Abstract
Multiple deformation in all the Precambrian metamorphic-migmatitic rocks has been reported from Rajasthan during the last three decades. But, whereas the Aravalli Group and the Banded Gneissic Complex show similarity in the style and sequence of structures in all their details, the rocks of the Delhi Group trace a partly independent trend. Isoclinal folds of the first generation (AF1) in the rocks of the Aravalli Group had gentle westerly plunge prior to later deformations. These folds show reclined, inclined, and upright attitude as a result of coaxial upright folding (AFla). Superposition of upright folds (AF2) of varying tightness, with axial plane striking N to NNE, has resulted in interference patterns of diverse types in the scale of maps, and deformation of earlier planar and linear structures in the scale of hand specimens. The structures of the third generation (AF3) are either open recumbent folds or reclined conjugate folds with axial planes dipping gently towards NE or SW. Structures of the last phase are upright conjugate folds (AF4) with axial planes striking NNE-SSW and E-W.
The Banded Gneissic Complex (BGC) underlies the Aravalli Group with a conglomerate horizon at the contact, especially in southern Rajasthan. But, for a major part of central and southern Rajasthan, migmatites representing BGC show a structural style and sequence identical with those in the Aravalli Group. Migmatization, broadly synkinematic with the AF1 folding, suggests extensive remobilization of the basement. Very rare relict fabric athwart to and overprinted by structures of AF, generation provide tangible evidence for a basement.
Although the structures of later phases in the rocks of the Delhi Group (DF3 and DF4) match with the late-phase structures in the Aravalli Group (AF3 and AF4), there is a contrast in the structural history of the early stages in the rocks of the two groups. The folds of the first generation in the Delhi Group (DF1) were recumbent to reclined with gentle plunge towards N to NNE or S to SSW. These were followed by coaxial upright folds of varying tightness (DF2). Absence of westerly trending AF1 folds in the Delhi Group, and extreme variation in plunge of the AF2 folds in contrast with the fairly constant plunge of the DF2 folds, provide evidence for an angular unconformity between the Aravalli and the Delhi Groups.
Depending on the importance of flattening attendant with and following buckling during AF2 deformation, the lineations of AF1 generation show different patterns. Where the AF1 lineations are distributed in circular cones around AF2 axes because of flexural-slip folding in layered rocks with high viscosity contrast, loci of early lineations indicate that the initial orientation of the AF1 axes were subhorizontal, trending towards N280°.
The orientation of the axial planes of the earlier folds has controlled the development of the later folds. In sectors where the AF, axial planes had N-S strike and gentle dips, or E-W strike with gentle to steep dips, nearly E-W horizontal compression during AF2 deformation resulted in well-developed AF2 folds. By contrast, where the AF, axial planes were striking nearly N-S with steep dips, E-W horizontal compression resulted in tightening (flattening) of the already isoclinal AF1 folds, and probably boudinage structures in some instances, without the development of any AF2 folds. A similar situation obtains when DF4 deformation is superposed on earlier structures. Where the dominant S-planes were subhorizontal, N-S compression during DF4 deformation resulted in either chevron folds with E-W striking axial plane or conjugate folds with axial plane striking NE and NW. In zones with S-planes striking E-W and dipping steeply, the N-S compression resulted in flattening of the earlier folds without development of DF4 folds.
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References
Ahmed T and Rajamani V 1988 Geochemistry and petrogenesis of mafic inclusion within the Banded Gneissic Complex, near Nathdwara: implications to BGC-Aravalli relationship;Geol. Soc. India Mem. 7 327–340
Anderson T B 1974 The relationship between kink-bands and shear fractures in the experimental deformation of slate;J. Geol. Soc. London 130 367–382
