Thermal History, and Chemical and Isotopic Compositions of the Ore-Forming Fluids Responsible for the Kuroko Massive Sulfide Deposits in the Hokuroku District of Japan

Pisutha-Arnond, Visut; Ohmoto, Hiroshi

doi:10.5382/mono.05.30

Cited by 44 publications

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“…These samples yielded a limited range of δ Table 3), which is similar to previous analytical results (9.6-10.4‰; Peng et al, 1995), except for one sample with a higher δ 18 O value. This range of δ 18 O values is slightly higher than that of quartz from the stringer zones of some Japanese Kuroko deposits (avg +9.1‰: Pisutha-Arnond and Ohmoto, 1983;Huston, 1999) Liu (1982) and Xia et al (1985). Liu (1982) and Xia et al (1985).…”

Section: δ 18 O In Quartz From Sulfide Oresmentioning

confidence: 73%

Geology, Fluid Inclusions, and Oxygen Isotope Geochemistry of the Baiyinchang Pipe-Style Volcanic-Hosted Massive Sulfide Cu Deposit in Gansu Province, Northwestern China

et al. 2008

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The Baiyinchang massive sulfide Cu deposit (Zheyaoshan and Huoyanshan mines) is hosted by an early Cambrian, submarine, felsic volcanic succession within an extrusive cryptodome associated with an overlying basaltic flow, in a Late Proterozoic-early Paleozoic submarine volcanic belt in the north Qilian orogen, northwestern China. The deposit is comprised of two mineralized zones: a 30-cm-thick, strata-bound Zn-rich sulfide lens associated with hematitic Fe-Mn cherts, and an underlying, discordant massive ore-dominated sulfide zone enveloped by a hydrothermal alteration pipe that is zoned from chlorite in the center to quartz-sericite at the margin. The discordant sulfide zone accounts for 90 percent of the Cu reserves of the Zheyaoshan mine. It consists of four main ore types: (1) pipelike pyrrhotite-pyrite ± chalcopyrite ore, (2) massive sulfide ore, (3) a disseminated ore halo, and (4) footwall stringer ore. The pyrrhotite-pyrite ± chalcopyrite pipe has an elliptical shape in plan and is 30 × 50 m across. The pipe partially replaces the overlying massive pyrite lens and extends downward at least 150 m, to be gradually replaced by chalcopyrite-rich stringer veins and chalcopyritebearing quartz veins surrounded by a discordant hydrothermal alteration envelope. Massive chalcopyrite-pyrite lenses discordant to volcanic bedding, containing relict patches of felsic volcanic host rocks, are commonly enveloped by a disseminated sulfide halo within a chloritized volcanic unit. These features suggest that Zheyaoshan is a pipe-style deposit that formed mainly by subsea-floor replacement of volcanic host rocks. Studies of fluid inclusions indicate that there are four types: (1) type I two-phase, aqueous fluid inclusions, (2) type II daughter mineral-bearing, multiphase fluid inclusions, (3) type III CO2-rich fluid inclusions, and (4) type IV CH4-rich fluid inclusions. Type II inclusions have high homogenization temperatures (Th) ranging from 320°to 430°C, contain high salinity fluids (31-38 wt % NaCl equiv), and coexist with CO2-rich fluids found in vapor-rich, high-Th (up to 487°C), moderate salinity (10-16 wt % NaCl equiv) inclusions in the discordant sulfide zone and associated altered rocks, suggesting a possible contribution of a magmatic fluid to the hydrothermal system. The coexistence of vapor-rich, high-Th (>300°C) and aqueous, low-Th (<220°C) type I fluid inclusions in the stringer zone suggests that heated seawater mixed with magmatic fluid (gas) in the feeder zone. Most type I fluid inclusions in the massive chalcopyrite-pyrite body and in the strongly chloritized pipe have a low Th (62°-225°C) and high salinities (15.0-23.0 wt % NaCl equiv), suggesting that a dense brine zone developed in fractures in the subsea floor where sulfides accumulated by open-space filling and replacement of host volcanic rocks. Eleven quartz samples from the overlying discordant sulfide zone yielded a restricted range of δ 18 O values between 8.8 and 11.1 per mil, from which we calculate that the corresponding hydrothermal fluids ha...

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Section: δ 18 O In Quartz From Sulfide Oresmentioning

confidence: 73%

Geology, Fluid Inclusions, and Oxygen Isotope Geochemistry of the Baiyinchang Pipe-Style Volcanic-Hosted Massive Sulfide Cu Deposit in Gansu Province, Northwestern China

et al. 2008

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“…For the hydrothermal origin, Ohmoto (1996) developed a six-stage model for the formation of this deposit in which the importance of submarine caldera in supplying the heat source and the fracture systems necessary for the transport of the hydrothermal fluids was emphasized. This model was based on earlier researches by Ohmoto et al (1983a, b) and Pisutha-Arnond and Ohmoto (1993). However, T. Urabe and his colleagues have pointed to a number of weaknesses in this model (Urabe et al 1983;Urabe, 1987;Urabe and Marumo, 1991).…”

