Journal of Geology and Mining Research Vol. 4(3) pp. 51-64, April 2012
Available online at http://www.academicjournals.org/JGMR
DOI: 10.5897/JGMR11.044
ISSN 2006-9766 ©2012 Academic Journals
Full Length Research Paper
Geochemistry of phosphorite deposits around HirapurMardeora area in Chhatarpur and Sagar Districts,
Madhya Pradesh, India
K. F. Khan1, Saif A. Khan1*, Shamim A. Dar1 and Z. Husain2
1
Department of Geology, Aligarh Muslim University, Aligarh-202002, Uttar Pradesh, India.
AMD Complex, Sector-5, Extension Pratapnagar, Sanganer, Jaipur-302030, (Rajasthan).
2
Accepted 8 March, 2012
The Hirapur-Mardeora phosphorite deposits are found to occur in Bijawar group of Gangau iron
formations over the basement of Bundelkhand granite complex in the Archean period. There are four
distinct units of phosphorites which include shale-phosphorite, secondary-phosphorite, ironstonephosphorite and quartz-breccia phosphorite. Chemical analysis of 24 representative samples of these
different units was carried out for qualitative and quantitative determination of their major and trace
element concentration, geochemical behaviour and inter-element relationship. The study reveals that
these elements were precipitated by direct, inorganic, syngenetic, and authigenic processes in the
primary phosphorites and by epigenetic, leaching, remobilization and reprecipitation in the cavities,
voids, fractures and fissure fillings in the secondary phosphorites during diagenesis. The
phosphogenic processes might have taken place during the slight reduction of fairly oxidising
conditions under tropical to arid climate in shallow water marine environment of the basin.
Key words: Hirapur-Mardeora, phosphorite, geochemistry, Chhatarpur and Sagar districts, diagenesis.
INTRODUCTION
Phosphorites today are regarded as one of the most
important economic minerals used. Nearly 90% of total
world phosphate output is utilised for the manufacture of
a number of fertilizers like superphosphate, triple superphosphate, diammonium-phosphate and monoammoniumphosphate which are essential for agro industries all over
the globe. Agricultural resources, followed closely and
intimately by energy, are the most basic of all the
resources available to man and today soil phosphorus
deficiency was identified as a major constraint preventing
upland soils from being used to produce adequate food
for the growing populations of developing countries in
tropical and sub-tropical regions (Buresh et al., 1997).
Phosphorite deposits of Hirapur-Mardeora with an
average of 26.40% P2O5 content can be proved as a suitable phosphorus rich alternative to the currently available
*Corresponding author. E-mail: saifkhan50j@gmail.com.
synthetic fertilizers.
The previous investigators concentrate on different
aspects of Bijawar group of rocks include geology
(Dubey, 1952); petrography (Krishnan, 1942, 1968);
petrography, geochemistry, classification and origin
(Israili, 1978); structure (Pant, 1980); uranium
mineralisation (Mahadevan, 1986); Bijawar and Vindhyan
tectonics of Central India (Misra, 1987). In the present
study, an attempt was made to interpret the data of
advance nature to ascertain the geochemical behaviour,
inter-element relationship of major and trace elements
and environment of depositional basin. The present study
indicated that within the interpreted and inferred basinal
conditions, the chemistry of basinal waters and subsequently post depositional alterations played significant
roles in producing different varieties of phosphorite in
different proterozoic basins. The original composition of
the sedimentational water was of prime importance.
Conceding the fact that, some of the trace elements and
as well as that of the major mobile elements were either
52
J. Geol. Min. Res.
introduced into the apatitic mud or left the indurated
apatite. The concentration or depletion of major and trace
elements was dependent primarily on such factors like
their mobility with respect to apatite associated
assemblage of elements, type and intensity of weathering
and the effects of secondary processes. Various
elements, both major and trace which combine to form
phosphorite of a particular composition changed their
character in course of geological history. Inspite of such
addition or subtractions of the primary elements, they left
some traces of their presence in the original sediments
and these have been used for making significant interpretations about various palaeo-environmental condition
(Saigal and Banerjee, 1987).
The inter-correlation of elements brings out three major
associations such as apatitic-phosphorite, ferruginous
clayey phosphorite and weathered (leached) aluminous
phosphorite. Each element association reflects a
grouping of elements – (a) structurally substituted in
major mineral apatite, (b) adsorbed onto the mineral
surface or (c) existing as discrete minerals derived from
apatite by weathering. The variations in major and trace
elements abundance are indication of a change in
environmental condition of deposition. The concentration
and kind of element adsorbed or entering into the crystal
structure depend on a number of factors, such as pH, Eh,
nature and structure of the adsorbant, availability and
concentration of ions, rate of nodule growth, nature and
rate of sedimentation and various other parameters.
Because such varied factors have complex interactive
elements in nodules, they can occur in several chemical
associations as weakly adsorbed, strongly adsorbed or in
the structure of carbonate or oxides.
GEOLOGICAL SETTING
The proterozoic phosphorite deposits of HirapurMardeora area in Sagar and Chhatarpur districts of
Madhya Pradesh (Lat. 24°19’N and 24°23’N and Long.
