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Chemical Weathering of the Indo-Gangetic Alluvium with SpecialReference to Release of Fluoride in the Groundwater,

Unnao District, Uttar Pradesh

S. KUMAR and A. SAXENA+

Centre of Advanced Study in Geology, University of Lucknow, Lucknow - 226 007+Present Address: SMEC India Pvt. Ltd., Gurgaon - 122 002

Email: [email protected]

Abstract: In the central part of Indo-Gangetic alluvium in the Unnao district, Uttar Pradesh there are many pockets

where groundwater shows high fluoride content. Drinking of fluorinated ground water has effected a large populationand in many villages more than 80% of the population is suffering from fluorosis. The source of this fluoride appears

to be the alluvial sediments deposited in the geological past as no hard rock terrain is present in the nearby areas. The

area is dominantly made up of mud with pockets of sand. The sand fraction is made up of quartz, plagioclase, microcline,

muscovite and biotite along with some accessory minerals like garnet, epidote, chlorite, tourmaline, hornblende, kyanite

and a few opaque minerals. Moreover, the fluoride content in the groundwater varies both spatially and with depth

indicating a sporadic occurrence. The surface water is devoid of high content of fluoride but is reported in hand pumps

and in the dug wells. This paper deals with the geochemical study of the sediments up to a depth of 45m as most of the

hand pumps are up to this depth to understand the source of fluoride. 14C dates of calcretes have suggested that the

45 m thick succession must have been formed in about 45000 years.

Two different location sites were selected; one showing higher concentration of fluoride (Marksnagar village) while

at other site which is about 4 km east of Marksnagar, the fluoride content was minimal (Durgajkhera village). Major

elements and 24 trace elements were determined using XRF and it was found that when major elements are normalized

with respect to upper continental crust (UCC) there is an enrichment of Si in all the samples. Na shows depletion whereas Ti and K show enrichment. Fe and Mn show enrichment probably due to the formation of clay minerals. Si, and K

enrichment is due to weathering of feldspar while Mg, Fe and K may have been released by the weathering of biotite.

The CIA for the ancient sediments ranges from 54 64 while for the modern sediments of the Ganga River it varies from

50 64 indicating that there is no change in the rate of weathering in both modern and ancient sediments. The rate of

weathering at all the sample locations was compared with that of UCC. The CIA values also suggest that there is an

incipient weathering and indicate that the weathering of biotite is more progressive than muscovite. There is also a

positive correlation between CIA values and the fluoride content in the ground water. Higher percentage of biotite and

chlorite (altered biotite) was found at Marksnagar in comparison to Durgajkhera. It appears that the fluoride content in

the ground water is due to dissociation/alteration of mica minerals mainly biotite.

Keywords: Groundwater, Chemical weathering, Fluoride, Uttar Pradesh.

In the Indo-Gangetic alluvium the groundwater is mainly

used for drinking purposes. In last one to two decades, some

water related problems are encountered in this region. It is

noted that in many areas of the Gangetic alluvial tract, a

large population is suffering from fluorosis, a deadly

incurable disease caused due to high intake of fluoride

(Pandey, 2001) from dugwells and hand pumps mainly in

rural areas. It is also reported by various government

agencies (CGWB, 1999) that this problem is spreading in

other areas also.

The cause of fluorosis is mainly due to the drinking of

INTRODUCTION

The Indo-Gangetic alluvial plain covers an area of about

700,000 km2 and separates the Peninsular India (Indian

Shield) from the Himalayas (Fig.1). It represents deposits

of an active foreland basin formed as a result of continent-

continent collision of the Indian plate with the Asian plate

(Singh, 1996). The rivers originating from the Himalaya

deposit their load in the alluvial plain constituting the worlds

largest alluvial tract (Singh, 1996). The alluvium represents

Quaternary and Recent deposits comprising mud, sand and

clays and devoid of any hard rocks.

JOURNAL GEOLOGICAL SOCIETY OF INDIA

Vol.77, May 2011, pp.459-477

0016-7622/2011-77-5-459/$ 1.00 GEOL. SOC. INDIA


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JOUR.GEOL.SOC.INDIA, VOL.77, MAY 2011

460 S. KUMAR AND A. SAXENA

fluoride contaminated groundwater. It has been now

confirmed that the villagers are drawing water from the

dugwells and the shallow hand pumps for their drinking

purposes and other domestic uses (Mukherjee et al. 1995).

These wells and hand pumps show a very high concentration

of fluoride in their water. In the year 1995 Mukherjee et al.

(1995) have identified that the Marksnagar village is the

most adversely affected area. At that time the value of

fluoride concentration in the dugwell measured 6.3 ppm andabout 50% of the population were reportedly suffering from

the fluorosis which was more pronounced in the children

below 20 years of age group (as per BIS 1991 norms the

permissible limit for fluoride in drinking water is 1.2 ppm).

They further added that the dental fluorosis was prevalent

in this area for the last 15-20 years. In a recent survey the

Marksnagar village of Unnao district, U.P. shows the

maximum of 9 ppm of fluoride in the dugwell (Saxena,

2005). This value shows a monthly fluctuation between 7 to

9 ppm throughout the year and in absence of any other

alternative source the villagers are forced to use this water

for the drinking and their domestic purposes. About 90% of

the population was found to be adversely affected by the

fluorosis in this village.

In the absence of any industrial effluents in the nearby

areas, the release of fluoride in the groundwater is definitely

due to the weathering of sediments. Since Marksnagar has

already been identified for the high fluoride contamination

in the groundwater, as confirmed by various other agencies

(Mukherjee et al. 1995; Rai, 1997; CGWB, 1999), this areawas selected for the detailed study of the weathering

processes active in the region for finding out any probable

source and mechanism for the release of fluoride in

groundwater.

GEOLOGICAL AND HYDROLOGICAL SETTING

The area under study forms a part of the Central Ganga

plain (Pathak, 1982 in Khanna, 1992). The alluvial sediments

of Ganga Basin have been classified as Older Alluvium and

Newer Alluvium; the former consists of sediments which

Fig.1. Geological setting of the study area (depicted by dot) (afterSingh, 1992).


