Jiulong methane reef: Microbial mediation of seep carbonates in the South China Sea

Han, Xiqiu; Suess, Erwin; Huang, Yong‐Jiang; Wu, N.; Bohrmann, Gerhard; Su, Xinming; Eisenhauer, Anton; Rehder, Gregor; Fang, Yuefa

doi:10.1016/j.margeo.2007.11.012

Cited by 199 publications

(120 citation statements)

References 28 publications

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“…The oceanic basement is dotted with buried volcanic structures and several have developed deep-reaching faults that act as methane-rich fluid pathways [6,28,29]. Methane-derived carbonates have been found in all three gas hydrates prospecting the target areas in the northern continental slope of the South China Sea, e.g.…”

Section: Geologic Setting and Samplesmentioning

confidence: 99%

“…The seepage of methane-rich fluids on passive margins is generally driven by the compaction of rapidly accumulating sediments and/or gas hydrate dissolution [1,6]. The abundant organic matter in the Shenhu sediments is therefore beneficial for methane formation.…”

Section: Sources Of Methane-rich Fluidsmentioning

confidence: 99%

“…The seepage of methane rich fluids on passive margins generally originates from hydrate water released during gas hydrate destabilization and/or is associated with rapidly accumulating sediments [1, 5,6]. These methane-rich fluids are generally derived from underlying sediments that migrate along deep-reaching faults or conduit upwards through the sediment column.…”

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confidence: 99%

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Glycerol ether biomarkers and their carbon isotopic compositions in a cold seep carbonate chimney from the Shenhu area, northern South China Sea

Jiang

Yang

et al. 2011

Chin. Sci. Bull.

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At modern cold seeps, the anaerobic oxidation of methane (AOM) is the dominant pathway for methane consumption in marine sediments. AOM, which is mediated by a consortium of methane oxidizing archaea and sulfate reducing bacteria, is proposed to be responsible for authigenic carbonate formation. A methane-derived carbonate chimney was collected from the Shenhu area, northern South China Sea. The membrane lipids and their very low carbon isotopic compositions (115‰ to 104‰) in the Shenhu chimney suggest the presence of an AOM process. Three specific archaeal and bacterial biomarkers were detected, including Ar, DAGE 1f, and monocyclic MDGD. Their strongly depleted   13 C values (115‰ to 104‰), which are lower than those of the normal marine lipids in sediments, reveal biogenic methane as their origin. The carbonate deposits exhibiting a chimney structure indicate that a vigorous methane-rich fluid expulsion may have occurred at the seafloor. We propose that the decomposition of gas hydrates at depth is the likely cause of seepage and cold seep carbonate formation in the Shenhu area.

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Section: Geologic Setting and Samplesmentioning

confidence: 99%

Section: Sources Of Methane-rich Fluidsmentioning

confidence: 99%

mentioning

confidence: 99%

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Glycerol ether biomarkers and their carbon isotopic compositions in a cold seep carbonate chimney from the Shenhu area, northern South China Sea

Jiang

Yang

et al. 2011

Chin. Sci. Bull.

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“…China launched its exploration plan of gas hydrates more than a decade ago [116], and in 2002, carbonate crust samples were collected by dredging from ~1000 m water depth in the northeastern SCS [117]. In 2004, the joint Chinese-German RV SONNE Cruise 177 conducted a thematic survey on gas hydrates by targeting methane seep carbonate crusts and associated microbes in the NE SCS, and discovered a "Jiulong methane reef" [118,119]. In March 2007, by applying ROV, scientists from Taiwan in collaboration with JAMSTEC of Japan discovered a chemosynthetic community at a cold seep site off SW Taiwan [120][121][122].…”

Section: Hydrothermal and Cold Seep Serpentinization Gas Hydratesmentioning

confidence: 99%

“…These pioneering works mostly devote to reporting microbial diversity in surface sediments [128][129][130][131][132], with only a few also including comparisons between microbial assemblages from different water depths [133] or discussions on a specific group of microbes such as alkane degrading bacteria [134]. Nevertheless, cold seepage studies have examined the role of chemosynthetic microbes in carbonate formation [119]. These types of biochemical reactions need to be kept in mind in geological observations in the SCS, as they are not restricted to the modern cold seep and hydrothermal vent, but also extensively reported in paleo-records [135].…”

Section: Deep Biosphere and Deep Carbon Reservoirmentioning

confidence: 99%

Tracing the life history of a marginal sea—On “The South China Sea Deep” Research Program

Wang

2012

Chin. Sci. Bull.

