scholarly journals 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

2014 ◽  
Vol 48 (4) ◽  
pp. 357-369 ◽  
Author(s):  
JUN-ICHIRO ISHIBASHI ◽  
TAKUROH NOGUCHI ◽  
TOMOHIRO TOKI ◽  
SHUNSUKE MIYABE ◽  
SHOSEI YAMAGAMI ◽  
...  
Keyword(s):  
Okinawa Trough ◽  
Fluid Geochemistry ◽  
Back Arc ◽  
Hydrothermal Fields

scholarly journals A Systematic Assessment of Stable Sr Isotopic Compositions of Vent Fluids in Arc/Back-Arc Hydrothermal Systems: Effects of Host Rock Type, Phase Separation, and Overlying Sediment

2020 ◽  
Vol 8 ◽  
Author(s):  
Toshihiro Yoshimura ◽  
Shigeyuki Wakaki ◽  
Tsuyoshi Ishikawa ◽  
Toshitaka Gamo ◽  
Daisuke Araoka ◽  
...  
Keyword(s):  
Host Rock ◽  
Okinawa Trough ◽  
Volcanic Rocks ◽  
Hydrothermal Systems ◽  
Systematic Assessment ◽  
Average Value ◽  
Carbonate Sedimentation ◽  
The North ◽  
Back Arc ◽  
Hydrothermal Fields

Variations in the stable isotopic composition of seawater Sr (δ88Sr) is a new tool for estimating the rates of global carbonate sedimentation over geologic time, yet the isotope compositions of the major sources and sinks of Sr to the world oceans are still in need of further constraint. We report δ88Sr values of vent fluids from arc/back-arc seafloor hydrothermal systems in the western Pacific. In the sediment-starved hydrothermal fields of the Manus Basin, Izu-Bonin Arc, and Mariana Trough, the δ88Sr values of end-member fluids for each site showed little variation (0.29–0.30‰) and were close to the average value of oceanic volcanic rocks, reflecting dissolved Sr sourced from host rocks. Chlorine-depleted fluids from phase-separated hydrothermal systems in the North Fiji Basin had the end-member δ88Sr values of 0.26, 0.28, and 0.29‰. Thus, both sediment-starved and phase-separated vent fluids had the end-member δ88Sr values indistinguishable from or very close to the range of oceanic volcanic rocks. Therefore, the δ88Sr compositions in these hydrothermal sites are controlled predominantly by Sr sourced from host rock with a small influence from secondary mineral precipitation/re-dissolution. Fluids from the sediment-hosted hydrothermal fields of the Okinawa Trough, however, were characterized by low δ88Sr values of approximately 0.22‰ and high 87Sr/86Sr ratios, indicating interactions with sedimentary carbonates. As for the modern oceanic δ88Sr budget, the sediment-hosted sites lower the global hydrothermal δ88Sr. Since both sediment-starved and -hosted hydrothermal systems provide a long-term control on the global Sr cycle, the end-member δ88Sr value is an important constraint on the evolution of Sr cycling in past oceans.

Active tectonics and volcanism in the southernmost Okinawa Trough back-arc basin derived from deep-towed sonar surveys

2021 ◽  
pp. 229047
Author(s):  
Ching-Hui Tsai ◽  
Shu-Kun Hsu ◽  
Song-Chuen Chen ◽  
Shiou-Ya Wang ◽  
Lien-Kai Lin ◽  
...  
Keyword(s):  
Okinawa Trough ◽  
Active Tectonics ◽  
Back Arc

scholarly journals Diverse Range of Mineralization Induced by Phase Separation of Hydrothermal Fluid: Case Study of the Yonaguni Knoll IV Hydrothermal Field in the Okinawa Trough Back-Arc Basin

2008 ◽  
Vol 58 (3) ◽  
pp. 267-288 ◽  
Author(s):  
Ryohei Suzuki ◽  
Jun-Ichiro Ishibashi ◽  
Miwako Nakaseama ◽  
Uta Konno ◽  
Urumu Tsunogai ◽  
...  
Keyword(s):  
Phase Separation ◽  
Hydrothermal Fluid ◽  
Okinawa Trough ◽  
Hydrothermal Field ◽  
Diverse Range ◽  
The Okinawa Trough ◽  
Back Arc

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

2011 ◽  
Vol 45 (2) ◽  
pp. 109-124 ◽  
Author(s):  
SHINSUKE KAWAGUCCI ◽  
HITOSHI CHIBA ◽  
JUN-ICHIRO ISHIBASHI ◽  
TOSHIRO YAMANAKA ◽  
TOMOHIRO TOKI ◽  
...  
Keyword(s):  
Hydrothermal Fluid ◽  
Okinawa Trough ◽  
Fluid Circulation ◽  
Fluid Geochemistry

scholarly journals Seismic structure of the crust and uppermost mantle in the incipient stage of back arc rifting - northernmost Okinawa Trough