79°9’E and 79°14’E) belongs to the gangau ferruginous
and phosphatic formations of the Bijawar group of rocks
(Mathur and Mani, 1978; Banerjee et al., 1982). The
megascopic, microscopic, scanning and X-Ray studies of
the phosphatic rocks of the study area revealed that there
are two distinct types of phosphorites, viz., primary and
secondary. Mineralogically, the primary phosphorites
being associated with shales, ironstones and quartzbreccia are mainly composed of collophane (a carbonate
fluorapatite phase), whereas the secondary phosphorites
contain crandallite (calc-aluminium phosphate).
According to Krishnan (1942, 1968) and Dubey (1952),
the quarzites and sandstones and sometimes
conglomerates form the basal member of the series
resting unconformably on the Bundelkhand gneissic
complex. Siliceous-limestones and hornstone-breccia are
also associated with the quartzites. These are rather
irregularly distributed and are less than 60 m in thickness.
They are overlain in turn by ferruginous sandstone
containing pockets of hematite. The rocks are either
horizontal or have a south easterly dips, though at few
places in the south, they were subjected to crushing and
disturbances before the Vindhyans were deposited. In the
Hirapur-Bassia area, the Bundelkhnad granites are either
directly overlain by Bajna dolomite or juxtaposed against
the ‘Gangau Ferruginous Formations’ made up of
conglomeratic-breccia and shales. There is no tillite in the
vicinity of the phosphorite horizon, but it has been
recorded in the adjacent regions (Mathur and Mani,
1978).
Stratigraphic succession of the study area is given in
Table 1. The authors have also prepared the geological
cross-section from the geological map (Figure 1) along
the profile line A-B across the phosphorite beds, just to
show more clearly the geological sequence of rock units
of the study area (Figure 2).
MATERIALS AND METHODS
Careful and systematic sampling was done in the area. 24
representative samples were collected from different lithologic units
such as shale phosphorites (06), secondary phosphorites (05),
ironstone phosphorites (06), and quartz-breccia phosphorites (07).
The samples were crushed in a steel mortar to a coarser fractions
and it was further crushed in porcelain mortar till it became medium
to fine grained. Finally, the material was finely powdered up to 300
to 400 mesh sizes in an agate mortar which was then transferred
into polythene bags, numbered and packed properly for
geochemical analysis. Two types of solution ‘A’ and ‘B’ were
prepared and kept in a 250 ml plastic bottle for the determination of
major oxides by adopting the procedure followed by Shapiro and
Brannock (1962). Solution ‘A’ was used for the determination of
SiO2 and Al2O3 and solution ‘B’ for the determination of TiO2, MnO,
CaO, MgO, Fe2 O3, Na2 O, K2O and P2O5. The oxides like, SiO2,
Al2 O3, TiO2, MnO, total iron and P2 O5 were determined by Beckman
DU-2 Spectrophotometer using various wave-lengths following
USGS standards (AGV-1, BCR-1 and GSP-1) for each major
oxides. CaO and MgO were analysed by titration method with
ethylenediaminetetraacetic acid (EDTA) using Erichrome Black
indicator-I. FeO was also analysed by titration method using
potassium dichromate solution, whereas both Na2O and K2 O were
determined with the help of flame photometer. CO2 was determined
volumetrically in a series of 250 ml beakers, of which 0.5 gm of
calcium carbonate (CaCO3) was used as standard and 0.5 gm of
the powdered sample was added to it. 25 ml of hydrochloric acid
(HCL, 0.5 N) was added to each beaker and allowed to remain
overnight. The remaining acid in the beaker was titrated with
sodium hydroxide (NaOH, 0.35 N) and bromophenol blue was used
as an indicator, which gave yellow to blue end point and then the
calculation of CO2 in percent was made. The trace elements were
determined adopting the procedure followed by Naqvi and Husain
(1972) by using X-ray flourescence (XRF) techniques except U 3O8
which was determined with the help of atomic absorption
spectrophotometer. An attempt was also made to determine the
content of organic matter, sulphate, Y, Zr and Sr but their presence
were almost negligible.
RESULTS
The major- and trace element concentrations are listed in
Khan et al.
53
Table 1. Stratigraphic succession of the Hirapur-Mardeora area.
Semri group
(Late/Upper Precambrian)
…………Unconformity………
Lower Vindhayan system
II
Gangue
Bijawar group
(Early to middle Precambrian)
Ferruginous and phosphatic
formations
Cuddapah system
Archean
-
Quartz-breccia phosphorites
Ironstone-phosphorites
Shale-phosphorites, at places
weathered/ leached formed
secondary phosphorites
I
Non-phosphatic formations
…………Unconformity………
Bundelkhand complex
Tables 2 and 3 respectively. The average concentrations
of CaO (34.35 wt.%) had the highest among the major
oxides followed by P2O5 (26.40 wt.%), SiO2 (21.05 wt.%),
Fe2O3 (9.76 wt.%), Al2O3 (4.19 wt.%), CO2 (1.38 wt.%)
and the concentrations of remaining oxides are less than
1 wt.%. In between trace elements Zn (233.19 ppm) has
the highest average concentration followed by Cr (210.50
ppm), Ni (197.05 ppm), Cd (177.53 ppm), Cu (138.17
ppm), Co (115.50 ppm) and the concentration of others
are less than 100 ppm. Average Concentration of U3O8
(0.07 ppm) is much less when compared to other
elements.
