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

Ishibashi, Jun Ichiro; Noguchi, Takuroh; Toki, Tomohiro; Miyabe, Shunsuke; Yamagami, Shosei; Onishi, Yuji; Yamanaka, Toshiro; Yokoyama, Yuka; Omori, Eriko; Takahashi, Yoshio; Hatada, Kenta; Nakaguchi, Yoshitsugu; Yoshizaki, Masanori; Konno, Uta; Shibuya, Takazo; Takai, Ken; Inagaki, Fumio; Kawagucci, Shinsuke

doi:10.2343/geochemj.2.0311

Cited by 75 publications

(115 citation statements)

References 44 publications

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“…Carbonate mineralization was found in the distal area where Cl-depleted and transparent fluid venting sometimes associated with discharge of CO 2 liquid droplets was observed. Similar intra-field diversity in fluid chemistry was recognized also in the Jade field (Ishibashi et al 2014). Such a geographical distribution of hydrothermal discharge is similar to the diversity of fluid discharges observed in a subaerial geothermal field.…”

Section: Diverse Range Of Mineralization and Fluid Chemistrysupporting

confidence: 56%

“…Abundant tuff breccia and woody pumice exposed on the slopes, and a center-cone like small knoll consisted of dacitic lava recognized at the center of the Hole, are evidence for recent magmatic activity Kato 1990). Hydrothermal activity has been observed over an area exceeding 500 m length during ROV studies (Ishibashi et al 2014). Vigorous high temperature fluid venting in the Hakurei field was often associated with a complex chimney structure which was more than 10 m in height and equipped with well-developed flange structure.…”

Section: Hakurei Hydrothermal Field In the Izena Holementioning

confidence: 99%

“…At the southwestern extension of the chimney line, thick layered consolidated structure plausibly consisted of amorphous silica and native sulfur was recognized at~500 m apart from the TBS chimney. In the vicinity, diffusive venting of hydrothermal fluid of 104 C associated with liquid CO 2 bubble was located, which was named as the Biwako vent (Ishibashi et al 2014). About 3 km southwest of the Biwako Vent, the Hakurei field is located; however, the sandwiched area between the Jade and Hakurei fields has not been explored.…”

Section: Jade Hydrothermal Field In the Izena Holementioning

confidence: 99%

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Hydrothermal Activity in the Okinawa Trough Back-Arc Basin: Geological Background and Hydrothermal Mineralization

Ishibashi

Ikegami

Tsuji

et al. 2014

Subseafloor Biosphere Linked to Hydrothermal Systems

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The Okinawa Trough is a back-arc basin behind the Ryukyu trench-arc system and located along the eastern margin of the Eurasian continent. Sulfide and sulfate mineralization associated with hydrothermal activity has been recognized in ten hydrothermal fields in the Okinawa Trough. Hydrothermal mineralization recognized in these fields is commonly represented by coexisting occurrence of zinc-and lead-enriched polymetallic sulfides and abundant sulfate minerals. The mineralogy and geochemical signatures present has led researchers to suggest these areas may be a modern analogue for the formation of ancient Kuroko-type volcanogenic massive sulfide (VMS) deposits. Recent seafloor drilling during IODP (Integrated Ocean Drilling Program) Expedition 331 documented the subseafloor structure of a hydrothermal system at the Iheya North Knoll. Mineral textures and hydrothermal assemblages present in the drilled cores obtained from a hydrothermal mound in the proximal area are consistent with Kuroko-type mineralization. Based on geochemical studies, the intra-field diversity of mineralization commonly recognized in the Okinawa Trough can be explained by subseafloor phase separation of the hydrothermal fluid, which reflects shallow water depth (from 700 to 1,600 m). The subseafloor phase separation may. play an important role to accumulate metal elements beneath the seafloor. Based on geophysical and geological studies, the Okinawa Trough is considered a back-arc basin in the rifting stage. Such a tectonic setting is characterized by development of normal faulting in brittle continental crust and frequent intrusion of a magma, which can be expected to provide favorable environment for development of a hydrothermal system Keywords

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Section: Diverse Range Of Mineralization and Fluid Chemistrysupporting

confidence: 56%

Section: Hakurei Hydrothermal Field In the Izena Holementioning

confidence: 99%

Section: Jade Hydrothermal Field In the Izena Holementioning

confidence: 99%

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Hydrothermal Activity in the Okinawa Trough Back-Arc Basin: Geological Background and Hydrothermal Mineralization

Ishibashi

Ikegami

Tsuji

et al. 2014

Subseafloor Biosphere Linked to Hydrothermal Systems

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“…This province has occurred in >10 4 Pa-H 2 culture but never observed in any natural samples from biologically functionable temperature environments (≤122°C). This finding is reasonable because such high-pH 2 environments are rare in nature, except for several H 2 -enriched geofluid systems (Charlou et al 2002;Proskurowski et al 2006;Ishibashi et al 2014). The high α C CH 4 -CO 2 value in >10 4 Pa-H 2 cultures has been thought to be a result of an almost straightforward progress of carbon reduction from CO 2 to CH 4 in a multistep methanogenic pathway (Valentine et al 2004;Penning et al 2005; Fig.…”

Section: Possible Mechanisms Exhibiting Variable Isotope Fractionationmentioning

confidence: 69%

Hydrogen and carbon isotope systematics in hydrogenotrophic methanogenesis under H2-limited and H2-enriched conditions: implications for the origin of methane and its isotopic diagnosis

Okumura

Kawagucci

Saito

et al. 2016

Prog. in Earth and Planet. Sci.

