Seafloor authigenic carbonate crusts along the submerged part of the North Anatolian Fault in the Sea of Marmara: Mineralogy, geochemistry, textures and genesis

Çağatay, M. Namık; Yıldız, Güliz; Bayon, Germain; Ruffine, Livio; Henry, Pierre

doi:10.1016/j.dsr2.2017.09.003

Cited by 17 publications

(21 citation statements)

References 102 publications

(182 reference statements)

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“…However, there is no systematic relationship between gas composition and proximity to fault zones. For instance, thermogenic methane dominates fluid emissions over the top of the Central High and within the MMF deformation zone in the Western High (Bourry et al, 2008;Çağatay et al, 2017;Ruffine et al, 2017) but we showed that the distributions of seepages have different characteristics at both locations (broad leakage zone over an anticline vs. 2 km wide swath along the main fault). Close examination of the relationship between faults and gas emissions within seafloor deformation zones also shows that even at the 10-100 m scale of AUV maps and submersible observations (Figure 7 and Grall et al, this issue), many acoustic anomalies are not located on the outcrops of small faults.…”

Section: Gas Migration Pathways In Shallow Sedimentsmentioning

confidence: 52%

A statistical approach to relationships between fluid emissions and faults: The Sea of Marmara case

Henry

Grall

Kende

et al. 2018

Deep Sea Research Part II: Topical Studies in Oceanography

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The Sea of Marmara is traversed by the North Anatolian Fault system and also presents abundant emission sites of methane gas into the water column. In order to assess the spatial relationship between gas emissions and active faults, the distribution of distances between gas emission sites and the nearest fault is calculated and compared with the distribution of distances between a uniform random distribution of points (Poisson process representing the null hypothesis of an absence of relationship between gas emissions and faults) and the nearest fault. Interestingly, the distance distribution for the Poisson process is nearly exponential, indicating that the fault map does not have a characteristic scale other than that representing the intensity of the fault network. The distance distribution for the observed gas emissions is significantly narrower than that arising from the Poisson process, with a Kolmogorov distance of 0.25±0.02. The crossing point between the two distributions defines the characteristic halfwidth of the swath of gas emission sites around the mapped active faults. For the whole Sea of Marmara data set a characteristic half-width of 900-1000 m is found which matches the half-width of the seafloor deformation zone observed around the main active fault. When the same analysis is applied to zones covering the Western High and the Central High it is found that the swath of gas emissions is wider on the Central High (2 km half-width), and not clearly related to the seafloor deformation zone there. This difference is put in perspective with recent work showing that creep is occurring on the western segment of the Main Marmara Fault (this also causing microseismicity) while the central Istanbul-Silivri segment may have remained locked since the 1766 magnitude 7+ earthquake. This suggests that aseismic slip (and not only earthquake occurrence) effectively maintains high permeability conduits in fault zones in sediments.

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Section: Gas Migration Pathways In Shallow Sedimentsmentioning

confidence: 52%

A statistical approach to relationships between fluid emissions and faults: The Sea of Marmara case

Henry

Grall

Kende

et al. 2018

Deep Sea Research Part II: Topical Studies in Oceanography

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“…gas hydrate is estimated to cover an area of about 55 km 2 today . Samples from water depths between 200 and 1,000 m represent sites with a possible link between hydrostatic pressure and hydrate dissociation (Çağatay et al, 2018;Crémière et al, 2013;Han et al, 2014;Himmler et al, 2016;Liebetrau et al, 2010Liebetrau et al, , 2014Mazzini et al, 2017;Prouty et al, 2016;Ruffine et al, 2013;Teichert et al, 2003;Tong et al, 2013;Yang, Chu, et al, 2018). 3. the average gas hydrate saturation estimated from pore water freshening analysis ranges from 45% to 55% of the total pore space we use 50% for calculation); 4.…”

Section: Estimating Past Methane Flux Caused By Gas Hydrate Dissociationmentioning

confidence: 99%

“…Using a simple model, we calculate methane flux as follows: Table S4 for detail) and seep carbonates in this study (red and blue circles; Table S3). Samples from water depths greater than 1,000 m (Aharon et al, 1997;Bayon, Loncke, et al, 2009;Bayon et al, 2013Bayon et al, , 2015Çağatay et al, 2018;Crémière et al, 2013;Feng et al, 2010;Himmler et al, 2015Himmler et al, , 2019Kutterolf et al, 2008;Lalou et al, 1992;Liebetrau et al, 2010Liebetrau et al, , 2014Mazumdar et al, 2009;Prouty et al, 2016;Watanabe et al, 2008) represent sites with a weak link between hydrostatic pressure and hydrate dissociation, whereas samples from water depths less than 200 m represent sites were hydrate dissociation was not involved (Aharon et al, 1997;Crémière, Lepland, Chand, Sahy, Kirsimäe, et al, 2016;Feng et al, 2010). Samples from water depths between 200 and 1,000 m represent sites with a possible link between hydrostatic pressure and hydrate dissociation (Çağatay et al, 2018;Crémière et al, 2013;Han et al, 2014;Himmler et al, 2016;Liebetrau et al, 2010Liebetrau et al, , 2014Mazzini et al, 2017;Prouty et al, 2016;Ruffine et al, 2013;Teichert et al, 2003;Tong et al, 2013;Yang, Chu, et al, 2018).…”

Section: Estimating Past Methane Flux Caused By Gas Hydrate Dissociationmentioning

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 sediments in the vicinity of the seeps host living benthic Foraminifera, and a study from samples collected on the Central High and the Çınarcık Basin show that Bolivina vadescens and Globobulimina affinis are the two dominant species at the study areas (Fontanier et al, 2018). Three articles (Akhoudas et al, 2018;Çağatay et al, 2018;Teichert et al, 2018) deal specifically with the texture, mineralogical and isotopic compositions and genesis of authigenic carbonate crusts associated with cold seeps in the SoM. These studies demonstrate the use of crusts as archives of past fluid activity and possibly of earthquake activity.…”

Section: Introductionmentioning

confidence: 99%

Fluids and processes at the seismically active fault zone in the Sea of Marmara

Ruffine

Çağatay

Géli

2018

Deep Sea Research Part II: Topical Studies in Oceanography

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Seafloor authigenic carbonate crusts along the submerged part of the North Anatolian Fault in the Sea of Marmara: Mineralogy, geochemistry, textures and genesis

Cited by 17 publications

References 102 publications

A statistical approach to relationships between fluid emissions and faults: The Sea of Marmara case

A statistical approach to relationships between fluid emissions and faults: The Sea of Marmara case

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

Fluids and processes at the seismically active fault zone in the Sea of Marmara

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