A5057922250- Methane Hydrates and Related Phenomena
- Geology and Paleoclimatology Research
- Geological and Geochemical Analysis
- Hydrocarbon exploration and reservoir analysis
- Geochemistry and Geologic Mapping
- earthquake and tectonic studies
- Isotope Analysis in Ecology
- Geological and Geophysical Studies
- Geochemistry and Elemental Analysis
- Geological Studies and Exploration
- Paleontology and Stratigraphy of Fossils
- Microbial Community Ecology and Physiology
- Drilling and Well Engineering
- Radioactive element chemistry and processing
- Reservoir Engineering and Simulation Methods
- Geomagnetism and Paleomagnetism Studies
- Groundwater and Isotope Geochemistry
- Marine Biology and Ecology Research
- Offshore Engineering and Technologies
- Atmospheric and Environmental Gas Dynamics
- Seismic Waves and Analysis
- Marine and coastal ecosystems
- Planetary Science and Exploration
- CO2 Sequestration and Geologic Interactions
- High-pressure geophysics and materials
Kobe University
2022-2025
Kyushu University
2015-2024
Shizuoka University
2023
Universidad Católica del Norte
2023
Graduate School USA
2014
Japan Agency for Marine-Earth Science and Technology
2009-2013
Planetary Science Institute
2007-2009
Tokyo University of Science
1995-2009
The University of Tokyo
1989-2004
Kanazawa University
1996
Carbon dioxide-rich fluid bubbles, containing approximately 86 percent CO(2), 3 H(2)S, and 11 residual gas (CH(4) + H(2)), were observed to emerge from the sea floor at 1335- 1550-m depth in JADE hydrothermal field, mid-Okinawa Trough. Upon contact with seawater 3.8 degrees C, hydrate immediately formed on surface of bubbles these hydrates coalesced form pipes standing sediments. Chemical composition carbon, sulfur, helium isotopic ratios indicate that CO(2)-rich was derived same magmatic...
Research Article| February 01, 1997 Acidic and sulfate-rich hydrothermal fluids from the Manus back-arc basin, Papua New Guinea Toshitaka Gamo; Gamo 1Ocean Institute, University of Tokyo, Nakano, Tokyo 164, Japan Search for other works by this author on: GSW Google Scholar Shipboard Scientific Party ManusFlux Cruise; Cruise Kei Okamura; Okamura Jean-Luc Charlou; Charlou 2IFREMER/Centre de Brest, B.P. 70, 29280 Plouzane Cedex, France Tetsuro Urabe; Urabe 3Geological Survey Japan, Tsukuba,...
Increasing levels of CO2 in the atmosphere are expected to cause climatic change with negative effects on earth's ecosystems and human society. Consequently, a variety disposal options discussed, including injection into deep ocean. Because dissolution seawater will decrease ambient pH considerably, consequences for deep-water have been predicted. Hence, associated natural reservoirs sea, dynamics gaseous, liquid, solid such environments, great interest science We report here biogeochemical...
Manned submersible studies have delineated a large and actively growing Kuroko-type volcanogenic massive sulfide deposit 400 kilometers south of Tokyo in Myojin Knoll submarine caldera. The body is located on the caldera floor at depth 1210 to 1360 meters, has an area by 30 notably rich gold silver. discovery polymetallic this arc-front raises possibility that numerous unexplored silicic calderas elsewhere might similar deposits.
The 2,500‐km Kermadec‐Tonga arc is the longest submarine on planet. Here, we report second of a series cruises designed to investigate large‐scale controls active hydrothermal venting this arc. 2002 NZAPLUME II cruise surveyed 12 volcanic centers along ∼580 km middle Kermadec (MKA), extending 1999 that 260 southern (SKA). Average spacing between increases northward from 30 backarc crust SKA, 45 MKA, 58 where MKA joins Ridge. Volcanic cones dominate in backarc, and calderas incidence higher...
A newly discovered hydrothermal field called the Mariner on Valu Fa Ridge in southern Lau Basin was explored and characterized with geochemical microbiological analyses. The fluid discharging from most vigorous vent (Snow Chimney, maximum discharge temperature 365°C) boiling at seafloor a depth of 1908 m, two distinct end‐member fluids were identified. chemistry typical Cl‐enriched Cl‐depleted analyzed, as mineralogy host chimney structures. variability potentially controlled by subseafloor...
Abstract Hydrogen‐rich hydrothermal areas, such as those in the Indian Ocean, may have had an influence on early evolution of life Earth and thus attracted interest because they be a proxy for ancient ecosystems. The Kairei Edmond fields Ocean are separated by 160 km, but exhibit distinct fluid chemistry: fluids hydrogen‐rich; hydrogen‐poor. At this region, Central Ridge shows intermediate spreading rate, 48 mm year −1 full where hydrothemal occur. field vent show persistently high...
We determined the chemical and isotopic compositions of liquid CO 2 found on Yonaguni IV knoll hydrothermal site, as well those in fluid venting from surrounding chimneys. The δ 13 C both CH 4 almost coincide with fluid, suggesting that must be derived fluid. While showing homogeneous C, fluids exhibit wide variation gas contents. Active phase separation taking place within conduits. Besides, H ‐depletion suggests formation solid ‐hydrate also precede . In conclusion, produced through...