DISCUSSION
Major elements geochemistry
The high P2O5 and CaO values indicate high apatite
content, and strong positive correlationship of P2O5 and
CaO (Figure 3a) might be the result of diagenetic
phosphatization in which CO2 might be removed by PO4
before the precipitation of phosphorite during high
oxidising conditions of the basinal water which gave rise
to carbonate flourapatite as an end product (Ames, 1959)
or it may be due to the increase and decrease of pH as
described by Krumbein and Garrels (1952) and Nathan
and Sass (1981). According to Banerjee (1979), there are
many evidences for the co-precipitation of carbonate in
rhythmic alternation of calc-phosphate and silica saturation cycles and as differentiation is prominent between
day and night formed phosphate-calcium layers and this
differentiation is diagenetically controlled, and shows
sympathetic relation between the two. CaO/P2O5 ratios is
much lower than the values derived for the most reactive
phosphate rock which shows the extent of its carbonate
substitution as interpreted for Ogun phosphate rock by
Adesanwo et al. (2009). The upwelling of deep ocean
currents to the shelf deliver dissolved phosphate and CO2
to coastal shallower waters, diffusion of phosphorous into
bottom water accompanied by change in alkalinity due to
CO2, which loss lead to the formation of grains and
nodules and phosphatization of coprolites (Kholodov,
2003). Random and linear but progressive positive
relationship of CO2 and Na2O with P2O5 (Figure 3b and c)
reflects that during phosphatization the CO3 content
might have replaced by PO4 within the basin and this
+2
+1
reaction is partly balanced by Ca
and Na
and
controlled by crystallographic control on the degree of
carbonate substitution (Adler et al., 1963; Youssef, 1965;
McClellan, 1980; Manheim and Gulbrandsen, 1979), but
one other cause for such a relationship between these
two oxides might be the mild weathering of these
phosphorites. Al2O3 shows a weak negative relationship
with P2O5 which might be due to the mutual ionic
+3
+2
substitution between Al and Ca in the apatite lattice
under high alkaline conditions of the basinal waters or the
Al2O3 may be adsorbed in hydrous aluminium-silicates,
ferruginous and clay minerals which is high in P2O5
content (Figure 3d). The irregular distribution of crandalite
CaAl3(PO4)2(OH)5•(H2O) particularly in secondary
phosphorite samples indicated the hidden leaching/
weathering of ore in which small amount of Ca+2 was
+3
replaced by Al during remobilization and recrystallization by means of the ground water circulation and seawaves tides and currents in the Bijawar basin. K2O shows
a progressive random but negative relationship with P2O5
in primary phosphorite samples and weak positive and
linear relationship in secondary phosphorite samples
(Figure 3e). The negative relationship indicated the
presence of minor amount of K2O in the outside of the
apatite crystal lattice (Cook, 1972), and on the other
hand, the positive correlation in secondary phosphorites
may be due to solution, reprecipitation, leaching and/
weathering of ore in an alkaline, marine, shallow water
conditions of the Bijawar basin. The weak relationship of
54
J. Geol. Min. Res.
Figure 1. Geological and sample location map of Hirapur-Mardeora area, district Sagar and Chhatarpur, Madhya Pradesh, India.
Khan et al.
55
Figure 2. Diagrammatic crossection along the line A-B across the phosphorite deposits, Hirapur-Mardeora area, district Sagar and
Chhatarpur, Madhya Pradesh, India.
Table 2. Major elements distribution (wt.%) in phosphate bearing rocks of Bijawar group around Hirapur-Mardeora area.
Sample
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Tr, trace.
