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Journal of Minerals & Materials Characterization & Engineering, Vol. 9, No.11, pp.1007-1026, 201 0
jmmce.org Printed in the USA. All rights reserved
Effect of Tsunami in the Ilmenite Population: An Examination through X-Ray
Diffraction, Scanning Electron Microscopy and Inductively Coupled Plasma
Babu Nallusamy1*, Si ni r ani Babu1, M. Sundararajan2, P. Seralathan1, R. Bhima Rao3 &
P.N. Mohan Das2
1Cochin University of Science and Technology, Kerala, India.
2National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum, India
3 Institute of Minerals and Materials Technology, Bhubaneswar, Orissa, India
*Corresponding Author: firstname.lastname@example.org
Kerala state in the SW part of Indian subcontinent hosts one of the best beach placer deposits in
the world. The near shore deposit is ~140Mt and is very rich in heavy minerals, often up to 70%,
and ilmenite forms its chief constituent. The seasonal enrichment of this deposit takes place
through monsoonal activity and the recent tsunami (24 December 2004) had significantly
contributed its share. Mineralogical and chemical variation of the surface (pre- and post-
tsunamigenic) as well as subsurface ilmenites (4-5m depth) of this deposit has been investigated.
SEM examination on ilmenites of pre-tsunamigenic period conveys that the micromorphology
represents mostly of mechanical activities rather than chemical and solution activities. Both
post-tsunamigenic and subsurface ilmenites were influenced dominantly by solution and
chemical alteration. The pre-tsunamigenic (surficial) ilmenite grains consist only of rutile as an
altered product with a small FeO – Fe2O3 ratio. However, the presence of considerable altered
products such as rutile and pseudorutile in the post-tsunamigenic and subsurface ilmenite
indicates that the ilmenite alteration is in an advanced state. Regarding trace element
composition, it was found that Al, Mg, Na, Ca, Cd, Co, K, Sr and Pb have higher contents in
both core and post-tsunamigenic ilmenite than the pre-tsunamigenic ilmenite. These elements
play an important role in understanding the behavior of the minerals during beneficiation and
further processing. The relative lesser content of such elements in the onshore pre-tsunamigenic
ilmenite grains reveals that the chemical leaching has not been active compared to the ilmenite
concentrates from the shallow sea that have been brought by the tsunami and also to that have
been deposited earlier and now seen underneath up to a depth of ~5m.
1008 B. Nallusamy, S. Babu, M. Sundararajan, P. Seralathan, R. B. Rao, P.N.M. Das Vol.9, No.11
The tsunami struck the southern Kerala coast at 11.30 a m and the central Kerala coast by 12. 30
pm on 26 December 2004. The tsunami run ups resulted in 172 casualties and an estimated loss
of property worth Rs.1358.6 crores. Eyewitnesses conveyed that three waves have struck the
low lying coastal plains sequentially and resulted in considerable damages. The impacts of
tsunami mineralo -granulometic evaluation of beach placers of Kerala state have already been
studied . The effect of tsunami on sediments as well as floral and faunal assemblages have
been reported elsewhere [2-9]. Occurrences of higher concentrations of economical heavy
minerals (placers) in the coastal zone have created interest for exploration and exploitation of
these marine mineral resources in many parts of the world [10-16]. Study of mono-mineralic
analysis such as ilmenite, sillimanite, zircon, garnet and rutile has been considered more
informative than the analysis of bulk sediments for understanding the geologic-geochemical
characteristics . Of these, the geochemistry of ilmenite holds an important role in the
assessment of its quality since ilmenite has high demand in several industries. Further, ilmenite is
identified as an object for provenance search by varietals method [18-19]. The major ilmenite
reserves in India are at Chavara, Manavalakurichy and Chatrapur. India stands first in terms of
ilmenite reserves which are estimated to be 348Mt out of which 150 Mt were processable. This
paper reports the effect of tsunami in the ilmenite population using XRD, SEM-EDX and ICP-
2. GEOLOGIC SETTING OF THE STUDY AREA
The modern black sand placer of the Thottappally – Kayamkulam (Fig.1) barrier island, with an
average width of about 250 m between the lagoon to the east and Laccadive sea to the west,
extends for about 20 km and at least 2 – 5 km width towards inland. The foreshore slopes at a
low angle seaward (4-10°) and the direction of longshore current remains in general, northerly in
this segment . Sporadic occurrence of a clay horizon having organic matter with peat is
observed from 2.5 to 4 m depth, where heavy mineral concentration becomes less significant.
