Magmatic fluids play a role in the development of active gas chimneys and massive gas hydrates in the Japan Sea

Snyder, G. T.; Sano, Yuji; Takahata, Naoto; Matsumoto, Ryo; Kakizaki, Yoshihiro; Tomaru, Hitoshi

doi:10.1016/j.chemgeo.2020.119462

Cited by 25 publications

(18 citation statements)

References 48 publications

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“…When analyzing the interpreted BSRs, it can be seen that the shallow stretches of BSRs in red are associated with gas chimneys (Figure 12), where the upward migration of hydrocarbon gases develops gas hydrates accumulations. These zones are also associated with occurrence of mounds and pockmarks (Figure 1), as noted in previous work (e.g., Matsumoto et al 2009Matsumoto et al , 2011Matsumoto et al , 2017Freire et al, 2011, Snyder et al 2020.…”

Section: Final Interpretation Of Bsrssupporting

confidence: 83%

“…According to Matsumoto et al, 2011, studies focusing on the origin and significance of shallow, massive to fracturefilling gas hydrates in Joetsu Basin have begun since 2004 by a research consortium of universities, national institutes and industries. Thus, miscellaneous studies involving gas hydrates issues in this area have been carried out, such as acoustic and seismic surveys (e.g., Saeki et al, 2009;Nakajima et al, 2014), geophysical (e.g., Santos et al, 2009), geochemical and geological analysis (e.g., Matsumoto et al, 2005Matsumoto et al, , 2009Matsumoto et al, , 2011Matsumoto et al, , 2017Freire et al, 2011;Snyder et al, 2020). The contribution this work is the knowledge of the effects of the application of six seismic attributes to enhance the BSRs and free gas zones in seismic profiles from this area, which is also useful for others areas of the world.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of seismic attributes to enhance Bottom Simulating Reflectors in the gas hydrates field, Umitaka Spur, eastern margin of Japan Sea

Neves¹,

Freire²,

Silva³

et al. 2021

Proceeding of the 17th International Congress of the Brazilian Geophysical

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This work aims to evaluate the best seismic attributes for identifying the BSRs of Umitaka Spur, a well-known gas hydrates field, from the Joetsu Basin, Japan. For this purpose, it uses 2D single-channel seismic data from Expeditions NT07-20 and NT08-09 made available by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). The methodology consisted of the analysis of six seismic attributes to highlight the Bottom Simulating Reflectors (BSRs), through Schlumberger's Petrel 2019 software. These attributes were Envelope, RMS Amplitude, Amplitude Volume Technique, Relative Acoustic Impedance, Spectral Decomposition and Instantaneous Frequency. Thus, this methodology was fundamental to reduce the ambiguities inherent to geophysics, by highlighting the real BSRs through the seismic assessment of more than one physical property (amplitude and frequency) and the geological attributes that highlighted the faults of the complex local geology.

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Section: Final Interpretation Of Bsrssupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Analysis of seismic attributes to enhance Bottom Simulating Reflectors in the gas hydrates field, Umitaka Spur, eastern margin of Japan Sea

Neves¹,

Freire²,

Silva³

et al. 2021

Proceeding of the 17th International Congress of the Brazilian Geophysical

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“…Nevertheless, the hydrate saturations obtained from pressure coring in this study substantiate that shallow hydrates in deepwater pockmarks have a significant methane storage capacity. In this context, it is worth mentioning that continuous intervals of deeper (greater than ~33 mbsf) massive gas hydrates several meters in lengths have been collected by drilling at the margins of a large pockmark located at the Umitaka Spur in the Japan Sea (Snyder et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

Shallow Gas Hydrate Accumulations at a Nigerian Deepwater Pockmark—Quantities and Dynamics

