Genesis of the plutonic-hydrothermal system around quaternary granite in the kakkonda geothermal system, Japan

Doi, Nobuo; Kato, Osamu; Ikeuchi, Ken; Komatsu, Ryo; Miyazaki, Shuichi; Akaku, Kohei; Uchida, Toshihiro

doi:10.1016/s0375-6505(98)00039-x

Cited by 68 publications

(42 citation statements)

References 10 publications

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“…The Kakkonda I geothermal power plant (50 MWe) has been in operation since 1978; the Kakkonda II geothermal power plant (30 MWe) began to generate in 1996. Geological features of the field were described by Nakamura and Sumi (1981a), Sato (1982), Doi et al (1988), Kanisawa et al (1994), Uchida et al (1996) and Doi et al (1998). The stratigraphy includes Miocene formations, pre-Tertiary formations, old intrusive rocks and Kakkonda granite (Fig.…”

Section: Geologic Setting and Geothermal Reservoirmentioning

confidence: 85%

Geochemical study of fluid inclusions in anhydrite from the Kakkonda geothermal system, northeast Japan.

Muramatsu

Komatsu²,

Sawaki

et al. 2000

Geochem. J.

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Anhydrite occurs as a representative hydrothermal mineral in the upflow zone of the Kakkonda geothermal field, northeast Japan. Gas analysis and microthermometry of fluid inclusions and sulfur isotope measurements were performed for these anhydrites in order to discuss origin of the reservoir fluids and precipitation mechanism of the anhydrite.Fluid inclusions are classified into two-phase, vapor-rich and liquid-rich inclusions, and polyphase inclusions comprising liquid, vapor and solids. The vapor-rich inclusions coexist with the liquid-rich inclusions in most samples, indicating that the fluid inclusions were trapped under boiling conditions. Bulk gas analyses of the liquid-rich inclusions show that the main non-condensable gas component is CO 2 (0.14-2.0 mol %) with subordinate amounts of N 2 , CH 4 and Ar. The two-phase liquid-rich inclusions homogenize to liquid phase at temperatures between 222 and 380°C, and have salinities mostly from 0 to 29 wt.% NaCl + CaCl 2 equivalent. The polyphase inclusions homogenize to liquid phase at temperatures between 302 and >480°C after dissolving halite between 104 and 220°C on heating, and have salinities from 28 to 35 wt.% NaCl + CaCl 2 equivalent. In the deep reservoir, the salinities vary over a large range at homogenization temperatures of approximately 320 to 360°C. The δ 34 S values of anhydrites ranging mostly from +21.6 to +24.2‰ suggest that sulfur in the anhydrite from the Kakkonda field is derived from marine anhydrite.These data indicate that the hypersaline fluid was produced by exsolution from a residual magma at the time of final crystallization of the Kakkonda granite, and moderate to low salinity fluids formed by dilution of the hypersaline fluid with the heated meteoric water and boiling of the dilute fluids. The precipitation of anhydrite might be explained by three mechanisms of a simple cooling of the hypersaline fluid, boiling of the reservoir fluid and pressure drop of the non-boiling reservoir fluid. the production wells in the Takigami (Takenaka and Furuya, 1991) and Fushime geothermal fields (Akaku et al., 1991). These previous studies suggest that even a slight change in fluid condition by flows might precipitate anhydrite from an anhydrite-saturated fluid within productive fracture, then anhydrite occurrence can provide useful information on evolution of fluid flow system in the active geothermal fields.

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Section: Geologic Setting and Geothermal Reservoirmentioning

confidence: 85%

Geochemical study of fluid inclusions in anhydrite from the Kakkonda geothermal system, northeast Japan.

Muramatsu

Komatsu²,

Sawaki

et al. 2000

Geochem. J.