Section: E T a L -B E L Tmentioning

confidence: 98%

Kuroko and Hydrocarbon Deposits from Northern Honshu, Japan: A Possible Common Hydrothermal/Magmatic Origin?

et al. 2004

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Northern Honshu is the most important area for mineral and oil resources in Japan. Many kuroko deposits and oil and gas fields are distributed in two belts along the northeast Japan arc, the kuroko metal-belt on the Pacific side and the oil-belt on the Sea of Japan side. The kuroko deposits are located mainly in the Green Tuff strata which formed as a result of submarine volcanism during the late Miocene and Pliocene. Most of the source rocks of the oil and gas deposits formed at the same time as the kuroko deposits and some of them are located in reservoirs of hydrothermally-altered volcanic rocks in the Green Tuff region. There is general agreement that the kuroko deposits formed as a result of submarine hydrothermal and magmatic activity whereas almost all petroleum geologists and geochemists consider that hydrocarbon deposits were generated independently of such activity. Since the discovery of hydrothermally-generated petroleum in the Guaymas Basin, Gulf of California, however, it is clear that petroleum can be formed almost instantaneously in terrestrial and submarine hydrothermal areas. The paleo-northeastern Sea of Japan is therefore considered to be a potential area for hydrothermal petroleum generation because thick organic-rich sediments overlie an active submarine volcanic area. Several lines of geological and geochemical evidence suggest the possibility of hydrothermally-enhanced maturation of organic matter and the contribution of magmatic activity to the formation of these deposits. Although most of the oil and gas in northern Honshu has been generated conventionally as a consequence of the high geothermal gradients there, it appears that some of the oil and gas fields may have formed as a result of extensive hydrothermal and magmatic activity during the late Miocene to Pliocene. Because of the much steeper angle of the faults in the vicinity of the Hokuroku basin than in the Akita basin, the magmatic contribution to the kuroko mineralization would have been far greater than to the oil and gas deposits of the Niigata and Akita basins. We therefore propose a strong relationship between metal and oil and gas generation in northern Honshu based on the structure and tectonics of the northern Honshu arc-backarc system.

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“…For mound-type deposits, a widely held viewpoint is that an accumulation process of massive sulfides was controlled by a thermally intensifying hydrothermal system (Eldridge et al, 1983;Lydon, 1988). In this model, medium to low-temperature black mineral assemblage was first deposited from seawater-genetic hydrothermal fluids on the seafloor and subsequently replaced by high-temperature Cubearing fluids (Eldridge et al, 1983;Pisutha-Arnond and Ohmoto, 1983). The process results in accumulation of high-temperature yellow ore (and pyrite ore) in the porous place, produced after the black ore assemblage was replaced and leached Pb and Zn were migrated outwards to form the black ore assemblage (Eldridge et al, 1983).…”

Section: Rhythmic Variation In 187 Os/ 188 Os and 187 Re/ 188 Os Ratiosmentioning

confidence: 99%

Re‐Os Dating of Sulfides from the Volcanogenic Massive Sulfide Deposit at Gacun, Southwestern China

Hou¹,

Wang²,

Du³

et al. 2003

Resource Geology

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Abstract:The Re-Os isotopic compositions of sulfide ores were analyzed for the Gacun, a volcanogenic massive sulfide deposit in southwestern China, to constrain the timing of mineralization. Sulfide ores from the deposit have a wide range of Re and Os concentrations, varying from 80.2 to 1543.2 ppb and from 0.307 to 8.83 ppb, respectively, and yielded a limited field of high 187 Re/ 188 Os and high 187 Os/ 188 Os ratios, ranging from 1452 to 3309 and from 5.77 to 13.24, respectively. All sulfide samples yielded an isochron with an age of 217±28 Ma and an initial 187 Os/ 188 Os ratio of around 0.52±0.73. The ReOs isochron age agrees with ages previously constrained by the other isotopic dating of the host rocks and fossil strata for the deposit. The rhythmic variation in 187 Os/ 188 Os and 187 Re/ 188 Os ratios within massive sulfide zone records a complicated process for ore-forming fluids episodically vented into the brine pool on the Mesozoic seafloor.

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Thermal History, and Chemical and Isotopic Compositions of the Ore-Forming Fluids Responsible for the Kuroko Massive Sulfide Deposits in the Hokuroku District of Japan

Cited by 44 publications

References 0 publications

Geology, Fluid Inclusions, and Oxygen Isotope Geochemistry of the Baiyinchang Pipe-Style Volcanic-Hosted Massive Sulfide Cu Deposit in Gansu Province, Northwestern China

Geology, Fluid Inclusions, and Oxygen Isotope Geochemistry of the Baiyinchang Pipe-Style Volcanic-Hosted Massive Sulfide Cu Deposit in Gansu Province, Northwestern China

Kuroko and Hydrocarbon Deposits from Northern Honshu, Japan: A Possible Common Hydrothermal/Magmatic Origin?

Re‐Os Dating of Sulfides from the Volcanogenic Massive Sulfide Deposit at Gacun, Southwestern China

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