Abstract
From the recent research by several workers it is becoming evident that the geology, particularly the structure and metamorphism of the Proterozoic sedimentary basins are not simple, which can at times be compared with foldthrust belts. In the southern part of the Pranhita-Godavari (PG) basin in its close proximity with the Eastern Ghat Mobile belt (EGMB) in the east and Eastern Dharwar craton (EDC) in the west there is a supracrustal association exposed near Kothagudem in Andhra Pradesh, which was earlier referred in published literature as Mulug and Mallampalle Groups of lower Pakhal sequence. From the field and petrological studies we have attempted to enumerate here the deformation and metamorphic characteristics and the tectonic setup of this schistose unit. It is revealed from our studies that this lithotectonic unit represents a strongly deformed and metamorphosed deeper crustal supracrustal assemblage, which is in sharp contrast with the unmetamorphosed and weakly deformed true Pakhal sequence occurring in the western part of the area. In order to explain the spatial association of these two contrasting litho-tectonostratigraphic units we propose a westerly verging thrust model, supported by convincing structural and metamorphic evidences, whereby the schistose terrane is tectonically juxtaposed with the unmetamorphosed Pakhal sequence. Imprints of polyphase deformation and metamorphism could be recognized to document the complex history of the schistose terrane. At least three generation structures (D1, D2, D3) are identifiable in quartzite-metapelite-carbonate assemblages. D1 and D2 are quite pronounced and conspicuous by the development of respective planar and linear elements, while D3 is relatively mild in intensity. Development of different generations of folds (F1, F2, F3) and associated axial planar cleavage/ schistosity (S1, S2, S3) together with different types of fold interference patterns, demonstrated mainly in carbonate rocks, bear testimony to successive events of fold formation as a result of superposed deformations. The tectonic trend defined by N-S to NNESSW (approx.) elongation of the belt results from the combined effects of all the three deformations. The structural pattern indicate a possible combination of predominantly pure shear and subordinate simple shear transpressional type of tectonism accompanied by considerable E-W (approx.) tectonic shortening across the belt. The rocks show low to medium grade metamorphism with the characteric appearances of chlorite, biotite, andalusite, chloritoid, staurolite and garnet porphyroblasts in pelitic rocks. From a study on ‘Si-Se’ tectonites in different mineral assemblages we have elucidated the history of deformation and metamorphic mineral growth in this assemblage. A variety of relationship exists between ‘Si’ and ‘Se’ demonstrating multi-stage growth of porphyroblasts, particularly of andalusite and staurolite, which took place during at least two deformational events. The important mineral assemblages include: (i) garnetbearing andalusite- biotite schist, (ii) garnet free andalusite-biotite schist, (iii) staurolite-andalusite-garnet-mica schist, (iv) andalusite-chloritoid-muscovite schist, and (v) garnet-chloritoid-chlorite-muscovite schist. The study establishes a prograde metamorphic evolution in each rock type followed by a retrograde history. But the relative timing of prograde and retrograde reactions with respect to successive phases of deformation varies widely.
Similar content being viewed by others
References
Baker, A.J. (1994) Interpretation of porphyroblast inclusion trails: Limitations imposed by growth kinetics and strain rates. Jour. Metam. Geol., v.12, pp.681–694.
Bell, T.H. (1985) Deformation partitioning and porphyroblast rotation in metamorphic rocks: a radical reinterpretation. Jour. Metam. Geol. v.3, pp.109–118.
Bell, T.H. and Johnson, S.E. (1989) Porphyroblast inclusion trails: the key to orogenesis. Jour. Metam. Geol. v.7, pp.109–118.
Bell, T.H. and Rubenach, M.J. (1983) Sequential porphyroblast growth and crenulation cleavage development during progressive deformation. Tectonophysics, v.92, pp.171–194.
Bell, T.H., Forde, A. and Hayward, N. (1992) Do smoothly curved, spiral-shaped inclusion trails signify porphyroblast rotation? Geology, v.20, pp.59–62.
Bickle, M.J. and Archibald, N.J. (1984) Chloritoid and staurolite stability: implications for metamorphismin the Archaean Yilgarn Block, western Australia. Jour. Metam. Geol., v.2, pp.179–203.
Butler, R.F., Gehrels, G.E., Mcclelland, W.C., May, S.R. and Klepacki, D. (1989) Discordant palaeomagnetic poles from the Canadian Coast Plutonic Complex: regional tilt rather than large scale displacement? Geology, v.17,pp.691–694.
