05 exploration of radioactive minerals in the late ordavician jordan
1. Exploration Of Radioactive
Elements in the Late Ordavician
Dubaydib Sandstone Formation /
South Jordan
By
Abu qudaira Mohammad
Ph. D in Remote Sensing and GIS Applications to Minerals )
(Exploration and Geology
(Jordan Energy Resources Inc. (JERI
Amman - Jordan
2.
3. Introduction
The Dubaydib
Formation covers an
area of more than
900 sq km, located
350 kms South of
Amman and 100kms
Northeast of Aqaba.
This formation is
extended, mainly,
within four 1:50,000
topographic sheets
(Jabal Ladghayn -
Dubaydib (3148I &
3148II); Ad Disa,
3149III; Batn Al
Ghul, 3149II and
Jabal Al Batra,
3149IV).
It extended as
elongated belt
trending NW-SE from
Jordan – Saudi border
in the south toward
the Northwest.
The name of
Dubaydib Formation
is taken from Jabal
Dubaydib in Dubaydib
sheet area.
4. Previous Exploration Studies
airborne radiometric survey of Jordan Carried out in 1980.
• Flight altitude
West=1500m
East= 120m
• Flight-line
spacing West=
1000 m
East= 2000m
• Control lines
spacing = 20 km
5.
6. Previous Exploration Studies
prospecting for uranium in 1987-1996
Two geological maps at scale of 1:10,000 of Wadi Al
Mezrab and Al Mudawwara areas were produced.
Radiometric and geological evaluation of radioactive
anomalies in the Ordovician Dubaydib Sandstone
Formation was done by Perrin (1989) and a positive
relationship between Th, U and Zr was recorded.
High concentration of zircon in the middle Dubaydib
unit was recorded by Nimry et al. (1996), who
indicated that the REE are concentrated in the fine sand
to silty sizes (<0.125mm). The study confirmed
thorium as the main source of radiation within the
Dubaydib area.
7. Prospecting for zircon and rare earth elements in wadi El
Mezrab area
The reconnaissance phase (NRA, Madanat and Mehyar, 1997).
Included drilling and well logging of 10 boreholes (5-60m
depth).
The study recorded a high gamma radiation in the zircon
- bearing bed and moderate values of zircon ranged from
0.28 to 1.71%.
.
8. Previous Exploration Studies
Phase I
a. (NRA, Medanat and Mehyar, (1999).
Thirty nine (39) boreholes were drilled and seven (7) trenches were dug.
The thickness of zircon-bearing beds, which was determined by using gamma well
logging, ranged between 1.5-5m with an overburden thickness ranged
between 0.0 and 18.7m.
Chemical analysis (ICP) showed that the zircon concentration ranged between
0.67 and 3.73% , TiO2% was between 0.73 – 4.91%. Ce was between 499
– 2168 ppm, and La was 242 – 1065ppm. It was found that there is a positive
relationship between the Zr, Ce, La, Y, and TiO2.
Mineralogical studies of the zircon – bearing beds indicated that quartz is the
main constituent with small amounts of feldspar, mica, rutile, brookite and
monazite. Cementing materials consist of calcite and iron oxides.
b. (NRA, Al Dalou et al., (2001 ).
Geochemical prospecting for minerals in Dubaydib sheet map area was carried out.
The geochemical analysis of the sampled area indicated that the concentration of
zirconium (Zr) was up to 2354ppm in rock samples.
c. (Geological survey of Egypt, (2003).
A bulk sample of 500kg was sent to Egypt for mineral processing and concentration
studies. The study showed that it is possible to separate zircon with 1.53%
and 80% purity.
9. Previous Exploration Studies
phase II, (NRA, Madanat and Shakkour, 2008)
thirty seven (37) boreholes were drilled, 6 trenches
and 8 pits were dug in four blocks within wadi Mezrab
area. Chemical analysis (ICP) showed that the average
zircon concentration ranged between 0.38 – 4.42%.
phase III, (NRA, Abuqudaira et al., 2009)
The studying of zircon and rare earth elements, taking
in consideration, the radioactive elements U & Th, in all
the outcrops of the Dubaydib Sandstone Formation was
carried out.
However the project was terminated because the
radioactive minerals became the responsibility of
Jordan Atomic Energy Commission (JAEC).
This study was limited to geological studies, radiometric
measurements and collecting samples for chemical
analysis.
10. Objective of the present study
The objective of the present study was to
delineate potential areas within all the
outcrops of Dubaydib Sandstone
Formation, for detailed study in the
future, depending on the last NRA study
and the result of samples collected by
JERI.
11. Stratigraphy
The Dubaydib Sandstone Formation is overlain by
Mudawwara Sandstone and underlain by Hiswa Sandstone
formations The formation (150-170m thick) has been
divided into three members by Masri (1988a); lower
(DB1), middle (DB2) and upper (DB3).
Formations Subdivisions Lithology Group Age
Mudawwara
Sandstone Conularia Sandstone Silurian
DB3
Dubaydib DB2 Sabellarifex Sandstone Khuraym
Sandstone
DB1 Ordovician
Hiswa Graptolite Sandstone
Sandstone
12. The lower member (25m thick)
starts with vertical sabellarifex.
consists of alternating beds of
micaceous sandstone and
siltstones.
This member could be separated
into two facies; quartzarenite and
silty shale facies.
13. The middle member (55m thick )
Consist of fine grained cross-bedded
sandstone, with subordinate very fine
silty sandstone, overlying channelled
bases.
