Carbon and oxygen isotope composition of carbonate in bulk sediment in the southwest Taiwan Basin, South China Sea: Methane hydrate decomposition history and its link to mud volcano eruption

Zhang, Jie; Lei, Huaiyan; Chen, Yong; Kong, Yuan; Kandasamy, Selvaraj; Ou, Wenjia; Cheng, Weidong

doi:10.1016/j.marpetgeo.2018.08.031

Cited by 19 publications

(25 citation statements)

References 76 publications

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“…Lin et al, 2015Shi et al, 2014;B. Zhang et al, 2018;J. Zhang et al, 2018b;Zhuang et al, 2015) or via correlation with the LR04 benthic oxygen isotope stack (diamonds; B. .…”

Section: Methodsmentioning

confidence: 99%

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Vivianite formation in methane-rich deep-sea sediments from the South China Sea

et al. 2018

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Abstract. Phosphorus is often invoked as the ultimate limiting nutrient, modulating primary productivity on geological timescales. Consequently, along with nitrogen, phosphorus bioavailability exerts a fundamental control on organic carbon production, linking all the biogeochemical cycles across the Earth system. Unlike nitrogen that can be microbially fixed from an essentially infinite atmospheric reservoir, phosphorus availability is dictated by the interplay between its sources and sinks. While authigenic apatite formation has received considerable attention as the dominant sedimentary phosphorus sink, the quantitative importance of reduced iron-phosphate minerals, such as vivianite, has only recently been acknowledged, and their importance remains underexplored. Combining microscopic and spectroscopic analyses of handpicked mineral aggregates with sediment geochemical profiles, we characterize the distribution and mineralogy of iron-phosphate minerals present in methane-rich sediments recovered from the northern South China Sea. Here, we demonstrate that vivianite authigenesis is pervasive in the iron-oxide-rich sediments below the sulfate–methane transition zone (SMTZ). We hypothesize that the downward migration of the SMTZ concentrated vivianite formation below the current SMTZ. Our observations support recent findings from non-steady-state post-glacial sedimentary successions, suggesting that iron reduction below the SMTZ, probably driven by iron-mediated anaerobic oxidation of methane (Fe-AOM), is coupled to phosphorus cycling on a much greater spatial scale than previously assumed. Calculations reveal that vivianite acts as an important burial phase for both iron and phosphorus below the SMTZ, sequestering approximately half of the total reactive iron pool. By extension, sedimentary vivianite formation could serve as a mineralogical marker of Fe-AOM, signalling low-sulfate availability against methanogenic and ferruginous backdrop. Given that similar conditions were likely present throughout vast swathes of Earth's history, it is possible that Fe-AOM and vivianite authigenesis may have modulated methane and phosphorus availability on the early Earth, as well as during later periods of expanded marine oxygen deficiency. A better understanding of vivianite authigenesis, therefore, is fundamental to test long-standing hypotheses linking climate, atmospheric chemistry and the evolution of the biosphere.

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“…Lin et al, 2015Shi et al, 2014;B. Zhang et al, 2018;J. Zhang et al, 2018b;Zhuang et al, 2015) or via correlation with the LR04 benthic oxygen isotope stack (diamonds; B. .…”

Section: Methodsmentioning

confidence: 99%

“…Zhang et al, 2018a). The carbon isotopic composition of total inorganic carbon was determined using a Finnigan MAT-252 IRMS after initial treatment with phosphoric acid (Ou, 2013;J. Zhang et al, 2018b).…”

Section: Methodsmentioning

confidence: 99%

Vivianite formation in methane-rich deep-sea sediments from the South China Sea

et al. 2018

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“…The 40% excess sulfate is used for organic clastic sulfate reduction by the oxidation of organic matter buried into the SMTZ [29,30]. At the SMTZ, reducing conditions can result in reductive dissolution of magnetic Fe-oxides and alteration of the initial sediment composition and magnetic properties due to the replacement of magnetic Fe-oxides by paramagnetic authigenic Fe-sulfides [31,32]. During this process, the surface-adsorbed P (referred to here as P Fe ) from metal oxides and hydroxides are released into the pore water.…”

