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Tectonics of Southern Granulite Terrain - Kuppam-Palani Geotransect
Gondwana Research (Gondwana Newsletter Section) V 6, No. 4, pp. 947-949. 02003 International Association f o r Gondwana Research, Japan.
GNL
BOOK REVIEW
Tectonics of Southern Granulite Terrain - Kuppam-Palani Geotr ansect M. Santosh Department of Natural Environmental Science, Faculty of Science, Kochi University, Kochi 780-8520, Japan M . Rarnakrishnan (Editor)Tectonics of southern granulite terrain - Kuppam-Palani geotransect. Geological Society of lndia Memoir 50,2003, p . xviii + 434. Price: India - Rs. 500; othev countries - $50. Geological Society of India, l? B. No. 1922, Gavipuram, Bangalore - 560 019, India. The book under review assembles the results from a team of geoscientists in India belonging to various disciplines under a geotransect project funded by the Department of Science and Technology (DST, Government of India). The Geological Society of India is well known for its publication of landmark Memoirs under the leadership of its President, Dr. B.P. Radhakrishna, an outstanding visionary. When the DST and the Geological Society of India joined hands to produce a Memoir volume, we have an excellent compendium for review in this column. Southern India is central to all discussions on supercontinent tectonics since it preserves the record of terrains assembled together over a wide span of earth history, and which were incorporated in some of the oldest supercontinental assemblies. The high-grade rocks here provide windows to the middle and lower levels of the continental crust and preserve important imprints of crustmantle interaction history. In addition, they also preserve the record of multiple tectonothermal events and multiphase exhumation paths. Of particular relevance are the number of shear zones which dissect the southern granulite terrain, which offer important clues to deep crustal structure and tectonic architecture. A multidisciplinary study on the tectonics of the granulite terrain of southern India is therefore of global interest, and I would like t o congratulate the Department of Science and Technology (DST) in formulating this programme and bringing scientists belonging to various disciplines from different institutes under a common umbrella. The seventeen papers assembled in this volume offering a wealth of new information to the global geoscience community reflect the success of the programme led by the DST Gondwann Research, I/: 6, No. 4, 2003
In the introduction to the Memoir, K.R. Gupta and D.N. Awasti from the DST explain how the studies conducted under the project so far have enabled identification of the suturing of a fragmented and imbricated ensemble of crustal blocks in the southern granulite terrain with the Dharwar craton in the north along the Moyar-Bhavani-Mettur shear zone that represents a high angle thrust fault. The shear zones further south show back thrusts and the combined effects of thrusting and transpressional tectonics associated with an upwarp in Moho has resulted in crustal uplift that developed into a flower structure. According to these authors, the southern granulite terrain south of these shear zones possibly represents a fragment of very low angle suture zone between two crustal blocks, one riding over the other. The editor of the Memoir has categorised the papers into four thematic sections: overviews, geophysical studies, structural geology, and petrology-geochemistrygeochronology. Three papers are included in the section on overviews starting with a state-of-the-artsummary on craton-mobile belt relations in southern granulite terrain (M. Ramakrishnan). This is followed by a scholarly review on the constraints on models related to the geological evolution of South Indian shield (TM. Mahadevan). The third overview is titled southern granulite terrain, constraints on reconstruction of the Precambrian assembly of Gondwanaland (K. Gopalakrishnan). Although the paper does not discuss much on the role of southern granulite terrain within the Gondwana assembly, we look forward to integrated models in future when data from the traverse southward into the granulite blocks of Madurai and Trivandrum are also available. The section on geophysical studies opens with the paper by P.R. Reddy and colleagues summarising results from deep seismic reflection and refraction/wide-angle reflection along the traverse. The study provides new insights into both tectonics of the crustal blocks as well
948
