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Nakatatsu - Nakayama, Hitokata, Senno, South Senno |
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Honshu, Japan |
| Main commodities:
Zn Pb Cu Ag
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Nakatatsu zinc-lead deposits are located in Fukui Prefecture, in west-central Honshu, Japan (#Location: 35° 52' 40"N, 136° 34' 17"E).
The deposit lies within the Hida marginal tectonic belt that occurs between the Hida metamorphic complex to the north and unmetamorphosed Paslaeozoic rocks the south.
Several lead-zinc-copper vein and skarn deposits, e.g., the Omodani copper-zinc vein deposit and the Nojiri copper skarn deposit, are also found in this belt.
In the Nakatatsu area, folded and faulted Palaeozoic sedimentary rocks of the Fujikuradani Formation are unconformably overlain by the and Mesozoic Tetori Group. The Fujikuradani Formation, which has a thickness of at least a few hundred metres, is cut by high-angle thrust faults on both the north and south sides. It is composed mainly of black limestone, containing carbonaceous matter concentrated in layers, with some intercalations of black slate and intrusions of dolerite, and strikes east-west, dipping at 40 to 80°S. Some limestone, slate and dolerite were recrystallised and altered to skarn over an area 0.3 x 2 km during emplacement of the Tertiary granite porphyry.
The Middle Jurassic to Lower Cretaceous Tetori Group is extensively exposed around the Fujikuradani Formation, and is chiefly composed of intensely folded conglomerate, sandstone, and shale with a maximum thickness of >1500.
A number of small skarn alteration associated zinc-lead deposits are concentrated near the contact between the Palaeozoic Fujikuradani Formation and granite porphyry intrusions of Tertiary age. Mineralisation is hosted by manganoan hedenbergite developed from Carboniferous to Permian limestones and grandite-andradite from dolerite and limestone pre-cursors, all of which are adjacent to a Tertiary granite porphyry.
The skarns are mainly composed of manganoan hedenbergite from alteration of limestone, zoned from limestone, to wollastonite-bustamite, to clinopyroxene, to garnet skarn. Clinopyroxene skarn is the most abundant in the deposits, and accompanies most of the orebodies.
Grandite-andradite skarn is from altered dolerite, occurring in three zones, frpm dolerite, to altered dolerite, to garnet-epidote, and garnet skarn.
Skarns that originated from slate of the Fujikuradani Formation, are divided into hornfels, banded skarn, epidote skarn and garnet skarn
In the vicinity of the orebodies, clinopyroxene was altered to nontronite, while below the orebodies, clinopyroxene in the same skarn was transformed into garnet.
Four productive deposits have been worked, namely Nakayama, Hitokata, Senno and South Senno.
Production from 1951-1977 totalled 7 Mt @ 5.5% Zn, 0.5% Pb, 0.3% Cu, 30 g/t Ag.
For detail see the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 1982.
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.
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Shimizu M, Iiyama J T 1982 - Zinc-lead skarn deposits of the Nakatatsu Mine, central Japan: in Econ. Geol. v77 pp 1000-1012
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