Bhola A M and Sabarwal K K 1982 Deformation structures in the Delhi Group of rocks around Nibhor, Rajasthan;J. Geol. Soc. India 23 521–538
Bhola A M and Varadarajan S 1981 Polyphase deformation in the Ajabgarh Stage rocks, Delhi Group, around Narnaul, Mohindergarh district, Haryana, India;J. Geol. Soc. India 22 153–163
Chattopadhyay A K and Mukhopadhyay D 1985 Delhi—pre-Delhi relation along the eastern flank of the Delhi synclinorium near Hira-ka-Baris, southeast of Beawar, central Rajasthan;Indian J. Earth Sci. 12 145–149
Chaudhuri A K and Mukherjee D 1978 Superposed folding in nepheline syenites and associated metamorphites around Kishangarh, Rajasthan, India;J. Geol. Soc. India 19 46–52
Choudhary A K, Gopalan K and Sastry C A 1984 Present status of the geochronology of the Precambrian rocks of Rajasthan;Tectonophysics 105 131–140
Crookshank H 1948 Minerals of the Rajputana pegmatites;Trans. Mining Geol. Met. Inst. India 42 105–189
Das A R 1988 Geometry of the superposed deformation in the Delhi Supergroup rocks, north of Jaipur, Rajasthan;Geol. Soc. India Mem. 7 247–266
Dasgupta S C 1982 Superposed folding in the Precambrians of the Pur area, Bhilwara district, Rajasthan;Q. J. Geol. Min. Met. Soc. India 54 1–17
Dasgupta S P 1964 Structural evolution of the Khetri Copper Belt, Rajasthan, India;Rep. 22nd Int. Geol. Congr., New Delhi 4 356–373
Dasgupta S P 1968 The structural history of the Khetri Copper Belt, Jhunjhunu and Sikar districts, Rajasthan, India;Geol. Surv. India Mem. 98 1–170
Gangopadhyay A and Mukhopadhyay D 1987 Structural geometry of the Delhi Supergroup near Sendra—an example of the impress of granite diapirism on tectonic structures. InGeologic evolution of Peninsular India-Petrological and structural aspects (ed) A K Saha (New Delhi: Hindustan Publishing Corporation)Recent Researches in Geol. 13 45–60
Gangopadhyay P K 1972 Structure and tectonics of Alwar region in northeastern Rajasthan, India, with special reference to Precambrian stratigraphy;Proc. 24th Int. Geol. Congr., Montreal Vol. 1, pp. 110–125
Gangopadhyay P K and Chatterjee N 1971 Structural pattern of rocks around Dariba, Alwar district, Rajasthan, with special reference to copper occurrence;J. Geol. Soc. India 12 43–50
Gangopadhyay P K and Das D 1974 Dadikar granite: a study on a Precambrian intrusive body in relation to structural environment in north-eastern Rajasthan;J. Geol. Soc. India 15 189–199
Gangopadhyay P K and Lahiri A 1984 Earth’s crust and evolution of the Delhi Supergroup in central Rajasthan;Indian J. Earth Sci. CEISM seminar pp. 92–113
Gangopadhyay P K and Lahiri A 1986 Some problems on geochronology of Precambrian rocks in Rajasthan: an appraisal;Indian J. Earth Sci. 13 169–188
Gangopadhyay P K and Pyne T K 1980 Delhi—pre-Delhi relation at Lalsot, Jaipur district, Rajasthan: a reappraisalJ. Geol. Soc. India 21 128–137
Gangopadhyay P K and Sen R 1975 Structural framework in Delhi Group of rocks with special reference to interference patterns: a study around Kushalgarh, north-eastern Rajasthan;J. Geol. Soc. India 16 317–325
Gay N C and Weiss L E 1974 The relationship between principal stress directions and geometry of kinks in foliated rocks;Tectonophysics 21 287–300
Ghosh S K and Chatterjee A 1985 Patterns of deformed lineations over later folds formed by buckling and flattening;J. Struct. Geol. 7 651–666
Ghosh S K and Naha K 1962 Recumbent folding in migmatites in the Archean “basement”, north of Nathdwara, Raiasthan, India;Am. J. Sci. 260 241–248
Gupta B C 1934 The geology of central Mewar;Geol. Surv. India Mem. 65 107–169
Gupta B C and Mukerjee P N 1938 The geology of Gujarat and southern Rajputana;Geol. Surv. India Rec. 73 163–208
Gupta S N, Arora Y K, Mathur R K, Iqbaluddin, Prasad B, Sahai T N and Sharma S B 1980 Lithostratigraphic map of Aravalli region, southern Rajasthan and northeastern Gujarat;Geol. Surv. India Publ. (Hyderabad)
Heron A M 1953 The geology of central Rajputana;Geol. Surv. India Mem. 79 1–389
Macdougall J D, Gopalan K, Lugmair G W and Roy A B 1983 The Banded Gneiss Complex of Rajasthan, India: early crust from depleted mantle at ∼ 3.5 AE?Eos 64 351
Mitra A 1970 Structural analysis of the metasediments and associated metavolcanics around Sheopura, district Ajmer, Rajasthan;Q. J. Geol. Min. Met. Soc. India 42 197–205