The hinterland area consists of crystalline rocks of Archeaen age, sedimentary rocks of Tertiary
period and laterite capping on crystalline and sedimentary rocks belonging to Recent to sub-
Recent. Climate in Kerala experiences a humid tropical with alternate wet and dry seasons. The
temperatures vary from 22 to 35oC and the highest temperatures fall during March to May and
the lowest in December and January. Humidity in Kerala varies from 79-84% in the morning’s
hours to 73-77% in the evenings. As far as annual rainfall concerned, Kerala receives 200-300
cm during the southwest monsoon i.e June – September and the northeast monsoon (October-
December) yields about 50 cm rainfall. The longshore sediment transport largely depends on the
wave approach and also on the near shore topography. In general, along the west coast, the
breaker angles w ere generally 5-10o during pre- and post-monsoon seasons and during monsoon
they changed to 160 – 170o thus indicating a reversal in the direction of the longshore current
Vol.9, No.11 Effect of Tsunami in the Ilmenite Population 1009
. The breaker height in the Chavara coast ranges from 0.3 – 0.5 m during pre-monsoon
season; during monsoon and post-monsoon, it varies from 1.0-2.0m . Groins at mouth bar of
Kayamkulam bar also play a significant role in concentratio n of black sand deposits in the study
3. MATERIALS AND METHODS
Along the Thottappally - Kayamkulam barrier island representative surficial sediment (pre-
tsunami and post tsunami event) samples were collected from the berm using a scooper up to a
depth 30 cm and four core samples following cable tool method up to 5 m depth in 2004 and
2005 respectively. The samples were initially washed and dried and repr esentative samples were
treated with 1:10 HCl, 30% by volume H2O2 and SnCl2 to remove carbonates, organic matter and
ferruginous coatings respectively. The samples were then sieved at a +GF+ DIN 4188 sieve
shaker for 15 minutes at half Phi interval . Magnetite was separated from the heavy mineral
fractions by a hand magnet. Magnetic (ilmenite) and non-magnetic fractions were separated
using Frantz Isodynamic separator. Forward slope of 15° and a slide tilt of 12° at 0.5 Amp, 0.4
Amp and 0.15 Amp were to separate ilmenite mineral.
X-ray diffraction using Philips (X’pert pro) powder diffractometer, (2°/min from 20° to 60°)
were carried out on ilmenite to understand mineral alteration. The pure ilmenite samples were
mounted on carbon adhesive tape and imaged using Jeol-JSM 5600 LV field emission scanning
electron microscope and analysed with a EDAX light element energy dispersive X-ray
spectrometer using a 20 kV electron accelerating voltage. Images of the various samples were
also collected at 5 kV in order to obtain high-resolution surface characteristics of the mineral
grains. The EDAX composition of selected grains was determined at 10 kV. Powdered ilmenite
was brought into solution by fusion with KHSO4 and dissolution in hot dilute H2SO4. Titanium
was determined by reducing titanium (IV) to titanium (III) using aluminum metal and titrating it
against standard ferric ammonium sulphate . The total iron was estimated by stannous
chloride reduction-K2Cr2O7 titration method. The content of FeO in the ilmenite was analy sed by
treating the powdered ilmenite with HF-H2SO 4 mixture and titrating it with standard K2Cr2O7
. The trace elemental composition studies are carried out using ICP-AES (IRIS INTREPID II
XSP MODEL, Thermo Electron Corporation make).
