Gangapur Fm

Pranhita-Godavari Basin: “Gangapur beds” placed in the Kota Group (King 1881) on the basis of lithology were separated by Kutty (1969) from the Kota to erect the Gangapur Formation, near the cave temple just north of Gangapur village in Adilabad District, Telangana. [Original Publication: King, W. 1881. The geology of the Pranhita-Godavari valley. Mem. Geol. Surv, Ind., 18(30), 150-311; Kutty T.S. 1969. Some contributions to the stratigraphy of the Upper Gondwana Formations of the Pranhita–Godavari Valley, central India. J. Geol. Soc. India, 10, 33–48.]

[Figure 1: Geological map of the northern Pranhita-Godavari valley between Pedda Vagu and Godavari River displaying the geographic extent of the Gangapur Formation (after Kutty et al., 1987)]

Clayey sandstone. Lithofacies identified are clay-clast-bearing sandstone, trough cross-stratified sandstone, planar cross-stratified sandstone and silty claystone. In its lower part, coarse and very coarse ferruginous sandstones with many pebble bands occur, succeeded upwards by a sequence of alternating sandstones and mudstones or silty mudstones. The Gangapur Formation is 100–250 m thick (Lakshminarayan, 1995, 1996).

Fish: The mudstones of the Gangapur Formation yielded Gyrolepis-type teeth, ? Caturus-type teeth (Prasad et al., 2004); Macroflora: Taeniopteris kutchensis, T. spatulata, Taeniopteris sp., Ptilophyllum cutchense, P. acutifolium, P. rarinervis, Ptilophyllum cf. P. distans, Elatocladus confertus, E. sehoraensis, Elatocladus cf. E. bosei, E. andhrensis, Pagiophyllum marwarensis, P. rewaensis (Chinnappa et al., 2014); Microflora: Callialasporites, Araucariates, Microcachryditites, Classopolis, Podocarpidites, Contignisporites, Cicatrisporites, Podocarpidites (Prabhakar, 1987).

The sedimentology of the Gangapur Formation indicates fluvial channel deposition. Poor sorting and random orientation of plant fragments in clay beds reflect frequent floods in the basin due to which the vegetation was transported and deposited in turbid conditions of floodwater. Based on the convergence of palaeocurrents, Lakshminarayana (1995, 2002) proposed that the sediments debauched from all sides silted up the basin.

References

Chinnappa C.H., Rajanikanth A., Rao Y.V. 2014. Gymnosperm fossils from the Gangapur Formation (early Cretaceous), of Adilabad District, Telangana. Geophytology, 44: 91–104. King, W. 1881. The geology of the Pranhita-Godavari valley. Mem. Geol. Surv, Ind., 18(30), 150-311; Kutty T.S. 1969. Some contributions to the stratigraphy of the Upper Gondwana Formations of the Pranhita–Godavari Valley, central India. J. Geol. Soc. India, 10, 33–48. Kutty T. S. Jain S. L. & Roy Chowdhury T 1987. Gondwana sequence of the northern Pranhita-Godavari Valley: its stratigraphy and vertebrate faunas. Palaeobotanist 36: 214-229 Lakshminarayana, G. 1995. Gondwana sedimentation in the Chintalapudi sub-basin, Godavari Valley, Andhra Pradesh, India. J. Geol. Soc. India, 46: 375–383. Lakshminarayana, G. 1996. Stratigraphy and structural framework of the Gondwana sediments in the Pranhita–Godavari Valley, Andhra Pradesh. Gondwana Nine (1), Geol. Surv. India: 311–330. Lakshminarayana, G. 2002. Evolution in basin fill style during the Mesozoic Gondwana continental break-up in the Godavari Triple junction, S.E. India. Gondwana Res., 5(1): 227–244. Prasad, G.V.R., Manhas, B.K. & Arratia, G. (2004): Elasmobranch and actinopterygian remains from the Jurassic and Cretaceous of India. In: G. Arratia & A. Tintori (eds.), Mesozoic Fishes 3 Systematics, Paleoenvironments and Biodiversity 625-638. Verlag Dr. Friedrich Pfeil, Munchen. Prabhakar M. 1987. Palynology of the Upper Gondwana Deposits of Rampur area, Pranhita-Godavari Basin, Andhra Pradesh, India. J. Palaeontol. Soc. India. 32: 114-121. Raiverman V., Rao M. R. & Pal D. 1985. Stratigraphy and structure of the Pranhita-Godavari Graben. Petrol. Asia J. 8(2): 174-189 Rudra D. K. 1982. Upper Gondwana stratigraphy and sedimentation in the Pranhita-Godavari valley, India. Quart. Jour. Geol. Min. Metall. Soc. India 54: 56-79.