Glacigenic sedimentation pulses triggered post-glacial gas hydrate dissociation

Karstens, Jens; Haflidason, Haflidi; Becker, Lukas W. M.; Berndt, Christian; Rüpke, Lars; Liebetrau, Volker; Schmidt, Mark; Mienert, Jürgen

doi:10.1038/s41467-018-03043-z

Cited by 41 publications

(44 citation statements)

References 52 publications

(64 reference statements)

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“…More rapid sedimentation and tectonic stress could increase significantly the pore‐fluid pressure of highly pressurized strata, leading to fluid migration to shallower depths (Flemings et al, , ; Yamamoto et al , ; Yamamoto & Kawakami, ). Increased pore pressure beyond the sediment shear strength could trigger methane‐rich fluid expulsion/seepage events (Crémière et al, ; Karstens et al, ). Episodic methane seepage would lead to multiple events of AOM‐coupled sulfate reduction to cause dissolution of primary magnetic mineral assemblages and precipitation of secondary magnetic iron sulfides to create a distinct sediment magnetic signature (Dewangan et al, ; Riedinger et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…It is possible that greigite was formerly present in Z‐II, Z‐III, and Z‐IV in the studied cores. Later, when conditions became disadvantageous for greigite formation/preservation due to gas hydrate dissociation caused by changing pressure‐temperature or increased sedimentation (Housen & Musgrave, ; Karstens et al, ; Larrasoaña et al, ; Musgrave et al, ), ferrimagnetic greigite would have been subsequently transformed into paramagnetic pyrite in Z‐II, Z‐III, and Z‐IV (Berner, ; Kao et al, ). Similar observations have been reported for a sediment core (Hole C0008C) from the megasplay fault zone of Nankai Trough (Kars & Kodama, , b).…”

Section: Discussionmentioning

confidence: 99%

“…For example, neotectonic activity can potentially alter the base of the gas hydrate stability zone, leading to the gas hydrate dissociation and intensified methane expulsion/seepage events (Dewangan et al, ; Goto et al, ; Jahren et al, ; Riedel et al, ; von Huene & Pecher, ). Rapid sediment loading triggered by abrupt climatic changes and supply from major river systems can generate overpressured sedimentary strata, thereby creating an efficient fluid migration system and sedimentary reservoir for methane trapping and gas hydrate formation (Hustoft et al, ; Karstens et al, ; Torres et al, ; Wang et al, ; Yu et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Magnetic Mineralogical Approach for the Exploration of Gas Hydrates in the Bay of Bengal

et al. 2019

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We evaluate the environmental magnetic, geochemical, and sedimentological records from three sediment cores from potential methane-hydrate bearing sites to unravel linkages between sedimentation, shale tectonics, magnetite enrichment, diagenesis, and gas hydrate formation in the Krishna-Godavari basin. Based on downcore rock magnetic variations, four sedimentary magnetic property zones (I-IV) are demarcated. A uniform band of enhanced magnetic susceptibility (zone III) appears to reflect a period of high-sedimentation events in the Krishna-Godavari basin. Highly pressurized sedimentary strata developed as a result of increased sedimentation that triggered the development of a fault system that provided conduits for upward methane migration to enter the gas hydrate stability zone, leading to the formation of gas hydrate deposits that potentially seal the fault system. Magnetic susceptibility fluctuations and the presence of iron sulfides in a magnetically enhanced zone suggest that fault system growth facilitated episodic methane venting from deeper sources that led to multiple methane seepage events. Pyrite formation along sediment fractures resulted in diagenetic depletion of magnetic signals and potentially indicates paleo sulfate-methane transition zone positions. We demonstrate that a close correlation between magnetic susceptibility and chromium reducible sulfur concentration can be used as a proxy to constrain paleomethane seepage events. Our findings suggest that the interplay between higher sedimentation events and shale tectonism facilitated fluid/gas migration and trapping and the development of the gas hydrate system in the Krishna-Godavari basin. The proposed magnetic mineralogical approach has wider scope to constrain the understanding of gas hydrate systems in marine sediments.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetic Mineralogical Approach for the Exploration of Gas Hydrates in the Bay of Bengal

et al. 2019

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“…One important characteristic of the oceanic gas hydrate reservoir is its sensitivity to environmental change (Karstens et al, 2018;Ruppel, 2011;Ruppel & Kessler, 2017), with possible impact on slope stability and global climate. Specifically, the dissociation of gas hydrate in marine sediments is primarily driven by changes in temperature, pressure, methane supply, and/or salinity (Dickens & Quinby-Hunt, 1994;Riboulot et al, 2018).…”

Section: 1029/2019gl085643mentioning

confidence: 99%

Gas Hydrate Dissociation During Sea‐Level Highstand Inferred From U/Th Dating of Seep Carbonate From the South China Sea

