Zonal Alteration around the Fukazawa Kuroko Deposits, Akita Prefecture, Northern Japan

Date, Jiro; Watanabe, Yoshihiro; Saeki, Yuji

doi:10.5382/mono.05.22

Cited by 24 publications

(13 citation statements)

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“…The intense depletion of Na 2 O throughout both the hanging wall and footwall (Fig. 8A) is due to the destruction of feldspar during hydrothermal alteration (e.g., Riverin and Hodgson 1980;Knuckey et al 1982;Date et al 1983;Barrett and MacLean 1994). The addition of most elements can be explained through the modification of seawater and leaching of felsic rock (e.g., Franklin et al 2005;Hannington et al 2005); however, the addition of most of the transition elements (i.e., Cr, Co, Ni, V) remains somewhat enigmatic.…”

Section: Characteristics and Controls On Hydrothermal Alterationmentioning

confidence: 99%

Hydrothermal alteration and lithogeochemistry of the Boundary volcanogenic massive sulphide deposit, central Newfoundland, Canada

Buschette

Piercey

2016

Can. J. Earth Sci.

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The Boundary volcanogenic massive sulphide deposit (0.50 Mt at 3.5% Cu, 4.0% Zn, and 1.0% Pb, 34 g/t Ag) is hosted by the Tally Pond group (∼510 Ma), Victoria Lake supergroup, central Newfoundland, Canada, and represents a subseafloor replacement-style massive sulphide deposit. The deposit is hosted by rhyolitic lapilli tuff of the Bindons Pond formation. The rhyolites have immobile element signatures consistent with the formation of felsic rocks through the melting of juvenile-weakly evolved crust within an extensional rift environment (rifted peri-continental arc). The host rocks of the Boundary deposit contain elevated alteration indices, including high Ba/Sr, Hg/Na2O, chlorite–carbonate–pyrite index, and Ishikawa alteration index values. The mobile element geochemistry effectively differentiates between three distinct hydrothermal alteration styles: intense chlorite, chlorite-sericite, and quartz-sericite. Intense chlorite alteration exhibits mass gains in MgO and Cu and depletions in K2O and Ba. Chlorite-sericite alteration contains variable gains and losses of SiO2, K2O, Ba, MgO, and Fe2O3 depending on the dominant matrix mineral phase (i.e., chlorite vs. sericite). The quartz-sericite assemblage has mass gains in SiO2, K2O, Ba, and Fe2O3. Short-wave infrared spectroscopic data, particularly AlOH and FeOH absorption hulls, differentiate alteration styles and correlate with lithogeochemical results: AlOH absorption features increase in length (>2208 nm) proximal to Zn mineralization and wavelength variations correspond to relative abundances of sericite and chlorite. Electron probe microanalyses indicate that increasing short-wave infrared wavelengths correlate with increasing Mg–Fe and Fe contents in sericite and chlorite, respectively. Collectively, these data have been used to develop a three-dimensional alteration model of the Boundary deposit.

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Section: Characteristics and Controls On Hydrothermal Alterationmentioning

confidence: 99%

Hydrothermal alteration and lithogeochemistry of the Boundary volcanogenic massive sulphide deposit, central Newfoundland, Canada

Buschette

Piercey

2016

Can. J. Earth Sci.

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“…The first reaction is typical of sericite replacement of albite in volcanic rocks in the outer parts of the alteration system (e.g., Date et al, 1983;Eastoe et al, 1987). The second reaction is important close to massive sulfide mineralization in footwall pipe zones where chlorite-rich assemblages become dominant over sericite-rich assemblages (e.g., Sangster, 1972;Lydon, 1988;Large, 1992;Lentz, 1999;Schardt et al, 2001).…”

Section: ) Chloritementioning

confidence: 99%

“…In fact many alteration studies have used sodium depletion rather than the AI as the principal measure of alteration intensity (e.g., Franklin et. al., 1975;Date et al, 1979Date et al, , 1983Hashiguchi et al, 1983;Ashley et al, 1988).…”

