A popular hypothesis of insitu transformation of amphibolite facies gneisses to patchy charnockites by CO2 influx from mantle was proposed primarily from the Kabbaldurga quarries in South Karnataka and subsequently reported from several south Indian localities. However, presence of abundant mafic granulite enclaves in Kabbaldurga and its neighborhood and its implications in relation to patchy charnockite genesis were not discussed. In these quarries patchy charnockites occur in various modes and associations. Some of these patches do occupy structural weak zones, such as shear bands and fold noses in the migmatitic gneisses, but many of the patchy charnockite bodies occur as branching veins transecting the gneissic foliation and hence do not account for fluid pathways. Most importantly, charnockitic leucosomes at margins of mafic granulite enclaves and charnockitic veins within some mafic granulite enclaves indicate a close genetic link between them via dehydration partial melting. This is further corroborated by trace element distribution between them. Dehydration partial melting in mafic rocks in a migmatite terrain such as Kabbaldurga, can explain all the different modes of the patchy charnockites as various stages of segregation and mobility relative to deformation. Abundant mafic granulite enclaves and field features suggesting a relatively late origin of the patchy charnockites, are compelling evidence against the notion of a transition zone. Mantle derivation age of the mafic source rocks (protoliths of mafic granulites) at Kabbaldurga at 3.08 ± 0.08 Ga with small positive ? values is virtually identical to the source of the massive charnockite of Karnataka craton at 3.08 Ga. This could imply a widespread mafic magmatism in South India around 3.0 Ga.
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Bhattacharya, S. and Chaudhary, A. (2013) Kabbaldurga charnockites revisited: Incipient growth or anatectic melt?. Natural Science, 5, 419-436. doi: 10.4236/ns.2013.53055.
 Pichamuthu, C.S. (1960) Charnockite in the making. Nature, 188, 135-136. doi:10.1038/188135a0
 Newton, R.C., Smith, J.V. and Windley, B.E. (1980) Carbonic metamorphism, granulites and crustal growth. Nature, 288, 45-50. doi:10.1038/288045a0
 Janardhan, A.S., Newton, R.C. and Hansen, E.C. (1982) The transformation of amphibolites facies gneiss to charnockite in Southern Karnataka and Northern Tamilnadu, India. Contributions to Mineralogy and Petrology, 79, 130-149. doi:10.1007/BF01132883
 Friend, C.R.L. (1985) Evidence for fluid pathways through Archean crust and the generation of the Closepet granite, Karnataka, South India. Precambrian Research, 27, 239- 250. doi:10.1016/0301-9268(85)90014-2
 Hansen, E.C., Janardhan, A.S., Newton, R.C., Prame, W.K.B.N. and Ravindra Kumar, G.R. (1987) Arrested charnockite formation in Southern India and Sri Lanka. Contributions to Mineralogy and Petrology, 96, 225-244.
 Stahle, H.J., Raith, M., Hoernes, S. and Delfs, A. (1987) Element mobility during incipient granulite formation at Kabbaldurga, Southern India. Journal of Petrology, 28, 803-834. doi:10.1093/petrology/28.5.803
 Friend, C.R.L. and Nutman, A. P. (1992) Response of zircon U-Pb isotopes and whole-rock geochemistry to CO2 fluid-induced granulite-facies metamorphism, Kabbaldurga Karnataka, South India. Contributions to Mineralogy and Petrology, 111, 299-310.
 Brown, M. (1994) The generation, segregation, ascent and emplacement of granite magma: The migmatite-tocrustally-derived granite connection in thickened orogens. Earth-Science Review, 36, 83-130.
 Peterson, J.W. and Newton, R.C. (1989). CO2-enhanced melting of biotite-bearing rocks at deep-crustal pressuretemperature conditions. Nature, 340, 378-380.
 Hansen, E.C., Newton, R.C., Janardhan, A.S. and Lindenberg, S. (1995) Differentiation of Late Archean crust in the Eastern Dharwar craton, Krishnagiri-Salem area, South India. Journal of Geology, 103, 629-651.
