Liquid CO<sub>2</sub> venting on the seafloor: Yonaguni Knoll IV hydrothermal system, Okinawa Trough

Konno, Uta; Tsunogai, Urumu; Nakagawa, Fumiko; Nakaseama, Miwako; Ishibashi, Jun Ichiro; Nunoura, Takuro; Nakamura, K.

doi:10.1029/2006gl026115

Cited by 108 publications

(136 citation statements)

References 19 publications

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“…The Okinawa Trough is a backarc basin in the rifting to spreading stage characterized by the development of normal faulting of transitional crust (atypical crust with mantle-derived material) and frequent magma intrusions, which provides a favorable geological environment for the development of seafloor hydrothermal systems [8,41,42]. As of 2016, there were at least 15 deep-sea hydrothermal fields reported in the Okinawa Trough based on the InterRidge data base, including the Minami-Ensei (e.g., [10]), Iheya North [9,11,43], Jade [7,13], Hakurei [8], Hatoma [44][45][46], Yonaguni Knoll IV [12,14,47], and Tangyin hydrothermal fields [48,49]. The Iheya North knoll hydrothermal field (27 ∘ 47.2 N, 126 ∘ 53.9 E) is located at a water depth about 1,000 m along the eastern slope of a small knoll, part of the Iheya North knoll volcanic complex ( Figure 1; [8]).…”

Section: Geological Settingmentioning

confidence: 99%

“…In the Okinawa Trough, the vent fluid chemistry of seafloor hydrothermal systems has been characterized by enrichment in CO 2 , CH 4 , NH 4 + , and K + compared with those in typical sediment-free midocean ridge (MOR) hydrothermal fluids (e.g., [6][7][8][9][10][11][12][13][14]). The high K + content (6.9-79.2 mmol kg −1 ) in the estimated source fluid is typical for the Iheya North knoll hydrothermal field due to hydrothermal reaction with K-enriched felsic rocks.…”

Section: Introductionmentioning

confidence: 99%

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Understanding the Compositional Variability of the Major Components of Hydrothermal Plumes in the Okinawa Trough

et al. 2018

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Studies of the major components of hydrothermal plumes in seafloor hydrothermal fields are critical for an improved understanding of biogeochemical cycles and the large-scale distribution of elements in the submarine environment. The composition of major components in hydrothermal plume water column samples from 25 stations has been investigated in the middle and southern Okinawa Trough. The physical and chemical properties of hydrothermal plume water in the Okinawa Trough have been affected by input of the Kuroshio current, and its influence on hydrothermal plume water from the southern Okinawa Trough to the middle Okinawa Trough is reduced. The anomalous layers of seawater in the hydrothermal plume water columns have higher K + , Ca 2+ , Mn 2+ , B 3+ , Ca 2+ /SO 4 2− , and Mn 2+ /Mg 2+ ratios and higher optical anomalies than other layers. The Mg 2+ , SO 4 2− , Mg 2+ /Ca 2+ , and SO 4 2− /Mn 2+ ratios of the anomalous layers are lower than other layers in the hydrothermal plume water columns and are consistent with concentrations in hydrothermal vent fluids in the Okinawa Trough. This suggests that the chemical variations of hydrothermal plumes in the Tangyin hydrothermal field, like other hydrothermal fields, result in the discharge of high K + , Ca 2+ , and B 3+ and low Mg 2+ and SO 4 2− fluid. Furthermore, element ratios (e.g., Sr 2+ /Ca 2+ , Ca 2+ /Cl − ) in hydrothermal plume water columns were found to be similar to those in average seawater, indicating that Sr 2+ /Ca 2+ and Ca 2+ /Cl − ratios of hydrothermal plumes might be useful proxies for chemical properties of seawater. The hydrothermal K + , Ca 2+ , Mn 2+ , and B 3+ flux to seawater in the Okinawa Trough is about 2.62-873, 1.04-326, 1.30-76.4, and 0.293-34.7 × 10 6 kg per year, respectively. The heat flux is about 0.159-1,973 × 10 5 W, which means that roughly 0.0006% of ocean heat is supplied by seafloor hydrothermal plumes in the Okinawa Trough.

