Kaul Gena - Academia.edu (original) (raw)

Papers by Kaul Gena

HAL (Le Centre pour la Communication Scientifique Directe), 1997

The Manus back arc basin is well known for hosting submarine hydrothermal deposits of Vienna Wood... more The Manus back arc basin is well known for hosting submarine hydrothermal deposits of Vienna Wood, Pacmanus, Onsen site and Solwara 1-12. The Vienna Wood located in the Central Manus basin is a typical Cu-Zn type of mineralization hosted by mid-oceanic ridge basalt and consists predominantly of sphalerite, wurtzite, chalcopyrite and gangue minerals of anhydrite, gypsum and silica. In contrast, the Pacmanus hydrothermal deposit in the eastern part of the Manus basin is hosted by rocks ranging from basalt to dacite and rhyodacite. The mineralization is of the polymetallic Zn-Cu-Pb-Au type consists of ore minerals of sphalerite, chalcopyrite, bornite, wurtzite, pyrite, marcasite, enargite, tennantite, galena, Pb-As-Sulphosalt, gold, covellite, digenite, chalcocite and gangue minerals of barite, amorphous silica, anhydrite and gypsum. The chemical composition of sphalerite, galena, gold and tennantite-tetrahedrite indicate high concentrations of Lead, Arsenic, Silver, Iron, Copper and Antimony compared to their stoichiometric composition. The Onsen site in the Eastern Manus Basin is the first deep sea acid sulfate type of mineralisation and consist of enargite, covellite, chalcopyrite, pyrite, marcasite and gangue minerals of pyrophyllite, alunite, quartz, cristoballite, amorphous silica and native sulfur. The PNG Government has granted exploration and mining licenses to Nautilus Mineral for commercial exploitation of these deposits and Solwara 1 deposit in the Eastern Manus Basin. Nautilus minerals has done extensive exploration and reports indicated and inferred a mineral resource of 1030 kt and 1540 kt respectively for their Solwara 1 project east of Pacmanus site at a 2.6% Cu equivalent cut off grade. Whether this mineral resource is sufficient to deliver PNG first deep sea mining or not will depend on the success of the trial mining method that is currently being developed. Studies done on nearby Pacmanus and Onsen submarine hydrothermal deposits indicate that the deposits contain a much higher proposition of deleterious elements such As, Pb and Sb. Nautilus did not disclose the full mineralogy and assay results of the Solwara 1 and 2 projects to the public domain apart from Cu, Au, Ag and Zn. Nautilus did not suggest how it will address toxic and heavy metals that are associated with the ore concentrate in its Environmental Impact Studies.

Resource Geology, Aug 8, 2008

The Yonaguni Knoll IV hydrothermal vent field (24°51′N, 122°42′E) is located at water depths of 1... more The Yonaguni Knoll IV hydrothermal vent field (24°51′N, 122°42′E) is located at water depths of 1370–1385 m near the western edge of the southern Okinawa Trough. During the YK03–05 and YK04–05 expeditions using the submersible Shinkai 6500, both hydrothermal precipitates (sulfide/sulfate/carbonate) and high temperature fluids (Tmax = 328°C) presently venting from chimney‐mound structures were extensively sampled. The collected venting fluids had a wide range of chemistry (Cl concentration 376–635 mmol kg−1), which is considered as evidence for sub‐seafloor phase separation. While the Cl‐enriched smoky black fluids were venting from two adjacent chimney‐mound structures in the hydrothermal center, the clear transparent fluids sometimes containing CO2 droplet were found in the peripheral area of the field. This distribution pattern could be explained by migration of the vapor‐rich hydrothermal fluid within a porous sediment layer after the sub‐seafloor phase separation. The collected hydrothermal precipitates demonstrated a diverse range of mineralization, which can be classified into five groups: (i) anhydrite‐rich chimneys, immature precipitates including sulfide disseminations in anhydrite; (ii) massive Zn‐Pb‐Cu sulfides, consisting of sphalerite, wurtzite, galena, chalcopyrite, pyrite, and marcasite; (iii) Ba‐As chimneys, composed of barite with sulfide disseminations, sometimes associated with realgar and orpiment overgrowth; (iv) Mn‐rich chimneys, consisting of carbonates (calcite and magnesite) and sulfides (sphalerite, galena, chalcopyrite, alabandite, and minor amount of tennantite and enargite); and (v) pavement, silicified sediment including abundant native sulfur or barite. Sulfide/sulfate mineralization (groups i–iii) was found in the chimney–mound structure associated with vapor‐loss (Cl‐enriched) fluid venting. In contrast, the sulfide/carbonate mineralization (group iv) was specifically found in the chimneys where vapor‐rich (Cl‐depleted) fluid venting is expected, and the pavement (group v) was associated with diffusive venting from the seafloor sediment. This correspondence strongly suggests that the subseafloor phase separation plays an important role in the diverse range of mineralization in the Yonaguni IV field. The observed sulfide mineral assemblage was consistent with the sulfur fugacity calculated from the FeS content in sphalerite/wurtzite and the fluid temperature for each site, which suggests that the shift of the sulfur fugacity due to participation of volatile species during phase separation is an important factor to induce diverse mineralization. In contrast, carbonate mineralization is attributed to the significant mixing of vapor‐rich hydrothermal fluid and seawater. A submarine hydrothermal system within a back‐arc basin in the continental margin may be considered as developed in a geologic setting favorable to a diverse range of mineralization, where relatively shallow water depth induces sub‐seafloor phase separation of hydrothermal fluid, and sediment accumulation could enhance migration of the vapor‐rich hydrothermal fluid.

