Abstract
The rocks of the Delhi Supergroup, which occur around Barr-Sendra and Phulad-Deogarh regions in Central Rajasthan, show three phases of deformational episodes: (i) phase D1—tight-to-long limbed isoclinal fold (F1); phase D2—open, asymmetric fold (F 2) controlling the map pattern of the formational boundaries; and (iii) phase D3—major warps (F3). Interference between nearly coaxial F1 and F2 on northerly axes produced hook-shaped and crescent patterns whereas superimposition of easterly trending F3 on F2 produced dome-and-basin patterns. The thermal peak was achieved during the second phase of deformation when the rocks were constructively metamorphozed and granites (850−750 m.y.), late synkinematic with respect to second phase of deformation, were emplaced. The sequence of deformation and the structural pattern of the rocks of the Delhi Supergroup in Central Rajasthan strikingly resemble those in northeastern Rajasthan. Structurally the characteristics of the Delhi Supergroup as verified in the entire region from NE to Central Rajasthan are: (a) the same sequence of development of folds, F1, F2 and F3, interspersed with nearly identical phases of recrystallization, (b) hook-shaped interference pattern due to near-coaxial refolding of F1 by F2, and (c) variation in axial plunge of F2 resulting in culminations and depressions. Lastly, phases of the recrystallization history indicates little time gap between F1 and F2, and a considerable gap between F2 and F3.
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Gangopadhyay, P.K., Lahiri, A. Structural characteristics of the rocks of the Delhi Supergroup with special reference to interference patterns: An appraisal with some examples from Central Rajasthan. Proc. Indian Acad. Sci. (Earth Planet Sci.) 99, 309–320 (1990). https://doi.org/10.1007/BF02839397
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DOI: https://doi.org/10.1007/BF02839397