Fang

Wang

et al. 2019

Geophysical Research Letters

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Gas hydrates represent a huge reservoir of methane in marine sediments, prone to dissociation in response to environmental changes. There is consensus that past events of gas hydrate dissociation in the marine environment mainly occurred during periods of low sea level. Here, we report geochemical data for 2-m-thick layers of seep carbonate collected from a hydrate-bearing drill core from~800-m water depth in the northern South China Sea. The aragonite-rich carbonates reveal positive δ 18 O values, confirming a genetic link with gas hydrate dissociation. Uranium-thorium dating of seep carbonates indicates that gas hydrates at the study site dissociated between 133,300 and 112,700 years BP, hence coinciding with the Last Interglacial (MIS 5e) sea-level highstand. We put forward the concept that a climate-driven increase in temperature was responsible for a period of pronounced gas hydrate dissociation.Plain Language Summary The gas hydrate reservoir is a dynamically changing system extremely susceptible to variations of seafloor temperature and pressure. Therefore, gas hydrate dissociation and subsequent methane seepage frequently occur during times of global climate change, especially during sea-level lowstands with reduced seabed pressure. However, this conclusion was mainly based on dating of seep carbonates sampled from the seabed. As a consequence, one cannot exclude that previous results have been compromised by a sampling bias since seafloor samples are easier to collect. Authigenic seep carbonates from drill cores represent a continuous record of gas hydrate dynamics. Our uranium-thorium dating of seep carbonate from drill cores provides a unique example of the effects of temperature and pressure on the stability of the hydrate system in the Dongsha area, northern South China Sea (SCS), during the last interglacial stage (MIS 5e, about 130,000 years BP). Representing the most similar and most contemporary analog to the current interglacial, the study of a methane release event in the SCS during MIS 5e will shed light on the expected trend of methane release events in the future, while providing insight into the response of low-latitude oceans to climate change.Supporting Information:• Data Set S1

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“…The terms seismic chimneys or pipes and pockmarks are attributed to the localized release of overpressure in the subsurface through hydraulic connection of deeper strata with the seafloor (Cole et al, 2000;Hustoft et al, 2009). Pockmarks that formed above pipe and chimney structures are observed globally, for example, at the Vestnesa Ridge NW off Svalbard (Hustoft et al, 2009;Plaza-Faverola et al, 2017), in the Nyegga pockmark field on the continental Norwegian margin (Karstens et al, 2018), offshore Nigeria (Løseth et al, 2011), in the Western Nile Deep Sea Fan (Moss et al, 2012), and in the Lower Congo Basin (Gay et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Pockmarks in the Witch Ground Basin, Central North Sea

Böttner

Berndt

Reinardy

et al. 2019

Geochem Geophys Geosyst

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Marine sediments host large amounts of methane (CH4), which is a potent greenhouse gas. Quantitative estimates for methane release from marine sediments are scarce, and a poorly constrained temporal variability leads to large uncertainties in methane emission scenarios. Here, we use 2‐D and 3‐D seismic reflection, multibeam bathymetric, geochemical, and sedimentological data to (I) map and describe pockmarks in the Witch Ground Basin (central North Sea), (II) characterize associated sedimentological and fluid migration structures, and (III) analyze the related methane release. More than 1,500 pockmarks of two distinct morphological classes spread over an area of 225 km2. The two classes form independently from another and are corresponding to at least two different sources of fluids. Class 1 pockmarks are large in size (>6 m deep, >250 m long, and >75 m wide), show active venting, and are located above vertical fluid conduits that hydraulically connect the seafloor with deep methane sources. Class 2 pockmarks, which comprise 99.5% of all pockmarks, are smaller (0.9–3.1 m deep, 26–140 m long, and 14–57 m wide) and are limited to the soft, fine‐grained sediments of the Witch Ground Formation and possibly sourced by compaction‐related dewatering. Buried pockmarks within the Witch Ground Formation document distinct phases of pockmark formation, likely triggered by external forces related to environmental changes after deglaciation. Thus, greenhouse gas emissions from pockmark fields cannot be based on pockmark numbers and present‐day fluxes but require an analysis of the pockmark forming processes through geological time.

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Glacigenic sedimentation pulses triggered post-glacial gas hydrate dissociation

Cited by 41 publications

References 52 publications

Magnetic Mineralogical Approach for the Exploration of Gas Hydrates in the Bay of Bengal

Magnetic Mineralogical Approach for the Exploration of Gas Hydrates in the Bay of Bengal

Gas Hydrate Dissociation During Sea‐Level Highstand Inferred From U/Th Dating of Seep Carbonate From the South China Sea

Pockmarks in the Witch Ground Basin, Central North Sea

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