Hanaoka Group - Doyashiki, Matsumine, Shakanai, Takadate, Matsuki

Honshu, Japan

Main commodities: Cu Zn Pb Ag FeS2
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The Hanaoka group of kuroko type Cu-Zn-Pb-Ag deposits has historically been the largest metal producer in Japan.   It is located just north of Ohdate City on the western side of the Hokuroko Basin, Akita Prefecture, in northern Honshu, Japan.

The Hanaoka cluster includes deposits that were mined by Dowa Mining at the Doyashiki and Matsumine mining units (collectively referred to as the Dowa Hanaoka mine) and the Shakanai mine of Nippon Mining immediately to the east, as well as the Mitsubishi Takadate and Matsuki deposits to the south-west, all of which are distributed over an area of approximately15 x 6 km.

For background information on the geology and setting of the Hokuroko Basin see the Hokuroko Basin - Kuroko Deposits record.

The geology of the Hanaoka district can be summarised as follows:
Basement - Strongly folded black phyllite and chert of possible Permian age and probable Cretaceous granitoids.
Meneichizawa Formation - altered andesitic pyroclastic flows with intercalated lavas, overlain by sandstones.   The unit is around 200 m thick.
Hotakizawa Formation - lower basaltic pillow lavas and upper mudstones which commenced with shallow water facies.
Hanaoka Formation - comprising two units, the upper of which hosts the ore deposits.   The lower unit is approximately 250 m thick and is composed mostly of pale green to pale grey volcanic breccias developed from blocky, flow banded rhyolitic lava.   The breccia overlies massive, un-brecciated rhyolitic lavas at the base of the unit.   The upper unit comprises around 200 m of pale green tuff, lapilli tuff and tuff breccia, of submarine pyroclastic flow origin,with locally developed rhyolite lava domes.   Nine such lava domes are outlined in the Hanaoka mine area, bearing a close genetic relationship to ore.   The ores are all in the upper section of this upper unit.
Tsutsumizawa Formation - mudstones and submarine tuffs overlie the ore deposits.
Younger Rhyolite - locally present, mostly at the same stratigraphic position as the Tsutsumizawa Formation.
Dolerite - as sheets, dykes or irregular massive bodies throughout the mine area.

The Hanaoka mine has exploited clusters of orebodies of varying sizes over an area of 3 km N-S by 2 km E-W which incorporates both the Doyashiki and Matsumine mining units.   Doyashiki alone includes more than 20 named lenses/bodies.   The table below provides details of the larger bodies.

There are/were at least 11 orebodies in the Shakanai mine with largest being No. 4 which is 400x300x40 m with a grade of 1.7% Cu, 0.70% Pb, 2.9% Zn, 22% S, while the highest grade lens is No. 1 which is 300x150x12 m and has 2.3% Cu, 3.2% Pb, 14.6% Zn, 14.0% S.   The geology is the same as at the Hanaoka mine, although different nomenclature is employed, with the ore bearing unit being the Shakanai Formation, with ore occurring in altered tuffs above the "white rhyolite" that is traced into the neighbouring Hanaoka mine.

OrebodyDepthDimensionsOre types
Matsumine215-325 m600x400x110 mKuroko, Oko, Keiko, Sekkoko
Doyashiki20-135 m270x200x100 mKuroko, Oko, Keiko, Sekkoko
Tsutsumizawa10-165 m150x80x110 mKuroko, Oko, Keiko, Sekkoko
Kamiyama75-130 m60x40x55 mKuroko, Oko
Nanatsudate20-75 m100x40x50 mKuroko, Oko
Kannondo20-65 m50x35x45 mKuroko, Oko, Keiko
Ochiaizawa60-137 m60x40x45 mKuroko, Oko, Keiko, Sekkoko
Oishizawa20-90 m50x35x20 mOko, Sekkoko
Inarizawa170-190 m60x15x20 mOko

For detail of the ore types and their composition, occurrence and relationships see the Hokuroko Basin - Kuroko Deposits record.

