Uranium Deposit Report
Deposit : |
Mas Lavayre |
Country : |
France |
General Information |
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Geological District |
Lodève | ||
Geological Region |
Lodève Basin | ||
Political/Geographical Province |
Languedoc-Roussillon (Hérault) | ||
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)
|
10,000 - 25,000 | ||
Grade Range (% U)
|
0.20 - 0.50 | ||
Deposit Status
|
Depleted | ||
Current Processing Plant
|
Lodève (dismantled) | ||
Cumulative Production (t U)
|
12250 | ||
Production Period
|
1975-1997 | ||
Produced Grade (% U)
|
0 | ||
General Remarks |
Mas Lavayre represents 80% of the uranium mined in the Lodève district. It was an underground mine discovered in 1964. Mining started in 1980. | ||
Geological Information |
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Deposit Type |
Sandstone - Tectonic/Lithologic | ||
Geological Setting |
Located in the permian Lodève basin, south of the Massif Central. The basement is composed of strongly folded cambrian schists and dolomites. Sedimentation of the basin starts with Stephanian to the south, covered with Permian fluvio-deltaic formations whose thickness is estimated to be 2500m. The Permian is separated from bottom to top into the basal grey Upper Autunian, the grey-red Saxonian and the red Thuringian. Most of the uranium,of the basin, as pitchblende and coffinite, is concentrated in the Autunian, which is about 600m thick and has been subdivided into at least 50 small (1 to 15m thick) elementary sequences which are remarquably continuous across the whole basin. They are made of silts, arénites with carbonate cement, bituminous shales and lutites. Also, about 20 layers of cinerites are intercalated which are used as marker horizon. | ||
Age of Mineralization |
- Permian preconcentration - 173±6 Ma (Jurassic, Dogger) - 108±5 Ma (Lower Cretaceous, Albian) | ||
Mineralization |
- « lanières » (straps) : thin enrichments (a few meters wide), but very long with a strong tectonic control. They correspond to the intersection between a tectonic structure and a favorable stratigraphic horizon. Grades can be elevated, but decrease rapidly away from the structure, | ||
MetallogenicAspects |
Pitchblende as diffuse impregnations in asphaltic layers or as hydrocarbon drops, pyrite, sphalerite, then less frequently marcassite, pyrrhotite, native antimony, galena, stibnite, , more rarely molybdenite, jordisite and Pb-Sb sulfides Baryte, carbonates and quartz are common in the fractures. | ||
Age of Mineralization |
- Permian preconcentration - 173±6 Ma (Jurassic, Dogger) - 108±5 Ma (Lower Cretaceous, Albian) | ||
DepositShape |
Three type of mineralisation have been recognised : - stratabound : in organic matter-rich facies high in the serie, thickness 1 to several meters, dip of 20-30°, - « lanières » (straps) : thin enrichments (a few meters wide), but very long with a st | ||
DepositDimensions |
- east-west lengh along faults : 1500m, - north-south width of the mineralised system : 200 to 600m, - depth : 310m | ||
GeologicalRemarks |
The base of the Autunian serie is characterized by the organic matter abundance. Organic matter has two origins : a small detrital part comes from plants and trees, but the main part is originating from planctonic organisms and algaes. It is present as we | ||
Metallogenic Aspects |
Pitchblende as diffuse impregnations in asphaltic layers or as hydrocarbon drops, pyrite, sphalerite, then less frequently marcassite, pyrrhotite, native antimony, galena, stibnite, , more rarely molybdenite, jordisite and Pb-Sb sulfides Baryte, carbonates and quartz are common in the fractures. | ||