1010 B. Nallusamy, S. Babu, M. Sundararajan, P. Seralathan, R. B. Rao, P.N.M. Das Vol.9, No.11
Figure 1 Location and sampling point in the study area
Vol.9, No.11 Effect of Tsunami in the Ilmenite Population 1011
4. RESULTS AND DISCUSSIO N
Altogether nineteen samples have been analysed for different major, minor and trace elements
contents (Table 1, 2), of which eight samples (3, 10, 13, 22, 28, 34 and 39) were collected before
the tsunami and three samples (3T, 13T and 39T) after the tsunami. Four samples each were
collected from the sub-surface layers, below and above water table respectively (Table 2). Above
water table and below water table samples belong to those samples collected from sub-surface
4.1 XRD Analysis
X-ray diffraction pattern of the ilmenite concentrate of Thottappally – Kayamkulam shows the
presence of ilmenite (50%) and rutile (50%) peaks in the pre-tsunami samples (Fig 2a), while in
the core and post-tsunamic it shows ilmenite (20 and 41%), rutile (25 and 16%), pseudorutile and
pseudobrookite (55 and 50%) peaks (Fig. 2b-d). This means that the grains are apparently more
altered in the core and post-tsunamic samples, which could be due to the sporadic burial under
reducing conditions in water-logged soils would provide the ideal environment for such
alteration to occur and mixing of shelf sediments with the onshore sands. The shelf of the Kerala
coast may host older sediments and possibly more altered or the shelf sediments could have been
subjected to intense weathering due to sub aqueous conditions.
4.2 SEM Analysis
Micromorphological studies of ilmenite pre-tsunami (Fig. 3 a-e), post-tsunamic and core (Figs.
4a-f and 5a-j) from the study area by SEM depict the development of a number of different
micro features on the ilmenite grain which support the XRD evidences. From these features one
could understand th e physical and chemical energy gradient, surface and sub-surface dissolutio n
process, and post depositional diagenitic modifications [25-26]. The surface textures of quartz
grains used in order to achieve an understanding of the post-depositional or diagenitic history of
the sediments . Pre-tsunamic ilmenite grains exhibits subrounded shape along with impact
‘V” marks and deep pits are seen resulting from mechanical collision and later from solution
activity. Mechanical feature like V-shaped pits suggest that grains are formed by grain to grain
collision in an aquatic medium [28-29]. Crescentic structures and pits are produced by solution
activity. Due to long residence time this type of features might have developed on the grains.
Sets of grooves oriented at different angles developed over the grains clearly indicate the
solution activity process (Fig. 3a-e). More precipitation corroded features ar e visible in the pos t-
tsunamic and core ilmenite grains (Fig. 4a-f and Fig. 5f, h and j) which were presumably
developed due to the chemical activity and solution activities prevailed over the grain surface
which replaced the ilmenite by pesudorutile and rutile. It is clear that core and post-tsunamic
ilmenite grains have undergone extensive weathering and alteration than surface ilmenite which
1012 B. Nallusamy, S. Babu, M. Sundararajan, P. Seralathan, R. B. Rao, P.N.M. Das Vol.9, No.11
supports XRD and wet chemical analysis results. Similar features have been observed in non-
opaques along the east coast of India . Undulatory wavy surfaces formed due to solution
effect and removals of blocks were also observed on tsunami and core ilmenite grains (Fig.4 e, f
and 5a-e, g and j). The post-tsunamic sediments might have been transported from the shelf
region of Kerala Coast where sporadic burial under reducing conditions in water-logged soils
would provide the ideal environment for such alteration to occur or partly formed due to the
reworking of deeper onshore sediments that were lying below the water table.