 Kumar, G.R.R. and Raghavan, V. (1992) Incipient charnockites in transition zone, khondalite zone and granulite zone of South India: Controlling factors and contrasting mechanisms. Journal Geological Society of India, 39, 293-302.
 Srikantappa, C., Raith, M. and Touret, J.L.R. (1992) Synmetamorphic high density carbonic fluids in the lower crust: Evidence from the Nilgiri granulites, South India. Journal of Petrology, 33, 733-760.
 Santosh, M. and Tsunogae, T. (2003) Extremely high density pure CO2 fluid inclusions in a garnet granulite from Southern India. Journal of Geology, 111, 1-16.
 Santosh, M., Tsunogae, T., Chayama, H., Sato, K., Li, J.H. and Liu, S.J. (2008) Carbonic metamorphism at ultrahightemperatures: Evidence from North China Craton. Earth and Planetary Science Letters, 266, 149-165.
 Naha, K., Srinivasan, R. and Jayaram, S. (1993) Structural relations of charnockites of the Archaean Dharwar craton, southern India. Journal of Metamorphic Geology, 11, 889-895. doi:10.1111/j.1525-1314.1993.tb00198.x
 Mojzsis, S.J., Devaraju, T.C. and Newton, R.C. (2003) Ion Microprobe U-Pb age determination on zircon from the Late Archean granulite facies transition zone of Southern India. Journal of Geology, 111, 407-425.
 Raith, M., Stahle, H.J. and Hoernes, S. (1988) Kabbaldurga-type charnockitization: A local phenomenon in the granulite to amphibolites grade transition zone. Journal of the Geological Society of India, 31, 116-117.
 Bhattacharya, S. and Sen, S.K. (2000) New insights into the origin of Kabbaldurga charnockites, Karnataka, South India. Gondwana Research, 3, 489-506.
 Gopalakrishna, D., Hansen, E.C., Janardhan, A.S. and Newton, R.C. (1986). The southern high-grade margin of the Dharwar Craton. Journal of Geology, 94, 247-260.
 Bhattacharya, S, Chaudhary, A.K., Saw, A.K. and Das, P. (2011) Mafic granulite xenoliths from the East Indian Shield: Evidence for recycled continental crust in the Archean mantle. Lithosphere, 3, 155-169.
 Harris, N.B.W., Santosh, M. and Taylor, P.N. (1994) Crustal evolution in South India: Constraints from Nd isotopes. Journal of Geology, 102, 139-150.
 Sawyer, E.W. (1991). Disequilibrium melting and the rate of melt-residuum separation during migmatization of mafic rocks from the Grenville Front Quebec. Journal of Petrology, 32, 701-738. doi:10.1093/petrology/32.4.701
 Srikantappa, C., Raith, M. and Spiering, B. (1985). Progressive charnockitization of a leptynite-khondalite suite in southern Kerala, India: Evidence for formation of charnockites through a decrease in fluid pressure? Journal of Geological Society of India, 26, 62-83.
 Raith, M. and Srikantappa, C. (1993). Arrested charnockite formation at Kottavattam, Southern India. Journal of Metamorphic Geology, 11, 815-832.
 Devaraju, T.C. and Laajoki, K. (1986) Mineralogy and mineral chemistry of the manganese-poor and manganiferous iron-formations from the high-grade metamorphic terrain of Southern Karnataka, India. Journal Geological Society of India, 28, 134-164.
 Choudhary, A.K., Jain, A.K., Singh, Sandip, Manickavasagam and R.M., Chandra, K. (2011) Crustal accretion and metamorphism of Mesoarchean granulites in Palghat- Cauvery shear zone, Southern India. Journal Geological Society of India, 77, 227-238.
 Taylor, S.R. and McLennan, S.M. (1995) The geochemical evolution of the continental crust. Review Geophysics, 33, 241-265. doi:10.1029/95RG00262