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CHEMICAL WEATHERING OF THE INDO-GANGETIC ALLUVIUM, U.P. 461

were formed in distant past and are partly undergoing

denudation, while the latter is under its process of formation

(Khanna, 1992). The Older Alluvium is made up of massive

beds of clay of a pale reddish brown colour, very often

yellowish with kanker (calcrete) present in between the clay

layers. The Newer Alluvium is light coloured and poor in

calcareous matter. The major part of the Central Ganga plain

is composed of Older Alluvium (Khanna, 1992). The area

in the Unnao district is a flat alluvial tract with soil exhibiting

a wide variance; sandy on the elevated locations, clayey in

the topographical lows and loamy on the flat surfaces. Figure

2 gives the location map of the study area.

The area is mud (silt + clay) dominated and thus leads

to water logged conditions which are supposed to be

responsible for the sodic soil present in the area. The Ganga

and Sai are the main rivers of the area and are responsiblefor many paleo-channels and ox-bow lakes. The general

trend of both the rivers is northwest to southeast. The study

area falls in doab of the rivers Ganga and Gomati, intersected

by Sai River and many other streamlets. The area shows

low regional surface gradient from northeast to southwest,

varying from 10 to 30 cm/km (Rai, 1997). The upper layer

of alluvium is composed of sandy loam and clayey loam.

The main source for irrigation in the area is Sharda canal

and shallow tubewells bored in the fields generally at about

45 m depth. The aquifer material is fine to medium grained

sand and generally micaceous in nature with calcrete. The

chemical analysis of groundwater (Rai, 1997) of Unnao

district indicates that both good and moderate/bad quality

groundwater found in the sand dominated areas and

moderate to bad quality groundwater occurs in clay

dominated areas under confined and semi-confined

conditions. The bad quality water is mostly found in

waterlogged areas and shows an increasing trend of

groundwater salinity/alkalinity. The problem of leaching of

fluoride in groundwater is more confined to this zone

and had effected the local population adversely. The

high fluoride content is found in well water which

intersects clay dominated sediments and the water table isvery shallow due to excess recharge from canals. Rai (1997)

suggested that since these soils are sodic the groundwater

contaminated with high fluoride is also alkaline with high

sodium bicarbonate and sulphates. Thus, the fluoride in

groundwater of Unnao district is closely related with soil/

groundwater alkalinity under waterlogged conditions.

The climate of the area falls under the warm temperate

type with dry winters (Cwg type) or C1 type of climate i.e.,

dry sub-humid type of climate (Ahmad, 1999). The climate

can be broadly divided into summer, monsoon and

winter. The average annual rainfall of the district is 837.80

millimeter (http://cgwblucknow.up.nic.in/hydro/dist36.pdf).

Almost 90% of the annual precipitation is received during

the period from June to September.

SAMPLING AND ANALYTICAL METHODS

As mentioned earlier, for understanding the weathering

process involved in the release of fluoride, two areas were

selected; one is Marksnagar village where excess fluoride

is reported in the groundwater and another is nearby village

Durgajkhera from where no such excess is known.

Six piezometers were installed in the study area in order

to get a representative water samples at various depths for

the water quality analysis as well as to get the vertical

sediment samples at uniform depth interval; four piezometers

were installed at Marksnagar (at depth intervals of 8, 21, 33and 45 m) and two at Durgajkhera (at 12 and 33 m of depth).

The piezometers were installed with the help of an augur by

rotary method and the sediment samples were collected

during the installation of the piezometers.

In all 26 sediment samples were collected at depth

interval of 3 m up to a depth of 45 m below ground level at

Marksnagar and up to a depth of 33 m at Durgajkhera. On

the basis of grain size analysis of the sediment samples, the

strata chart was also prepared representing the vertical

variation in the lithology of the selected sites. The vertical

variation in the sediments in Marksnagar and Durgajkhera

are shown in Fig.3. In addition to the above sediments, the

recent sand and mud samples were also collected from the

left bank of Ganga River at Bithur and Kanpur (Jajmau

Bridge) for the comparative study with older sediments.

There is some basic difference in the nature of sediments at

Marksnagar and Durgajkhera. The sediments of Marksnagar

are generally mud dominated with few regular patches of

calcrete while that of Durgajkhera are sand dominated with

kanker formation invariably at a depth below 18 m. The

basic mineralogy of the sand fraction confirmed the

dominant presence of quartz, muscovite, feldspar and biotite

as major minerals with hornblende, garnet, tourmaline,kyanite and epidote present in minor amount. Two samples

of calcrete collected at a depth of 7 m and 30 m were dated

by 14C method in the laboratory of the Birbal Sahani Institute

of Paleobotany, Lucknow (pers. commn. Dr. G. Rajgopalan)

to have an idea about the approximate age of the calcrete

bearing horizons. The radiometric dates of calcretes at

the depth of 7 and 30 m are 3060140 years B.P. and

276701490 years B.P. On this basis it can be inferred that

ca. 23 m thick succession was deposit in ca. 24000 years. It

can be presumed that about 1 m was deposited in ca. 1000

years. Thus, the total profile of 45 m thick succession must


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have been deposited in ca. 45000 years B.P., this is not an

absolute age of the sediments but an approximation for the

deposition of the sediments of about 45 m thick profile.

The chemical analysis of sediments was done by X-ray

Fluorescence Spectrometry (XRF) at the laboratory of the

Institute of Geology and Mineralogy, University of Erlangen-

Nurenberg, Erlangen, Germany. Philips PW 2400 X-Ray

fluorescence spectrophotometer was used for the

determination of major and trace elements.

Loss of Ignition (LOI)

The dry weight of the porcelain crucible was noted and

2 gm of the bulk sample was weighed in the crucible and

again the weight was noted. These crucibles were kept in

the furnace for 24 hours at about 1000oC. After 24 hours

these crucibles were cooled in an exsiccator and wereweighed again.

Calculation of the LOI

LOI = (Empty crucible weight + weight of sample before

heating) (weight after heating/ weight of sample before

tempering) X 100 [%]

Tablet Preparation: About 1.0000.0005 gm of the

samples were taken in bigger crucibles and were mixed

thoroughly with 4.830 gm of Li3B

2O

7. This mixture was

then kept in the platinum crucible and was melted. All the

five burners were used starting from the extreme left. The

crucibles were left over at each burner for 5 10 minutes.

In front of the last one laid the form for the tablets. After

10 - 20 minutes on the last burner the liquefied material was

poured in the tablet holder and was kept for cooling. The

samples are labeled as required. Then after melting these

crucibles were kept in a plasticbox with 25% HCl and was

processed in the ultrasonic bath for 10 minutes. Finally

douched them with normal water and aqua dest and dried

with paper.