as the major shear zones in the area. The authors propose that the opposite dipping reflection fabric obtained in their study is indicative of collision of terrains during late Archaean. The velocity structure with a convergent point below the Palghat-Cauvery Shear Zone furthers the notion that the shear zone represents a terrain boundary between two crustal blocks. The convergent point is along what is termed as the Mettur shear zone. This shear zone has been variably designated as Grady’s fault zone, Dharmapuri suture or Dharrnapuri rift in literature (cf. article by T.M. Mahadevan in the Memoir). According to Reddy and colleagues, the Palghat-Cauvery Shear Zone with a system of faults represents a graben. The blocks to the south and north of this shear zone have subtle differences, but a 4-layered structure is a n important feature of both the regions. According to T.M. Mahadevan (DCS Newsletter, 2003, v. 13, p p ~14-15), the reflection fabric and MOHO undulations may be debatably a product of collision tectonics or merely a picture of the large-scale exhumation of the lower crust a n d accompanying thermal and magmatic episodes. Indeed, Reddy e t al.’s study is significant because it brings to light the crustal architecture in this zone characterised by intracontinental rift zones; however these results need to be carefully evaluated with crustal exhumation models based on petrology, mineral reactions, and pressure-temperature-time paths. This is particularly relevant in the light of recent reports on ultrahigh temperature metamorphism followed by isothermal decompression defining multiple exhumation paths in some of these regions. T. Harinarayana and others summarise results from magnetotelluric investigations along the traverse and present 2-D modelling results. Their study brings out a notable contrast in the deep crustal resistivity between the Archaean and Proterozoic terrains. The anomalous high conducting region beneath the shear zone correlates with large gravity high in this region, thus tracing the structure to great crustal depths. In the subsequent paper, S.B. Singh and others report results from deep resistivity sounding studies across the various tectonic units within the traverse, imaging resistivity contrasts between the Archaean and Proterozoic crustal blocks on either side of the Palghat-Cauvery Shear Zone, and proposing a major zone of terrain amalgamation along this zone. In the subsequent paper, A.P. Singh and colleagues present a wealth of data from 3000 closely spaced gravity and magnetic measurements along the transect. This study confirms the 4-layer seismic model. Their data also indicate Late Archaean continental collision along the transition zone and intense crust-mantle interaction beneath the Palghat-Cauvery Shear Zone. We are overwhelmed with the wealth of information generated by our colleagues in geophysics along this geotraverse.
The transect possibly represents a spectacular cross section along two rifts. According to T.M. Mahadevan (pers. comm., 2003) a thorough scan along the shoulders of the Dharmapuri rift may yield the real cross section of the continental architecture. The scientific contributions from such a study would be of extreme global relevance, as it would provide important insights into the processes within intracontinental rift zones. Mita Rajaram and colleagues conclude that there is a thin magnetic crust in the granulite terrain of southern India from aeromagnetic data, confined to a depth of about 22 km. They infer either a change in lithology/mineralogy at around 22 km depth or that the Curie isotherm is shallow. The former is possibly d u e to magmatic underplating. This is a thought provoking suggestion, since petrologists have long been looking for magmas as sources of heat and fluids for the high (or even ultrahigh) temperature crust in parts of the southern granulite belt, as well as their fluid-rich nature. Mita Rajaram and colleagues’ inferences are, however, not supported by the Reddy et al. model since the latter fails to identify any significant underplating, and perhaps this aspects needs to be addressed in more detail in future studies. S. Roy et al. measure the heat flow and heat production in the gneiss-granulite province from the northern and southern parts of the Palghat-Cauvery Shear Zone. This is by far the first geophysical evidence for the degree of heat flow from the mantle. It also lends strong geophysical support for an enriched mantle, supporting previous geochemical models. This land mark contribution to heat flow studies in southern India with improved methodology and high resolution techniques needs to be extended in future to look at the several intrusive plutons including alkaline rocks that crop out along shear systems and puncture the granulite blocks. T. Radhakrishna and others summarise results from palaeomagnetic studies on mafic dyke swarms in the Dharwar craton. They find no evidence for large-scale crustal displacements in this region since the Paleoproterozoic (1.65 Ga). Perhaps the data presented in this study may have no immediate bearing on evaluating the tectonics of terrain assembly in the southern granulite terrain. However, the finding that these dykes constitute a consanguineous igneous suite related to a large single magmatic event a t ca. 1.65 Ga is of interest. It was around this time in the earth history that one of the major supercontinents (Columbia - in which southern India was a n integral p a r t ) attained its ‘maximum packing’ and started disrupting. The disruption of Columbia started with the development of incipient rifts that provided conduits for mafic magmas from the mantle (J.J.W. Rogers and M. Santosh, Gondwana Research, 2002, v. 5, pp. 5-22). Some of these later opened into major intracrustal rift zones. It would be worthwhile Gondwana Research, I/. 6 , No. 4, 2003
949