SiO2
22.10
17.98
16.32
33.05
31.23
39.07
4.29
2.81
2.01
3.04
2.05
20.83
23.01
22.31
17.98
21.19
20.54
41.32
29.70
23.10
18.45
40.16
33.50
19.25
Al2O3
6.70
5.10
5.00
7.09
6.98
10.01
1.54
1.74
5.09
6.83
6.24
2.95
1.29
0.98
1.32
2.00
3.16
6.19
2.41
2.93
1.23
5.40
6.97
1.39
TiO2
0.45
0.02
0.95
0.41
Tr
0.66
1.00
Tr
0.02
Tr
0.04
0.03
0.25
Tr
0.04
0.50
0.50
0.43
Tr
0.40
Tr
0.50
0.77
0.19
MnO
0.12
0.14
0.39
0.20
0.03
0.19
Tr
Tr
0.01
0.39
Tr
0.02
0.13
Tr
0.11
0.10
0.10
0.13
Tr
0.09
Tr
0.10
Tr
0.12
CaO
29.91
35.92
32.21
23.81
26.08
22.27
43.00
49.41
48.17
44.92
40.42
35.02
32.19
33.02
37.59
36.00
36.00
17.95
33.19
36.32
40.98
27.00
26.00
36.98
MgO
0.32
0.39
0.95
0.20
1.03
0.69
0.20
0.24
Tr
0.41
Tr
1.01
0.09
0.39
0.12
1.60
1.25
0.92
1.01
0.39
0.92
0.74
0.80
0.65
Fe2O3
10.32
9.85
11.65
12.71
10.09
9.83
14.08
8.17
1.12
3.01
7.32
11.32
15.17
16.01
10.00
9.27
10.88
14.01
8.35
8.10
7.32
6.66
10.08
8.98
FeO
1.63
0.85
1.05
0.05
0.23
Tr
0.29
Tr
Tr
0.03
0.21
0.21
0.48
0.31
0.41
0.38
0.38
0.11
0.12
0.19
0.01
0.19
0.29
0.21
Na2O
2.10
2.39
2.65
1.05
1.87
1.21
0.25
0.19
0.07
0.24
0.89
0.24
0.31
0.21
0.31
0.25
0.25
0.31
0.43
0.21
0.52
0.19
0.25
0.31
K2O
1.05
1.21
1.78
0.83
1.01
Tr
0.27
0.33
0.13
0.14
0.53
0.21
0.74
0.71
Tr
0.48
0.52
1.12
1.01
1.11
1.32
1.58
2.45
2.39
P2O5
22.95
25.05
23.10
16.95
18.00
14.79
32.10
35.76
42.80
40.30
39.21
27.48
25.99
26.73
29.70
28.50
26.96
15.32
23.70
26.56
28.30
18.23
17.85
27.35
CO2
1.08
2.10
2.85
0.89
1.81
0.93
1.32
1.81
1.32
0.79
1.01
1.23
2.03
1.04
1.53
1.03
0.95
2.01
1.02
1.03
2.01
0.59
Tr
1.35
56
J. Geol. Min. Res.
Table 3. Trace elements distribution (ppm) in phosphate bearing rocks of Bijawar group around Hirapur-Mardeora area.
Sample
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Ni
10
152
47
92
9
69
ND
159
15
5
Tr
50
310
1129
112
508
603
48
39
300
361
Tr
111
9
V
169
141
155
172
98
132
Tr
ND
4
Tr
25
Tr
15
29
75
Tr
101
Tr
41
ND
ND
105
9
48
Cr
Tr
215
25
82
58
39
300
149
Tr
38
ND
76
152
280
Tr
305
692
210
ND
300
265
195
408
Tr
Cu
104
37
Tr
68
19
Tr
295
ND
Tr
59
15
170
192
Tr
180
160
145
185
154
112
305
Tr
145
142
Ga
5
11
15
22
Tr
18
ND
Tr
290
9
18
9
ND
Tr
2
25
38
ND
ND
4
Tr
9
18
29
Pb
ND
9
37
Tr
Tr
5
Tr
17
5
ND
12
ND
ND
12
Tr
22
4
Tr
ND
ND
12
4
2
Tr
Co
Tr
ND
24
29
113
49
502
195
22
53
Tr
161
130
141
ND
11
Tr
25
119
109
Tr
Tr
165
Tr
Zn
308
550
104
Tr
141
225
409
187
Tr
635
20
260
Tr
ND
178
210
Tr
200
110
59
Tr
Tr
135
ND
Cd
ND
101
Tr
179
42
Tr
110
113
205
596
610
Tr
198
125
230
210
109
113
165
Tr
120
110
8
29
U3O8
0.102
0.105
0.035
0.005
0.006
0.005
0.083
0.101
0.138
0.130
0.110
0.063
0.049
0.050
0.069
0.061
0.053
0.003
0.069
0.071
0.103
0.051
0.040
0.097
Tr, trace; ND, not detected.
of Fe2O3 and FeO with P2O5 particularly in primary rocks
(Figure 3f and g) may be due to non-deposition of Fe2O3
and FeO content with P2O5 at the time of
phosphatization. On the other hand, the stronger
negative relationship of Fe2O3 in secondary phosphorites
(Figure 3f) may be due to leaching and mild weathering
of iron from the ores and reprecipitation along with P2O5
in the pore spaces, cavities/ voids, veins etc. in highly
oxidising marine environment or due to the presence of
different sources of phosphorous, as in the case of other
phosphorite deposits (O’Brien et al., 1990; Baioumi,
2007). The absence of pyrite in these phosphatic rocks of
the study area clearly indicates a high oxidising
environment. The total iron content may be due to the
upwelling currents observed in the shallower parts of the
basin where phosphatization was in progress as
described by Holland (1973) that, during early
proterozoic, at least the disposal and concentration of
phosphorous in marine sediments was supposed to be
controlled largely by the distribution of iron and the
periodic upwellings of reducing iron-rich ocean waters.