The precision and accuracy of the preparation and the

instrumental performance of the XRF was checked using

the international reference samples. With few exceptions,

there were no discrepancies between the analytical data

obtained and the consensus data in the international reference

samples.

RESULTS

The grain size analysis was done for the sediment

samples collected during the installation of piezometers.

The piezometers were installed for two villages; one is

Marksnagar where maximum number of fluorosis patients

were recorded and the other is a near by village Durgajkhera,

where only about 10% patients were noted. Durgajkhera is

about 3 km east of Marksnagar (Fig. 2). Mud is the dominant

fraction in both the villages. In Marksnagar mud is about

Fig.2. Location map of the study area, Unnao district, Uttar Pradesh


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76% while in Durgajkhera it is 57%. Besides mud, the

variation in the content of sand and calcretes was also noted

up to the maximum depth of 45m below the ground surface.

At Durgajkhera more calcrete was found. The sediment

samples at Marksnagar generally show moderate sorting

while the samples collected at Durgajkhera the sorting lies

between moderately well sorted to well sorted. The samples

were found to be very coarse skewed for Marksnagar and

very coarse skewed to fine skewed for Durgajkhera.

Mineralogically, the sand fraction is dominantly composedof quartz, plagioclase, microcline, muscovite and biotite

along with some accessory minerals like garnet, epidote,

chlorite, tourmaline, hornblende, kyanite and a few opaque

minerals. It was noted that the minerals identified at

Marksnagar were found in more altered form as compared

to Durgajkhera. The minerals dominantly identified in their

altered form were plagioclase and biotite. In the silt fraction

quartz, albite, microcline, muscovite and biotite were

identified where as in the clay fraction the minerals of mica

(illite and muscovite), smectite (sauconite and

montmorillonite), chlorite (vermiculite and clinochlore) and

kaolinite (kaoline and amesite) groups were found (Saxena,

2005).

The geochemical analysis for these sediments was done

for all the ten major elements viz. Si, Ti, Al, Fe, Mn, Mg,

Ca, Na, K, P were determined and analyzed in their oxide

form. 24 trace elements viz. As, Ba, Bi, Ce, Co, Cr, Cu, Ga,

Hf, La, Mo, Nb, Ni, Pb, Rb, Sr, Ta, Th, U, V, W, Y, Zn, Zr

were also analyzed along with the major elements. Table 1

gives the concentration of the major elements for all the

sediment samples and Table 2 gives the concentration of

the trace elements. The correlation coefficients between

each pair of elements were calculated in order to search for

the inter-elemental relationship. The results are further

compared with the data of Upper Continental Crust (UCC)

sediments for better understanding of the chemical maturity

of the sediments. Furthermore, an attempt was also made tostudy the enrichment and depletion of the elements along

with the depth. We also tried to establish the relationship

between the CIA values of the sediment samples with the

fluoride content in the groundwater at the respective depth

of the sediment sample.

Major Elements

Major element composition of the bulk sediments of

Marksnagar and Durgajkhera indicates that these sediments

mainly consist of three elements; Si, Al and Ca. Silica is the

dominant major component in the sediments of the two

sites as well as in the recent sediments of Ganga River. The

greater amount of Al2O

3was found at Marksnagar where it

was about 12% while CaO was only about 8%. But at

Durgajkhera the average percentage of CaO is marginally

higher than Al2O

3; here CaO is about 11.2% where as Al

2O

3

is just about 10%. The relatively high percentage of Ca in

these bulk sediments is due to the extensive calcrete

formation. The average concentration of Al2O

3and CaO in

the recent sediments was 11% and 1.5 % respectively. The

other dominant major elements are Fe2O

3, K

2O and Na

2O.

Not much variation was noted for the average concentration

of MgO in these villages and it ranges between 2.6% to 3%.Marginally higher concentration of K

2O was found for

Marksnagar compared to Durgajkhera, and this difference

in the concentration of K2O may be due to the difference in

the altered feldspar present in the sediments. The high

content of clay was found at Marksnagar which is indicated

by the relatively higher percentage of Al2O

3, Fe

2O

3and K

2O.

Relative Mobility of Elements with Respect to Al2O

3

Elemental Ratio for Major Elements

The chemical composition of the sediments is expected

Fig.3. Strata charts for the piezometers installed at the selected

sites of Nawabganj Block, Unnao District, U.P.


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to demonstrate well established concepts on the mobility of

various elements during the weathering (Berner and Berner,

1996). The elemental ratio refers to the relative enrichment

or depletion of the element with respect to the least mobile

element, Al. It is given by dividing the ratio of the elementX and Al

2O

3of the sediment sample with the ratio of the

same element content in the UCC. i.e.

Element Ratio (X) =[X/ Al

2O

3(sediment sample)]

[ X/ Al2O

3(UCC)]

X > 1 indicates enrichment

X < 1 indicates depletion

X = 1 indicate no change in relative abundance of the

element.

Figures 4a and b display the elemental ratios of the major

elements of the sediments of Marksnagar (where M1 to M15

are sampling codes number each representing a sample of 3

m depth; M1 ranges from 0-3 m while M15 increases to

depth range of 42-45 m) and Durgajkhera (D1 to D11 are

sampling codes number each representing a sample of 3 mdepth; D1 ranges from 0-3 m while D11 increases to depth

range of 33-36 m).

As demonstrated in Figs. 4a and b, the SiO2

content in

the sediments of all the sites is found to be enriched. TiO2

is

considered relatively immobile and thus remains enriched

in all the samples. Whereas Na2O, which is highly mobile

(Singh et al. 2004) shows a relative depletion. Though CaO

is also very mobile in nature but due to secondary formation

of calcrete a relative enrichment is seen for the calcium.