AGU Fall Meeting Abstracts, Dec 1, 2006

Increasing levels of CO2 in the atmosphere are expected to cause climatic change with negative ef... more Increasing levels of CO2 in the atmosphere are expected to cause climatic change with negative effects on the earth's ecosystems and human society. Consequently, a variety of CO 2 disposal options are discussed, including injection into the deep ocean. Because the dissolution of CO2 in seawater will decrease ambient pH considerably, negative consequences for deep-water ecosystems have been predicted. Hence, ecosystems associated with natural CO2 reservoirs in the deep sea, and the dynamics of gaseous, liquid, and solid CO 2 in such environments, are of great interest to science and society. We report here a biogeochemical and microbiological characterization of a microbial community inhabiting deep-sea sediments overlying a natural CO 2 lake at the Yonaguni Knoll IV hydrothermal field, southern Okinawa Trough. We found high abundances (>10 9 cm ؊3) of microbial cells in sediment pavements above the CO2 lake, decreasing to strikingly low cell numbers (10 7 cm ؊3) at the liquid CO2͞CO2-hydrate interface. The key groups in these sediments were as follows: (i) the anaerobic methanotrophic archaea ANME-2c and the Eel-2 group of Deltaproteobacteria and (ii) sulfur-metabolizing chemolithotrophs within the Gamma-and Epsilonproteobacteria. The detection of functional genes related to one-carbon assimilation and the presence of highly 13 C-depleted archaeal and bacterial lipid biomarkers suggest that microorganisms assimilating CO2 and͞or CH4 dominate the liquid CO2 and CO 2-hydrate-bearing sediments. Clearly, the Yonaguni Knoll is an exceptional natural laboratory for the study of consequences of CO 2 disposal as well as of natural CO2 reservoirs as potential microbial habitats on early Earth and other celestial bodies. anaerobic oxidation of methane ͉ chemolithotroph ͉ CO2 disposal ͉ CO 2 hydrate ͉ liquid CO2 Conflict of interest statement: No conflicts declared. Abbreviation: AOM, anaerobic oxidation of methane. Data deposition: The 16S rRNA, mcrA, and cbbL gene sequences reported in this paper have been deposited in the DNA Data Bank of Japan͞European Molecular Biology Laboratory͞ GenBank databases (accession nos. AB252422-AB252455).

AGU Fall Meeting Abstracts, Dec 1, 2004

The active sulfide chimney ore sampled from the flank of the active TIger chimney in the Yonaguni... more The active sulfide chimney ore sampled from the flank of the active TIger chimney in the Yonaguni Knoll N hydrothermal system, South Okinawa Trough, consists of anhydrite, pyrite, sphalerite, galena. chalcopyrite and bismuthinite. Electron microprobe analyses indicated that the chalcopyrite and bismuthinite contain up to 2.4 wt. % Sn and 1.7 wt. % Pt, respectively. The high Sn-bearing chalcopyrite and Pt-bearing bismuthinite are the first occurrence of such minerals on the submarine hydrothermal systems so far reported. The results confirm that the Sn enters the chalcopyrite as a solid solution towards stannite by the coupled substitution of Sn#Fe 2 + for Fe3+Fe3+ while Pt enters the bismuthinite structure as a solid solution during rapid growth. The homogenization temperature of the fluid inclusions in anhydrite (220-31O°C) and measured end-member temperature of the vent fluids (325°C) indicate that the minerals are precipitated as metastable phases at temperature around 300°C. The Sn-bearing chalcopyrite and Pt-bearing bismuthinite express the original composition of the minerals deposited from a hydrothermal fluid with temperatures of about 300°C.