This member was divided into two facies;
channelled sand and silty sand facies.
Large scale trough cross-bedding, ripples
sole marks, parallel lamination, low angle
cross stratification, load cast and locally
trace fossils as Cruziana sp. and
Sabellarifex sp., are all common.
14. The upper member (76m thick)
consists of greenish silty shales and fine
grained sandstone.
The member could be separated into two facies
greenish silty shale and cross-stratified
sandstone facies.
Depositional Environment
The Lower member: subtidal to lower intertidal
marine environments
The middle member : a high energy mid shelf
zone or a wave-dominated subtidal
environment.
The upper member: Inner shelf
15. The Radioactive Zone
The radioactive zone occupies the
lower part of the Middle Dubaydib
Formation (DB2).
The total thickness of this
sequence is ranging between 1.5
and 5m with an average
thickness of about 3m.
It consists of alternating beds of
siltstone to sandstone. The
pinkish dark grey siltstone bed of
about 40-75cm thick is the main
target bed for radioactive and
rare earth elements.
The sequence is well recognized
by the yellowish green marker
bed.
20. The results of the chemical analysis, from the previous
study (Abu Qudaira et al. 2009) and the chemical
analysis carried out by the team of JERI
These results indicate that the thorium is the main
source of radiation with concentration up to 2337ppm.
Uranium concentration, on the other hand, is up to
308ppm.
The samples show high concentrations of Zr, La, Ce, Nb
Hf and TiO2. They show, also, a positive relationship
between uranium and thorium and Th, Zr, La, Ce, Y
and TiO2
A good correlation is shown between the concentrations
of :
Th Vs U where R² = 0.8165, TiO2 Vs Th where R² =
0.9488, Zr Vs U, where R² = 0.8145 and Zr Vs Th,
where R² = 0.9622.
Bad correlation is shown between P2O5 Vs U (R² =0.0638).
23. Zr Vs U
Zr Concentration )ppm(
70000
60000 R2 = 0.8145
50000
40000 Zr
30000 Linear (Zr)
20000
10000
0
0 50 100 150 200 250 300 350
U Concentration (ppm(
)d(
P2O5 Vs U
20000
P2O5 Concentration
15000
)ppm(
10000 R2 = 0.0638 P2O5
5000 Linear
(P2O5)
0
0 50 100 150 200 250 300 350
U Concentration )ppm(
24. Mineralogical investigation
X-ray diffraction method: quartz as a major mineral with moderate
amounts of feldspar and trace minerals of kaolinite, zircon, muscovite,
goethite and smectite.
Thin section: Quartz as a major constituent and feldspar, mica and
kaolinate as a minor constituent. Heavy minerals occurs as accessories
and include:- zircon, Rutile, Brookite and Epidote. Cementing materials
consists of calcite and iron oxide.
(Itamar et al., (1999).
primary rocks from which the sandstones were derived are acid magmatic
rocks, probably granites or microgranites.
The presence of micas with some schistosity in places, indicate that some
metamorphic processes were took place.
The study recorded zircon and monazite as dominant heavy minerals.
Rutile and anatase appear in small amount, and less amount of ilmenite
were also observed. The enrichment in REE, Th and U within the monazite
is typical to the “placer type”.
25.
26. Conclusion
The studies carried out on the Late Ordovician Dubaydib
Sandstone Formation were started as a result of radiometric
survey carried out on all Jordan in 1980. Most of the studies were
concentrated on the Dubaydib area, (Wadi El Mezrab).
A radioactive zone of 1.5 – 5m thick (average is 3m) was
determined where the main source of radiation is thorium. The
thorium concentration was up to 2337ppm.
Thorium and uranium are found within the Monazite structure.
Depending on the chemical analyses used in this study, the
following concentrations were calculated which are close to the
previous results:
Th concentration ranges from 0 - 2337ppm (average = 593ppm).
U concentration ranges from 0 - 308ppm (average = 70ppm).
Zr concentration ranges from 0.014 – 5.66 % (average=1.49%).
La concentration ranges from 0.012 – 0.28% (average=0.08%).
Ce concentration ranges from 0.49 – 0.71% (average=0.27%).
Y concentration ranges from 0.005 – 0.029% (average=0.014%).
Nb concentration ranges from 0.0 – 0.24% (average=0.04%).
TiO2 concentration ranges from 0.108 – 6.22% (average=3.05%).
27. A positive relationship between uranium and thorium and Th, Zr, La, Ce, Y
and TiO2 was recorded. A good correlation was recorded between the
concentrations of the following:
Th Vs U where R² = 0.8165., TiO2 Vs Th where R² = 0.9488.
Zr Vs U, where R² = 0.8145, Zr Vs Th, where R² = 0.9622.
Bad correlation was recorded between P2O5 and U which confirmed the
monazite mineral as the source of uranium.
An abnormal concentration of Zr, La, Ce, Hf, Lb and TiO2 were recorded
which make these elements could be viable for investment.
Mineralogical studies indicated that quartz is the main constituent of the
radioactive beds, with small amounts of feldspar and heavy minerals
(zircon, rutile, brookite, epidote and monazite). The cementing material is
calcite and iron oxides.
The concentrations of radioactive and rare earth elements increase toward
the middle area (wadi Mezrab) which mean that the middle area was
more affected by the source of radioactive and rare earth elements.
Five promising areas are delineated within the Dubaydib Sandstone
Formation for the futures studies. These areas are closed to the surface
with low overburden thickness.