Summary To extend knowledge of subseafloor microbial communities within the oceanic crust, abundance, diversity and composition in crustal fluids at back‐arc hydrothermal fields Southern Mariana Trough (SMT) were investigated using culture‐independent molecular techniques based on 16S rRNA gene sequences. Seafloor drilling was carried out two fields, on‐ off‐ridge spreading centre SMT. clone libraries for bacterial archaeal constructed from fluid samples collected boreholes. Phylotypes...
The Integrated Ocean Drilling Program (IODP) Expedition 331 investigated the Iheya North hydrothermal field in Okinawa Trough. Several post‐drilling underwater vehicle investigations were conducted over 2 years to identify changes fluid discharge pattern, mineral deposition, and chemistry. Drilling‐induced high‐temperature vents identified at deep holes not only near naturally occurring NBC vent (Site C0016) but also seafloor ∼450 m distal C0014), where no was observed prior drilling. A...
Abstract Seafloor hydrothermal deposits form when fluid mixes with ambient seawater, and constituent sulfide minerals are usually interpreted to precipitate abiogenically. Recent research drilling at Izena Hole Iheya North Knoll in the middle Okinawa Trough (East China Sea), combined secondary ion mass spectrometry determinations of δ34S pyrite grains, provides compelling evidence that initial stage subseafloor mineralization is closely associated microbial sulfate reduction. During...
Deep-sea massive sulfide deposits formed by hydrothermal fluid circulation are potential metal resources. They can exist not only as mound manifestations on the seafloor (seafloor sulfides) but also embedded anomalies buried beneath (embedded sulfides). The distribution of sulfides is largely unknown, despite their expected high economic value. Recent drilling surveys have revealed a complex model suggesting coexist sulfides. In coexisting case, geophysical methods required to distinguish...
Gold (or electrum) in hydrothermal fluid precipitates directly from gold sulfide complex and/or partly via suspended nanoparticles. The contains “invisible gold” that is atomically dispersed minerals or as nanoparticles with a size of less than 10 nm. However, the contribution these to formation native and its alloy silver (electrum) remains unclear. Higashi–Aogashima Knoll Caldera field, south Tokyo, Japan, an area significant seafloor activity known for high-grade gold-containing...
We present novel data sets of rare earth element (REE) distributions in a hydrothermal vent field at Yonaguni Knoll IV the Okinawa Trough. Vertical REE profiles three water columns showed horizontal variation concentrations within 1000–1200 m. Hydrothermal plumes were discovered by anomalous values methane, manganese and transmissometry that site. Europium anomalies North Pacific deep (NPDW) (Nozaki et al., 1999) normalized pattern decreased with distance from site, indicating dilution fluid...
Abstract Seafloor massive sulphide (SMS) deposits, modern analogues of volcanogenic (VMS) deposits on land, represent future resources base and precious metals. Studies VMS have proposed two emplacement mechanisms for SMS deposits: exhalative deposition the seafloor mineral void space replacement beneath seafloor. The details latter mechanism are poorly characterised in detail, despite its potentially significant role global metal cycling throughout Earth’s history, because in-situ studies...
A survey of hydrothermal activity along the superfast-spreading (approximately 150 millimeters per year) East Pacific Rise shows that plumes overlay approximately 60 percent ridge crest between 13 degrees 50' and 18 40'S, a plume abundance nearly twice known from any other rige portion comparable length. Plumes were most abundant where axial cross section is inflated an magma chamber present. with high ratios volatile ((3)He, CH(4), H(2)S) to nonvolatile (Mn Fe) species marked circulation...
Quantifying hydrothermal venting at the boundaries of tectonic plates is an outstanding geoscience problem. Considerable progress has been made by detailed surveys along mid‐ocean ridges (MORs), but until recently little was known about fluid volcanic arcs. We present first systematic survey for 425‐km‐long south Tonga arc and new chemistry data particle thermal plumes previously reported adjacent 88‐km‐long section back‐arc Valu Fa Ridge (VFR). Eleven plumes, recognized their anomalous...
Abstract We report horizontal sliding of the kilometre-scale geologic block under Aso hot springs (Uchinomaki area) caused by vibrations from 2016 Kumamoto earthquake (Mw 7.0). Direct borehole observations demonstrate along geological formation at ~50 m depth, which is where shallowest hydrothermal reservoir developed. Owing to >1 northwest movement block, as shown differential interferometric synthetic aperture radar (DInSAR), extensional open fissures were generated southeastern edge...
Shallow submarine volcanoes have been newly discovered near the Tokara Islands, which are situated at volcanic front of northern Ryukyu Arc in southern Japan. Here, we report for first time volatile geochemistry shallow hydrothermal plumes, were sampled using a CTD-RMS system after analyzing water column images collected by multi-beam echo sounder surveys. These surveys performed during research cruise KS-14-10 R/V Shinsei Maru region stretching from Wakamiko Crater to Islands. The 3He flux...