to evaluate the mafic dyke activity in relation to Columbia history proposed by Rogers and Santosh. The section on structural geology starts with the paper by A.K. Jain and others who evaluate the kinematics and evolution of the iritracontinental shear zone in the southern granulite terrain. They believe that the ductile nature of the shear zones, as well as the sense of shearing, are important clues to the Proterozoic tectonics and assembly of Gondwana. The Palghat-Cauvery Shear Zone is identified to he a complex and composite shear system, negating earlier views on the lack of any shearing in this zone. T.R.K. Chetty and colleagues present a detailed structural cross-section along the Krishnagiri-Palni corridor, and their results support the earlier conclusion drawn by petrologists that the Moyar-Bhavani Shear Zone might represent a palaeosuture along which the Nilgiri crust was thrust o n t o t h e Dharwar craton. D. Mukhopdhyay and others evaluate the nature of PalghatCauvery ‘lineament’ in view of the terrain assembly in southern India. They provide a different view for the Palghat-Cauvery zone, and believe that although small scale shear zone with diverse age, orientation and sense of movement occur in this zone, there is no evidence for any crustal scale shear zone passing through this area. According to them, the crustal blocks on either side evolved independently and were dragged into parallelism along the zone. Retrogression and hydration observed along the zone resulted by influx of aqueous fluids from granitic melts. The opening paper in the final section is byY.J. Bhaskar Rao and others who present Rb-Sr and Sm-Nd isotope ages from a suite of high-grade rocks across the PalghatCauvery Shear Zone and evaluate the debated ArchaeanNeoproterozoic terrain boundary in southern India. They provide a wealth of new geochronological data and suggest an Archaean-Neoproterozoic terrain boundary along the Karur-Oddanchatram shear zone. We land up with yet another new terrain boundary in southern India! This reflects the importance of the geotransect chosen by the DST as a potential region for studies related to crustal assemblies, and we await further interesting results from this region. Although not a contribution to the Memoir under review, another recent geochronologic study on the granulite blocks of southern India, which was also initiated as part of the DST geotransect project, revealed multiple tectonothermal events in the different blocks. The results were recently published in this journal (M. Santosh et al., 2003, Gondwana Research, v. 6, pp. 29-63), which trace the crustal evolution history in southern India with respect to the terrain assembly and
Gondzunnn Research, V. 6 , No. 4, 2003
supercontinent tectonics. It would be worthwhile to integrate results from both these studies. C. Srikantappa and others document metamorphic evolution and fluid regimes of high-grade rocks along the transect and give a detailed account of mineral assemblages, reactions, pressure-temperature conditions and fluid inclusion characteristics. This systematic study enhances our knowledge on the mineral phase equilibria and fluid regimes in deep continental crust. In another study that was initiated from the same DST project, extremely high density pure CO, fluid inclusions were reported from a garnet granulite near Salem, close to the Palghat-Cauvery Shear Zone (M. Santosh and T Tsunogae, Journal of Geology, 2003, v. 111, pp. 1-16). The CO, trapped in various minerals within this 2.4-2.7 Ga granulite is by far the highest density carbonic fluids yet reported from continental crust and have important implications on deep crustal fluids and crust-mantle interaction processes in southern India. The paper by S.B. Harish Kumar and others present geochemical data on the granitic plutons and gneisses along the traverse, correlating the input of heat and volatiles to the impact of a mantle plume. They invoke the currently popular slab avalanche model as the cause for triggering the production of the plume. The Memoir concludes with a contribution from G.R. Ravindra Kumar and colleague who describe the petrology and geochemistry of rocks from within the Palghat-Cauvery Shear Zone. The volume is well-edited, profusely illustrated and elegantly brought out. The format is attractive, with colour plates and large foldouts of maps. Perhaps, with a little more care in the selection of figures to be reproduced in colour, the problems associated with certain figures could have been avoided. For example, it is difficult to make out the lithologic units from the gray shades in the map appearing in between pages 306 and 307 attached to the paper byY.J. Bhaskar Rao et al. Also, a little more attention on finer details of uniformity and formatting would have enhanced the overall quality of the compilation; for example, terrain and terrane are differently spelt in different places, even in titles. The international community may feel that the title of the book is incomplete, because those who are not aware of the ‘Southern Granulite Terrain’ or ‘Kuppam-Palani’ have no way to identify the region; southern India does not figure in the title of the Memoir. None of these minor shortcomings, however, eclipse the overall value of the Memoir and its importance as a useful reference to all those who are interested in the history of one of the most fabulous segments of the continental crust.