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the first large-scale basic-research program in ocean science in the country aiming to reconstruct the life history of a marginal sea. The overall scientific objective of the program is to dissect this typical marginal sea by studying its history of evolution and its modern processes, including the following three major components: (1) Development of the deep basin: utilizing new techniques to re-measure magnetic anomaly lineations, to explore the deep tectonic features, to drill the oceanic crust, and to study volcanic seamount chains; (2) deep-water sediments: observing the modern processes to reveal the patterns of deep-water circulations and sedimentation, analyzing deep-sea sediments to recognize paleoceanographic response to basin evolution, and subsequently to bridge the modern and paleo-studies of the deep-sea processes; and (3) biogeochemical processes: using a variety of techniques including deploying submarine observation and deep-water diving device to investigate the distribution patterns and environmental impacts of deepwater seepages and subbottom circulation, and to reveal the role of microbes in deep-sea carbon cycling. As compared with the open ocean and other marginal seas, the South China Sea enjoys many more advantages as a marine basin for reconstructing the life history. Meanwhile, the South China Sea Deep Program provides unique opportunities in studying the evolution and variations of the sea-land interactions between the Pacific and Asia.the South China Sea Deep, marginal sea, deep-sea process, life history, tectonic evolution, sedimentological response, biogeochemistry Citation:Wang P X. Tracing the life history of a marginal

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In Situ Raman Detection of Gas Hydrates Exposed on the Seafloor of the South China Sea

Zhang

Luan

et al. 2017

Geochem Geophys Geosyst

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Gas hydrates are usually buried in sediments. Here we report the first discovery of gas hydrates exposed on the seafloor of the South China Sea. The in situ chemical compositions and cage structures of these hydrates were measured at the depth of 1,130 m below sea level using a Raman insertion probe (RiP‐Gh) that was carried and controlled by a remotely operated vehicle (ROV) Faxian. This in situ analytical technique can avoid the physical and chemical changes associated with the transport of samples from the deep sea to the surface. Natural gas hydrate samples were analyzed at two sites. The in situ spectra suggest that the newly formed hydrate was Structure I but contains a small amount of C3H8 and H2S. Pure gas spectra of CH4, C3H8, and H2S were also observed at the SCS‐SGH02 site. These data represent the first in situ proof that free gas can be trapped within the hydrate fabric during rapid hydrate formation. We provide the first in situ confirmation of the hydrate growth model for the early stages of formation of crystalline hydrates in a methane‐rich seafloor environment. Our work demonstrates that natural hydrate deposits, particularly those in the early stages of formation, are not monolithic single structures but instead exhibit significant small‐scale heterogeneities due to inclusions of free gas and the surrounding seawater, there inclusions also serve as indicators of the likely hydrate formation mechanism. These data also reinforce the importance of correlating visual and in situ measurements when characterizing a sampling site.

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Jiulong methane reef: Microbial mediation of seep carbonates in the South China Sea

Cited by 199 publications

References 28 publications

Glycerol ether biomarkers and their carbon isotopic compositions in a cold seep carbonate chimney from the Shenhu area, northern South China Sea

Glycerol ether biomarkers and their carbon isotopic compositions in a cold seep carbonate chimney from the Shenhu area, northern South China Sea

Tracing the life history of a marginal sea—On “The South China Sea Deep” Research Program

In Situ Raman Detection of Gas Hydrates Exposed on the Seafloor of the South China Sea

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