Conversely, a progressive negative relationship of SiO2
-3
with P2O5 might be due to the replacement of (PO4)
trivalent anions by similar equidimentional anions such as
divalent (SO4)-2 and tetravalent (SiO4)-4 (Krishnan, 1942;
Betekhtin, 1959; Manheim et al., 1980), which reflect that
-3
in the study area, the (PO4) has been mutually
-4
substituted by (SiO4) before the final precipitation of
phosphorites in the depositional environment (Figure 3h)
and this is the considerable factor which lead to lowering
the phosphorite grade (Awadalla, 2010). Besides this, the
ionic radii and charges of silicon and phosphorous are
very close to each other and they helped in the
replacement of the apatite lattices. The high content of
SiO2 in few phosphorite samples may be due to
silicification of ores by diagenetic process in the
sedimentary basin as described by Banerjee et al. (1982)
for the phosphatic rocks of the Hirapur area in Sagar
district. The precipitation took place in the marine, in
shallower conditions of the basin which is a well known
fact for all older phosphorites. Weak negative relationship
of MnO with P2O5 in all the samples (Figure 3i) suggest
its non-affinity with P2O5 and minor occurrences of Mn in
the outside of apatite lattices as found earlier in the
phosphatic stromatolites from jhamarkotra and other
areas that P2O5 and Mn shows antipathetic relationship
and such a relationship indicates that neither Mn has any
direct affinity with phosphates nor it occurs in apatite
structure (Banerjee et al., 1984; Banerjee and Saigal,
1988). MgO is having a random and weak negative
Khan et al.
50
a
40
40
30
30
P2O5(%)
P2O5(%)
50
20
10
10
0
0.00
20.00
40.00
CaO(%)
CaO(%)
50
0.00
60.00
2.00
4.00
6.00
CO
2(%)
C2O(%)
50
c
40
8.00
d
40
P2O5(%)
P2O5(%)
b
20
0
30
20
30
20
10
10
0
0
0.00
1.00
2.00
Na O(%)
N2O(%)
50
0.00
3.00
5.00
10.00
15.00
AlAlOO(%)
(%)
2
3
e
40
P2O5(%)
57
30
20
10
0
0.00
2.00
4.00
K O(%)
K2O(%)
50
6.00
8.00
K2O(%)
50
g
P2O5(%)
P2O5(%)
30
20
30
20
10
10
0
0
0.00
2.00
4.00
FeO(%)
FeO(%)
50
6.00
0.00
8.00
10.00 20.00 30.00 40.00 50.00
SiO
Si2(%)
O(%)
50
i
j
40
P2O5(%)
40
P2O5(%)
h
40
40
30
20
30
20
10
10
0
0
0.00
2.00
4.00
MnO(%)
MnO(%)
6.00
8.00
0.00
2.00
4.00
MgO(%)
MgO(%)
6.00
Figure 3. Scatter plots showing mutual relationship of CaO, CO 2, Na2 O, Al2O3,
K2O, Fe2 O3, FeO, SiO2, MnO and MgO Vs P2O5 in the phosphorites of HirapurMardeora area.
relationship in primary phosphorite and merely positive
relationship in the secondary phosphorites (Figure 3j)
+2
which may be the result of the substitution of Mg by
+2
Ca in the apatite that may decrease the crystallite size
of the apatite by the increase in size of Mg ions or it may
be due to the precipitation in the marine and shallower
parts of the basin as the inhibiting effect of Mg on the
crystallization of apatite is evident weather it is in solution
or in the original carbonate. These experimental results
suggest a pathway for the genesis of apatite and
indicated conditions for its formation, which could prevail
within the sediments in shallower water, during a very
58
J. Geol. Min. Res.
early diagenetic stage (Morse, 1979; Lucas, 1984). Poor
relationship between Mg and P also indicates that Mg
may not have been incorporated into the apatite structure
as described by the quaternary phosphorites of southeast
coast of India by Rao et al. (2002). Low MgO value
indicates very little or no dolomitization has occurred in
the area. Like MnO and MgO, the TiO2 also shows a
weak and linear negative relationship with P2O5 in all
phosphorite types in the study area (Figure 4a).
Goldschmidt (1954) reports that under some conditions,
TiO2 is absorbed by clay minerals. The antipathetic
relationship shown by ‘detrital trace elements’ is an
inverse correlation with P2O5 content and such a
relationship is clearly exhibited by TiO2, which is located
predominantly in detrital rutile, ilmenite and leucoxene
(Cook, 1972).
