JOUR
T1 - Silicate weathering in anoxic marine sediment as a requirement for authigenic carbonate burial
AU - Torres, Marta E.
AU - Hong, Wei Li
AU - Solomon, Evan A.
AU - Milliken, Kitty
AU - Kim, Ji Hoon
AU - Sample, James C.
AU - Teichert, Barbara M.A.
AU - Wallmann, Klaus
N1 - Funding Information:
This work was supported by grants from the National Science Foundation to MET (OCE-1029972, OCE-1029981, OCE-1833296), EAS (OCE-1233587, OCE-1753617), JCS (OCE-1029972, OCE-1029981), and KM (OCE-1833296). Support for WH comes from NORCRUST project 255150, funded by Norwegian Research Council. Additional funding was received from US Department of Energy (DE-FE0013531). MET also acknowledges support from a fellowship from the Hanse Wissenschaftskolleg, Germany. Samples and data from the India margin used in this study were collected from National Gas Hydrate Program Expedition 01 (NGHP01), managed through collaboration between the Directorate General of Hydrocarbons (DGH) under the Ministry of Petroleum and Natural Gas (India), the U.S. Geological Survey (USGS), and the Consortium for Scientific Methane Hydrate Investigations (CSMHI) led by Overseas Drilling Limited (ODL) and FUGRO McClelland Marine Geosciences (FUGRO). Samples and data from the Nankai margin were collected by the Integrated Ocean Drilling Program (IODP), which is sponsored by the US National Science Foundation and participating countries under management of IODP-MI. Samples and data from the Ulleung Basin was acquired during the Second Gas Hydrate Expedition to the Ulleung Basin (UBGH2) with the support of the Gas Hydrate Research and Development Organization (GHDO) of the Ministry of Knowledge Economy, Republic of Korea. Any opinions, findings and conclusions expressed in this paper are those of the authors and do not necessarily reflect the views of these funding agencies. This manuscript benefited significantly from the contributions of two anonymous reviewers, which are gratefully acknowledged.
Funding Information:
This work was supported by grants from the National Science Foundation to MET ( OCE-1029972 , OCE-1029981 , OCE-1833296 ), EAS ( OCE-1233587 , OCE-1753617 ), JCS ( OCE-1029972 , OCE-1029981 ), and KM ( OCE-1833296 ). Support for WH comes from NORCRUST project 255150, funded by Norwegian Research Council . Additional funding was received from US Department of Energy ( DE-FE0013531 ). MET also acknowledges support from a fellowship from the Hanse Wissenschaftskolleg, Germany . Samples and data from the India margin used in this study were collected from National Gas Hydrate Program Expedition 01 (NGHP01), managed through collaboration between the Directorate General of Hydrocarbons (DGH) under the Ministry of Petroleum and Natural Gas (India), the U.S. Geological Survey (USGS), and the Consortium for Scientific Methane Hydrate Investigations (CSMHI) led by Overseas Drilling Limited (ODL) and FUGRO McClelland Marine Geosciences (FUGRO). Samples and data from the Nankai margin were collected by the Integrated Ocean Drilling Program (IODP), which is sponsored by the US National Science Foundation and participating countries under management of IODP-MI. Samples and data from the Ulleung Basin was acquired during the Second Gas Hydrate Expedition to the Ulleung Basin (UBGH2) with the support of the Gas Hydrate Research and Development Organization (GHDO) of the Ministry of Knowledge Economy, Republic of Korea. Any opinions, findings and conclusions expressed in this paper are those of the authors and do not necessarily reflect the views of these funding agencies. This manuscript benefited significantly from the contributions of two anonymous reviewers, which are gratefully acknowledged.
Publisher Copyright:
© 2019
PY - 2020/1
Y1 - 2020/1
N2 - We emphasize the importance of marine silicate weathering (MSiW) reactions in anoxic sediment as fundamental in generating alkalinity and cations needed for carbonate precipitation and preservation along continental margins. We use a model that couples thermodynamics with aqueous geochemistry to show that the CO2 released during methanogenesis results in a drop in pH to 6.0; unless these protons are buffered by MSiW, carbonate minerals will dissolve. We present data from two regions: the India passive margin and the active subduction zone off Japan, where ash and/or rivers supply the reactive silicate phase, as reflected in strontium isotope data. Offshore India and Korea, alteration of continent-derived silicates results in pore water enriched in radiogenic 87Sr, with 87Sr/86Sr ratios as high as 0.7095 and 0.7104, respectively. Off Japan, strontium in pore water influenced by ash alteration is depleted in 87Sr, with 87Sr/86Sr as low as 0.7065. Carbonate minerals formed by alkalinity and cations generated through MSiW carry these strontium isotopic signals, and are typically dolomite, siderite, and Fe-rich calcite. These contrast with the aragonite and high-magnesium calcite that form during anaerobic oxidation of methane and incorporate the coeval seawater 87Sr/86Sr signal. We show that MSiW is necessary for authigenic carbonate formation and preservation along continental margins, which remove carbon from Earth's surface at rates previously estimated to be at least 1012 mol yr−1. In addition, these authigenic carbonates are of relevance to studies of the deep biosphere, fluid flow, seismogenesis, slope stability, and reservoir characteristics.
AB - We emphasize the importance of marine silicate weathering (MSiW) reactions in anoxic sediment as fundamental in generating alkalinity and cations needed for carbonate precipitation and preservation along continental margins. We use a model that couples thermodynamics with aqueous geochemistry to show that the CO2 released during methanogenesis results in a drop in pH to 6.0; unless these protons are buffered by MSiW, carbonate minerals will dissolve. We present data from two regions: the India passive margin and the active subduction zone off Japan, where ash and/or rivers supply the reactive silicate phase, as reflected in strontium isotope data. Offshore India and Korea, alteration of continent-derived silicates results in pore water enriched in radiogenic 87Sr, with 87Sr/86Sr ratios as high as 0.7095 and 0.7104, respectively. Off Japan, strontium in pore water influenced by ash alteration is depleted in 87Sr, with 87Sr/86Sr as low as 0.7065. Carbonate minerals formed by alkalinity and cations generated through MSiW carry these strontium isotopic signals, and are typically dolomite, siderite, and Fe-rich calcite. These contrast with the aragonite and high-magnesium calcite that form during anaerobic oxidation of methane and incorporate the coeval seawater 87Sr/86Sr signal. We show that MSiW is necessary for authigenic carbonate formation and preservation along continental margins, which remove carbon from Earth's surface at rates previously estimated to be at least 1012 mol yr−1. In addition, these authigenic carbonates are of relevance to studies of the deep biosphere, fluid flow, seismogenesis, slope stability, and reservoir characteristics.
KW - Alkalinity
KW - Authigenic carbonate
KW - Carbon cycling
KW - Organogenic dolomite
KW - Silicate weathering
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U2 - 10.1016/j.earscirev.2019.102960
DO - 10.1016/j.earscirev.2019.102960
M3 - Review article
AN - SCOPUS:85075027451
SN - 0012-8252
VL - 200
JO - Earth-Science Reviews
JF - Earth-Science Reviews
M1 - 102960
ER -