Table 1 Major Elemental Distribution in Beach Ilmenite of Thottappally-Kayamkulam Deposit
S.No. TiO2 FeO Fe2O3 T.IronTi/Ti+Fe Alt.Stage
3 60.83 8.96 24.81 24.320.60 PR
4 64.20 8.94 26.75 25.660.58 HI
6 64.66 9.11 26.52 25.630.58 HI
10 61.83 8.88 25.92 25.030.58 HI
13 60.48 8.47 26.16 24.880.59 HI
18 63.58 9.20 26.66 25.800.58 HI
22 61.66 9.05 26.66 25.680.59 HI
24 61.45 9.22 26.56 25.750.57 HI
28 61.10 9.12 24.79 24.430.58 HI
30 63.69 8.74 25.75 24.800.59 HI
34 64.10 8.79 28.27 26.600.57 HI
39 62.13 9.03 25.15 24.610.60 PR
AWT 1c2 63.07 6.71 25.57 23.100.62 PR
2c2 63.56 7.55 25.46 23.680.62 PR
3c2 62.94 6.72 27.39 24.380.61 PR
4c2 64.40 7.87 25.69 24.090.62 PR
BWT 1c4 63.67 7.85 25.33 23.820.61 PR
2c4 62.06 6.92 27.31 24.480.62 PR
3c5 63.79 6.74 25.92 23.370.62 PR
4c6 66.08 9.28 24.36 24.250.62 PR
3T 62.86 7.81 25.28 23.470.61 PR
13T 62.45 7.32 25.82 23.750.61 PR
39T 62.01 6.75 27.84 24.720.60 PR
PR - Pseudo Rutile
HI - Hydrated Ilmenite
Vol.9, No.11 Effect of Tsunami in the Ilmenite Population 1013
Surface (pre-tsunami) Core Surface (post-
Water Table Sub-Surface Below
Elements 3 10 13 18 222834391c22c23c2 4c21c42c43c54c63T13T39T
Al 0.49 0.619 0.5 0.545 0.470.8960.2360.590.8590.5090.446 0.3321.3041.0970.4460.9550.780.50.63
Mg 0.49 0.239 0.46 0.654 0.490.3720.1450.470.6350.2380.221 0.1631.3680.4390.2130.440.490.520.55
Mn 0.37 0.141 0.35 0.402 0.360.3040.0920.350.2830.1170.121 0.1580.1370.3440.2140.3450.350.390.4
Na 0.014 0.15 0.042 0.158 0.0810.5010.1930.2760.2540.1380.484 0.2390.3140.6930.0780.4830.2980.1270.083
Ca 249.4 384.1 206 1686 513.7299.3845.4104.423621132234.1 259.234991024236.31019207.8591.61084
Cd 0.7 2.7 1 3.2 188.8.131.5203.1 0026.56.115.10.90.90.9
Co 60.4 298 61.9 672.2 62.1618.311662.2602.8197274.3 260.4185.7671.2431.5697.263.170.569.2
Cr 812.8 264.7 851.2 601.3 750.1729.2118.7833.9631.1173.3246.7 293.7243.8668.9538.9888.31067863.1922.9
Cu 309 0 309.3 0 274.700307.5000 0000 296.8332.8323.6
K 0 218 19.7 594.2 24.786.1245.44.9144.7139.976.2 142.6556.6303.879.6192.71331.522
Li 2.8 0 3.6 0 2.1002.2000 0000.303.52.92.8
Ni 18.8 0 21.2 0 17.411.7017.8000 00039.116.418.218.4
Sr 23.1 0 23.2 0 26.60020.2022.319 25.160.9049.887.124.327.639.7
Zn 192.2 40.2 189.1 0 190.3115.30176.3132.300 00166.50192.6187.7282202.1
P 518.7 147.8 457.9 99 34127.117.6421.1451.5121.999.7 121.7304247.2147.6211.5529.3340.5407.5
Pb 0 1072 0 2240 074218.40137 123.2 282.5 181.5 206.871493205010000
1014 B. Nallusamy, S. Babu, M. Sundararajan, P. Seralathan, R. B. Rao, P.N.M. Das Vol.9, No.11
20 25 30 35 40 45 50 55 60
ο 2 Theta
Fig. 2a X- Ray diffractrograms of representative ilmenite shows the presence of
ilmenite and r u til e in the pre-tsuna mi surf ace ilmenite.