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Hydrogen and carbon isotope systematics of H 2 O-H 2 -CO 2 -CH 4 in hydrogenotrophic methanogenesis and their relation to H 2 availability were investigated. Two H 2 -syntrophic cocultures of fermentatively hydrogenogenic bacteria and hydrogenotrophic methanogens under conditions of <10 2 Pa-H 2 and two pure cultures of hydrogenotrophic methanogens under conditions of~10 5 Pa-H 2 were tested. Carbon isotope fractionation between CH 4 and CO 2 during hydrogenotrophic methanogenesis was correlated with pH 2 , as indicated in previous studies. The hydrogen isotope ratio of CH 4 produced during rapid growth of the thermophilic methanogen Methanothermococcus okinawensis under high pH 2 conditions (~10 5 Pa) was affected by the isotopic composition of H 2 , as concluded in a previous study of Methanothermobacter thermautotrophicus. This "δD H 2 effect" is a possible cause of the diversity of previously reported values for hydrogen isotope fractionation between CH 4 and H 2 O examined in H 2 -enriched culture experiments. Hydrogen isotope fractionation between CH 4 and H 2 O, defined by (1000 + δD CH 4 )/(1000 + δD H 2 O ), during hydrogenotrophic methanogenesis of the H 2 -syntrophic cocultures was in the range 0.67-0.69. The hydrogen isotope fractionation of our H 2 -syntrophic dataset overlaps with those obtained not only from low-pH 2 experiments reported so far but also from natural samples of "young" methane reservoirs (0.66-0.74). Conversely, such hydrogen isotope fractionation is not consistent with that of "aged" methane in geological samples (≥0.79), which has been regarded as methane produced via hydrogenotrophic methanogenesis from the carbon isotope fractionation. As a possible process inducing the inconsistency in hydrogen isotope signatures between experiments and geological samples, we hypothesize that the hydrogen isotope signature of CH 4 imprinted at the time of methanogenesis, as in the experiments and natural young methane, may be altered by diagenetic hydrogen isotope exchange between extracellular CH 4 and H 2 O through reversible reactions of the microbial methanogenic pathway in methanogenic region and/or geological methane reservoirs.

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“…The uniformly higher major ion concentrations in the pNoho site, compared to Hitoshi and CLAM sites also in the Sakai field (Gamo, 1995), are likely caused by the greater extent of vapor-lost phase formed through subseafloor fluid boiling. Such intra-field variation of fluid chemistry has also been confirmed in the Izena Hole and Daiyon-Yonaguni fields, Okinawa Trough (Suzuki et al, 2008;Ishibashi et al, 2014) and is considered to be a result of preferable emanation of the more mobile vapor-rich phase. Both maximum fluid temperature and endmember Cl concentration were highest at the pNoho site, suggesting that this is the center of activity in the Sakai field.…”

Section: Examples Of Results From In Situ Sampling At Deep-sea Hydrotmentioning

confidence: 74%

WHATS-3: An Improved Flow-Through Multi-bottle Fluid Sampler for Deep-Sea Geofluid Research

et al. 2017

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Deep-sea geofluid systems, such as hydrothermal vents and cold seeps, are key to understanding subseafloor environments of Earth. Fluid chemistry, especially, provides crucial information toward elucidating the physical, chemical, and biological processes that occur in these ecosystems. To accurately assess fluid and gas properties of deep-sea geofluids, well-designed pressure-tight fluid samplers are indispensable and as such they are important assets of deep-sea geofluid research. Here, the development of a new flow-through, pressure-tight fluid sampler capable of four independent sampling events (two subsamples for liquid and gas analyses from each) is reported. This new sampler, named WHATS-3, is a new addition to the WHATS-series samplers and a major upgrade from the previous WHATS-2 sampler with improvements in sample number, valve operational time, physical robustness, and ease of maintenance. Routine laboratory-based pressure tests proved that it is suitable for operation up to 35 MPa pressure. Successful field tests of the new sampler were also carried out in five hydrothermal fields, two in Indian Ocean, and three in Okinawa Trough (max. depth 3,300 m). Relations of Mg and major ion species demonstrated bimodal mixing trends between a hydrothermal fluid and seawater, confirming the high quality of fluids sampled. The newly developed WHATS-3 sampler is well-balanced in sampling capability, field usability, and maintenance feasibility, and can serve as one of the best geofluid samplers available at present to conduct efficient research of deep-sea geofluid systems.

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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

Cited by 75 publications

References 44 publications

Hydrothermal Activity in the Okinawa Trough Back-Arc Basin: Geological Background and Hydrothermal Mineralization

Hydrothermal Activity in the Okinawa Trough Back-Arc Basin: Geological Background and Hydrothermal Mineralization

Hydrogen and carbon isotope systematics in hydrogenotrophic methanogenesis under H2-limited and H2-enriched conditions: implications for the origin of methane and its isotopic diagnosis

WHATS-3: An Improved Flow-Through Multi-bottle Fluid Sampler for Deep-Sea Geofluid Research

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