日本鉱物学会年会・日本岩石鉱物鉱床学会学術講演会講演要旨集, 2004

The Manus Basin spreading system consists of three main ridge segments separated by Wuillaumez, D... more The Manus Basin spreading system consists of three main ridge segments separated by Wuillaumez, Djaul and Weitin Fracture Zones. The aim of Manusflux cruise of the R/V "Yokosuka" and the submersible "Shinkai 6500" was the in situ exploration of the Central and Eastern ridge segments and the study of the associated hydrothermal activity. On each segment active hydrothermal sites have been explored and sampled. They show all types of activity from low temperature diffusion up the black smoker stage. They are located on the fault zones which affect the basaltic or dacitic rocks constituting respectively the Central and Eastern ridge segments.

The active sulfide chimney ore sampled from the flank of the active TIger chimney in the Yonaguni... more The active sulfide chimney ore sampled from the flank of the active TIger chimney in the Yonaguni Knoll N hydrothermal system, South Okinawa Trough, consists of anhydrite, pyrite, sphalerite, galena. chalcopyrite and bismuthinite. Electron microprobe analyses indicated that the chalcopyrite and bismuthinite contain up to 2.4 wt. % Sn and 1.7 wt. % Pt, respectively. The high Sn-bearing chalcopyrite and Pt-bearing bismuthinite are the first occurrence of such minerals on the submarine hydrothermal systems so far reported. The results confirm that the Sn enters the chalcopyrite as a solid solution towards stannite by the coupled substitution of Sn#Fe 2 + for Fe3+Fe3+ while Pt enters the bismuthinite structure as a solid solution during rapid growth. The homogenization temperature of the fluid inclusions in anhydrite (220-31O°C) and measured end-member temperature of the vent fluids (325°C) indicate that the minerals are precipitated as metastable phases at temperature around 300°C. The...

The active sulfide chimney ore sampled from the flank of the active TIger chimney in the Yonaguni... more The active sulfide chimney ore sampled from the flank of the active TIger chimney in the Yonaguni Knoll N hydrothermal system, South Okinawa Trough, consists of anhydrite, pyrite, sphalerite, galena. chalcopyrite and bismuthinite. Electron microprobe analyses indicated that the chalcopyrite and bismuthinite contain up to 2.4 wt. % Sn and 1.7 wt. % Pt, respectively. The high Sn-bearing chalcopyrite and Pt-bearing bismuthinite are the first occurrence of such minerals on the submarine hydrothermal systems so far reported. The results confirm that the Sn enters the chalcopyrite as a solid solution towards stannite by the coupled substitution of Sn#Fe 2 + for Fe3+Fe3+ while Pt enters the bismuthinite structure as a solid solution during rapid growth. The homogenization temperature of the fluid inclusions in anhydrite (220-31O°C) and measured end-member temperature of the vent fluids (325°C) indicate that the minerals are precipitated as metastable phases at temperature around 300°C. The Sn-bearing chalcopyrite and Pt-bearing bismuthinite express the original composition of the minerals deposited from a hydrothermal fluid with temperatures of about 300°C.

Publikationsansicht. 38896407. Actively-forming sulfide deposits at the PACMANUS Hydrothermal Fie... more Publikationsansicht. 38896407. Actively-forming sulfide deposits at the PACMANUS Hydrothermal Field, Eastern Manus Basin, Papua New Guinea (1996). ...

The Manus Basin spreading system is made of 3 main ridge segments limited by Wuillaumez, Djaul an... more The Manus Basin spreading system is made of 3 main ridge segments limited by Wuillaumez, Djaul and Weitin FZ. The aim of the Manusflux cruise of the R/v Yokosuka and the submersible Shinkai-6500 was the in situ exploration of the central and eastern ridge segments and the study of the associated hydrothermal activity. Both segments show a different morphology, a basaltic or dacitic basement and all types of hydrothermal activity from low temperature diffusion up the black smoker stage.