The Takadate and Matsuki deposits are similarly in the same stratigraphic setting as the other mines in the Hanaoka group of deposits, again with a varying nomenclature - the ore bearing unit being the 1000 m thick Hotakizawa-Okuzu Formation.   The orebodies are composed of Kuroko, Oko, Keiko and Sekkoko ores.   The Takadate deposit is composed of 7 sulphide orebodies and one 600x200x20 m gypsum deposit.   Matsuki is made up of six sulphide and one gypsum deposit, the latter being 900x300x40 m with associated disseminated sulphides (mainly pyrite and chalcopyrite).

Each of the ore bearing units with differing nomenclatures at the various mines, corresponds to the regional Nishihurasawa stage of the Green Tuff Region as detailed in the Hokuroko Basin - Kuroko Deposits record, with the ore being deposited at a position equivalent to the top of that stage.

Tonnage and grade figures include:
    Hanaoka Mine - production to 1975 - 17 Mt @ 2.2% Cu, 0.7% Pb, 3.5% Zn, 20% FeS2.
    Hanaoka - Matsumine - reserve in 1990 - 10 Mt @ 2% Cu, 1% Pb, 3.5% Zn.
    Shakanai - production to 1975 - 1.821 Mt @ 2.15% Cu, 0.90% Pb, 3.3% Zn, 24.5% S.
    Takadate & Matsuki - reserve, 1975 - 3 Mt @ 3.0% Cu, 1.0% Pb, 3.0% Zn.

The total tonnage in the Hanaoka group of deposits is believed to have been approximately 80 Mt.

For detail consult the reference(s) listed below.

The most recent source geological information used to prepare this summary was dated: 1975.    
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd.   Unauthorised copying, reproduction, storage or dissemination prohibited.

  References & Additional Information
   Selected References:
Ito T, Takahashi T, Omori Y  1974 - Submarine volcanic-sedimentary features in the Matsumine Kuroko deposits, Hanaoka Mine, Japan: in Ishihara S (Ed.), 1974 Geology of Kuroko Deposits The Society of Mining Geologists of Japan   Mining Geology Special Issue 6 pp 115-130
Kajiwara Y  1970 - Syngenetic features of the Kuroko ore from the Shakanai Mine: in Tatsumi T (Ed.), 1970 Volcanism and Ore Genesis University of Tokyo Press, Tokyo    pp 197-206
Ogawa Y, Shikazono N, Ishiyama D, Sato H, Mizuta T and Nakano T,   2007 - Mechanisms for anhydrite and gypsum formation in the Kuroko massive sulfide-sulfate deposits, north Japan : in    Mineralium Deposita   v42 pp 219-233
Ohtagaki T, Tsukada Y, Hirayama H, Fujioka H, Miyoshi T  1974 - Geology of the Shakanai Mine, Akita Prefecture: in Ishihara S (Ed.), 1974 Geology of Kuroko Deposits The Society of Mining Geologists of Japan   Mining Geology Special Issue 6 pp 131-139
Sato N, Kusaka H  1974 - Geology of the Matsuki Mine, Ohdate City, Akita Prefecture: in Ishihara S (Ed.), 1974 Geology of Kuroko Deposits The Society of Mining Geologists of Japan   Mining Geology Special Issue 6 pp 141-146
Takahashi T, Suga K  1974 - Geology and ore deposits of the Hanaoka Kuroko Belt, Akita Prefecture: in Ishihara S (Ed.), 1974 Geology of Kuroko Deposits The Society of Mining Geologists of Japan   Mining Geology Special Issue 6 pp 101-113
Terakado Y and Walker R J  2005 - Nd, Sr and Pb isotopic and REE geochemical study of some Miocene submarine hydrothermal deposits (Kuroko deposits) in Japan: in    Contrib. to Mineralogy & Petrology   v149 pp 388-399

Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge.   It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published.   While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

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