Trace elements geochemistry
The higher concentration of nickel may be due to
adsorbtion by ferric oxides, ferruginous and clay minerals
and on the surfaces of apatites or during early diagenesis
may have been incorporated with the crystal structure of
apatite (Altschuler, 1980; Jarvis et al., 1994), and low
uranium content can be interpreted to the fact that they
are deposited in a shallow marine condition under arid
climate. The negative relationship between nickel and
uranium (Figure 4b) may be due to mutual ionic
substitution during high oxidising, marine conditions of
the basin before the precipitation of apatites (Debrabant
and Paquet, 1975; Lucas et al., 1978). The weaker
negative correlation between uranium and vanadium
(Figure 4c) indicates that perhaps there was not a proper
mutual substitution of these elements in the apatite
crystal lattices during the inorganic processes of the
phosphorites. The antipathetic relationship of Cr with
U3O8 (Figure 4d) may be due to adsorbtion of Cr by U in
the gangue of phosphorites like other trace elements. It
also indicates the incomplete mutual substitution of these
two elements in the apatite crystal lattices (Howard and
Hough, 1979). Uranium and copper are associated with
phosphatic shales, secondary phosphorite, ironstones
and quartz-breccia but not with limestones. On the other
hand, there is no bio-hermal limestone and iron and
copper sulphide mineralization in these sediments. Thus,
the progressive positive relationship between uranium
and copper (Figure 4e) in the samples of phosphatic
shales, ironstones and quartz-breccia indicated the
formations of these rocks during the fair oxidisation to
slight reduction of shallow marine conditions of the
proterozoic basin. It may be suggested that during the
geochemical environment of the basin, there might be
+2
mutual substitution, though on minor scale of Ca by
+2
+5
+6
Cu and of P by U in the apatite crystal lattices. The
progressive weaker negative relationship between U and
Cu in the samples of secondary phosphorites may be due
to leaching and lateritization generated by groundwater
action. The weathering, remobilization and redeposition
of these phosphorites were perhaps responsible for the
enrichment of secondary uranium (Verma, 1980; AlBassam et al., 1983). Progressive weak positive
correlation between uranium and lead in the primary
phosphorite samples (shale, ironstone and quartzbreccia) and negative correlation in the secondary
phosphorite samples (Figure 4f) supports the depositional
environment accompanied by sedimentary processes
during phosphatization as seen in between uranium and
copper (Howard and Hough, 1979). The negative
correlation between V and Cr in the primary phosphorite
samples of shales and quartz-breccia perhaps indicates
that Cr+6 may be replaced by V+5 during highly oxidising
conditions of the basinal-sea waters, and on the other
hand, a positive relationship between the two elements in
ironstone phosphorites (Figure 4g) supported the affinity
of Cr with Fe in the ironstone and other phosphorites.
These elements may be adsorbed in the iron-oxide,
ferruginous and clayey fine grained minerals during
phosphatization processes. In the secondary phosphorite
samples, the absence of any relationship between these
two elements may be due to weathering and/leaching of
the ore by groundwater action (Gulbrandsen, 1966;
Bliskovskiy, 1969; Banerjee et al., 1984; Saigal and
Banerjee, 1987). Negative correlation of V with Ni and Co
in all phosphorite samples (Figure 4h and 5a) supports
the occurrence of these elements in the marine
environment and adsorbtion by the gangue constituents
of the phosphorites (Krauskopf, 1955; Gulbrandsen,
1966). The natural affinity of Cr for the group of elements
like V-Ni-Cr-Zn is considered to be typical of organic
matter (Saigal and Banerjee, 1987). The progressive
positive relationship between Ni and Cr (Figure 5b)
supports the elements association group in the
phosphorite samples suggested by Saigal and Banerjee
(1987). The weaker progressive positive relationship
between Ni and Cu supported the trace elements group
associations in these marine sediments (Figure 5c). It
was also suggested that these elements in the
phosphorites may occur as ‘trapped ions’ (Krauskopf,
1955; Gulbrandsen, 1966; Saigal and Banerjee, 1987).
The weaker and/or poor positive relationship between Ni
and Co (Figure 5d) supported that the Co’s ionic radii
differ from those of phosphorus and it is not so easy to
accommodate Co in the apatite structure. The weaker
relationship between these elements also indicates the
adsorption by means of higher contents of iron and clay
and elemental group associations in these phosphorites.
This relationship also indicated the formation of
phosphatic sediments in the ‘red bed’ environments
(Gulbrandsen, 1966; Saigal and Banerjee, 1987; Boyle,
1984). The progressive positive relationship between Ni
and Cd (Figure 5e) supported the affinity with iron in the
Gangau-Ferruginous formations which form distinct group
of elements during oxidization to reducing marine and
shallower conditions of the proterozoic basins
Khan et al.
50
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
a
U3O8(%)
P2O5(%)
40
30
20
10
0
0
2
4
6
TiOTiO
(%)
2
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
U3O8(%)
U3O8(%)
c
0
50
100
V(ppm)
V(ppm)
Ni(ppm)
Ni(ppm)
1000
200
400
Cr(ppm)
Cr(ppm)
0.15
0.10
0.05
1500
d
0
e
600
800
f
0.10
0.05
0.00
0.00
0
100
200
Cu(ppm)
Cu(ppm)
200
300
0
400
10
20
30
Pb(ppm)
Pb(ppm)
200
g
150
40
h
150
V(ppm)
V(ppm)
500
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
200
U3O8(%)
U3O8(%)
0.15
150
b
0
8
59
100
100
50
50
0
0
0
200
400
600
800
Cr(ppm)
Cr(ppm)
0
500
1000
1500
Ni(ppm)
Ni(ppm)
Figure 4. Scatter plots showing mutual relationship between TiO 2 and P2 O5 as well as
between trace elements in the phosphorites of Hirapur-Mardeora area.
