Gas geochemical characteristics of hydrothermal plumes at the HAKUREI and JADE vent sites, the Izena Cauldron, Okinawa Trough

Kawagucci, Shinsuke; Shirai, Kotaro; Lan, Tefang; Takahata, Naoto; Tsunogai, Urumu; Sano, Yuji; Gamo, Toshitaka

doi:10.2343/geochemj.1.0100

Cited by 37 publications

(38 citation statements)

References 53 publications

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“…3). This difference is in agreement with the chemical signature of the hydrothermal plumes above these fields; an order of magnitude higher H 2 /CH 4 ratio in water column above the Hakurei field than the Jade field (Kawagucci et al, 2010a).…”

Section: Intra-field Diversity In Minor Gas Chemistry Caused By Fluidsupporting

confidence: 79%

“…Since 2008, the Hakurei field has been explored intensively by JOGMEC (Japan Oil, Gas and Metals National Corporation) under a framework of the ocean energy and mineral resources development program. Despite the vicinity of these two sites within 3 km, a previous water column survey above the Izena Hole revealed more than one-order higher H 2 /CH 4 ratio in the hydrothermal plume above the Hakurei field than that above the Jade field (Kawagucci et al, 2010a). On the other hand, seismological investigations during the R/V Kaiyo KY02-11 cruise in 2002 reported notable geological differences between these two fields.…”

Section: Fig 1 Topographic Maps Of the Izena Hole (A) The Jade Hydmentioning

confidence: 90%

“…The most likely process to cause H 2 enrichment in the Hakurei fluid is thermal degradation of sedimentary organic matter during the fluid upwelling (Seewald et al, 1994;Cruse and Seewald, 2006), as pointed out in the previous plume study (Kawagucci et al, 2010a). This process could be represented by a general reaction of hydrocarbons degradation as following, R -CH 2 CH 2 CH 3 + 4H 2 O = R + 2CO 2 + CH 4 + 5H 2 where R is some hydrocarbon moiety (Seewald, 2003).…”

Section: Intra-field Diversity In Minor Gas Chemistry Caused By Fluidmentioning

confidence: 99%

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Diversity of fluid geochemistry affected by processes during fluid upwelling in active hydrothermal fields in the Izena Hole, the middle Okinawa Trough back-arc basin

et al. 2014

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Section: Intra-field Diversity In Minor Gas Chemistry Caused By Fluidsupporting

confidence: 79%

Section: Fig 1 Topographic Maps Of the Izena Hole (A) The Jade Hydmentioning

confidence: 90%

Section: Intra-field Diversity In Minor Gas Chemistry Caused By Fluidmentioning

confidence: 99%

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Diversity of fluid geochemistry affected by processes during fluid upwelling in active hydrothermal fields in the Izena Hole, the middle Okinawa Trough back-arc basin

et al. 2014

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“…Concentration of H 2 (<200 µmol/kg) is not so high relative to those in other felsic-rock based fields (e.g., Takai et al, 2008b) and results in a H 2 /CH 4 ratio lower than 0.07. While H 2 /CH 4 ratios in sedimentfree fields are typically higher than 1, those in sedimentassociated fields are lower than 1 (Kawagucci et al, 2010b). In addition, the stable hydrogen isotope ratio of CH 4 (δD CH4 ) was -132‰, comparable with those so far Proskurowski et al (2006) (Horibe and Craig, 1995) Fig.…”

Section: Methanementioning

confidence: 51%

Hydrothermal fluid geochemistry at the Iheya North field in the mid-Okinawa Trough: Implication for origin of methane in subseafloor fluid circulation systems