Mohanty S 1982 Structural studies around Kathar, Udaipur district, Rajasthan;J. Geol. Soc. India 23 209–218
Mohanty S and Naha K 1986 Stratigraphie relations of the Precambrian rocks in the Salumbar area, southeastern Rajasthan;J. Geol. Soc. India 27 479–493
Mukhopadhyay D and Dasgupta S 1978 Delhi—pre-Delhi relations near Badnor, central Rajasthan;Indian J. Earth Sci. 5 183–190
Mukhopadhyay D and Ghosh K P 1980 Deformation of early lineation in the Aravalli rocks around Fatehpur, Udaipur district, southern Rajasthan, India;Indian J. Earth Sci. 7 64–75
Mukhopadhyay D and Sengupta S 1979 “Eyed Folds” in Precambrian marbles from southeastern Rajasthan, India;Geol. Soc. Am. Bull. 90 397–404
Naha K, Chaudhuri A K and Bhattacharyya A C 1966 Superposed folding in the older Precambrian rocks around Sangat, central Rajasthan, India;N. Jb. Geol. Palaont. Abh. 126 205–231
Naha K, Chaudhuri A K and Mukherji P 1967 Evolution of the Banded Gneissic Complex of central Rajasthan, India;Contrib. Mineral. Petrol. 15 191–216
Naha K and Halyburton R V 1974a Early Precambrian stratigraphy of central and southern Rajasthan, India;Precambrian Res. 1 55–73
Naha K and Halyburton R V 1974b Late stress systems deduced from conjugate folds and kink bands in the “Main Raialo Syncline”, Udaipur district, Rajasthan, India;Geol. Soc. Am. Bull. 85 251–256
Naha K and Halyburton R V 1977a Structural pattern and strain history of a superposed fold system in the Precambrian of central Rajasthan, India. I. Structural patterns in the “Main Raialo Syncline”, central Rajasthan;Precambrian Res. 4 39–84
Naha K and Halyburton R V 1977b Structural pattern and strain history of a superposed fold system in the Precambrian of central Rajasthan, India. II. Strain history;Precambrian Res. 4 85–111
Naha K and Majumdar A 1971a Re-interpretation of the Aravalli basal conglomerate at Morchana, Udaipur district, Rajasthan, western India;Geol. Mag. 108 111–114
Naha K and Majumdar A 1971b Structure of the Rajnagar marble band and its bearing on the Early Precambrian stratigraphy of central Rajasthan, western India;Geol. Rund. 60 1550–1571
Naha K, Mitra S K and Biswal T K 1987 Structural history of the rocks of the Delhi Group around Todgarh, central Rajasthan;Indian J. Geol. 59 126–156
Naha K and Mohanty S 1988 Response of basement and cover rocks to multiple deformations: a study from the Precambrian of Rajasthan, western India;Precambrian Res. 42 77–96
Naha K, Mukhopadhyay D K and Mohanty R 1988 Structural evolution of the rocks of the Delhi Group around Khetri, northeastern Rajasthan;Geol. Soc. India Mem. 7 207–245
Naha K, Mukhopadhyay D K, Mohanty R, Mitra S K and Biswal T K 1984 Significance of contrast in the early stages of the structural history of the Delhi and the pre-Delhi rock groups in the Proterozoic of Rajasthan, western India;Tectonophysics 105 193–206
Naha K and Roy A B 1983 The problem of the Precambrian basement in Rajasthan, western India;Precambrian Res. 19 217–223
Naha K, Venkitasubramanyan C S and Singh R P 1969 Upright folding of varying intensity on isoclinal folds of diverse orientation: a study from the early Precambrian of western India;Geol. Rund. 58 929–950
Niyogi D 1960 Structural pattern of the Kishengarh alkaline rocks;Q. J. Geol. Min. Met. Soc. India 32 27–38
Paterson M S and Weiss L E 1962 Experimental folding in rocks;Nature (London) 195 1046–1048
Paterson M S and Weiss L E 1966 Experimental deformation and folding in phyllite;Geol. Soc. Am. Bull. 77 343–374
Poddar B C 1965 Stratigraphie position of the Banded Gneissic Complex of Rajasthan;Curr. Sci. 34 483–484
Raja Rao C S 1967 On the age of the Precambrian Groups of Rajasthan;J. Mines Met. Fuels 15 306–309
Raja Rao C S, Poddar B C, Basu K K and Dutta A K 1971 Precambrian stratigraphy of Rajasthan—a review;Geol. Surv. India Res. 101 60–79
Ramsay J G 1967Folding and fracturing of rocks (New York: McGraw-Hill) pp. 1–568
Ramsay J G and Huber M I 1987The techniques of modern structural geology. Volume 2: Folds and fractures (London: Academic Press) pp. 1–700
Ray J N 1983 Superposed deformation in Delhi rocks near Patan, Sikar district, Rajasthan;J. Geol. Soc. India 24 229–236