(Gulbrandsen, 1966; Saigal and Banerjee, 1987). The
negative correlation between Cd and Co (Figure 5f)
indicated that, due to difference in ionic radii, Co could
not be replaced in the apatite crystal lattices. Cd might
have been found in the apatite site or both elements
might have been adsorbed in the gangue minerals of the
phosphorites (Saigal and Banerjee, 1987). Cd and Cu
show strong positive relationship in the shale-phosphorite
samples but they have weaker negative correlation in the
ironstones, quartz-breccia and secondary phosphorite
samples (Figure 5g). It may be possible that both the
trace elements were replaced in the apatite crystal lattice
on a minor scale and the remaining contents were
adsorbed by the crypto to micro-crystalline masses of
60
J. Geol. Min. Res.
200
1200
a
b
1000
150
Ni(ppm)
V(ppm)
800
100
600
400
50
200
0
0
0
200
400
0
600
Co(ppm)
Co(ppm)
1200
800
800
Ni(ppm)
1000
600
400
800
d
600
400
0
0
0
100
200
300
0
400
200
1200
400
600
Co(ppm)
Co(ppm)
Cu(ppm)
Cu(ppm)
700
e
f
600
1000
500
Cd(ppm)
800
Ni(ppm)
600
200
200
600
400
200
400
300
200
100
0
0
0
200
400
Cd(ppm)
Cd(ppm)
700
600
800
0
200
400
Co(ppm)
Co(ppm)
600
g
600
600
h
500
Co(ppm)
500
Cd(ppm)
400
Cr(ppm)
Cr(ppm)
1200
c
1000
Ni(ppm)
200
400
300
200
400
300
200
100
100
0
0
0
100
200
Cu(ppm)
Cu(ppm)
300
400
0
200
400
600
800
Cr(ppm)
Cr(ppm)
Figure 5. Scatter plots between trace elements in the phosphorites of HirapurMardeora area.
phosphatic, ferruginous and clayey minerals. The ironoxide and hydrated iron-oxide may play an important role
during highly oxidising conditions of the basin (Saigal and
Banerjee, 1987). Co and Cr show progressive positive
relationship in the samples of phosphatic shales, quartzbreccia and remobilised rock types, but a weaker or
random relationship exists in the ironstone-phosphorites
(Figure 5h). The geochemistry and other features of this
relationship are also similar to those of the trace elements
discussed previously.
Relationship between P2O5 and trace elements
The strong sympathetic correlation of P2O5 with U3O8 in
all four types of phosphorite samples (Figure 6a)
indicates co-precipitation of phosphorus and uranium in
the sedimentary environment in which the Eh and pH of
Khan et al.
50
50
a
P2O5(%)
P2O5(%)
30
20
20
10
0
0
0.050
0.100
(%)
UU3OO8(%)
50
0.150
0
500
1000
Ni(ppm)
Ni(ppm)
50
c
1500
d
40
P2O5(%)
P2O5(%)
40
30
20
30
20
10
10
0
0
0
10
20
Pb(ppm)
Pb(ppm)
50
30
0
40
P2O5(%)
20
0
0
400
50
800
f
20
10
Cd(ppm)
Cd(ppm)
Pb(ppm)
600
30
10
200
400
Cr(ppm)
Cr(ppm)
40
30
0
200
50
e
40
P2O5(%)
30
10
0.000
b
40
40
600
0
800
200
50
g
400
Co(ppm)
Po(ppm)
Co(ppm)
600
h
40
P2O5(%)
P2O5(%)
40
30
20
10
30
20
10
0
0
0
100
200
Cu(ppm)
Cu(ppm)
300
400
0
50
50
100
V(ppm)
V(ppm)
150
200
i
P2O5(%)
40
30
20
10
0
0
200
400
Zn(ppm)
Zn(ppm)
600
800
Figure 6. Scatter plots showing mutual relationship of U3 O8, Ni, Pb, Cr, Cd, Co, Cu, V, and Zn Vs
P2O5 in the phosphorites of Hirapur-Mardeora area.
61
62
J. Geol. Min. Res.
the basinal waters were very close to each other for their
precipitation (Elliot, 1968; Nathan and Shillony, 1976;
Viqar, 1981). The occurrence of uraniferous phosphatic
rocks in the ferruginated zone indicates the oxidising
conditions of the basin (Mckelvey and Carlswell, 1956).