et al. 2011

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Geochemical characteristics of hydrothermal fluids in the Iheya North hydrothermal field, mid-Okinawa Trough, was investigated. Twelve-years observation reveals temporal variation of vent fluid chemistry potentially controlled by temporally varying pattern of the phase-separation and -segregation, while the constant Element/Cl ratios among the periods and chimneys indicate the stable chemical composition of the source hydrothermal fluid prior to undergoing phaseseparation. The high K contents in the estimated source fluid are typical in the arc-backarc hydrothermal systems due to the hydrothermal reaction with the K-enriched felsic rocks. The high I, B and NH 4 contents and alkalinity are derived from decomposition of the sedimentary organic matters.Compositional and isotopic properties of gas species, CH 4 , H 2 , CO 2 , and C 2 H 6 , strongly suggest a dominance of biogenic CH 4 associated with the sedimentary organic matter. Based on the carbon mass balance calculation and the multidisciplinary investigations of the Iheya North hydrothermal system since the discovery, we hypothesized that the microbial methanogenesis occurs not only within the Central Valley where hydrothermal vents exist, but also in the spatially abundant and widespread basin-filling sediments surrounding the Iheya North Knoll, and that the microbially produced CH 4 is recharged together with the source fluid into the deep hydrothermal reaction zone. This "Microbial Methanogenesis at Recharge area in hydrothermal circulation" (MMR) model would be an implication for the generation and incorporation of hydrothermal fluid CH 4 in the deep-sea hydrothermal systems but also for those of cold seep CH 4 and for the presently uncertain hydrothermal fluid paths in the subseafloor environments. In the near future, the IODP drilling will be conducted in the Iheya North hydrothermal system, and give an excellent opportunity to testify our MMR model.

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“…Because the sedimentary settings of the discharge stages are quite different between the fields (thick sediment-covered Hakurei field and sediment-starved Jade field), it is reasonable that thermogenic hydrocarbons and molecular hydrogen entrained into the upwelling fluid occur only in the Hakurei field (Fig. 30.8c) (Kawagucci et al 2010a;Ishibashi et al 2014). Hydrothermal fluid reservoir underlying the southern part of the bottom and north-eastern inner wall of the Izena Hall imply that the fluid recharge occurs not only within the Izena Cauldron but also in the volcanic body of the Izena Hall and the OT-filling sediment surrounding the Izena Hall, >4 km from the vents (Fig.…”

Section: Izena Hall (Jade and Hakurei)mentioning

confidence: 99%

Fluid Geochemistry of High-Temperature Hydrothermal Fields in the Okinawa Trough

Kawagucci

2014

Subseafloor Biosphere Linked to Hydrothermal Systems

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This review compiles fluid chemistries of the six known high-temperature hydrothermal fields in the Okinawa Trough (OT) and compares them to global representative fields with various tectonic/geologic backgrounds. The comparisons indicate that the chemical characteristics of the OT hydrothermal fluids are explained by linkages between (1) shallow water depth that constrains the maximum fluid temperature, (2) back-arc tectonic setting that introduces magmatic volatiles into the fluid, (3) probable silicic rock-based fluidmineral interaction at the hydrothermal reaction zone, and (4) seafloor sediment around the vents that provides both compounds derived from sedimentary organic matter and biogenic compounds, such as methane, produced by microbial ecosystems in the sedimentary environment.To explain the highly diverse gas compositions and stable isotope ratios of methane among the OT hydrothermal fields, "fluid-sediment interaction" has been further classified into several types with respect to processes (microbial or chemical) and stages of subseafloor fluid circulation (recharge or discharge). This concept, called the Microbial Methanogenesis at Recharge stage (MMR) model, enables us not only to deduce the geochemical origins of the hydrothermal fluid CH 4 in each OT field but also to estimate the geographical distribution of hydrothermal fluid circulation via a two-dimension schematic illustration. The model, which links the fluid geochemistry with the subseafloor fluid migration path, will serve as a base for future studies also for any subseafloor geofluid systems that include hydrothermal systems, subseafloor methane hydrate, and seismogenic fault zone. Keywords

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Gas geochemical characteristics of hydrothermal plumes at the HAKUREI and JADE vent sites, the Izena Cauldron, Okinawa Trough

Cited by 37 publications

References 53 publications

Diversity of fluid geochemistry affected by processes during fluid upwelling in active hydrothermal fields in the Izena Hole, the middle Okinawa Trough back-arc basin

Diversity of fluid geochemistry affected by processes during fluid upwelling in active hydrothermal fields in the Izena Hole, the middle Okinawa Trough back-arc basin

Hydrothermal fluid geochemistry at the Iheya North field in the mid-Okinawa Trough: Implication for origin of methane in subseafloor fluid circulation systems

Fluid Geochemistry of High-Temperature Hydrothermal Fields in the Okinawa Trough

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