Chaudhuri, A.K. and Howard, J.D. (1985) Ramgundam Sandstone: a middle Proterozoic shoal-bar sequence. Jour. Sedimen. Petrol., v.55, pp.392–397.
Coney, P.J., Jones, D.L. and Monger, J.W.H. (1980) Cordilleran suspect terranes. Nature, v.288, pp.329–333.
Connolly J.A.D. (2006). Computation of phase equilibria by linear programming: a tool for geodynamic modeling and its application to subduction zone decarbonation. Earth Planet. Sci. Lett., v.236, pp.524–541.
Conrad, J.E., Hein, J.R., Chaudhuri, A.K., Patranabis-Deb, S., Mukhopadhyay, J., Deb, G.K. and Beukes, N.J. (2010) Constraints on the development of Proterozoic basins in Central India from 40Ar/39Ar analyses of authigenic glauconite minerals. Geol. Soc. Amer. Bull., v.123, pp.11–12.
Das, S., Nasipuri, P., Bhattacharya, A. and Swaminathan, S. (2008) The thrust-contact between the Eastern Ghats Belt and the adjoining Bastar craton (Eastern India): evidence from mafic granulites and tectonic implications. Precambrian Res., v.160, pp.70–85.
Deb, G. (1999) Deformation style and evolution of the structures in the Penganga Group, Pranhita-Godavari valley, India. Geology of the Pranhita-Godavari Valley: Current status and future directions. Indian Stat. Inst., Calcutta. pp.14–16.
Ganguly, J. (1969). Chloritoid stability and related paragenesis: theory, experiment and application. Amer. Jour. Sci., v.267, pp.910–944.
Ganguly, J. (1972). Staurolite stability and related parageneses: theory, experiments and applications. Journal of Petrology; v.13, pp.335–365.
Ghosh, G. and Saha, D. (1999) Deformation of the Proterozoic Somanpalli Group, Pranhita-Godavari Velley–implication for a Mesoproterozoic basin inversion. Geology of the Pranhita- Godavari valley: Current Status and Future Directions: Indian Statistical Institute, Calcutta. pp.14–16.
Gibbons, W. (1990) Transcurrent ductile shear zones and the dispersal of the Avalon Superterrane. In: R.S. D’Lemos R.A. Strachan and C.G. Topley (Eds.), The Cadomian Orogeny Spec. Publ. Geol. Soc. London, v.51, pp.407–423.
Gibbons, W. (1994) Suspect Terranes. In: Paul L. Hancock (Ed.), Continental Deformation. Pergamon Press, U.K. pp.305–319.
Holland, T.J.B. and Powell, R. (1990) An enlarged and updated internally consistent thermodynamic dataset with uncertainties and corrections: the system K2O–Na2O–CaO–MgO–FeO–Fe2O3–Al2O3–TiO2–SiO2–C–H2–O2. Jour. Metam. Geol., v.8, pp.89–124.
Hoscheck, G. (1967) Untersuchungen zum Stabilitatscbereich von Chlorotoid und Staurolith. Contributions to Mineralogy and Petrology, v.14, pp.123–162.
Irwin, W.P. (1972) Terranes of the western Palaeozoic and Triassic belt in the southern Klamath Mountains, California, U.S. Geol. Surv. Prof. Pap.v. 800-C, pp.103–111.
Johnson, S.E. (1993) Unravelling the spirals: a serial thin-section study and three-dimensional computer–aided reconstruction of spiral-shaped inclusion trails in garnet porphyroblasts. Jour. Metam. Geol. v.11, pp.621–634.
Kaila, K.L. and Tiwari, H.C. (1985) Structural trends in the Cuddapah basin from deep seismic soundings (DSS) and their tectonic implication. Tectonophysics, v.115, pp.69–86.
King, W. (1881) Geology of the Pranhita-Godavari valley. Geol. Surv. India Mem., v.18, pp.151–311.
Mathur, S.M. (1982) Precambrian sedimentary sequences of India; their geochronology and correlations. Precambrian Res., v.18, pp.139–144.
Mcwilliams, M.O. and Howell, D.G. (1982) Exotic terranes of western California. Nature, v.297, pp.215–217.