Potassium is considered to be less mobile than Na and thus

generally shows enrichment. Mg also shows a relative

Table 1. Chemical composition of the major elements

SiO2

TiO2

Al2O

3Fe

2O

3MnO MgO CaO Na

2O K

2O P

2O

5LOI SUM

% % % % % % % % % % % %

Marksnagar

M1 59.5 0.63 12.39 4.76 0.095 3.08 6.36 1.47 2.75 0.158 9.26 100.4

M2 54.6 0.63 12.57 5 0.079 3.99 7.36 1.35 3.12 0.162 10.66 99.6

M3 54 0.67 13.97 5.7 0.092 4 7.2 1.41 3.47 0.13 9.73 100.4

M4 57.3 0.71 13.62 5.56 0.084 3.1 6.08 1.32 3.14 0.133 8.69 99.7

M5 57.2 0.68 12.34 5.04 0.093 2.94 7.7 1.37 2.6 0.123 9.92 100.1

M6 51.8 0.62 11.36 4.59 0.093 2.81 11.99 1.22 2.44 0.114 12.97 100

M7 57.2 0.68 12.79 5.08 0.081 3.06 7.1 1.38 2.84 0.131 11.29 101.7

M8 52.8 0.62 12.49 4.82 0.081 4.64 8.26 1.38 3.06 0.129 11.49 99.7

M9 58.4 0.69 12.74 5.03 0.082 2.8 7 1.38 2.76 0.137 9.11 100.1

M10 67.4 0.56 9.84 3.05 0.056 2.28 6.01 1.73 2.08 0.152 6.67 99.9

M11 53.4 0.6 11.55 4.55 0.098 2.79 11.19 1.15 2.52 0.121 12.59 100.6

M12 63.3 0.53 10.48 3.39 0.074 2.64 7.09 1.58 2.41 0.137 8.19 99.8

M13 61.3 0.64 11.29 4.03 0.081 2.54 7.15 1.54 2.52 0.144 8.38 99.6

M14 58.4 0.64 11.61 4.37 0.093 2.58 8.48 1.47 2.66 0.143 9.5 99.9

M15 58.4 0.56 10.9 4.02 0.124 2.15 9.65 1.43 2.55 0.13 9.96 99.8

Durgajkhera

D1 35.9 0.33 6.52 2.61 0.139 2.6 26.57 0.8 1.6 0.075 23.45 100.6

D2 56.8 0.47 8.87 3.07 0.088 2.43 12.54 1.22 2.13 0.107 12.38 100.2

D3 74.9 0.38 9.16 2.5 0.049 1.59 3.59 1.63 2.22 0.103 3.94 100.1

D4 73.5 0.41 9.83 2.86 0.046 1.85 3.39 1.6 2.45 0.094 4.05 100.1

D5 59.3 0.52 10.52 4 0.097 2.81 8.54 1.27 2.54 0.1 10.15 99.8

D6 50.8 0.62 11.99 4.93 0.081 3.89 10.9 1.15 2.68 0.121 13.26 100.5

D7 49.8 0.55 11.06 4.55 0.137 3.65 12.44 1.18 2.54 0.116 13.87 99.9

D8 57.4 0.54 10.28 3.94 0.105 3.1 9.52 1.1 2.38 0.104 11.42 99.9

D9 53.7 0.56 10.52 4.07 0.094 2.77 12.08 1.08 2.3 0.11 13.12 100.4

D10 52.4 0.54 10.9 4.29 0.084 3.98 11.08 1.1 2.45 0.082 13.51 100.4

D 11 48.6 0.56 10.99 4.56 0.119 3.67 12.92 1 2.61 0.109 11.2 99.8

Recent sediments (of Ganga at Kanpur and Bithur)

Bit1 82.1 0.3 8.29 2.11 0.04 0.94 1.07 1.64 1.97 0.067 1.37 99.8

Bit2 73 0.59 11.14 3.94 0.06 1.94 1.68 1.41 2.5 0.108 3.92 100.3

Kan1 82.9 0.23 8.23 1.69 0.029 0.77 0.8 1.7 2.04 0.052 1.21 99.6

Kan2 62.7 0.74 15.11 5.95 0.097 2.83 1.91 1.11 3.3 0.13 5.57 99.5

Kan3 63.7 0.66 12.84 5.02 0.079 2.49 1.91 1.24 2.94 0.118 5.58 96.5


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JOUR.GEOL.SOC.INDIA

,VOL.77,MAY2011

Table 2. Concentration of trace elements (in ppm)

As Ba Bi Ce Co Cr Cu Ga Hf La Mo Nb Ni Pb Rb Sr Ta Th

Marksnagar

M1 8 501 0 93 17 80 16 17 4 36 1 11 34 29 135 321 3 16M2 11 499 2 69 18 73 18 18 4 40 0 10 37 28 161 394 3 10

M3 15 560 0 66 14 73 18 18 5 35 0 11 36 30 185 252 0 12

M4 11 530 0 99 17 86 21 19 5 40 2 11 40 28 168 182 3 16

M5 8 466 1 99 14 83 18 15 5 40 2 13 46 25 133 316 0 16

M6 4 421 1 83 17 69 10 15 4 24 2 9 33 26 127 297 0 15

M7 9 499 0 96 19 80 16 18 5 32 0 13 40 27 149 241 0 14

M8 4 516 0 85 17 74 7 17 5 372 2 11 21 24 163 396 0 14

M9 7 441 1 95 14 82 17 18 5 33 3 11 41 29 143 221 0 21

M10 4 377 3 107 8 56 12 12 3 27 2 12 21 22 102 162 1 22

M11 10 456 0 77 15 63 20 16 3 29 0 11 32 25 139 183 0 12

M12 2 469 2 95 8 55 2 14 4 23 2 11 11 24 124 191 1 17

M13 7 534 1 116 11 65 12 15 5 31 2 13 23 27 127 165 1 23

M14 8 564 1 107 17 67 12 16 5 36 1 13 29 31 141 163 0 25

M15 8 561 2 118 18 54 14 14 3 34 0 12 28 38 138 154 0 18

Durgajkhera

D1 0 312 2 54 16 23 7 11 0 13 0 8 7 29 93 139 0 11

D2 3 373 2 115 11 38 5 14 3 23 1 9 11 21 114 150 0 18

D3 0 359 4 72 5 34 5 11 3 18 2 9 13 26 110 113 0 18

D4 3 385 3 71 10 37 0 13 3 18 2 9 11 22 126 116 0 13

D5 6 482 2 72 13 55 9 15 3 30 2 11 25 33 132 228 2 12

D6 11 463 2 70 13 71 21 18 4 30 0 10 37 23 145 396 0 12

D7 9 576 2 107 21 58 14 16 2 29 0 10 30 34 142 435 1 15

D8 5 523 1 97 16 52 7 15 3 28 1 10 21 33 124 307 0 21

D9 5 458 0 100 14 56 10 15 3 28 2 9 23 31 123 279 0 17

D10 7 433 0 96 15 49 13 16 3 34 2 8 20 33 135 219 2 17

D11 6 495 0 93 16 61 10 16 3 29 1 7 28 33 139 282 0 14

Recent sediments (of Ganga at Kanpur and Bithur)

Bit1 1 311 5 63 6 25


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enrichment trend because of incipient weathering in the area.