20 25 30 3540 45 50 5560
ο 2 Theta
Fig. 2b X-Ray diffractrograms of representative ilmenite Above Water Table
(Core) shows the presence of pesudorutile, ilmenite and rutile
Vol.9, No.11 Effect of Tsunami in the Ilmenite Population 1015
20 25 30 35 40 455055 60
ο 2 Theta
Fig. 2c X-Ray diffractrograms of representative ilmenite Below Water Table
(Core) shows the presence of pesudorutile , ilmenite and rutile
20 25 30 35 40 45 50 55 60
ο 2 Theta
Fig. 2 d X- Ray diffractrograms of representative ilmenite shows the presence of
ilmenite, rutile, pesudorutile, pesudobrookite in the post-tsunami samples.
(Legend: IL = Ilmenite, R= Rutile, PR= Pseudorutile and PB= Pseudobrookite)
1016 B. Nallusamy, S. Babu, M. Sundararajan, P. Seralathan, R. B. Rao, P.N.M. Das Vol.9, No.11
Fig. 3 a-e Scanning electron microscopic view of ilmenite grains separated from
Vol.9, No.11 Effect of Tsunami in the Ilmenite Population 1017
Fig. 4 a-f Scanning electron microscopic view of ilmenite grains separated from post-
tsunami samples. Note the intensity changes in the post-tsunami samples.
4.3 Chemical Analyses
4.3.1Wet chemical analysis
Major elemental compositions of the ilmenite samples of pre-tsunami, post-tsunamic and drill
core sediments analysed by wet chemical method  are summarized in Table I. Alteration
stages of ilmenite under weathering also studied . Abundance of TiO2 in the pre-tsunami
ilmenite sediments are relatively high, range from 60.48 to 64.1 % (av. 62.48 %) and in core
ilmenites concentrations average 63.70%, ranging from 62.94 to 66.08 %. On average the
tsunami ilmenite contains 62.44% TiO2, ranging from 62.01-62.86 %. FeO and Fe2O3
concentrations in the pre-tsunami ilmenites range from 8.47 to 9.22 and 24.79 to 28.27 % with
averages of 8.96 and 26.16 %, respectively. The range of FeO and Fe2O3 in the core ilmenite
show 6.71 to 9.28 and 24.36 to 27.39 % with averages of 7.46 and 25.88 %, respectively. The
1018 B. Nallusamy, S. Babu, M. Sundararajan, P. Seralathan, R. B. Rao, P.N.M. Das Vol.9, No.11
contents of FeO and Fe2O3 in post-tsunamic ilmenite range from 6.75 to 7.81 and 25.28 to
27.84% (av. 7.29 and 26.31%). It was observed that the enrichment of TiO2 in the core and post-
tsunamic ilmenite might have undergone deep weathering and alteration more than the pre-
tsunami ilmenites. Core ilmenites and post-tsunamic ilmenite show pseudorutile alteration phase
(Table 1), whereas most of pre-tsunami ilmenites show only hydrated ilmenite phase. A higher
amount of TiO2 present in ilmenites of pre-tsunami, tsunami and core is ascribable to higher
presence of rutile and pseudo-rutile exsolved phases. The above observations were supported by
XRD and SEM examination (Fig. 2a-d and Fig. 3a-c , 4a-f and 5a-j) Dissolution and / or
oxidation of iron from ilmenite in natural water or in acidic water lead to an enrichment of
titanium and other elements in th e residuu m, which may be the main cause for ilmenite alteration