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“…Type-G anhydrite occurs with chlorite, muscovite and biotite whereas type-T occurs with albite and hematite ( Kato and Sato, 1995): zones of montmorillonite (Mnt), mix-layered montmorillonite/sericite (M/S), sericite (Ser), biotite (Bt), cordierite (Crd) and anthophyllite (Ath) to andalusite (And). Vein minerals in Mnt zone are cited from Koshiya et al (1994), NEDO (1994), Kato and Sato (1995) and Doi et al (1998) while vein minerals in the other zones after Sasaki et al (1998) with the exception of "other minerals" after Kato and Sato (1995). The asterisk symbol (*) indicates tourmaline, axinite, fluorite and molybdenite.…”

Section: Cathodoluminescence Observationmentioning

confidence: 99%

“…The surface and subsurface geology of the field has been studied by Kato and Doi (1993), Kanisawa et al (1994), Kato and Sato (1995), Uchida et al (1996) and Doi et al (1998), as shown in Figures 1 to 3. Pre-Tertiary formations are composed of slate, sandstone and andesitic tuff (Figs.…”

Section: Geology Of the Kakkonda Geothermal Systemmentioning

confidence: 99%

Geochemical Features of Vein Anhydrite from the Kakkonda Geothermal System, Northeast Japan

et al. 2003

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. Cathodoluminescence (CL) color, rare earth element (REE) content, sulfur and oxygen isotopes and fluid inclusions of anhydrite, which frequently filled in hydrothermal veins in the Kakkonda geothermal system, were investigated to elucidate the spatial, temporal and genetical evolution of fluids in the deep reservoir. The anhydrite samples studied are classified into four types based on CL colors and REE contents: type‐N (no color), type‐G (green color), type‐T (tan color) and type‐S (tan color with a high REE content). In the shallow reservoir, only type‐N anhydrite is observed. In the deep reservoir, type‐G anhydrite occurs in vertical veins whereas type‐T and ‐N in lateral veins. Type‐S anhydrite occurs in the heat‐source Kakkonda Granite. The CL textures revealed that type‐G anhydrite deposited earlier than type‐T in the deep reservoir, implying that fracture system was changed from predominantly vertical to lateral. Studies of fluid inclusions and δ34S and δ18O values of the samples indicate that type‐N anhydrite deposited from diluted fluids derived from meteoric water, whereas type‐G, ‐T and ‐S anhydrites deposited from magmatic brines derived from the Kakkonda Granite with the exception of some of type‐G with recrystallization texture and no primary fluid inclusion, which deposited from fossil seawater preserved in the sedimentary rocks. Type‐G, ‐T and ‐S anhydrites exhibit remarkably different chondrite‐normalized REE patterns with a positive Eu anomaly, with a convex shape (peak at Sm or Eu) and with a negative Eu anomaly, respectively. The difference in the patterns might result from the different extent of hydrothermal alteration of the reservoir rocks and contribution of the magmatic fluids.

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“…In general then, pre-production field evidence indicates many magmatic geothermal systems have PT conditions along the two-phase boundary, extending to supercritical conditions at depth in Figure 32: Temperature-Pressure depth profiles for two Japanese geothermal systems. Pressure calculated assuming pure H 2 O given temperature-depth data of Doi et al (1998) for well WD-1 at Kakkonda, Japan. Reconstructed P-T data for Matsukawa from Hanano and Matsuo (1990), who assumed pure H 2 O, and corrected for P CO 2 ("Ptotal" line).…”

Section: E11 Directly Observed Supercritical Conditions In Naturementioning

confidence: 99%

Final Report: Natural State Models of The Geysers Geothermal System, Sonoma County, California

Brikowski¹,

Norton²,

Blackwell³

2001

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Genesis of the plutonic-hydrothermal system around quaternary granite in the kakkonda geothermal system, Japan

Cited by 68 publications

References 10 publications

Geochemical study of fluid inclusions in anhydrite from the Kakkonda geothermal system, northeast Japan.

Geochemical study of fluid inclusions in anhydrite from the Kakkonda geothermal system, northeast Japan.

Geochemical Features of Vein Anhydrite from the Kakkonda Geothermal System, Northeast Japan

Final Report: Natural State Models of The Geysers Geothermal System, Sonoma County, California

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