Molecular and isotopic signatures in sediments and gas hydrate of the central/southwestern Ulleung Basin: high alkalinity escape fuelled by biogenically sourced methane

Kim, Ji Hoon; Park, Myong-Ho; Chun, Jong-Hwa; Lee, Joo Yong

doi:10.1007/s00367-010-0214-y

Cited by 49 publications

(30 citation statements)

References 55 publications

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“…Ethane concentration does not show vertical variation with depth at Site U1380, whereas it increases with depth at Sites U1412 and U1413. In general, C 1 /C 2+ ratios are >1000 in biogenic gases and <300 in thermogenic gases (Claypool and Kvenvolden, 1983;Whiticar et al, 1986;Whiticar, 1999;Milkov et al, 2005;Pape et al, 2010;Kim et al, 2011Kim et al, , 2012. In this study, the C 1 /C 2+ ratio is lowest (<300) in lithostratigraphic Unit I at Site U1380 and Unit III at Site U1413.…”

Section: Headspace Gassupporting

confidence: 43%

Data report: gas isotope and conversion ratio of headspace and void gas, IODP Expedition 344

Choi¹,

Kim²,

Kim³

et al. 2016

Proceedings of the IODP

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Gas stable isotopes (δ 13 C CH4 , δD CH4 , and δ 13 C CO2 ) and the conversion ratios of headspace gas and void gas have been analyzed at Integrated Ocean Drilling Program Expedition 344 Sites U1380, U1412, and U1413 to reveal the origin and migration of gas. The results of headspace gas and void gas analyses illustrate that methane (C 1 ) is the dominant component and ethane (C 2 ) is a minor component. Variations in C 1 /C 2+ ratios with depth display differing trends across sites. The δ 13 C CH4 and δD CH4 values are less than -57.0‰ and -181‰, respectively, indicating that hydrocarbon gas might be originated through CO 2 reduction. In addition, the organic matter to hydrocarbon gas conversion ratios of biogenic void gas at Sites U1412 and U1413 range from 22% to 30%. IntroductionThe Costa Rica Seismogenesis Project, Program A Stage 2, drilled at five sites located offshore of the Osa Peninsula near the incoming Cocos Ridge to study the processes controlling earthquakes in an erosional subduction zone (see the "Expedition 344 summary" chapter [Harris et al., 2013a]). Among the five sites, Sites U1380, U1412, and U1413 were studied to investigate deep fluid transportation. Several studies on the sources and evolution of the magmas are well advanced, even though subduction zone settings can be quite complex (e.g., Stern, 2002; van Keken, 2003;Hall and Kincaid, 2001). In contrast, we know little about fluid migration in subduction zones. The characterization of gas isotope and conversion ratio in headspace gas (HS) and void gas (VG) could help to understand deep fluid systems and the origin of gases. In this study, we provide the molecular and stable isotopic compositions of HS and VG, which are indicators for the origin and migration of the gases. Furthermore, we show the organic matter to hydrocarbon gas conversion ratios at the drilled sites. Methods and materials Gas compositionThe HS samples were analyzed onboard by an Agilent 6890 Series II gas chromatograph (GC3) (see the "Methods" chapter [Harris Harris, R.N., Sakaguchi, A., Petronotis, K., and the Expedition 344 Scientists

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Section: Headspace Gassupporting

confidence: 43%

Data report: gas isotope and conversion ratio of headspace and void gas, IODP Expedition 344

Choi¹,

Kim²,

Kim³

et al. 2016

Proceedings of the IODP

View full text Add to dashboard Cite

show abstract

“…However, high DIC concentrations (e.g. 430 mM) around SMI may invalidate the diagram as suggested by many others previously (Snyder et al, 2007;Kim et al, 2011;Hong et al, 2013). The DIC concentrations in the four studied cores are all below 15 mM, and the validity of the diagram is expected.…”

Section: Osr Vs Aom: Implication From Sulfate Concentration Dic Conmentioning

confidence: 73%

Impact of anaerobic oxidation of methane on the geochemical cycle of redox-sensitive elements at cold-seep sites of the northern South China Sea

Dong

Liang

et al. 2015

Deep Sea Research Part II: Topical Studies in Oceanography

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“…2e4, and Snyder et al, 2007). The lack of correlation with SO 4 2À gradients is probably due to the effect of alkalinity flux from greater sediment depths (e.g., Chatterjee et al, 2011;Kim et al, 2011). An increase in alkalinity flux from depth [number*] next to SO 4 2À gradient; one data from the seawater value (28.0 mM at 0 cmbsf).…”

Section: C Dic At the Smt Versus D 13 C Of Deep Methanementioning

confidence: 96%

“…The minimum d 13 C DIC value at the SMT depends on several factors, such as the carbon isotopic composition of each HCO 3 À source and the proportion of HCO 3 À contributed from each source (e.g., Chatterjee et al, 2011;Formolo et al, 2004;Kim et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Influence of the carbon isotopic composition of methane and the proportion of methane-derived bicarbonate on the 13C/12C ratio of dissolved inorganic carbon at the sulfate–methane transition in the Joetsu Basin area, eastern margin of the Sea of Japan

Hiruta

Ishizaki

Tuchinaga

et al. 2015

Marine and Petroleum Geology

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Molecular and isotopic signatures in sediments and gas hydrate of the central/southwestern Ulleung Basin: high alkalinity escape fuelled by biogenically sourced methane

Cited by 49 publications

References 55 publications

Data report: gas isotope and conversion ratio of headspace and void gas, IODP Expedition 344

Data report: gas isotope and conversion ratio of headspace and void gas, IODP Expedition 344

Impact of anaerobic oxidation of methane on the geochemical cycle of redox-sensitive elements at cold-seep sites of the northern South China Sea

Influence of the carbon isotopic composition of methane and the proportion of methane-derived bicarbonate on the 13C/12C ratio of dissolved inorganic carbon at the sulfate–methane transition in the Joetsu Basin area, eastern margin of the Sea of Japan

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