International Journal of Basic and Applied Sciences Prakash et. al., Vo. 1 No. 1 ISSN: 2277-1921

International Journal of Basic and Applied Sciences Vol.1 No.1. 2012 . 61-67 ©Copyright by CRDEEP. All Rights Reserved

Full Length Research Paper

Tectonic significance of the area west of Kodaikanal (South India): Applying Remote Sensing and GIS techniques

D. Prakash*, C. K. Singh, U. K. Shukla, P. Chandra Singh and Deepak Center of Advanced Study in Geology, Banaras Hindu University, Varanasi 221 005 India

*Corresponding Author: D. Prakash; E- Mail: [email protected]

ABSTRACT Kodaikanal area resting over the Precambrian carton is characterized by a complicated structural pattern signified by a number of major regional scale and minor shear planes of local significance. These lineaments show all the evidences of geologically past and Quaternary tectonics that have greatly affected the geomorphological evolution of the area. Present study based on Digital Terrain Model (DTM), remote sensing, structural fabric supported by ground thruthing has revealed presence of two major lineament trends aligned in ENE-WSW and WNW-ESE directions and seems have developed in response to two major tectonic episodes in the area. Crosscutting relationship of these two trends suggests that ENE-WSW is older than the WNWESE which has been off stetted by the former one. Drainage pattern and the nature of escarps also point to a possible Quaternary reactivation of these two shear trends implying neotectonic activity in the area.

Key Words: DTM, Kodaikanal, Remote Sensing, Tectonics,

INTRODUCTION southern part of the Indian peninsula (Vaidyanathan The Kodaikanal massif encompasses the Annamalai, 1967; Vemban et al. 1977; Ramasamy et al. 1987; Palani and Cardamom Hills and is the largest upland Ramakrishnan, 1988; Ramasamy, 1989; Narsimhan, block (rising to 2800 meters) of granulites of South 1990; Kumanan 2001 among others). India (Fig.1a, b). In the western part of this massif (Annamalai hills), charnockites are extensively The present study is an attempt to evolve tectonic retrogressed. In Kodaikanal area, massive and implications deduced from the analysis of Digital homogenous charnockites are in sub-vertical contact Terrain Model, satellite remote sensing data with with a thick sequence of metasediments, the contact ground truthing in combination with field work. For zone coinciding with the eastern margin of the upland this purpose an area of 120 sq. km. west of massif (Prakash, 1999). At the contact zone, Kodaikanal (Tamil Nadu) has been selected. The cordierite-garnet-spinel-sillimanite migmatites study area (77°20΄00˝ to 77°29΄15˝ and 10°15΄00˝ to represent metapelites, but further east garnet- 10°21΄15˝) is situated 125 km NW of Madurai in sillimanite-biotite gneisses (Khondalite) predominate Tamil Nadu (Fig. 1c). The area is accessible by bus/ and are interlayered with calc-silicate rocks, train from Chennai via Madurai or Kodaikanal road quartzites, pelitic schists and conformable mafic- railway station. Frequent bus service on Kodaikanal- ultramafic layers (Prakash et al., 2007). Numerous Palani road and good logistics at Kodaikanal make screens of charnockite are interlayered with field works pleasant and easy. metasediments (Harris et al., 1982; Prakash et al., 2006, 2010; Prakash, 2010). TOPOGRAPHY Kodaikanal Plateau corresponds to the “Upper Studies carried out in the Peninsular India during last Palani”. The western or the Upper Palani from at the 3-4 decades have shown indications of possible top a plateau of around 170 sq. km. areas with an recent plate movements. These studies indicate average elevation of 2,500 meters above the mean sea evidences for Quarternary earth movements in the level. These comprises the three valley namely

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Figure 1. a). Reference map of India. b). Structural patterns for Southern Granulite Terrain (after Drury et al., 1984) c). Geological map of the study area (Modified after Prakash, 2010).