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Section: Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Understanding the Compositional Variability of the Major Components of Hydrothermal Plumes in the Okinawa Trough

et al. 2018

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“…Observations during dive surveys indicate the elongated valley is covered mainly with muddy sediment, except for active hydrothermal sites, and that the northern slope of the valley has volcanic breccia . A diverse style of fluid emanations occurs within the Daiyon-Yonaguni Knoll hydrothermal field (Inagaki et al 2006;Konno et al 2006;Suzuki et al 2008). A large chimney-mound complex called the Tiger site, which is approximately 10-m high, is located near the boundary between the slope of the knoll and sediment seafloor at water depth of~1,370 m. Vigorous venting of blackish-smoky fluids up to 328 C has been recorded from the basal part of the mound complex, which seems to mark the central part of the present hydrothermal activity in the field.…”

Section: Daiyon-yonaguni Knoll Hydrothermal Fieldmentioning

confidence: 99%

“…Venting of clear fluid with the highest temperature of 220 C was observed at the foot of the mound, which was accompanied with discharge of significant amount of liquid CO 2 droplets. Liquid CO 2 emanation from altered sediment has been observed in many places around the active hydrothermal mounds (Inagaki et al 2006;Konno et al 2006). In the southern part of the hydrothermal field (the Abyss Vent site), diffusive fluid venting was observed from the seafloor which is covered with sediment associated whitish hydrothermal crusts (Inagaki et al 2006).…”

Section: Daiyon-yonaguni Knoll Hydrothermal Fieldmentioning

confidence: 99%

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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“…Subcritical phase separation produces a volatiledominant ''vapor phase'' and a volatile-stripped ''liquid phase,'' which differs from the solutecondensed ''brine phase'' produced by supercritical phase separation . Volatile stripping associated with subcritical phase separation would be accompanied by slight carbon isotope fractionation for CO 2 , as suggested by the observation at the Yonaguni IV hydrothermal field [Konno et al, 2006]. Thus, the slight Cl enrichment and strong CO 2 depletion without an altered 13 C CO2 in the post-drilling fluid are consistent with a ''liquid phase'' fluid from subcritical phase separation beneath the seafloor.…”

Section: à430mentioning

confidence: 69%

Post‐drilling changes in fluid discharge pattern, mineral deposition, and fluid chemistry in the Iheya North hydrothermal field, Okinawa Trough

Kawagucci

Miyazaki

Nakajima

et al. 2013

Geochem Geophys Geosyst

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[1] The Integrated Ocean Drilling Program (IODP) Expedition 331 investigated the Iheya North hydrothermal field in the Okinawa Trough. Several post-drilling underwater vehicle investigations were conducted over 2 years to identify post-drilling changes in fluid discharge pattern, mineral deposition, and fluid chemistry. Drilling-induced high-temperature hydrothermal fluid vents were identified at deep holes not only near the naturally occurring NBC hydrothermal fluid vent (Site C0016) but also at the seafloor $450 m distal to the NBC vent (Site C0014), where no hydrothermal fluid discharge was observed prior to drilling. A chimney structure at Hole C0016A grew rapidly at the NBC mound crest, where only small chimneys had been found before drilling. A drilling-induced diffuse hydrothermal flow region spread at Site C0014, and this area was newly colonized by the galatheid crab. From a fluid chemistry perspective, the post-drilling hydrothermal fluids were enriched in Cl relative to seawater, although this fluid chemistry was not observed during the 12 years prior to drilling. The Cl-enriched fluid reservoir underlying the subseafloor impermeable layers, observed by IODP Expedition 331, is likely source for the Cl-enriched fluids discharging from the post-drilling vents. The drilling-induced physical disturbance of subseafloor hydrogeological structures would release such fluids to the seafloor. In turn, the rapid chimney growth at the NBC mound crest may also be attributed to highly turbulent fluid flow with the enlarged artificial vent of Hole C0016A, which can contribute to the retention of the fluidseawater mixture for a sufficiently long period to precipitate sulfide/sulfate minerals on the seafloor.

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Liquid CO₂ venting on the seafloor: Yonaguni Knoll IV hydrothermal system, Okinawa Trough

Cited by 108 publications

References 19 publications

Understanding the Compositional Variability of the Major Components of Hydrothermal Plumes in the Okinawa Trough

Understanding the Compositional Variability of the Major Components of Hydrothermal Plumes in the Okinawa Trough

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

Post‐drilling changes in fluid discharge pattern, mineral deposition, and fluid chemistry in the Iheya North hydrothermal field, Okinawa Trough

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Liquid CO2 venting on the seafloor: Yonaguni Knoll IV hydrothermal system, Okinawa Trough

Cited by 108 publications

References 19 publications

Understanding the Compositional Variability of the Major Components of Hydrothermal Plumes in the Okinawa Trough

Understanding the Compositional Variability of the Major Components of Hydrothermal Plumes in the Okinawa Trough

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

Post‐drilling changes in fluid discharge pattern, mineral deposition, and fluid chemistry in the Iheya North hydrothermal field, Okinawa Trough

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Product

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Liquid CO₂ venting on the seafloor: Yonaguni Knoll IV hydrothermal system, Okinawa Trough