HAL (Le Centre pour la Communication Scientifique Directe), 1997

The Manus back arc basin is well known for hosting submarine hydrothermal deposits of Vienna Wood... more The Manus back arc basin is well known for hosting submarine hydrothermal deposits of Vienna Wood, Pacmanus, Onsen site and Solwara 1-12. The Vienna Wood located in the Central Manus basin is a typical Cu-Zn type of mineralization hosted by mid-oceanic ridge basalt and consists predominantly of sphalerite, wurtzite, chalcopyrite and gangue minerals of anhydrite, gypsum and silica. In contrast, the Pacmanus hydrothermal deposit in the eastern part of the Manus basin is hosted by rocks ranging from basalt to dacite and rhyodacite. The mineralization is of the polymetallic Zn-Cu-Pb-Au type consists of ore minerals of sphalerite, chalcopyrite, bornite, wurtzite, pyrite, marcasite, enargite, tennantite, galena, Pb-As-Sulphosalt, gold, covellite, digenite, chalcocite and gangue minerals of barite, amorphous silica, anhydrite and gypsum. The chemical composition of sphalerite, galena, gold and tennantite-tetrahedrite indicate high concentrations of Lead, Arsenic, Silver, Iron, Copper and Antimony compared to their stoichiometric composition. The Onsen site in the Eastern Manus Basin is the first deep sea acid sulfate type of mineralisation and consist of enargite, covellite, chalcopyrite, pyrite, marcasite and gangue minerals of pyrophyllite, alunite, quartz, cristoballite, amorphous silica and native sulfur. The PNG Government has granted exploration and mining licenses to Nautilus Mineral for commercial exploitation of these deposits and Solwara 1 deposit in the Eastern Manus Basin. Nautilus minerals has done extensive exploration and reports indicated and inferred a mineral resource of 1030 kt and 1540 kt respectively for their Solwara 1 project east of Pacmanus site at a 2.6% Cu equivalent cut off grade. Whether this mineral resource is sufficient to deliver PNG first deep sea mining or not will depend on the success of the trial mining method that is currently being developed. Studies done on nearby Pacmanus and Onsen submarine hydrothermal deposits indicate that the deposits contain a much higher proposition of deleterious elements such As, Pb and Sb. Nautilus did not disclose the full mineralogy and assay results of the Solwara 1 and 2 projects to the public domain apart from Cu, Au, Ag and Zn. Nautilus did not suggest how it will address toxic and heavy metals that are associated with the ore concentrate in its Environmental Impact Studies.

Resource Geology, Aug 8, 2008

The Yonaguni Knoll IV hydrothermal vent field (24°51′N, 122°42′E) is located at water depths of 1... more The Yonaguni Knoll IV hydrothermal vent field (24°51′N, 122°42′E) is located at water depths of 1370–1385 m near the western edge of the southern Okinawa Trough. During the YK03–05 and YK04–05 expeditions using the submersible Shinkai 6500, both hydrothermal precipitates (sulfide/sulfate/carbonate) and high temperature fluids (Tmax = 328°C) presently venting from chimney‐mound structures were extensively sampled. The collected venting fluids had a wide range of chemistry (Cl concentration 376–635 mmol kg−1), which is considered as evidence for sub‐seafloor phase separation. While the Cl‐enriched smoky black fluids were venting from two adjacent chimney‐mound structures in the hydrothermal center, the clear transparent fluids sometimes containing CO2 droplet were found in the peripheral area of the field. This distribution pattern could be explained by migration of the vapor‐rich hydrothermal fluid within a porous sediment layer after the sub‐seafloor phase separation. The collected hydrothermal precipitates demonstrated a diverse range of mineralization, which can be classified into five groups: (i) anhydrite‐rich chimneys, immature precipitates including sulfide disseminations in anhydrite; (ii) massive Zn‐Pb‐Cu sulfides, consisting of sphalerite, wurtzite, galena, chalcopyrite, pyrite, and marcasite; (iii) Ba‐As chimneys, composed of barite with sulfide disseminations, sometimes associated with realgar and orpiment overgrowth; (iv) Mn‐rich chimneys, consisting of carbonates (calcite and magnesite) and sulfides (sphalerite, galena, chalcopyrite, alabandite, and minor amount of tennantite and enargite); and (v) pavement, silicified sediment including abundant native sulfur or barite. Sulfide/sulfate mineralization (groups i–iii) was found in the chimney–mound structure associated with vapor‐loss (Cl‐enriched) fluid venting. In contrast, the sulfide/carbonate mineralization (group iv) was specifically found in the chimneys where vapor‐rich (Cl‐depleted) fluid venting is expected, and the pavement (group v) was associated with diffusive venting from the seafloor sediment. This correspondence strongly suggests that the subseafloor phase separation plays an important role in the diverse range of mineralization in the Yonaguni IV field. The observed sulfide mineral assemblage was consistent with the sulfur fugacity calculated from the FeS content in sphalerite/wurtzite and the fluid temperature for each site, which suggests that the shift of the sulfur fugacity due to participation of volatile species during phase separation is an important factor to induce diverse mineralization. In contrast, carbonate mineralization is attributed to the significant mixing of vapor‐rich hydrothermal fluid and seawater. A submarine hydrothermal system within a back‐arc basin in the continental margin may be considered as developed in a geologic setting favorable to a diverse range of mineralization, where relatively shallow water depth induces sub‐seafloor phase separation of hydrothermal fluid, and sediment accumulation could enhance migration of the vapor‐rich hydrothermal fluid.