Thus, both Mg and K are preferentially adsorbed and tightly

incorporated in clay minerals of the sediments (Singh et al.

2005). It can also be seen that there is a remarkable

enrichment of both Fe2O

3and MnO. This is probably due to

the formation of clay minerals. During the mineral

weathering in the area the SiO2, Na and K originate by

incongruent dissolution of feldspar while the magnesium,

iron and potassium may be released from the biotite and

ferromagnesium minerals. Calcium may be derived from

the dissolution of calcretes

Inter-Element Relationship Between Major Elements

The inter-element relationships were plotted on the

variation diagram considering Al2O

3(Singh et al. 2005) and

TiO2

(Sharma and Rajamani, 2000) as relatively stable

phases. Figure 5 shows the relationship of Al2O

3,Fe

2O

3and

K2O with TiO2 for the sediments of Marksnagar andDurgajkhera.

There is a very good positive correlation between Al2O

3,

Fe2O

3and K

2O with TiO

2with correlation coefficient of 0.9,

0.95 and 0.79 respectively at Durgajkhera whereas at

Marksnagar this correlation coefficient value for Al2O

3,

Fe2O

3and K

2O with TiO

2was 0.84, 0.85 and 0.6 respectively

(Table 3). The positive trend of Al2O

3,Fe

2O

3and K

2O

with

TiO2

indicates the enrichment of these elements as the

concentration of TiO2increases. This is due to the formation

of secondary clay minerals such as illite, which is the result

of the weathering of mica and feldspar (Wilson, 1987). Some

amount of iron may also have been released from heavy

minerals. A more positive correlation of these elements is

seen at Marksnagar as compared to Durgajkhera.

The interrelationship of TiO2

with Na2O, SiO

2and CaO

is given in Fig.6. A poor negative trend of Na2O and SiO

2

with TiO2

was found with average correlation coefficient of

about -0.40 and -0.23, at Marksnagar and Durgajkhera

respectively (Table 3). Both Na2O and SiO

2are mobile

elements and thus are lost due to their dissolution in the

water while TiO2being the least mobile element remains in

the sediments. This negative correlation is better seen for

Marksnagar indicating a comparatively higher rate of

weathering in the area. According to Middelberg et al. (1988)

both Na and Ca (in silicate form) decrease more rapidly

than K and thus are depleted more than K. The negative

trend of Na2O and CaO and positive trend of K2O with TiO2result from the greater alteration rate of plagioclase as

compared to that of K feldspar. However, CaO does not

show a good negative trend due to its secondary precipitation

in the form of calcrete in Durgajkhera thus it is not lost due

to dissolution in water while remains in the sediments as

calcrete. In general the relationship between TiO2

and CaO

gives a strong negative trend on weathering and could be

seen in Marksnagar.

Inter elemental relationship between Al2O

3with MgO,

Fe2O

3and K

2O is given in Fig.7. There exists a very strong

positive correlation between Al2

O3

with MgO, Fe2

O3

and

K2O which is 0.66, 0.97 and 0.91 respectively for the

sediments of Marksnagar and 0.62, 0.86 and 0.96

respectively for Durgajkhera. The positive correlation

between K2O with Al

2O

3is indicative of the feldspar and

mica weathering that may lead to the formation of illite,

which is the dominant clay mineral in these sediments and

controls the concentration of Al and K. The weathering/

alteration of biotite may be responsible for the presence of

MgO in the sediments.

As compared to Na2O and CaO, K

2O and MgO are less

mobile and remain in the sediments during the incipient

weathering and only become mobile in the solution duringthe latter stage of weathering. A positive correlation between

Al2O

3with Fe

2O

3indicates that their source of origin could

be the alteration of biotite into aluminosilicates and Fe (III)

oxides due to biotite weathering (Appelo and Postma, 1993)

as per the following equation:

2K[Mg2Fe][AlSi

3]O

10(OH)

2+10H+.5O

2+7H

2O

Al2Si

2O

5(OH)

4+2K++4Mg2++2Fe(OH)

3+4H

4SiO

4

Figure 8 shows a strong negative correlation of SiO2

with the major elements; MgO, Fe2O

3and Al

2O

3with

correlation coefficient of -0.6, -0.7 and -0.6 respectively

Fig.4. Relative abundance of the elements at (a) Marksnagar.

(b) Durgajkhera.


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for Marksnagar. This indicates the grain size control on the

geochemistry of the sediments; with higher grain size higher

is the silica content. This silica dilution effect lowers the

concentration of other major and trace element. At

Marksnagar the negative correlation between SiO2is better

seen with MgO, Fe2O

3and Al

2O

3.

Chemical Maturity of the Sediments

A-CN-K Diagram and Chemical Index of Alteration

To ascertain the chemical maturity of the sediments the

CIA value scheme has been selected.

Nasbitt and Young (1982) proposed the quantification

of chemical weathering intensity as the Chemical Index of

Alteration (CIA) where:CIA = [ Al

2O

3/ (Al

2O

3+ CaO+ Na

2O + K

2O)] X 100

CaO : CaO in silicate form only (Nesbit et al. 1997).

Here the molecular proportions of the above elements

are used for the calculation of CIA of the samples. In case

CaO in silicate form is not available then it is assumed to be

equivalent to Na2O because Ca is lost more rapidly than

Na during weathering and it will give lesser CIA values

than that of Na (Singh, 2004). Since the study area

dominantly contains calcrete in abundance therefore the

values of CaO is invariably greater than that of Na2O.

Because of this the values of CaO were assumed to be

equivalent to Na2

O. A CIA value of 100 indicates intense

chemical weathering where all the alkali and alkaline earth

elements are leached out of the system whereas CIA values

of 45 55 indicate virtually no weathering . The fresh

granodiorite composition is also considered to be very close

to UCC and gives the CIA value of 47~50. With the initiation

of weathering Ca and Na component of the sediments starts

leaching out first, as both of these are highly mobile in nature

and the trend of the weathering is seen parallel to A-CN line

of the A-CN-K diagram. During the intermediate phase of

weathering when the above trend reaches close to the

formation of illite, K which was stable in the incipient

phase of weathering also becomes mobile and the weatheringtrend starts moving towards the apex i.e., A corner of the

A-CN-K diagram.