Ray S K 1974a Structural history of the Saladipura pyrite-pyrrhotite deposit and associated rocks, Khetri copper belt, Rajasthan;J. Geol. Soc. India 15 227–238
Ray S K 1974b Inversion of fold hinge in superposed folding: an example from the Precambrian of central Rajasthan, India;Precambrian Res. 1 157–164
Ray S K 1976 Tectonic styles in the Delhi Group of rocks, western India;Geol. Surv. India Misc. Publ. 34 239–246
Ray S K 1988 Structural control of copper mineralisation near Bajta, Ajmer district, Rajasthan;Geol. Soc. India Mem. 7 363–372
Roday P P 1977 Deformational history of the Delhi rocks around Biliawas, central Rajasthan;Proc. Indian Natl. Sci. Acad. A43 332–351
Roday P P 1979 Structural pattern in the Ajabgarh rocks around Anakhar, district Ajmer;J. Geol. Soc. India 20 441–445
Roy A B 1972 Significance of variable trend and plunge of small scale upright folds in the type Aravalli rocks around Udaipur, Rajasthan, western India;Geol. Soc. Am. Bull. 83 1553–1556
Roy A B 1973 Nature and evolution of subhorizontal crenulation cleavage in the type Aravalli rocks around Udaipur, Rajasthan;Proc. Indian Natl. Sci. Acad. A39 119–131
Roy A B 1985 Tectonic and stratigraphie framework of the Early Precambrian rocks of Rajasthan and northern Gujarat;Bull. Geol. Min. Met. Soc. India 53 100–114
Roy A B 1988 Stratigraphie and tectonic framework of the Aravalli Mountain range;Geol. Soc. India Mem. 7 3–31
Roy A B and Jain A K 1974 Polyphase deformation in the lead-zinc-bearing Precambrian rocks of Zawarmala, district Udaipur, southern Rajasthan;Q. J. Geol. Min. Met. Soc. India 46 81–86
Roy A B, Nagori D K, Golani P R, Dhakar S P and Choudhuri R 1980 Structural geometry of the rock phosphate bearing Aravalli rocks around Jhamarkotra Mines area, Udaipur district, Rajasthan;Indian J. Earth Sci. 7 191–202
Roy A B and Paliwal B S 1981 Evolution of Lower Proterozoic epicontinental deposits: stromatolite bearing Aravalli rocks of Udaipur, Rajasthan, India;Precambrian Res. 14 49–74
Roy A B, Paliwal B S and Goel O P 1971 Superposed folding in the Aravalli rocks of the type area around Udaipur, Rajasthan;J. Geol. Soc. India 12 342–348
Roy A B, Paliwal B S, Shekhawat S S, Nagori D K, Golani P R and Bejarniya B R 1988 Stratigraphy of the Aravalli Supergroup in the type area;Geol. Soc. India Mem. 7 121–138
Roy A B, Somani M K and Sharma N K 1981 Aravalli—pre-Aravalli relationship: a study from the Bhindar region, southern Rajasthan;Indian J. Earth Sci. 8 119–130
Sen S 1971 Precambrian structural history around Rajgarh, central Aravallis Rajasthan;Q. J. Geol. Min. Met. Soc. India 43 181–211
Sengupta Subhashish 1976 Structures and stratigraphie relations of the Aravallis, south eastern Rajasthan;J. Geol. Soc. India 17 461–470
Sengupta Subhashish 1983 Superposed folding in the Aravalli rocks around Deola, southeastern Rajasthan; InStructure and tectonics of the Precambrian rocks of India (ed.) S Sinha-Roy. (New Delhi: Hindustan Publishing Corporation)Recent Researches in Geol. 10 120–126
Sengupta Sugata 1984 A reinterpretation of the stratigraphy of the Delhi Supergroup of central Rajasthan between Rajosi and Chowdasya, Ajmer Dt., Rajasthan;Indian J. Earth Sci. 11 38–49
Sharma B L, Chauhan N K and Bhu H 1988 Structural geometry and deformation history of the early Proterozoic Aravalli rocks from Bagdunda, district Udaipur, Rajasthan;Geol. Soc. India Mem. 7 169–191
Sharma N L 1953 Problems in the correlation of the pre-Vindhyan igneous rocks of Rajasthan;Presid. Addr. 40th Indian Sci. Congr., Lucknow pp. 1–28
Sinha-Roy S 1985 Granite-greenstone sequence and geotectonic development of south-east Rajasthan;Bull. Geol. Min. Met. Soc. India 53 115–123
Weiss L E 1969 Flexural-slip folding of foliated model materials. InKink bands and brittle deformation (eds) A J Baer and D K Norris. Geol. Surv. Canada Paper Vols 68-52 pp. 294–359
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Naha, K., Mohanty, S. Structural studies in the Pre-Vindhyan rocks of Rajasthan: A summary of work of the last three decades. Proc. Indian Acad. Sci. (Earth Planet Sci.) 99, 279–290 (1990). https://doi.org/10.1007/BF02839395
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DOI: https://doi.org/10.1007/BF02839395