et al. 2020

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The evolution of submarine pockmarks is often related to the ascent of fluid from the subsurface. For pockmarks located within the gas hydrate stability zone, methane oversaturation can result in the formation of gas hydrates in the sediment. An~600 m-wide sea floor depression in deep waters offshore Nigeria, Pockmark A, was investigated for distributions and quantities of shallow gas hydrates, origins of hydrocarbons, and time elapsed since the last major fluid ascent event. For the first time, pressure coring of shallow sediments and drilling of more than 50 m-long cores with the sea floor drill rig MARUM-MeBo70 were conducted in this pockmark. Unusually, high hydrate saturations of up to 51% of pore volume in the uppermost 2.5 m of sediment in the pockmark center substantiate that deepwater pockmarks are a relevant methane reservoir. Molecular and stable C and H isotopic compositions suggest that thermogenic hydrocarbons and secondary microbial methane resulting from petroleum biodegradation are injected into shallower sediments and mixed with primary microbial hydrocarbons. Two independent pore water chloride and sulfate modeling approaches suggest that a major methane migration event occurred during the past one to three centuries. A rough sea floor topography within the pockmark most likely results from combined sediment removal through ascending gas bubbles, hydrate clogging and deflection of migration pathways, gas pressure build-up, and hydrate sea floor detachment. This study shows for the first time the chronological interrelationship between gas migration events, hydrate formation, and sea floor shaping in a deep sea pockmark.

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“…Mantle-derived gases are more abundant in 3 He, whereas radiogenic 4 He is generated in uranium-and thorium-rich crustal rocks such as granite. As such, 3 He/ 4 He ratios have been used to determine, for example, whether mantle helium is present in methane hydrates located in gas chimneys in the eastern margin of the Japan Sea (Snyder et al, 2020). Adjacent to Tatar Strait, seeps and hydrocarbon wells on Sakhalin Island have shown consistent mantle helium signatures in the southern part of the island with crustal signatures being predominant in the northern part of the island (Lavrushin et al, 1996).…”

Section: Introduction Backgroundmentioning

confidence: 99%

Ocean Dynamics and Methane Plume Activity in Tatar Strait, Far Eastern Federal District, Russia as Revealed by Seawater Chemistry, Hydroacoustics, and Noble Gas Isotopes

et al. 2022

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This investigation presents methane, noble gas isotopes, CTD, and stable isotopic data for water samples collected in Niskin bottles at Tatar Strait during the spring seasons of 2015 and 2019 onboard the Russian R/V Akademik M.A. Lavrentyev. The results are compared to previous research carried out in 1999 in a nearby portion of the Strait and demonstrate that salinity and temperature can change appreciably. The CTD data from 1999 shows warm surface waters underlain by cold subsurface waters. In contrast, the 2015 data show the CTD data that show warm temperatures and high salinity extending down from the surface well into intermediate waters, while the 2019 data show cold surface waters underlain by even colder subsurface waters. CTD data collected above active gas plume sites along Sakhalin Island’s western shore show no substantial difference in temperature or salinity from the non-plume sites, and the methane concentrations at all of the measured sites are significantly above saturation, even in the shallow waters. Hydroacoustic data also suggest the presence of free gas and gas hydrate–coated methane bubbles from the seafloor at least to the base of upper intermediate waters. All of the intermediate and deep Japan Sea Proper waters in Tatar Strait still retain tritiogenic 3He, similar to that observed throughout much of the Japan Sea, indicating limited vertical exchange between these layers and surface waters. An analysis of the δ13C of dissolved inorganic carbon in the seawater shows that positive values are limited to surface waters and that the waters become progressively more depleted in 13C with depth. The results are consistent with research over the past several decades which has shown that ventilation of intermediate and deep Japan Sea Proper water is somewhat limited, while both the temperature and salinity of surface and subsurface water layers within the strait are sensitive to the balance between cold, less saline waters contributed by the Amur River/Primorye Current from the north and warm, saline waters contributed by the Tsushima Current from the south.

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Magmatic fluids play a role in the development of active gas chimneys and massive gas hydrates in the Japan Sea

Cited by 25 publications

References 48 publications

Analysis of seismic attributes to enhance Bottom Simulating Reflectors in the gas hydrates field, Umitaka Spur, eastern margin of Japan Sea

Analysis of seismic attributes to enhance Bottom Simulating Reflectors in the gas hydrates field, Umitaka Spur, eastern margin of Japan Sea

Shallow Gas Hydrate Accumulations at a Nigerian Deepwater Pockmark—Quantities and Dynamics

Ocean Dynamics and Methane Plume Activity in Tatar Strait, Far Eastern Federal District, Russia as Revealed by Seawater Chemistry, Hydroacoustics, and Noble Gas Isotopes

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