The CIA values of the sediment samples of Marksnagar

and Durgajkhera are given in Table 4. In Marksnagar the

CIA value ranges from 54.4 to 63.2 while in Durgajkhera

this value ranges from 53.2 to 63.6. It is indicative of the

fact that at both the places the rate of weathering is almost

same. In addition to this the bank sediments of Ganga River

were also analysed and CIA values are calculated. The CIA

value for Ganga River sediments ranges between 50.9 to

63.6. Singh et al. (2005) have done the geochemical analysis

Table 3. Inter elemental relationship between the major elements

SiO2

TiO2

Al2O

3Fe

2O

3MnO MgO CaO Na

2O K

2O P

2O

5

Marksnagar

SiO2 1TiO

2-0.39 1

Al2O

3-0.59 0.843 1

Fe2O

3-0.72 0.851 0.971 1

MnO -0.47 0.02 0.143 0.2695 1

MgO -0.61 0.331 0.659 0.6103 -0.14 1

CaO -0.60 -0.26 -0.24 -0.043 0.556 -0.119 1

Na2O 0.89 -0.41 -0.49 -0.651 -0.50 -0.305 -0.648 1

K2O -0.59 0.611 0.916 0.8534 0.143 0.793 -0.236 -0.37 1

P2O

50.52 -0.13 -0.1 -0.234 -0.40 0.0295 -0.65 0.586 0.0224 1

(CI) -0.63 -0.24 0.037 0.1361 0.525 0.2687 0.7239 -0.49 0.166 -0.62

Durgajkhera

SiO2

1

TiO2 -0.20 1Al

2O

30.147 0.9 1

Fe2O

3-0.38 0.953 0.858 1

MnO -0.87 0.163 -0.14 0.3402 1

MgO -0.64 0.78 0.615 0.8985 0.524 1

CaO -0.92 -0.18 -0.52 -0.014 0.795 0.2959 1

Na2O 0.963 -0.25 0.135 -0.377 -0.84 -0.619 -0.878 1

K2O 0.296 0.789 0.961 0.7497 -0.23 0.4823 -0.636 0.294 1

P2O

50.156 0.662 0.663 0.5456 -0.04 0.2302 -0.379 0.186 0.6355 1

(CI) -0.93 -0.08 0.44 0.0785 0.812 0.3688 0.9704 -0.91 -0.56 -0.36


10/19



Fig.6. Relationship of TiO2 with SiO2 , Na2O and CaO.

Fig.5. Relationship of Al2O

3,Fe

2O

3and K

2O with TiO

2


11/19



Fig.7. Relationship between Al2O

3with MgO, Fe

2O

3and K

2O.

Fig.8. Relationship between SiO2 with MgO, Fe2O3 and Al2O3


12/19



for the channel sediments, flood sediments and suspended

sediments of Gomati River which is about 80 km east of

Ganga River, where the CIA value ranges between 53 to 68

with an average value of 60. The comparison of CIA values

of the recent sediments of Ganga and Gomati Rivers (Table

5) suggests that the rate of weathering is more or less same

for the sediments of both the rivers. However, Gomati River

sediments show maximum value of CIA as 68 where as it is

only 63.6 for Ganga River. This difference is due to the fact

that the Gomati River is a ground water fed river and the

sediments it carries are second cycle sediments (Kumar and

Singh, 1978).

In Marksnagar the minimum value of CIA was found to

be 54.4 at the depth of around 30 m i.e., at this level there

was virtually no weathering while the sediment at 33 m depth

shows the maximum weathering with CIA value at 63.3

which is of incipient nature. The sediment samples of the

Durgajkhera show lower CIA values up to a depth of 15 m

with the minimum of 53.23 value at the depth of 9 m. After

15m the CIA values increase and reach maximum around

64 up to the depth of 33 m. To illustrate these results the

ternary variation A-CN-K diagram was plotted for both thevillages (see Figs. 10 and 11). This clearly indicates that the

rate of weathering is not the prime factor for the release of

fluoride in the groundwater rather it is the different minera-

logical composition which is playing a key role in the release

of fluoride. The detailed geochemical analysis of the sedi-ments also shows more presence of mica minerals (especially

biotite) at Marksnagar as compared to Durgajkhera.

There is a loss of the most mobile elements i.e., Na and

Ca in the sediments as compared to the UCC (Fig.11). The

weathering trend was found running parallel to A CN line.

As the chemical weathering progresses, the clay minerals

are produced due to dissociation of primary minerals into

secondary clay minerals. During the incipient weathering

Na and Ca are rapidly lost to the weathering solution and

thus are not retained by the clay minerals while K due to its

nature of being adsorbed by the clay minerals retained as

the weathering product. This is due to the specific size and

charge characteristic of K that leads it to retain in the layer

position of 2:1 type clay mineral i.e. illite thus making it

present in the sediments till the weathering of illite also

initiates. Thus, K is stable during the incipient and moderate

weathering and is mobile at higher degree of weathering.

The retention of K and loss of Na and Ca with the progress

Table 4. CIA values of Marksnagar (M1 to M15) and Durgajkhera (D1 to

D11)

Sl. No. CIA Sl. No. CIA Sl. No. CIA

M1 60.634 Ganga B1 50.86 D1 59.15

M2 60.9496 Ganga B2 56.03 D2 57.595M3 61.79 Ganga K1 51.93 D3 53.23

M4 63.08 Ganga K2 63.55 D4 54.54

M5 62.012 Ganga K3 59.12 D5 59.54246

M6 62.327 Mean 56.298 D6 63.52664

M7 61.955 D7 61.80034

M8 60.68 D8 61.68221

M9 62.124 D9 62.8052

M10 54.413 D10 62.78137

M11 63.29 D11 63.60445

M12 56.465 Mean 60.02342

M13 58.34

M14 59.292

M15 58.56

Mean 60.39411

Fig.9. Comparison between the CIA values of recent and ancient

sediments.

Table 5. Range of CIA values for sediments of Gomati River, Ganga

River, Marksnagar and Durgajkhera

Location sites CIA values

Min. Max. Avg.

Recent sediments (Gomati River, after 53.0 68.0 60.1

Singh et al. 2004)

Recent sediments (Ganga River) 50.9 63.6 56.3

Ancient sediments I (Marksnagar village) 54.4 63.2 60.4

Ancient sediments II (Durgajkher village) 53.2 63.6 60.0 Fig.10. A CN K diagram for Marksnagar.


13/19



of chemical weathering leads to the general trend of A CN

parallel weathering for both the sites. A-CN-K diagram was

also plotted for the recent sediments collected from the bank

of Ganga River at Kanpur and Bithur. This ternary variation

diagram for the recent sediments is shown in Fig 12. There

is a similar trend of weathering parallel to A-CN line for the

recent sediments also.