. The higher amount of TiO2 may be ascribed to repeated cycles of burial and exhu mation of
sediments along beaches and streams and river banks during transport . This would keep
ilmenite under condition s well-suited to th e re moval of iron for considerable lengths of time. The
main reason for such a high alteration below ground water levels (core ilmenites) is due to the
low Eh, high pH and high SO4 content in the ground waters of the study area  and
complexing with organic acids under such reducing conditions would further enhance the
solubility of iron . Humic acids as a collection of organic acids resulting from the
decomposition of vegetation . Thus both of these leaching agents would be present in near
surface zones and no doubt contribute to weathering. Organic matter enrichments were found in
the core sediments during procurement of sampling in the study area. Hence, the extent of
alteration of ilmenite depends not only on the geological history of the deposits but also the
intensity of subsurface chemical leaching the deposits underwent in a low energy, sub surface
Vol.9, No.11 Effect of Tsunami in the Ilmenite Population 1019
Fig . 5 a- j Scanning electron microscopic view of ilmenite (Core samples)
1020 B. Nallusamy, S. Babu, M. Sundararajan, P. Seralathan, R. B. Rao, P.N.M. Das Vol.9, No.11
4.3.2 Minor and trace element concentration
Major, minor and trace element concentration were analysed using ICPAES method. These
elements are important in the modern mineralogical panorama, as they provide witness for the
provenance of mineral suite, the alteration patterns and trend of minerals and the quality of raw
mineral ores before industrial processing. Ilmenite trace element variation is dependent on its
paragenesis [37-38]. The surf ace pre-tsunami, core (AWT and BWT) and surface post -tsunamic
ilmenite samples in the present study were analysed (Table 2) for seventeen minor and trace
elements, namely, Fe, Al, Mg, Mn, Na, Ca, Cd, Co, Cr, Cu, K, Li, Ni, Sr, Zn, P and Pb. These
elements were selected based on their relevance in the delineation of weathering history and
Figure 6a-f shows behavioral pattern of each element determined in ilmenite collected from
beach sands i.e., surface pre-tsunamic,core (AWT and BWT) and surface post-tsunamic. It was
observed that elements like Al, Mg, Na, Ca, Cd, Co, K, Sr and Pb have higher contents in
ilmenite from core ilmenite. i.e., ilmenite from below water table than the ilmenite from above
water table, pre- and post-tsunamic ilmenite which supports dissolution and / or oxidation of iron
from ilmenite in natural water or in acidic water leading to an enrichment of titanium and other
elements in the residuum. This may be the main cause for ilmenite alteration  and the
alteration products could be due to the exogenic processes that operated on these ilmenites after
their release from the parent rocks . The higher contents present in core ilmenite (BWT) is
ascribed to the local concentration of such elements.