Parappar-Devaikarai Valley, the Gundar valley and spot height point map (Fig. 2). This DTM is useful the Upper Amaravathi Valley with several tool to interpret the geomorphic and tectonic features intervening peaks as- Perumal Hills (2,190 m), of any area in conjunction with satellite data and Obeservatory Hills (2,305m), Karumarkadu Hills, ground truthing. The digitized drainage map was Vembali Hills and Vandaravu Hills. Kodaikanal lies prepared under GIS software. Ordering of drainages on the southern edge of Vembali hill. The Upper has been done on the basis of Horton (1945) (Fig. 2). Palani consists largely of plateaus of rolling down A precise lineament pattern was prepared from the covered with coarse grasses and isolated sheltered raw and the digitally processed IRS Landsat7-ETM+, woods, hidden from general view. Theses shoals are dated - 2006-11-23, Path Row 141/48 data on the well watered and form the higher ranges. No less basis of tone, texture, relief, vegetation, soil tone and than thirty streams take their course from these hill drainage linearities and curvilinearities (Fig. 3). ranges which unite as they come downhill and form eleven sizable streams. The general fall on the hills is STRUCTURE to the north but they terminate abruptly into Utilizing Landsat Imagery, Drury and Holt (1980); precipitous cliffs in the south. These streams are Drury (1983) and Drury et al., (1984) deciphered the perennial, well supplied with water from the structural elements together with a regional model of innumerable springs arising out of joints in the rocks. tectonic evolution of south India. They recognized tectonics subdivisions in south India bounded by MATERIALS AND METHODS shear system along which crustal blocks have moved In the present study SOI toposheet no.58F/7, has laterally and vertically and along which crustal been used to digitize contour values, drainages and shortening appears to have occurred. spot heights to generate DTM of the area and analysis Transcurrent shear belts which juxtapose dissimilar of drainage configuration. Extensive field work has Archaean blocks deserve special mention. South of been done to provide ground check validity to DTM northernmost granulite massifs, a number of nearly and drainage patterns. E-W trending shear zones cut the terrane (Fig. 1b). The contour map of the area has been prepared by These may be connected to the N-S thrust system of digitizing contours using GIS software. The contour the Eastern Ghats by a multiplicity of small arcuate ranges from 400 to 2250 meter at the interval of 20 shears at the eastern extremity of the E-W shear meter. The spot heights given in toposheet have been system (Drury and Holt, 1980). The most important digitized to create spot height point map. of these are the Moyar-Bhavani and Palghat-Cauvery The DTM of the study area has been prepared by Shear System. Together, they form a dextral oblique- interpolation of rasterised segment contour map and slip shear system. Drury et al., (1984) estimated that

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the shear system involves a dextral lateral shift of trend of NW-SE and have a moderate northeasterly c.70 km. The structural trend swing from N-S in the dip . Prominent mineral lineations in the present area region north of the shear system through NE-SW, to near Tinna Varai are defined by parallel arrangement E-W within the most intensely sheared zone. of biotites and prismatic crystals of sillimanite in garnet-cordierite sillimanite gneiss respectively.

Figure 2. Digital Terain Model of the study area Figure 3. Remote sensing satellite data showing showing geomorphic features, trends of lineaments geomorphic features, trends of lineaments and and drainage pattern. drainage patterns of the study area.

The strike and attitude of both compositional banding The lineament pattern has been deduced from the and tectonic fabric are extremely variable in the DTM and remote sensing satellite data (Fig. 2, 3). southern block. In the Palani Hills, the regional Some of the lineaments are showing curvilinear attitude of the planer fabrics changes eastwards from pattern and majority of them are striking in NNW- virtually flat-lying to a NNE-SSW strike with steep SSE direction. Another lineament trend i.e. ENE- WNW dip and defines an extremely large wave WSW is also common. In south-eastern part of the length, southward closing, north-ward-plunging study area few arcuate shape of lineament has been synform between the Annamalai Hills in the west and noticed (Fig. 4 a, b). Extensive field work suggests Kodaikanal in the east. that the study area is entirely bedrock terrain having To the east of the Kodaikanal massif a major high elevated structural ridges and adjacent structural lithological and structural change occurs where valleys striking NNW-SSE and ENE-WSW. As the supracrustal rocks become dominant, although they lineaments are weak zones provide significant are interlayered with granulite sheets. The regional information regarding tectonics of the area, field strike of the supracrustals and granulite sheets is NE- observation indicates that these WNW-ESE and SW, roughly conformable to the banding/fabric of the ENE-WSW striking lineaments are in actual Kodaikanal massif and parallel to its eastern margin. representing either the fold axis or fault planes Key structural feature of this supracrustal rock zone present in the form of ridges and valleys. The is an array of isoclinal folds, comprising the Porandalar River, which course is roughly from SW Varushanad and Andipatti Hills west of Madurai to NE, appears to follow a synclinal fold axis as rocks (Drury et al., 1984). The regional fabric and fold of either sides of the river dipping towards each patterns of the Kodaikanal and Madurai areas are other. These features can easily be picked on DTM truncated to the south by major WNW-ESE, and remote sensing data of the study area (Fig. 2, 3). Achankovil Shear belt. From lineament analysis (Fig. 4b) and profile section In the present study area, both planar and linear study (Fig. 5) it signifies that the study area has fabric elements have been recorded. Prominent joint suffered at least two phases of compressional planes are observed at some places near Vaikunta

Malai and Pallangi. These joints have a general strike

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Figure 4. Lineament map of the study area with rose diagram showing two prominent trends of lineaments.