It is inferred that the weathering pattern is same on the

surface sediments of Ganga River as well as for the ancient

sediments of Marksnagar and Durgajkhera. Since the

approximate age of the sediments as revealed by the carbon

dating should be around 45,000 years at the depth of 45 m,

it is suggested that there is no remarkable change in the

weathering pattern since last 40 - 50,000 years. Moreover

it is clear from the A-CN-K diagram for both ancient

sediments and recent sediments that the weathering trend

active in the area is A-CN parallel.

Trace Elements

Trace element behavior in the sediments is influenced

by weathering, diagenesis, sediment sorting and hydro-

geochemistry. Tables 2 give the concentration of the trace

elements. Zirconium is known to be least mobile and

insoluble thus it remains in sediments. The higher

concentration of Zr at Marksnagar is probably due to the

higher degree of chemical weathering. Since the sediments

of Marksnagar are mud dominated while that of Durgajkhera

contains higher amount of sand so a general trend of higher

concentration of trace elements is noted in Marksnagar in

comparison to Durgajkhera indicating a marginal higher

rate of weathering at Marksnagar. Fritz (1988) had stated

that biotite and perthetic microcline are the important phases

of fresh rocks which are enriched in Ba and Rb. He furtheradded that the alteration of biotite results in the loss of Ba

and enrichment of Rb. The average concentration of Ba in

Marksnagar and Durgajkhera is 482 ppm and 441 ppm

respectively while Rb is 135 ppm at Marksnagar and at

Durgajkhera it is 125 ppm. Thus, the comparatively higher

content of Ba and Rb at Marksnagar supports the higher

amount of biotite and high rate of weathering. The relative

higher average concentration of Cr and Ni suggests the

higher content of clay in Marksnagar samples thereby giving

a direct evidence of higher degree of weathering (Sharma

and Rajamani, 2001). Slightly higher concentration of Sr at

Durgajkhera confirms the formation of calcrete, which could

act as barrier for the release of fluoride in the groundwater

of Durgajkhera.

Chemical Mobility of Elements with respect to

Weathering

Weathering involves redistribution of the major and

trace elements present in the parent rock material. This

mobilization and redistribution is facilitated by the process

of dissolution of primary minerals, formation of secondary

minerals, transportation of materials and its co-precipitation.

According to Nesbitt (1979), titanium is relatively immobileduring weathering and thus could be used for the calcu-

lation of the chemical mobility of the major and trace

elements. The chemical mobility of an element is determined

by plotting the CIA values against the percentage change

of the element with respect to TiO2. The percentage change

is calculated in terms of percentage increase or decrease

of the element X (of samples) with respect to X in

UCC.

Percentage change =(X/ TiO

2)

sample x 100(X/ TiO

2)

UCC 1}

Fig.11. A CN K diagram for Durgajkhera.

Fig.12. A-CN-K diagram for the recent sediments.


14/19



The increasing or decreasing trend of the variation

diagrams plotted for percentage change of element X against

its CIA value indicates the increase or decrease of chemical

mobility of that element. The chemical mobility of the major

elements of the sediments of the Marksnagar, and

Durgajkhera is given in Fig. 13 (a and b). From Fig.13a it is

clear that during the chemical weathering there is a definite

mobility in the major element concentrations. The significant

increasing trend of chemical mobility of Fe and Mg prove

the instability of the biotite and muscovite content of the

sediments as these two minerals are the most important host

for Fe and Mg present in these sediments. This dissociation

of biotite and muscovite is due to the weathering process

active in the area. The increasing trend of CaO depicts that

as the weathering progresses, the chemical mobility of Ca

increases. This may be due to aqueous dissociation and co-precipitation of the calcrete during weathering.

Al2O

3gives neither decreasing nor increasing trend,

rather it is parallel to CIA and indicates that it is

comparatively very stable during weathering (Fig.13b).

Silicon, sodium and potassium showed a decreasing trend

of chemical mobility. The mobility of SiO2is very important

for understanding the weathering process as it plays an

important role in soil formation. It can also be concluded

that sodium decreases more rapidly than potassium. This is

due to the greater alteration of plagioclase as compared to

K feldspar, which is also shown in the A-CN-K diagram.

Another reason for this could be that K is more preferentially

adsorbed in the clay minerals and could also be incorporated

with the silicate minerals.

Distribution of Major Elements with Depth

The variation in the concentration of major elements

with the depth was plotted on the logarithmic variation

diagrams. The value of the major elements is in percentage.

However, the average concentration of fluoride (in ppm)for two years at the respective depth was also depicted in

the graph to search for any correlation between the fluoride

in the groundwater and the concentration of major elements

in the sediments.

Fig.13a. Chemical mobility of the major elements during the weathering process.


15/19



The scatter plot shows (Fig.14) that pair SiO2

and CaO

and TiO2

and Na2O

3are inversely proportional to each other.

In Marksnagar as the SiO2

decreases with the depth there is

an increase in CaO and simultaneously the fluoride content

in the water of that depth zone (M2, M6, M11 and M15 at 6

m, 18 m, 33 m and 4 5m bgl respectively) also increases.

While with the increase in SiO2

content there is a decrease

of CaO and the fluoride content in the water in those depth

zones also decreases (i.e. at M3 and M10, which are in the

depth zone of 6-9 m and 27-30 m respectively). A positive

correlation in the variation of the concentration of Al2O3,

Fe2O

3, MgO and K

2O along with the depth suggests that the

concentration of all these elements is controlled by the

variation in grain size characteristic of the sediments and

the change in the rate of weathering. Moreover, the increase

in the content of Fe and Mg in the sediments indicates the

higher content of biotite which is also probably releasing

the fluoride in the ground water due to its alteration. The

source of K and Al may be K feldspar or any other alumino-

silicate. The positive correlation of fluoride with the variation

of these elements confirms its release from the biotite, as

fluoride is present in the lattice of biotite and could be

Fig.13b. Chemical mobility of the major elements during the weathering process.


16/19



released during the weathering of this mineral. There is a

general trend of decrease in the concentration of all the major

elements except for SiO2

and Na2O at the depth interval of

27-30 m (M10) suggesting a comparative dominance of

SiO2. This zone also coincides with the low value of fluoridein the water. However, at depth interval of 30-33 m (M11)

there is a remarkable decrease of SiO2

and increase of other

major elements. The CIA value of M10 is 54 while that of

M11 is 63 indicating the incipient weathering phenomenon

in the depth zone M11 while this phenomenon is inactive

in M10 resulting in much lower values of fluoride in the

water at 27-30 m (M10) of depth as compared to the water

at 30-33 m of depth. The TiO2

and Na2O gives a negative

correlation as TiO2

is most immobile in nature while Na is

very mobile, both of these elements vary with the depth as

is shown in Fig.12.