Section: The Alteration Box Plot: a Simple Approach To Understanding mentioning

confidence: 99%

The Alteration Box Plot: A Simple Approach toUnderstanding the Relationship between Alteration Mineralogy andLithogeochemistry Associated with Volcanic-Hosted Massive Sulfide Deposits

Large¹,

Gemmell²,

Paulick³

et al. 2001

Economic Geology

120

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Zonal alteration is a common feature in volcanic rocks surrounding sea-floor massive sulfide deposits. Alteration indexes, such as the Ishikawa alteration index (AI) and the chlorite-carbonate-pyrite index (CCPI), have been developed to measure the intensity of sericite, chlorite, carbonate, and pyrite replacement of sodic feldspars and glass associated with hydrothermal alteration proximal to the orebodies. In this paper a simple graphical representation of the Ishikawa AI plotted against the CCPI, termed the "alteration box plot," is used to characterize the different alteration trends related to massive sulfide ores and to assist in the distinction of volcanic-hosted massive sulfide (VHMS)-related hydrothermal alteration from regional diagenetic alteration. Although there are some limitations with the technique, a series of case studies are used to demonstrate that the alteration box plot is a powerful means of understanding the relationship between mineralogy, lithogeochemistry, and intensity of alteration in zoned alteration systems related to VHMS deposits and should assist the exploration geologist in determining vectors to the center of the ore system.

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“…Changes in element concentrations in hydrothermally altered rocks around VMS deposits have been used as guides in the search for kuroko deposits in Japan (e.g. Ishikawa et al, 1976;Date et al, 1983;Hashiguchi et al, 1983). Chloritized cores exhibit mass depletions in SiO 2 coupled with mass additions of Fe 2 O 3 +MgO (Fe 2 O 3 equivalent to total iron).…”

Section: Introductionmentioning

confidence: 99%

Mass Change Calculations as Applied to the Search for Volcanogenic Massive Sulfide Deposits: An Example from Malusok, Siocon, Zamboanga del Norte, Mindanao, Philippines

Querubin¹,

Yumul²

2005

Resource Geology

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Abstract:The Malusok volcanogenic massive sulfide (VMS) deposits comprise two adjacent ore bodies, the Main Malusok and the Malusok Southeast ore bodies, hosted within Cretaceous metamorphic rocks. Owing to the structural and metamorphic overprinting combined with intense hydrothermal alteration, primary textures of the Malusok volcanic rocks have been obliterated. The stratigraphic correlation of the Main Malusok and the Malusok Southeast ore bodies show that both deposits are essentially confined within a single stratigraphic interval. The lithogeochemical analysis of the Malusok samples shows that constituent lithologies have precursor compositions ranging from sub-alkaline basalts to rhyodacites. Field and mass flux data suggest that the Main Malusok VMS deposits were derived as a consequence of axial hydrothermal activity. The Malusok Southeast ore bodies represent satellite deposits generated by off-axis hydrothermal activities from vents aligned along a NW-SE trend with the Main Malusok zone. This alignment represents an ancient fissure that served as a pathway for the upwelling metalliferous hydrothermal fluids. In searching for lateral extensions of these VMS deposits, this NW-SE alignment should serve as a possible exploration guide.

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Zonal Alteration around the Fukazawa Kuroko Deposits, Akita Prefecture, Northern Japan

Cited by 24 publications

References 0 publications

Hydrothermal alteration and lithogeochemistry of the Boundary volcanogenic massive sulphide deposit, central Newfoundland, Canada

Hydrothermal alteration and lithogeochemistry of the Boundary volcanogenic massive sulphide deposit, central Newfoundland, Canada

The Alteration Box Plot: A Simple Approach toUnderstanding the Relationship between Alteration Mineralogy andLithogeochemistry Associated with Volcanic-Hosted Massive Sulfide Deposits

Mass Change Calculations as Applied to the Search for Volcanogenic Massive Sulfide Deposits: An Example from Malusok, Siocon, Zamboanga del Norte, Mindanao, Philippines

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