Meijerink, A. M. J., Rao, D.P. and Rupke, J. (1984) Stratigraphy and structural development of Precambrian Cuddapah Basin, SE India. Precambrian Res., v.26, pp.57–104.
Moeen, S. (1998) P±T estimates from the Nellore schist belt (India) and evidence for superimposed metamorphic events. Geol. Jour., v.33, pp.1–15.
Mosar, J., Stampfli, G.S. and Girod, F. (1996) Western Préalpes Médianes Romandes: timing and structure. A Review, Eclogae Geologicae Helvetiae.v. 89, pp.389–425.
Kumar, R., Okudaira, T. and Yoshida, M. (2000) Neoproterozoic Deformation at a Boundary Zone between the Nellore- Khammam Schist Belt and Pakhal Basin, SE India: Strain Analysis of Deformed Pebbles. Gondwana Res., v.3, No.3, pp.349–359.
Okudaira, T., Hamamoto, T., Hari Prasad, B. and Kumar, R. (2001) Sm–Nd and Rb–Sr dating of amphibolite from the Nellore–Khammam schist belt, SE India: constraints on the collision of the Eastern Ghats terrane and Dharwar–Bastar craton. Geol. Magz., v.138, No.4, pp.495–498.
Pascoe, E.H. (1973) A Manual of the Geology of India and Burma. 3rd ed., v.1, Geol. Surv. India, Calcutta. pp. 371–372.
Passchier, C. W. and Trouw, R. A.J. (2005) Micro-tectonics. 2nd edition. Springer, Germany, 366p.
Passchier, C.W., Trouw, R.A.J., Zwart, H.J. and Vissers, R.L.M.(1992) Porphyroblast rotation: Eppur si muove? Jour. Metam. Geol. v.10, pp.283–294.
Rammohana Rao, T. (1964) The age of the Pakhals of the Godavari Valley. Proc. Indian Acad. Sci., v.60, pp.70–80.
Rammohana Rao, T. (1970) Metamorphism of the Pakhals of Yellandlapad area, Andhra Pradesh. West Commemoration Volume, pp.225–235.
Rammohana Rao, T. (1978) Structural control of metamorphism of the Pakhals of the Yellandlapad area, Andhra Pradesh. Proc. Sym. on the ‘Purana Formations of Peninsular India.’ University of Sagar, 1970, pp. 74–77.
Ramsay, J.G. and Lisle, R. (2000) The Techniques of Modern Structural Geology. Academic Press, London, 1061p.
Ramsay, J.G. (1967) Folding and fracturing of rocks. McGraw-Hill. New York, 568p.
Roberts D. (1988) The terrane concept and the Scandenavian Caledonides: a synthesis: Norges Geol. Undersock. Bull. v.413, pp.93–99.
Saha, D. (1990) Internal Geometry of a thrust sheet, eastern Proterozoic Belt, Godavari Valley, South India. Proc. Indian Acad. Sci. (Earth Planet. Sci.), v.99, pp.339–355.
Saha, D. (1992a) Contractional deformation of a faulted sedimentary prism. Indian Jour. Geol., v.64, pp.365–376.
Saha, D. (1992b) Geologic constrains on depth of tectonic mobility in a Proterozoic intracratonic basin. Indian Minerals, v.46, pp.259–270.
Saha, D. and Ghosh, G. (1998) Lithostratigraphy of deformed Proterozoic rocks from around the confluence of the Godavari and Indravati rivers, South India, Indian Jour. Geol., v.70, pp.217–230.
Saha, D. (2002) Multi-stage deformation in the Nallamalai Fold Belt, Cuddapah Basin, South India–Implications for Mesoproterozoic Tectonism along Southeastern Margin of India. Gondwana Res., v.5, pp.701–719.
Saha, D. and Chakraborty, S. (2003) Deformation pattern in the Kurnool and Nallamalai Groups in the northeastern part (Palnad area) of the Cuddapah basin, South India and its implication on Rodinia/Gondwana Tectonics. Gondwana Res. v.6, pp.573–583.
Saha, D. (2004) Structural asymmetry and Plate tectonic set-up for a Proterozoic Fold and Thrust belt: Nallamalai Fold Belt and Adjoining Terrain, South India. Geol. Surv. India Spec. Publ., v.84, pp.101–119.
Saha, D., Ghosh, G., Chakraborty, A.K. and Chakraborty, S. (2009) Comparable Neoproterozoic sedimentary sequences in Palnad and Kurnool subbasins and their paleogeographic and tectonic implications. Indian Jour. Geol., v.78, pp.175–192.