Section: Introductionmentioning

confidence: 99%

“…Carbonates with δ 13 C values less than −30‰ VPDB are generally consistent with carbon sourced from gas hydrate, and MDAC is often composed of aragonite, high-Mg calcite [20]. MDAC provides direct geological evidence of AOM and methane seepage in the sedimentary record [28,29,30,31]. Studies of the morphological distribution of pyrite have shown that the sulfate methane transition zone (SMTZ) where AOM occurs is mainly made up of three forms of pyrite: framboids, framboids with overgrowths, and euhedral crystals [27].…”

Section: Introductionmentioning

confidence: 99%

“…Studies of pore water and pyrite value of δ 34 S in the northern South China Sea have found that the SO 4 2− -AOM results in a positive deviation of δ 34 S [33]. During SO 4 2− -AOM sulfate is usually consumed under semi-closed or closed conditions, reflected in 34 S-enriched sulfide minerals [31,32,33]. Often, when methane is present, the majority of sulfate available in marine pore fluids is reduced through SO 4 2− -AOM.…”

Section: Introductionmentioning

confidence: 99%

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Geochemical Evidence of Metal-Driven Anaerobic Oxidation of Methane in the Shenhu Area, the South China Sea

Xie

Liu

et al. 2019

IJERPH

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Anaerobic oxidation of methane (AOM) is a common biochemical process in the ocean and it plays an important role in global climate change, elemental circulation, and atmospheric evolution over geological time. In this paper, we analyzed of δ34S, Fe, Mn, Ca/Ti, and Sr/Ti ratios, and the date of carbon and sulfur from the site SH3 of Shenhu area. Result showed that (1) 0–6 mbsf (meter blow the sea floor) was mainly affected by OSR (anaerobic oxidation of organic matters) and 7–15 mbsf was a paleo-SMTZ (sulfate–methane transition zone) position. The modern SMTZ was mainly distributed at 19–25 mbsf. The barium sulfate precipitation above the modern SMTZ indicating that the current methane leakage was stable and lasted longer during geological history. (2) By studying the change of magnetic and the different carbonate minerals, results showed that there were two AOM stages. During the early stage, Fe2+ were mainly produced by sulfide abiotic reductive dissolution. During the later stage, Fe2+ were mainly produced by the metal-AOM. (3) Study of the mineral characteristics of the paleo-SMTZ and the modern SMTZ showed that the modern SMTZ carbonate minerals were mainly low-Mg calcite and aragonite, while the paleo-SMTZ carbon minerals were mainly high Mg minerals. The reason for this difference is that the modern SMTZ layer was only experienced the first stage of anaerobic oxidation of methane. In the paleo-SMTZ layer, it has experienced two stage of anaerobic oxidation of methane. During the last stage of metal-AOM, the low Mg carbonate minerals were converted into high Mg carbonate minerals. This research confirms the presence of metal-driven methane anaerobic oxidation at the bottom of sulfate-driven methane anaerobic oxidation and during the metal-driven methane anaerobic oxidation, methane and metal oxides or hydroxides would couple to convert the in situ metal oxides or hydroxides into metal ions, meanwhile the phosphorus adsorbed on the surface of the metal oxides is released into adjacent pore water, and convert to new P-bearing minerals under suitable conditions.

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The influence of coupling mode of methane leakage and debris input on anaerobic oxidation of methane

Xie

Liu

et al. 2021

Acta Oceanol. Sin.

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Carbon and oxygen isotope composition of carbonate in bulk sediment in the southwest Taiwan Basin, South China Sea: Methane hydrate decomposition history and its link to mud volcano eruption

Cited by 19 publications

References 76 publications

Vivianite formation in methane-rich deep-sea sediments from the South China Sea

Vivianite formation in methane-rich deep-sea sediments from the South China Sea

Geochemical Evidence of Metal-Driven Anaerobic Oxidation of Methane in the Shenhu Area, the South China Sea

The influence of coupling mode of methane leakage and debris input on anaerobic oxidation of methane

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