GNL
BOOK REVIEW
Tectonics of Southern Granulite Terrain - Kuppam-Palani Geotr ansect M. Santosh Department of Natural Environmental Science, Faculty of Science, Kochi University, Kochi 780-8520, Japan M . Rarnakrishnan (Editor)Tectonics of southern granulite terrain - Kuppam-Palani geotransect. Geological Society of lndia Memoir 50,2003, p . xviii + 434. Price: India - Rs. 500; othev countries - $50. Geological Society of India, l? B. No. 1922, Gavipuram, Bangalore - 560 019, India. The book under review assembles the results from a team of geoscientists in India belonging to various disciplines under a geotransect project funded by the Department of Science and Technology (DST, Government of India). The Geological Society of India is well known for its publication of landmark Memoirs under the leadership of its President, Dr. B.P. Radhakrishna, an outstanding visionary. When the DST and the Geological Society of India joined hands to produce a Memoir volume, we have an excellent compendium for review in this column. Southern India is central to all discussions on supercontinent tectonics since it preserves the record of terrains assembled together over a wide span of earth history, and which were incorporated in some of the oldest supercontinental assemblies. The high-grade rocks here provide windows to the middle and lower levels of the continental crust and preserve important imprints of crustmantle interaction history. In addition, they also preserve the record of multiple tectonothermal events and multiphase exhumation paths. Of particular relevance are the number of shear zones which dissect the southern granulite terrain, which offer important clues to deep crustal structure and tectonic architecture. A multidisciplinary study on the tectonics of the granulite terrain of southern India is therefore of global interest, and I would like t o congratulate the Department of Science and Technology (DST) in formulating this programme and bringing scientists belonging to various disciplines from different institutes under a common umbrella. The seventeen papers assembled in this volume offering a wealth of new information to the global geoscience community reflect the success of the programme led by the DST Gondwann Research, I/: 6, No. 4, 2003
In the introduction to the Memoir, K.R. Gupta and D.N. Awasti from the DST explain how the studies conducted under the project so far have enabled identification of the suturing of a fragmented and imbricated ensemble of crustal blocks in the southern granulite terrain with the Dharwar craton in the north along the Moyar-Bhavani-Mettur shear zone that represents a high angle thrust fault. The shear zones further south show back thrusts and the combined effects of thrusting and transpressional tectonics associated with an upwarp in Moho has resulted in crustal uplift that developed into a flower structure. According to these authors, the southern granulite terrain south of these shear zones possibly represents a fragment of very low angle suture zone between two crustal blocks, one riding over the other. The editor of the Memoir has categorised the papers into four thematic sections: overviews, geophysical studies, structural geology, and petrology-geochemistrygeochronology. Three papers are included in the section on overviews starting with a state-of-the-artsummary on craton-mobile belt relations in southern granulite terrain (M. Ramakrishnan). This is followed by a scholarly review on the constraints on models related to the geological evolution of South Indian shield (TM. Mahadevan). The third overview is titled southern granulite terrain, constraints on reconstruction of the Precambrian assembly of Gondwanaland (K. Gopalakrishnan). Although the paper does not discuss much on the role of southern granulite terrain within the Gondwana assembly, we look forward to integrated models in future when data from the traverse southward into the granulite blocks of Madurai and Trivandrum are also available. The section on geophysical studies opens with the paper by P.R. Reddy and colleagues summarising results from deep seismic reflection and refraction/wide-angle reflection along the traverse. The study provides new insights into both tectonics of the crustal blocks as well
948
as the major shear zones in the area. The authors propose that the opposite dipping reflection fabric obtained in their study is indicative of collision of terrains during late Archaean. The velocity structure with a convergent point below the Palghat-Cauvery Shear Zone furthers the notion that the shear zone represents a terrain boundary between two crustal blocks. The convergent point is along what is termed as the Mettur shear zone. This shear zone has been variably designated as Grady’s fault zone, Dharmapuri suture or Dharrnapuri rift in literature (cf. article by T.M. Mahadevan in the Memoir). According to Reddy and colleagues, the Palghat-Cauvery Shear Zone with a system of faults represents a graben. The blocks to the south and north of this shear zone have subtle differences, but a 4-layered structure is a n important feature of both the regions. According to T.M. Mahadevan (DCS Newsletter, 2003, v. 