Uranium Deposit Report
Deposit : |
Pen Ar Ran |
Country : |
France |
General Information |
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Geological District |
Guèrande | ||
Geological Region |
Massif Armoricain | ||
Political/Geographical Province |
Pays de la Loire (Loire Atlantique) | ||
Last Data Update |
2009-01-01 | ||
Owner(s) |
CEA/COGEMA | ||
Operator |
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Technical Information |
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Tonnage Range (t U)
|
500 - 1,000 | ||
Grade Range (% U)
|
0.50 - 1.00 | ||
Deposit Status
|
Depleted | ||
Current Processing Plant
|
Ecarpiere (dismantled) | ||
Cumulative Production (t U)
|
602 | ||
Production Period
|
1976-1990 | ||
Produced Grade (% U)
|
0 | ||
General Remarks |
The deposit was discovered in 1966. Part of it is located below the Atlantic Ocean. 19 t of uranium were produced from an open pit, 583 t from underground mining. The average grade (0.6%) was the highest for the Vendée mining Division. | ||
Geological Information |
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Deposit Type |
Vein | ||
Geological Setting |
The deposit is located to the south of the Piriac synform. From top to bottom it comprises coarse-grained porphyroids with large augens, micaschists and graphitic schists, medium-grained porphyroids with small augens and basal micaschists. The metamorphic units are sitting on the intrusive Guérande two micas leucogranite. Porphyroids are considered to be acidic volcanic rocks. Thrusting and folding of the metamorphic sequence took place before the intrusion of the granite. The two units are faulted with formation of a east-west graben, then a late compressive phase forms the Piriac synform. | ||
Age of Mineralization |
Late Hercynian (Permian) for most of the french vein-type deposits in crystalline rocks (270-260 Ma) | ||
Mineralization |
Mineralisation, forming a single deposit plunging 30° to the west, is located at the contact between the graphitic schists and the porphyroids with small augens, with most of the mineralisation in the porphyroids. The orebody is in detail composed of numerous veins, veinlets and fissures filled with pitchblende. It is crosscut by late faults with senestral displacements. The deposit is still open at depth below the ocean, reaching the contact with the granite. Mineralisation was very rich up to 20 cm of massive pitchblende in the veins with very little matrix if present (quartz and carbonates). Pyrite, marcassite and galena were also present. | ||
MetallogenicAspects |
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Age of Mineralization |
Late Hercynian (Permian) for most of the french vein-type deposits in crystalline rocks (270-260 Ma) | ||
DepositShape |
succession of east-west veins | ||
DepositDimensions |
the deposit was more than 1 km long when mining stopped with a depth of 240m. | ||
GeologicalRemarks |
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Metallogenic Aspects |
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