Figure 5. Geological cross section of the study area showing dominant ridge and valley Topography. Porandalar are flowing through the axial plane of the tectonics with a faulting episode. Field evidences are folds. In the second phase of deformation ENE-WSW also showing signatures of intense deformational trending regional folds came into existence. As signatures such as isoclinal folding and shearing (Fig. mentioned above the course of River Porandalar is 6). In the first phase of deformation WNW-ESE following the axial plane of the fold developed trending regional folds developed. The WNW-ESE during second phase of deformation. Interestingly it trending ridges and valleys are manifestation of the has been found that ENE-WSW trends of lineaments first phase of folding. Most of the tributaries of River are continuous and intersecting the NW-SE trends at most of the places. It is clearly visible on DTM and

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remote sensing satellite data (Fig. 2, 3). It implies that ENE-WSW trends of lineament are younger than

Figure 6. (a) Field photograph showing (a) Isoclinal folding in gneissic rock from Vaikunta Malai. (b) Gneissic rock showing shearing effect near Periya Varai.. the WNW-ESE trends. Linear and curvilinear scarps Kambam tectonic valley which is demonstrated to be have been noticed through out the area. of Pleistocene-Holocene tectonic graben (Ramasamy The crestline features and the pattern of escarpments & Balaji, 1995, and Ramasamy & Karthikayan, were significantly analysed with the help of DTM 1998). The WNW-ESE trending tectonic weak zones and RS data. The pattern of the profile section is are in close proximity (with slight deflection) of the showing that the eastern half of the study area is the E-W trending cymatogenic arch (Ramasamy et mostly an undissected ridges and valleys, where as al., 1987, and Kumanan & Ramasamy, 2001) and it the western half is mostly dissected (Fig. 5). may be correlated with the E-W trending Palghat tectonic gap of Subramanian and Muraleedharan DISCUSSION (1985). It is worthwhile to mention here that E-W In the background view of the existing literatures trending Palghat tectonic gap was subsequently such as Ramasamy and Balaji, 1995; Ramasamy et doubted for the ongoing tectonic subsidence al., 1987,1998, and Kumanan & Ramasamy, 2001 (Ramasamy and Balaji, 1995). The crest line features among others, the ENE-WSW trending weak zones and the pattern of escarpments were critically anlysed (Fig. 4a, b) is sub-parallel to the NE-SW trending and it has been observed that crest line features are tectonically significant. These features have shown

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curvilinearity at some places while ‘S’ or sigmoidal based on Landsat interpretation. Journal Geological shaped in other places. The ‘S’ or sigmoidal shaped Society of India, 24, 167-184. crest line and escarps indicate probable sinistral drags Drury, S.A., Harris, N.B.W., Holt, R.W., Reeves- (Singh and Srivastava, 2011). Badgly (1965) has Smith, G.J., Waghtman, R.T. (1984). Precambrian demonstrated in clay deformation model that tectonics and crustal evolution in south India. The development of sigmoidal fractures in the blocks Journal of Geology, 92, 3-20. entrapped in between two sinistral faults when they were subjected to compressive force with little Harris, N.B.W., Holt, R.W. & Drury, S.A. (1982). obliqueness to the preexisting sinistral faults. The Geobarometry, geochemistry and late Archaean Pleistocene tectonic model for Tamil Nadu geotherms from granulite facies terrain of south (Ramasamy and Balaji 1995), has described that most India. The Journal of Geology, 90, 509-528. of the NE-SW trending lineaments are Pleistocene sinistral faults. The sigmoidal shaped escarps and Horton, R. E. (1945). Erosional development of crestlines of the study area which are roughly in NE- stream and their drainage basins: hydrophysical SW directions may be correlated with the Pleistocene approach to quantitative morphology. Bulletin of the tectonic model for Tamil Nadu (Ramasamy and Balaji Geological Society of America, 56, 275–370. 1995). As profile section analysis of the study area indicates Kumanan, C.J. & Ramasamy, S.M. (2001). Ground that occurrence of dissected ridge and valleys in the water targeting in Kumbam Valley, south India with west and undissected ridges and valleys in east the aid of satellite imagery. Escape Water Resources suggest that the eastern part of the study area must Journal Bangkok, 63-73. be static and the western part might have undergone block upliftment along the N- S trending lineaments Kumanan, C.J. (2001). Remote Sensing revealed (Ramasamy et al., 1995). morphotechtonic anomalies as a tool to neotectonic mapping-experience from south India. In 22nd Asian CONCLUSION Conference on Remote Sensing, November 5-9, The analysis of lineament anomalies, crestlines and 2001, Singapore. escarpments, the pattern and spatial distribution of various ridges and valleys indicates that N-S, NE- Narasimhan, T.N. (1990). Paleochannels of the Palar SW, and E-W trending lineaments are tectonically River, west of Madras city, possible implications for active in the area. This study has further indicated vertical movement. Journal Geological Society of that such type of remote sensing derived India, 36(5), 471-474. morphotectonic analysis in coincidence with detail structural studies can give latent information for Prakash, D. (1999). Cordierite-bearing gneisses from neotectonic mapping. Kodaikanal, South India: textural relationship and P- T conditions. Journal Geological Society of India, 54, ACKNOWLEDGMENTS 347-358. The project from which this article arose was financed by University Grants Commission (P-01- Prakash, D. (2010). New SHRIMP U-Pb Zircon ages 614) to first author. We are thankful to Head of the of metapelitic granulites from NW of Madurai, Department of Geology, Banaras Hindu University Southern India. Journal Geological Society of India, for providing the working facilities. The authors are 76, 371-383. thankful to anonymous reviewers for their valuable suggestions and comments to upgrade the quality of Prakash, D., Arima, M., Mohan, A. (2006). UHT the work. metamorphism in the Palni Hills, South India: insights from feldspar thermometry and phase REFERENCES equilibria. International Geology Review, 48(6), 619- Badgley, C.P. (1965). Structure and Tectonics 638. principles. Harper and Row publishers (pp. 521). New York. Prakash, D., Arima, M., Mohan, A. (2007). Ultrahigh-temperature mafic granulites from Drury, S.A. & Holt, R.W. (1980). Tectonic Panrimalai, South India: Constraints from phase framework of south Indian shield. Tectonophysics, equilibria and thermobarometry. Journal of Asian 65, T1-T15. Earth Sciences, 29, 41-61. Drury, S.A. (1983). A regional tectonic study of the Archaean Chitradurga greenstone belt, Karnataka,

