1. SUMMARY and CONCLUSIONS (i)
105 participants from xxx countries
45 papers have been presented during 3 ½ days
All major districts of the World have been covered
except the Niger and Vitim districts (Russia)
New or poorly known occurrences have been presented
From: Algeria, Argentina, Brazil, Egypt, India, Jordan,
Indonesia, Malawi, Morocco, Poland, Tanzania,
2. SUMMARY and CONCLUSIONS (ii)
From the Central Asia Uranium Province, the largest world U province,
associated with sandstone we got contributions from :
- Kazakhstan, with a series of presentations covering from the geological
metallogenic aspects to the mining techniques by ISR. However, it would have
been interesting to have a contribution on the history of the development of the
exploration discoveries through this province, because these deposits are
essentially blind.
- China where a series a basin located in the northern part of China where
intensive uranium exploration and scientific sudies are going on.
- Mongolia, with two talks on the prospectivity of Mongolia for sandstone U
deposits and the interest of the use of geophysical techniques
3. SUMMARY and CONCLUSIONS (ii)
The Western US uranium province has been also well covered by a series of
four complementary presentations especially concerning the roll fronts of
Wyoming and the Texas districts.
We should have had a presentation on its continuation to the NE of Mexico.
Australian sandstone uranium deposits
The presentations have shown the great potentiality of Australia for the
discovery of further deposits.
The control of the formation of the uranium deposits in sandstone basins at
specific time periods in specific climatic conditions, which can be compared with
the results obtained for the ages of mineralization for roll front in Wyoming
South Hoggar uranium province
We do not have had the presentation scheduled on Niger, but we got one on the
northern part of this province in Algeria an interesting occurrence of uranium at
the base of the basin, each side of the unconformity.
4. SUMMARY and CONCLUSIONS (ii)
The Karoo uranium province with presentations :
-On the original Karoo province in South Africa, but most of the deposits seems
to be of relatively small size and relatively well cemented precluding their mining
by ISL
- and its extension : * in Malawi with the Kayelekara deposit with the combination
of a stratabound mineralization and a fault related one with the question of the
effective role of the structure,
* in Tanzania
- this province desserve further exploration in many countries and further
discoveries have to awaited in this province.
- Middle East :
•The presentation have dominantly concerned refractory accumulation of
accessory minerals in sandstone in Jordan and Egypt,
• But there is probably a interesting potential to be looked for in the recent
sedimentary basin overlying the oil fields which may have provide the
reductants., to the U leached from outcropping U-rich pan-Afriacan granites
5. SUMMARY and CONCLUSIONS (ii)
-The SE Asia uranium deposits associated with sandstone:
• Relatively new discoveries have reported in India, with deposits located at
the foot of the Himalayas (the Mahadek Cretaceous Basin) and on going
exploration in Gonwana related basins in Central India
• discoveries from the 70’s – 80’s are being reevaluated in Indonesia and
Thailand
6. SUMMARY and CONCLUSIONS (ii)
Some specific points:
- Role of the migrated organic matter and its nature for the reduction of U:
• Evidences about the direct role of migrated organic matter in the initial
deposition of uranium are still very weak except the initial exemples from
Texas
• Evidence of re-reduction of former roll front have been given in the Ordos
basin in China, with rather complexify the geometry of the distribution of the
redox zonation which can be misleading in exploration
• Are the low O/C ratios measured in the tabular U-V deposits hosted by the
Morrison Formation are a primary signature corresponding to humic acids or
result from the oxidation of organic matter from marine origin.
- Role of the depositional environment with the importance of the deltaic to
marginal marine settings for many occurrences
7. SUMMARY and CONCLUSIONS (ii)
Major points:
-Role of the depositional environment (ii)
For the uranium province of South Kazakhstan its has been shown that the
Karatau uplift is a very recent feature with no direct role in the paleogeography
of the sedimentation and on the hydrodynamic of the mineralizing fluids
8. SUMMARY and CONCLUSIONS (ii)
Major points:
- Contribution on « exploration » methodologies:
• characterization of the uranium source in granites by detailed
mineralogical geochemical studies using drill core samples
• use of geophysics and especially of shallow seismic methodologies with
improvment of the traitment of the signal to reveal the structure of the
uppermost layers in sedimentary basins
• use of 3D modeling techniques, which were not available during the
development of roll front ming in the 70’s and 80’s
• use of mass independant fractionation of 235U/238U isotopes as an
indicator of redox processes with presentation of example of application on
roll fronts;
• Use of irradiation halos in quartz by cathodoluminescence in roll front
deposit. The oxidized part of the sandstone present evidences of past
irradiation indicating the former presence of U accumulation and thus the
possible presence of a U deposit downwards
•
9. SUMMARY and CONCLUSIONS (ii)
Major points:
-
- Mining techniques :
• Conditions for efficient use ISR technology in the Kazakh deposits have
been presented extensively
• Use of bacteries for U leaching from refractory sandstone ore and wastes
- Others :
• Importance of calibration of uranium concentration measurement in drilling
in relation with disequilibrium which is especially important in sandstone
related uranium deposits.
10. IAEA Nuclear Energy Series Publication
Proposed organization of the TEC-DOC
on Sandstone Uranium Deposits
11. SANDSTONE URANIUM DEPOSITS
PART I : An overview of the origin of sandstone uranium deposits,
exploration, resources and production
• A- Classification of Sandstone U deposits & examples (~10 p)
1.Basal Channel
2.Tabular
a.Continental fluvial, U associated with intrinsic reductant
b.Continental fluvial, U associated with extrinsic humate/bitumen
c.Continental fluvial vanadium-uranium
3.Roll front
a.Continental basin, U associated with intrinsic reductant
b.Continental to marginal marine, U associated with intrinsic reductant
c.Marginal marine, U associated with extrinsic reductant
4.Tectonic - lithologic
5.Mafic dikes / sills in Proterozoic sandstone
12. Sandstone Uranium deposits
PART I : An overview of the origin of sandstone uranium deposits,
exploration, resources and production (suite)
B- Sandstone uranium systems (~ 20 p)
1.Basin formation and evolution:
a. Tectonic controls
b. Paleoclimate
c. Depositional environments
d. Diagenesis
2. Source rocks
3. Nature and dynamic of the mineralizing fluids
4. Reducing mechanisms
5. Mineralogy/Geochemistry
• C- Sandstone uranium provinces (~30 p)
1.Central Asia Uranium Mega Province
2.USA-Mexico
3. South Hoggar (Niger – Algeria)
4.Australia
5.Gondwana – Karoo province
6.[Other]
13. Sandstone Uranium deposits
PART I : An overview of the origin of sandstone uranium deposits,
exploration, resources and production
• C- Recent advances in exploration (~20 pages)
1.Radiometric (PFN)
2.Disequilibrium
3.Geophysics
• D- Resources and production (20 pages)
1. Production history and outlook
2. Resources(UDEPO)
a. Deposits
b. Resources and grades
c. Status
3. Overview of the production methods
4. Environment
5. Socio-economics
• E- Summary and conclusions (~2 pages)