Saha, D., Chakraborti, S. and Tripathy, V. (2010) Intracontinental thrusts and inclined transpression along eastern margin of the Eastern Dharwar Craton, India. Jour. Geol. Soc. India, Spec. Issue, v.75(1), pp.323–337.
Sarvathaman, H. (1995) Amphibolites of Khammam schist belt: evidence for the Precambrian Fe-tholeiitic volcanism in marginal zone. Indian Mineralogist, v.49, pp.177–86.
Schoneveld C. (1977) A study of some typical inclusion patterns in strongly paracrystalline rotated garnets. Tectonophysics. v.39.pp.453–471.
Shaw, R.K., Arima, M., Kagima, H., Fanning, C. M., Shiraishi, K. and Motoyoshi, Y. (1997) Proterozoic events in the Eastern Ghats belt, India: evidence from Rb-Sr, Sm-Nd systematic and SHRIMP dating. Jour. Geol., v.105, pp.645–656.
Spear, F.S. (1993). Metamorphic Phase Equilibria and Pressure- Temperature-Time Paths, Monograph 1. Mineralogical Society of America, Washington DC.
Sreenivasa Rao, T. (1987) The Pakhal Basin–a perspective. Purana Basins of Peninsular India. Mem. Geol. Soc. India No.6, pp.161–187.
Stuwe, K. and Ehlers, K. (1997). Multiple metamorphic events at Broken Hill, Australia. Evidence from Chloritoid-bearing parageneses in the Nine-Mile Mine Region. Jour. Petrol., v.30, No.9, pp.1167–1186.
Tinkhan, D.K., Zuluaga, C.A. and Stowell, H.H. (2001) Metapelitic phase equilibria modeling in MnKFMASH: The effect of variable Al2O3 and MgO/(MgO + FeO) on mineral stability. Mineral. Soc. Amer., Geol. Materials Re., v.3, no.1, pp.1–42.
Tripathy, V. and Saha, D. (2010) Structure and low grade metamorphism of the east central part of the Proterozoic Nallamalai Fold Belt, South India–thrust stacking and discontinuous metamorphic gradients along eastern margin of east Dharwar craton. Indian Jour. Geol., v.80, nos.1–4, pp.173–188.
Vernon, R.H. (1988) Microstructural evidence of rotation and non-rotation of mica porphyroblasts. Jour. Metam. Geol., v.6, pp.595–601.
Vernon, R.H. (1975) Deformation and recrystallization of a plagioclase grain. Amer. Mineralogist. v.60. pp.884–888.
Vernon, R.H. (1976) Metamorphic processes. Allen and Unwin, London.
Vijay Kumar, K., Narsimha Reddy, M. and Leelanandam, C. (2006) Dynamic melting of the Precambrian mantle: Evidence from Rare Earth Elements of the amphibolites from Nellore- Khammam schist belts, South India. Contrib. Mineral. Petrol., v.152, pp. 2443–256.
Vijaya Kumar and Leelanandan, C. (2008) Evolution of the Eastern Ghats belt, India: a plate tectonic perspective. Jour. Geol. Soc. India, v.72, pp.720–749.
Wang, P. and Spear, F. S. (1991). A field and theoretical analysis of garnet + chlorite + chloritoid + biotite assemblage from the tri-state (MA, CT, NY) area, USA. Contrib. Mineral. Petrol., v.106, pp.217–235.
Wei, C. J., Powell, R. and Clarke, G.L. (2004) Calculated pahse equilibria for low- and medium-pressure metapelites in the KFMASH and KMnFMASH systems. Jour. Metamorph. Petrol., v.22, pp.495–508.
Williams, P.F. and Jiang, D. (1999) Rotating garnets. Jour. Metam. Geol. v.17. pp.367–378.
Zwart, H.J. (1962) On the determination of polymetamorphic mineral associations, and its application to the Bosost area (central Pyrenees). Geol. Rdsch. v.52. pp.38–65.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Roy, A., Chakraborty, K. & RoyChoudhury, M. Deformation and metamorphism of a schistose terrane accreted with the Proterozoic Pakhal sequence of Godavari valley near Kothagudem, Andhra Pradesh. J Geol Soc India 85, 45–70 (2015). https://doi.org/10.1007/s12594-015-0193-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12594-015-0193-8