13, p p ~14-15), the reflection fabric and MOHO undulations may be debatably a product of collision tectonics or merely a picture of the large-scale exhumation of the lower crust a n d accompanying thermal and magmatic episodes. Indeed, Reddy e t al.’s study is significant because it brings to light the crustal architecture in this zone characterised by intracontinental rift zones; however these results need to be carefully evaluated with crustal exhumation models based on petrology, mineral reactions, and pressure-temperature-time paths. This is particularly relevant in the light of recent reports on ultrahigh temperature metamorphism followed by isothermal decompression defining multiple exhumation paths in some of these regions. T. Harinarayana and others summarise results from magnetotelluric investigations along the traverse and present 2-D modelling results. Their study brings out a notable contrast in the deep crustal resistivity between the Archaean and Proterozoic terrains. The anomalous high conducting region beneath the shear zone correlates with large gravity high in this region, thus tracing the structure to great crustal depths. In the subsequent paper, S.B. Singh and others report results from deep resistivity sounding studies across the various tectonic units within the traverse, imaging resistivity contrasts between the Archaean and Proterozoic crustal blocks on either side of the Palghat-Cauvery Shear Zone, and proposing a major zone of terrain amalgamation along this zone. In the subsequent paper, A.P. Singh and colleagues present a wealth of data from 3000 closely spaced gravity and magnetic measurements along the transect. This study confirms the 4-layer seismic model. Their data also indicate Late Archaean continental collision along the transition zone and intense crust-mantle interaction beneath the Palghat-Cauvery Shear Zone. We are overwhelmed with the wealth of information generated by our colleagues in geophysics along this geotraverse.
The transect possibly represents a spectacular cross section along two rifts. According to T.M. Mahadevan (pers. comm., 2003) a thorough scan along the shoulders of the Dharmapuri rift may yield the real cross section of the continental architecture. The scientific contributions from such a study would be of extreme global relevance, as it would provide important insights into the processes within intracontinental rift zones. Mita Rajaram and colleagues conclude that there is a thin magnetic crust in the granulite terrain of southern India from aeromagnetic data, confined to a depth of about 22 km. They infer either a change in lithology/mineralogy at around 22 km depth or that the Curie isotherm is shallow. The former is possibly d u e to magmatic underplating. This is a thought provoking suggestion, since petrologists have long been looking for magmas as sources of heat and fluids for the high (or even ultrahigh) temperature crust in parts of the southern granulite belt, as well as their fluid-rich nature. Mita Rajaram and colleagues’ inferences are, however, not supported by the Reddy et al. model since the latter fails to identify any significant underplating, and perhaps this aspects needs to be addressed in more detail in future studies. S. Roy et al. measure the heat flow and heat production in the gneiss-granulite province from the northern and southern parts of the Palghat-Cauvery Shear Zone. This is by far the first geophysical evidence for the degree of heat flow from the mantle. It also lends strong geophysical support for an enriched mantle, supporting previous geochemical models. This land mark contribution to heat flow studies in southern India with improved methodology and high resolution techniques needs to be extended in future to look at the several intrusive plutons including alkaline rocks that crop out along shear systems and puncture the granulite blocks. T. Radhakrishna and others summarise results from palaeomagnetic studies on mafic dyke swarms in the Dharwar craton. They find no evidence for large-scale crustal displacements in this region since the Paleoproterozoic (1.65 Ga). Perhaps the data presented in this study may have no immediate bearing on evaluating the tectonics of terrain assembly in the southern granulite terrain. However, the finding that these dykes constitute a consanguineous igneous suite related to a large single magmatic event a t ca. 1.65 Ga is of interest. It was around this time in the earth history that one of the major supercontinents (Columbia - in which southern India was a n integral p a r t ) attained its ‘maximum packing’ and started disrupting. The disruption of Columbia started with the development of incipient rifts that provided conduits for mafic magmas from the mantle (J.J.W. Rogers and M. Santosh, Gondwana Research, 2002, v. 5, pp. 5-22). Some of these later opened into major intracrustal rift zones. It would be worthwhile Gondwana Research, I/. 6 , No. 4, 2003
949