2004 ◽  
Vol 31 (2) ◽  
Author(s):  
Kazuo Nakahigashi ◽  
Masanao Shinohara ◽  
Sadaomi Suzuki ◽  
Ryota Hino ◽  
Hajime Shiobara ◽  
...  
Keyword(s):  
Okinawa Trough ◽  
Seismic Structure ◽  
Uppermost Mantle ◽  
Incipient Stage ◽  
Back Arc

scholarly journals Moho Geometry of the Okinawa Trough Based on Gravity Inversion and Its Implications on the Crustal Nature and Tectonic Evolution

2021 ◽  
Vol 9 ◽  
Author(s):  
Liang Zhang ◽  
Xiwu Luan
Keyword(s):  
Early Stage ◽  
Okinawa Trough ◽  
High Heat ◽  
Crustal Thickness ◽  
Moho Depth ◽  
Gravity Inversion ◽  
The Okinawa Trough ◽  
Oceanic Spreading ◽  
Thickness Variations ◽  
Back Arc

The Okinawa Trough (OT) is an incipient back-arc basin, but its crustal nature is still controversial. Gravity inversion along with sediment and lithospheric mantle density modeling are used to map the regional Moho depth and crustal thickness variations of the OT and its adjacent areas. The gravity inversion result shows that the crustal thicknesses are 17–22 km at the northern OT, 11–19 km at the central OT, and 7–19 km at the southern OT. Because of the crust with a thickness larger than 17 km, the slow southward arc movement, and scarce contemporaneous volcanisms, the northern OT should be in the stage of early back-arc extension. All of the moderate crustal thickness, high heat flow, and intense volcanism at the central OT indicate that this region is probably in the transitional stage from the back-arc rifting to the oceanic spreading. A crust that is only 7 km thick, lithosphere strength as low as the mid-ocean ridge, and MORB-similar basalts at the southern OT demonstrate that the southern OT is at the early stage of seafloor spreading.

scholarly journals Spatial and temporal distribution of low frequency volcanic earthquakes in the southern Okinawa Trough back-arc basin

2019 ◽  
Vol 30 (5) ◽  
pp. 621-631
Author(s):  
Jing-Yi Lin ◽  
Wen-Nan Wu ◽  
Chih-Chieh Su ◽  
Ching-Hui Tsai ◽  
Hsu-Hsiao Sun ◽  
...  
Keyword(s):  
Okinawa Trough ◽  
Low Frequency ◽  
Temporal Distribution ◽  
Spatial And Temporal Distribution ◽  
Volcanic Earthquakes ◽  
Southern Okinawa Trough ◽  
Back Arc

scholarly journals Lithium, Oxygen and Magnesium Isotope Systematics of Volcanic Rocks in the Okinawa Trough: Implications for Plate Subduction Studies

2021 ◽  
Vol 10 (1) ◽  
pp. 40
Author(s):  
Zhigang Zeng ◽  
Xiaohui Li ◽  
Yuxiang Zhang ◽  
Haiyan Qi
Keyword(s):  
Basaltic Andesite ◽  
Subduction Zones ◽  
Okinawa Trough ◽  
Volcanic Rocks ◽  
Philippine Sea Plate ◽  
Material Transfer ◽  
Magma Compositions ◽  
Subduction Input ◽  
Back Arc ◽  
Plate Subduction

Determining the influence of subduction input on back-arc basin magmatism is important for understanding material transfer and circulation in subduction zones. Although the mantle source of Okinawa Trough (OT) magmas is widely accepted to be modified by subducted components, the role of slab-derived fluids is poorly defined. Here, major element, trace element, and Li, O and Mg isotopic compositions of volcanic lavas from the middle OT (MOT) and southern OT (SOT) were analyzed. Compared with the MOT volcanic lavas, the T9-1 basaltic andesite from the SOT exhibited positive Pb anomalies, significantly lower Nd/Pb and Ce/Pb ratios, and higher Ba/La ratios, indicating that subducted sedimentary components affected SOT magma compositions. The δ7Li, δ18O, and δ26Mg values of the SOT basaltic andesite (−5.05‰ to 4.98‰, 4.83‰ to 5.80‰ and −0.16‰ to −0.09‰, respectively) differed from those of MOT volcanic lavas. Hence, the effect of the Philippine Sea Plate subduction component, (low δ7Li and δ18O and high δ26Mg) on magmas in the SOT was clearer than that in the MOT. This contrast likely appears because the amounts of fluids and/or melts derived from altered oceanic crust (AOC, lower δ18O) and/or subducted sediment (lower δ7Li, higher δ18O and δ26Mg) injected into magmas in the SOT are larger than those in the MOT and because the injection ratio between subducted AOC and sediment is always >1 in the OT. The distance between the subducting slab and overlying magma may play a significant role in controlling the differences in subduction components injected into magmas between the MOT and SOT.

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