Online version available at: www.crdeep.org 66 International Journal of Basic and Applied Sciences Prakash et. al., Vo. 1 No. 1 ISSN: 2277-1921

Prakash, D., Prakash, S., & Sachan, H.K. (2010). Petrological evolution of the high pressure and Ramasamy, S.M., Panchanathan, S. & Palanivelu, R. ultrahigh temperature mafic granulites from Karur, (1987). Pleistocene Earth movements in Peninsular Southern India: evidence for decompressive and India: evidences from Landsat MSS and thematic cooling retrograde Trajectories. Mineralogy and mapper data. Proceeding of International Geoscience Petrology, 100, 35-53. and Remote Sensing Symposium, Michigan Ramakrishnan, M. (1988). Tectonic evolution of the University, May 18-21, 1987, 1157-1161, Ann Arbor, Archaean high-grade terrain of south India. Journal Michigan. Geological Society of India, 32, 118-119. Singh, C.K., & Srivastava, V. (2011). Ramasamy, S.M. & Balaji, S. (1995). Remote Morphotectonics of the area around Renukoot, Sensing and Pleistocene Tectonics of southern Indian district Sonbhadra, U.P. using Remote Sensing and Peninsula. International Journal of Remote Sensing, GIS Techniques. Journal of the Indian Society of Taylors and Francis London, 16(13), 2375-2391. Remote Sensing, doi 10.1007/s12524-0072-8 (in press). Ramasamy, S.M. & Karthikeyan, N. (1998). Pleistocene/ Holocene Graben along Pondichery- Subramanian, K.S. & Muraleedharan, M.P. (1985). Cumbum valley, Tamil Nadu, India. Geocarto Origin of the Palghat-Gap in southern India. Journal International, 13(3), 83-90. Geological Society of India, 26, 28-37.

Ramasamy, S.M. (1989). Morphotectonic evolution Vaidyanathan, R. (1967). An outline of the of East and West coast of Peninsular India. geomorphic history of India, South of north latitude Geological Survey of India, Spec. Publication No. 24, 18˚. Proc. on seminar on geomorphological studies in 336-1161. India, centre for advanced study in Geology, Sagar, pp. 21-30. Ramasamy, S.M. (1995). Enechlon faults along west coast of India and their geological significance. Vemban, N.A., Subramanyan, K.S., Gopalakrishnan, Current Science, 69(10), 811-814. K. & Venkata Rao, V. (1977). Major Faults/ Dislocatiuons/ Lineaments of Tamil Nadu. Ramasamy, S.M., Balaji, S., Venkatasubramanian, V. Geological Survey of India, Misc.Publications No.31, & Paul, M.A. (1995). Evidences of neotectonism pp. 53-56. along coromandal coast of Tamil Nadu using IRS data INTERFACE. A Bulletin from NRSA Data Centre, 6(4), 5-6.

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