AGU Fall Meeting Abstracts, Dec 1, 2006

Increasing levels of CO2 in the atmosphere are expected to cause climatic change with negative ef... more Increasing levels of CO2 in the atmosphere are expected to cause climatic change with negative effects on the earth's ecosystems and human society. Consequently, a variety of CO 2 disposal options are discussed, including injection into the deep ocean. Because the dissolution of CO2 in seawater will decrease ambient pH considerably, negative consequences for deep-water ecosystems have been predicted. Hence, ecosystems associated with natural CO2 reservoirs in the deep sea, and the dynamics of gaseous, liquid, and solid CO 2 in such environments, are of great interest to science and society. We report here a biogeochemical and microbiological characterization of a microbial community inhabiting deep-sea sediments overlying a natural CO 2 lake at the Yonaguni Knoll IV hydrothermal field, southern Okinawa Trough. We found high abundances (>10 9 cm ؊3) of microbial cells in sediment pavements above the CO2 lake, decreasing to strikingly low cell numbers (10 7 cm ؊3) at the liquid CO2͞CO2-hydrate interface. The key groups in these sediments were as follows: (i) the anaerobic methanotrophic archaea ANME-2c and the Eel-2 group of Deltaproteobacteria and (ii) sulfur-metabolizing chemolithotrophs within the Gamma-and Epsilonproteobacteria. The detection of functional genes related to one-carbon assimilation and the presence of highly 13 C-depleted archaeal and bacterial lipid biomarkers suggest that microorganisms assimilating CO2 and͞or CH4 dominate the liquid CO2 and CO 2-hydrate-bearing sediments. Clearly, the Yonaguni Knoll is an exceptional natural laboratory for the study of consequences of CO 2 disposal as well as of natural CO2 reservoirs as potential microbial habitats on early Earth and other celestial bodies. anaerobic oxidation of methane ͉ chemolithotroph ͉ CO2 disposal ͉ CO 2 hydrate ͉ liquid CO2 Conflict of interest statement: No conflicts declared. Abbreviation: AOM, anaerobic oxidation of methane. Data deposition: The 16S rRNA, mcrA, and cbbL gene sequences reported in this paper have been deposited in the DNA Data Bank of Japan͞European Molecular Biology Laboratory͞ GenBank databases (accession nos. AB252422-AB252455).

AGU Fall Meeting Abstracts, Dec 1, 2004

The active sulfide chimney ore sampled from the flank of the active TIger chimney in the Yonaguni... more The active sulfide chimney ore sampled from the flank of the active TIger chimney in the Yonaguni Knoll N hydrothermal system, South Okinawa Trough, consists of anhydrite, pyrite, sphalerite, galena. chalcopyrite and bismuthinite. Electron microprobe analyses indicated that the chalcopyrite and bismuthinite contain up to 2.4 wt. % Sn and 1.7 wt. % Pt, respectively. The high Sn-bearing chalcopyrite and Pt-bearing bismuthinite are the first occurrence of such minerals on the submarine hydrothermal systems so far reported. The results confirm that the Sn enters the chalcopyrite as a solid solution towards stannite by the coupled substitution of Sn#Fe 2 + for Fe3+Fe3+ while Pt enters the bismuthinite structure as a solid solution during rapid growth. The homogenization temperature of the fluid inclusions in anhydrite (220-31O°C) and measured end-member temperature of the vent fluids (325°C) indicate that the minerals are precipitated as metastable phases at temperature around 300°C. The Sn-bearing chalcopyrite and Pt-bearing bismuthinite express the original composition of the minerals deposited from a hydrothermal fluid with temperatures of about 300°C.