The assay data in Table 2 and Fig. 6 show strong positive correlations (r>0.85) were observed
between the concentrations of Fe and Cr, Ni and Zn and between Mn and Mg and Cr and Mn,
and also between Cu and Li, Ni, Sr and Zn and positive concentration of element pairs Li-Ni, Li-
Sr, Li-Zn and Li-P, Ni-Sr, Ni-Zn and Ni-P, and Cd-Pb and Sr-Zn and Sr-P in the surface ilmenite
(pre-tsunami) concentrates. Mg and Al concentrations are generally high at beaches where also
Cr and Fe concentrations are the highest, although there is no significant positive correlation
between Al-Mg where as a strong positive correlation exists between Cr-Fe in the pre-tsunami
ilmenites. Negative or poor relationships for Zn and K suggest a differing control for these
Vol.9, No.11 Effect of Tsunami in the Ilmenite Population 1021
Fig. 6a-f Comparisons of minor and trace element distrinbution in beach ilmenite of
3101318222834391c2 2c23c2 4c2 1c42c4 3c5 4c63T13T39T
Mn & Na
3101318222834391c22c2 3c2 4c2 1c42c4 3c5 4c63T13T39T
Al & M g
310 13 1822 28 34391c22c23c24c21c42c43c54c63T13T39T
1022 B. Nallusamy, S. Babu, M. Sundararajan, P. Seralathan, R. B. Rao, P.N.M. Das Vol.9, No.11
Fig. 6a-f conti…
Ca, Cr & Pb
3101318222834391c2 2c23c2 4c2 1c4 2c4 3c5 4c63T13T39T
3101318222834391c22c2 3c2 4c21c42c4 3c54c63T13T 39T
P , Zn, Co & K
3101318222834391c2 2c2 3c24c21c42c4 3c54c63T13T39T
Vol.9, No.11 Effect of Tsunami in the Ilmenite Population 1023
Non-significant correlations for Al, Mg, Mn, Na, Cd and Co reflect a different source or
difference in substitution of other cations in the ilmenite structure during crystallization.The
substitution of other cations in the ilmenite s tructure is contr olled by several factors including the
temperature of cry stallization, oxygen fugacity, the amount of suitable cations available, and the
size, charge, and electronegativity of those cations relative to iron and titanium during
crystallization . High element concentrations but with much lower value belong to drill core
ilmenites also evident from the correlation coefficient. Very strong and positive correlations
exist among the concentrations of elements pairs Al-Fe, Mn-Fe, Cd–Fe, Zn-Fe, Mg-Al, K-Al,
Cd-Mn, Co-Mn, Cr-Mn, Zn-Mn, Co-Cd, Pb-Cd, Zn-Cr and Pb-Zn. Negative concentration of
element pairs Al-K, Mn-Na, Mn-Li, Cr-K and Li-Sr and positive concentration of element pairs
Mg-Ca, Na-Li and Cr-Pb were found in tsunami ilmenites. Over all high concentration of TiO2,
Fe, Mg, Al, Cr, Ni, Zn and Mn recorded in beach sediments from the surface, core as well as
post-tsunamic ilmenites are in good agreement with composition of Khondalites and Charnokitic
rocks which are w idely distributed on coastal hinter land  (Soman, 1985)
Titanium enrichment, predominately through removal of iron, is widespread among ilmenite
populations of post-tsunamic and core samples than pre-tsunami ones. The pre-tsunamigenic
(surficial) ilmenite grains consist only of rutile as an altered product with a small FeO-Fe2O3
ratio. However, the presence of considerable altered products such as rutile and pseudorutile in
the post-tsunamigenic and subsurface ilmenite indicates that the ilmenite alteration is in an
advanced state. Chemical alteration of ilmenite predominates over mechanical abrasion as
exemplified by the SEM investigation in the post-tsunamic as well sub-as surface (core)
sediments than pre-tsunami (surface) ilmenites. Regarding trace element data, it was found that
Al, Mg, Na, Ca, Cd, Co, K, Sr and Pb have higher contents in both core and post-tsunamigenic
ilmenite than the pre-tsunamigenic. The relative lesser content of such elements in the onshore
pre-tsunamigenic ilmenite grains reveals that the chemical leaching has been less active
compared to the ilmenite concentrates from the shallow sea that have been brought by the
tsunami and also to that have been deposited earlier and now seen underneath up to a depth of
We acknowledge CSIR New Delhi for funding and Director NIIST, Thiruvanthapuram, for
extending Laboratory Facilities. First author’s due thanks to the organizer of ICAM 2008, which
was held at Brisbane, Australia for given opportunity to present this paper in the international
congress on Applied Mineralogy. Special thanks due to Dr. D.S. Suresh Babu, Scientist, Center
for Earth Sciences Studies, Kerala, India for fine tuning the manuscript.
1024 B. Nallusamy, S. Babu, M. Sundararajan, P. Seralathan, R. B. Rao, P.N.M. Das Vol.9, No.11
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