to evaluate the mafic dyke activity in relation to Columbia history proposed by Rogers and Santosh. The section on structural geology starts with the paper by A.K. Jain and others who evaluate the kinematics and evolution of the iritracontinental shear zone in the southern granulite terrain. They believe that the ductile nature of the shear zones, as well as the sense of shearing, are important clues to the Proterozoic tectonics and assembly of Gondwana. The Palghat-Cauvery Shear Zone is identified to he a complex and composite shear system, negating earlier views on the lack of any shearing in this zone. T.R.K. Chetty and colleagues present a detailed structural cross-section along the Krishnagiri-Palni corridor, and their results support the earlier conclusion drawn by petrologists that the Moyar-Bhavani Shear Zone might represent a palaeosuture along which the Nilgiri crust was thrust o n t o t h e Dharwar craton. D. Mukhopdhyay and others evaluate the nature of PalghatCauvery ‘lineament’ in view of the terrain assembly in southern India. They provide a different view for the Palghat-Cauvery zone, and believe that although small scale shear zone with diverse age, orientation and sense of movement occur in this zone, there is no evidence for any crustal scale shear zone passing through this area. According to them, the crustal blocks on either side evolved independently and were dragged into parallelism along the zone. Retrogression and hydration observed along the zone resulted by influx of aqueous fluids from granitic melts. The opening paper in the final section is byY.J. Bhaskar Rao and others who present Rb-Sr and Sm-Nd isotope ages from a suite of high-grade rocks across the PalghatCauvery Shear Zone and evaluate the debated ArchaeanNeoproterozoic terrain boundary in southern India. They provide a wealth of new geochronological data and suggest an Archaean-Neoproterozoic terrain boundary along the Karur-Oddanchatram shear zone. We land up with yet another new terrain boundary in southern India! This reflects the importance of the geotransect chosen by the DST as a potential region for studies related to crustal assemblies, and we await further interesting results from this region. Although not a contribution to the Memoir under review, another recent geochronologic study on the granulite blocks of southern India, which was also initiated as part of the DST geotransect project, revealed multiple tectonothermal events in the different blocks. The results were recently published in this journal (M. Santosh et al., 2003, Gondwana Research, v. 6, pp. 29-63), which trace the crustal evolution history in southern India with respect to the terrain assembly and
Gondzunnn Research, V. 6 , No. 4, 2003
supercontinent tectonics. It would be worthwhile to integrate results from both these studies. C. Srikantappa and others document metamorphic evolution and fluid regimes of high-grade rocks along the transect and give a detailed account of mineral assemblages, reactions, pressure-temperature conditions and fluid inclusion characteristics. This systematic study enhances our knowledge on the mineral phase equilibria and fluid regimes in deep continental crust. In another study that was initiated from the same DST project, extremely high density pure CO, fluid inclusions were reported from a garnet granulite near Salem, close to the Palghat-Cauvery Shear Zone (M. Santosh and T Tsunogae, Journal of Geology, 2003, v. 111, pp. 1-16). The CO, trapped in various minerals within this 2.4-2.7 Ga granulite is by far the highest density carbonic fluids yet reported from continental crust and have important implications on deep crustal fluids and crust-mantle interaction processes in southern India. The paper by S.B. Harish Kumar and others present geochemical data on the granitic plutons and gneisses along the traverse, correlating the input of heat and volatiles to the impact of a mantle plume. They invoke the currently popular slab avalanche model as the cause for triggering the production of the plume. The Memoir concludes with a contribution from G.R. Ravindra Kumar and colleague who describe the petrology and geochemistry of rocks from within the Palghat-Cauvery Shear Zone. The volume is well-edited, profusely illustrated and elegantly brought out. The format is attractive, with colour plates and large foldouts of maps. Perhaps, with a little more care in the selection of figures to be reproduced in colour, the problems associated with certain figures could have been avoided. For example, it is difficult to make out the lithologic units from the gray shades in the map appearing in between pages 306 and 307 attached to the paper byY.J. Bhaskar Rao et al. Also, a little more attention on finer details of uniformity and formatting would have enhanced the overall quality of the compilation; for example, terrain and terrane are differently spelt in different places, even in titles. The international community may feel that the title of the book is incomplete, because those who are not aware of the ‘Southern Granulite Terrain’ or ‘Kuppam-Palani’ have no way to identify the region; southern India does not figure in the title of the Memoir. None of these minor shortcomings, however, eclipse the overall value of the Memoir and its importance as a useful reference to all those who are interested in the history of one of the most fabulous segments of the continental crust.