日本鉱物学会年会・日本岩石鉱物鉱床学会学術講演会講演要旨集, 2004

The Manus Basin spreading system consists of three main ridge segments separated by Wuillaumez, D... more The Manus Basin spreading system consists of three main ridge segments separated by Wuillaumez, Djaul and Weitin Fracture Zones. The aim of Manusflux cruise of the R/V "Yokosuka" and the submersible "Shinkai 6500" was the in situ exploration of the Central and Eastern ridge segments and the study of the associated hydrothermal activity. On each segment active hydrothermal sites have been explored and sampled. They show all types of activity from low temperature diffusion up the black smoker stage. They are located on the fault zones which affect the basaltic or dacitic rocks constituting respectively the Central and Eastern ridge segments.

The active sulfide chimney ore sampled from the flank of the active TIger chimney in the Yonaguni... more The active sulfide chimney ore sampled from the flank of the active TIger chimney in the Yonaguni Knoll N hydrothermal system, South Okinawa Trough, consists of anhydrite, pyrite, sphalerite, galena. chalcopyrite and bismuthinite. Electron microprobe analyses indicated that the chalcopyrite and bismuthinite contain up to 2.4 wt. % Sn and 1.7 wt. % Pt, respectively. The high Sn-bearing chalcopyrite and Pt-bearing bismuthinite are the first occurrence of such minerals on the submarine hydrothermal systems so far reported. The results confirm that the Sn enters the chalcopyrite as a solid solution towards stannite by the coupled substitution of Sn#Fe 2 + for Fe3+Fe3+ while Pt enters the bismuthinite structure as a solid solution during rapid growth. The homogenization temperature of the fluid inclusions in anhydrite (220-31O°C) and measured end-member temperature of the vent fluids (325°C) indicate that the minerals are precipitated as metastable phases at temperature around 300°C. The...

The active sulfide chimney ore sampled from the flank of the active TIger chimney in the Yonaguni... more The active sulfide chimney ore sampled from the flank of the active TIger chimney in the Yonaguni Knoll N hydrothermal system, South Okinawa Trough, consists of anhydrite, pyrite, sphalerite, galena. chalcopyrite and bismuthinite. Electron microprobe analyses indicated that the chalcopyrite and bismuthinite contain up to 2.4 wt. % Sn and 1.7 wt. % Pt, respectively. The high Sn-bearing chalcopyrite and Pt-bearing bismuthinite are the first occurrence of such minerals on the submarine hydrothermal systems so far reported. The results confirm that the Sn enters the chalcopyrite as a solid solution towards stannite by the coupled substitution of Sn#Fe 2 + for Fe3+Fe3+ while Pt enters the bismuthinite structure as a solid solution during rapid growth. The homogenization temperature of the fluid inclusions in anhydrite (220-31O°C) and measured end-member temperature of the vent fluids (325°C) indicate that the minerals are precipitated as metastable phases at temperature around 300°C. The Sn-bearing chalcopyrite and Pt-bearing bismuthinite express the original composition of the minerals deposited from a hydrothermal fluid with temperatures of about 300°C.

Publikationsansicht. 38896407. Actively-forming sulfide deposits at the PACMANUS Hydrothermal Fie... more Publikationsansicht. 38896407. Actively-forming sulfide deposits at the PACMANUS Hydrothermal Field, Eastern Manus Basin, Papua New Guinea (1996). ...

The Manus Basin spreading system is made of 3 main ridge segments limited by Wuillaumez, Djaul an... more The Manus Basin spreading system is made of 3 main ridge segments limited by Wuillaumez, Djaul and Weitin FZ. The aim of the Manusflux cruise of the R/v Yokosuka and the submersible Shinkai-6500 was the in situ exploration of the central and eastern ridge segments and the study of the associated hydrothermal activity. Both segments show a different morphology, a basaltic or dacitic basement and all types of hydrothermal activity from low temperature diffusion up the black smoker stage.