This relationship also indicates high oxidising conditions
due to absence of organic matter, micro-organisms and
pyrite. The positive relationship between Ni and P2O5 in
primary phosphorites (Figure 6b) might be due to minor
adsorbtion of Ni by large bodies cryptocrystalline masses
of iron, clay and phosphatic materials, as such, the
relationship was found earlier in the phosphatic rocks of
Jammu and Kashmir (Khan and Khaki, 2008), but
random or negative correlation between Pb and P2O5
(Figure 6c) may be due to mutual divalent ionic
substitution of Ca+2 by Pb+2 in the apatite lattices as ionic
radii and charges of both are very close and similar
(Howard and Hough, 1979). The bright red colour of the
phosphorites may be due to the presence of Cr2O3. The
negative correlation of P2O5 with Cr (Figure 6d) supported
the chemical affinity with V-Ni-Cr-Zn associations in the
clay minerals. The mild weathering of ores might have
redistributed within the sediments packages. The very
high concentrations of iron and phosphate may entrap
some Cr. On a minor scale, Cr+6 might have been
+5
replaced by p in the sedimentary basin at the time of
diagenesis (Minguzzi, 1941; Heinrich, 1958; Frohlick,
1960; Prevot and Lucas, 1980; Saigal and Banerjee,
1987), whereas P2O5 shows positive as well as negative
relationship with Cd in primary and also in secondary
phosphorite (Figure 6e). In the primary phosphorites, the
presence of Cd may be due to its adsorption by apatite,
clay and iron bearing minerals. On the other hand, in
case of secondary phosphorites, the weak negative
correlation between the two may be due to weathering of
the ores in which the Cd metal might have been
redistributed within the sediments group or partly loosing
during diagenesis processes. The similar and/close ionic
radii of Cd and Ca may help in ionic substitution in the
apatite lattice (Krauskopf, 1955; Gulbrandsen, 1966;
Saigal and Bannerjee, 1987). Like Cd, the Co also shows
a more or less similar behaviour with P2O5 in all four
types of phosphorites (Figure 6f). Co may be present on
the crystal surfaces of apatite, clay and iron bearing
minerals, during diagenesis of these sediments (Saigal
and Banerjee, 1987; Banerjee and Saigal, 1988) while
P2O5 shows positive correlation with Cu in primary
phosphorites and negative in the secondary phosphorites
(Figure 6g). Cu might have been replaced on a minor
scale by Ca in apatite lattice or it may be present as
adsorptive element. This relationship also indicates a
common source of Cu and P2O5. Conversely, a negative
relationship may be due to leaching/mild weathering of
the ore in which part of Cu might have been lost during
diagenesis (Cruft, 1966; Al-Bassam et al., 1983; Saigal
and Banerjee, 1987; Singh and Subramanian, 1988). The
relationship of P2O5 with both V and Zn is strongly
negative (Figure 6h and i) which supports the mutual
pentavalent ionic substitution of P2O5 by V+5 or Zn+5 in the
apatite lattices. The presence of V and Zn in the
phosphorites may be due to chemical affinity with P2O5
and adsorbtion by clay minerals (Cook, 1972; Banerjee
and Saigal, 1988).
Most of the major and trace elements are inter-related
to each other and with P2O5 directly or indirectly in the
carbonate, silicate and phosphate bearing rocks. The
presence or absence of certain elements in the rocks is
much helpful and most significant to know the palaeoclimates and nature of deposition of the sediments in the
area. The variations in major and trace elements
abundance are indication of a change in environmental
condition of deposition (Mahadevan, 1986). The concentration and kind of element adsorbed or entering into the
crystal structure depend on a number of factors such as
pH, Eh, nature and structure of the adsorbant, availability
and concentration of ions (Krauskopf, 1967), rate of
nodule growth and rate of sedimentation and various
other parameters (Cronan, 1969; Ghosh, 1975; Glasby,
1977; Roy, 1981).
Conclusions
The abundance, distribution and inter element
relationship of major and trace elements in the primary
and secondary phosphorites reveal that these elements
were precipitated by direct, inorganic, syngenetic and
authigenetic processes in the primary phosphorites and
epigenetic weathering, remobilization and reprecipitation
in the voids and cavities fillings in the secondary
phosphorites. The phosphatization was taken place in the
fairly oxidising to slightly reducing environment, tropical to
arid climate, saline sea-basinal waters, shallow marine
environmental conditions and epicontinental sea shoals
along continental margin in the Bijawar basin. The
random distributions and poor correlations among the
constituents may be due to mild leaching of the deposit.
The study reveals that most of the phosphorites are in
primary state while secondary phosphorites were mostly
derived from the primary ones through eustatic sea level
changes, actions of sea waves, tides, currents and
groundwater as most of chemical constituents have same
trend of distributions and relationships as that of the
primary phosphorites. The formation of epigenetic
secondary phosphorites was mainly due to lateritization
as indicate by the concentration trends of each element.
There are innumerable cases of absorbtion, adsorbtion
and partial replacement of certain minor elements out
and inside the crystal lattices of apatite. The narrow and
wide variations in the concentrations of certain elements
attribute possibly to the mild leaching of the syngenetic
phosphorites. The formation of crandallite (calcaluminium phosphate) in the epigenetic ore samples may
be due to ionic substitution of Ca+2 by Al+3 inside the
Khan et al.
crystal lattice of apatite. It is apparent that the transferred
concentrations or leaching of certain minor elements from
the primary phosphorites to the secondary ones may be
largely dependent on the absorbtion and adsorbtion
capabilities of the secondary or primary minerals.
ACKNOWLEDGMENTS
We are very thankful to the chairman of the department
of geology, Aligarh Muslim University, Aligarh, for
providing necessary facilities. We express our thanks to
the Director, National Geophysical Research Institute,
Hyderabad (A. P.) for providing us with laboratory
facilities to carry out the geochemical analysis of the rock
samples.
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