The above finding were also confirmed when the fluoride

concentration in the water was plotted against the trace

elements like Ba, Ga and Rb (see Fig.15). From the above

figure it can be seen that in Marksnagar as the concentration

of Ba, Rb and Ga varies with the depth there is a variationin the fluoride content in the water. There exists a positive

trend between the two. The variation in the concentration

of Ba and Rb coincides with the variation in the biotite

content of the sediments suggesting their source of origin to

be biotite. This finding further supports the fact that the

source of release of fluoride in the water is mainly due to

the alteration of biotite.

The variation in the concentration of major elements as

well as the trace elements, along with the depth was also

plotted for Durgajkhera and the similar trend was noted as

it was seen for Marksnagar (Fig.14).

Fig.14. Variation of major elements with depth.


17/19



Weathering and Release of Fluoride in Groundwater

The concentration and mobility of both the major

elements and the trace elements are controlled by the

weathering processes. This is because these elements areeither the primary products or the secondary products of

the weathering. So, an attempt was made to correlate the

fluoride content in the ground water with the CIA value at

that depth for the samples of Marksnagar.

Shaji et al. (2007) suggests that high fluoride in

groundwater is mainly derived from the hornblende biotite

gneiss. The fluoride released into the groundwater could be

the weathering product of mica minerals, probably of

muscovite or biotite or both. It is also known that biotite is

an alumino-silicate mineral containing magnesium, iron and

potassium; thus the enrichment of these elements also

suggests the active weathering of biotite.

The chemical mobility and enrichment of Fe and Mg

and enrichment of Al in the sediments indicates that the

weathering of the mica minerals is still active. So, in order

to understand the mobility of fluoride in the ground water

with the changing trend of the chemical weathering intensity

i.e. the CIA values, a graph is plotted (Fig. 16) and the

correlation was established where the groundwater samples

were available at the respective sediment sample depth. As

the CIA value increases the fluoride content of the ground

water also increases indicating the positive correlation

between the two. The correlation coefficient between thefluoride content in the ground water and the CIA value at

that depth zone for Marksnagar was about 0.8. The maximum

fluoride was released at 30-33 m (M11) of depth and the

CIA value was also found maximum for this sample. The

minimum fluoride was released at the depth interval of 27-

30 m (M10) which also coincides with the minimum CIA

values. However, at the depth interval of 6-9 meters (M3)

the fluoride content decreases with some increase in CIA.

This might be due to difference in lithological character of

the sediments at that depth. The CIA value at this depth

interval also coincides with the sediment age of 20 to 30

thousand of years as revealed by the carbon dating. Moreover

this period also happened to be the last event of global

glaciations. So, the role of the last event of global glaciations

in the weathering and ultimately in the release of fluoride

could not be ruled out.

CONCLUSION

The geochemical data indicates the dominant presence

of quartz, feldspar and mica in the sediments of Marksnagar

and Durgajkhera. The high percentage of CaO suggests the

secondary formation of the calcium in the form of calcrete.The enrichment of Fe

2O

3and MgO in the sediments indicates

the presence of high content of biotite and the clay minerals

like vermiculite and smectite (Murphy, 1998). The presence

of Na in sediments is mainly due to the plagioclase (albite).

The depletion of Na2O with loss of SiO

2indicates the

preferential disappearance of plagioclase as weathering

proceeds (Weijden and Weijden, 1995). The depletion of

Na corresponds to the extensive weathering of plagioclase

(albite) in the area (White et al. 1998) while the some

depletion and some enrichment of K suggests that the active

weathering of K-feldspar (microcline) is not very

Fig.15. Variation of trace element distribution and the fluoride content with the depth.

Fig.16. Relationship between F and CIA with the variation in depth

at Marksnagar.


18/19



progressive. The presence of TiO2

confirms the presence of

biotite as Murphy et al. (1998) suggest that Ti is the part of

biotite and the trace elements Ni & Cr confirm the presence

of vermiculite (Ramesam, 1979). Na, Ca and K are mainly

concentrated in feldspar and the significant decreasing trend

of Na and some depletion of K, therefore reflects the

alteration of feldspar (Middelburg et al. 1988). Since Na

decreases more rapidly than K, greater alteration rate of

plagioclase than K-feldspar is suspected. Ca (in silicate form)

is also present in feldspar and normally gets depleted along

with Na. But in the present case due to its secondary pre-

cipitation as calcrete, enrichment of Ca is noted. The trace

element Rb is known to be more contained in K-feldspar

than biotite and is expected to be less depleted than K

(Middleburg et al. 1988). In, Marksnagar some depletion

of Rb was noted, confirming some alteration of K-feldspar.Since, according to Goldich cycle of weathering, K-feldspar

is more resistant of weathering than biotite, so its alteration

confirms the weathering of biotite. The CIA value also

suggests the incipient weathering of the sediments in the

area and support the weathering of biotite [K (Mg,

Fe)3(AlSi

3) O

10(OH, F)

2] to be more progressive than

muscovite [KAl2(AlSi

3)O

10(OH, F)

2].

A positive correlation between the CIA value and the

fluoride content in the ground water was also noted. Thus,

the rate of weathering active in the area is incipient in

nature, suggesting more prominent weathering of Na

feldspar and biotite. Probable reason for the high content

of fluoride in the groundwater of the study area is mainly

due to the dissociation/alteration of mica minerals, mainly

biotite.

Acknowledgement: We are thankful to the UP Council

of Agricultural Research for the financial support in the form

a research project, to Dr. Anupam Sharma for his help during

the course of investigation and to Dr. A.K. Jauhri for

extending working facilities in the Geology Dept., University

of Lucknow, India. S. Kumar is indebted to the Alexandervon Humboldt Foundation, Germany for the grant of a

fellowship to work in the University of Erlangen, Germany.

Authors are indebted to Prof. H.J. Tobschall for extending

working facility to S. Kumar at the Institute of Geology and

Mineralogy, University of Erlangen-Nurenberg and to Ms.

M. Drr for the analytical assistance in XRF analysis.

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(Received:23 March 210; Revised form accepted: 21 September 2010)

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