Browsing by Author "J.P. Gautam"

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Ammonoid biozonation in the lower Albian (Lower Cretaceous) succession of the Ariyalur Sub-basin, Cauvery basin, south India
(Palaeontological Society Of India, 2021) Bindhyachal Pandey; A.K. Jaitly; J.P. Gautam; D.N. Tiwari
The ever-recognized Lower Albian succession of the Cauvery Basin has been revisited in conjunction with the revision of the exact extent of the Lower Albian horizons. This work also entails the formulation of ammonoid biozones in the précised Lower Albian record in the Ariyalur Sub-basin of the Cauvery Basin. This endeavor embodies the formal creation of Tetragonites rectangularis Zone in the revised Lower Albian sedimentary record of the Cauvery Basin for the first time which has been further differentiated into four Beudanticeras newtoni, Beudanticeras revoili, Jauberticeras collignoni, and Jauberticeras villoutreysi subzones in ascending order. The occurrences of distinctive Lower Albian ammonoid fauna in the Tetragonites rectangularis Zone make its close resemblance with Douvilleiceras mammillatum Zone of the standard ammonoid zonal framework. This biostratigraphic refinement is a noteworthy input in the marine Cretaceous biostratigraphy of the Cauvery Basin. It will also enhance the knowledge of the exposed marine Lower Cretaceous sedimentary record in India and abroad. © 2021 Palaeontological Society Of India. All rights reserved.
Microfacies analysis and depositional environments of the upper Cretaceous (Campanian-Maastrichtian) succession in the Cauvery Basin, southern India
(Palaeontological Society Of India, 2021) A.K. Jaitly; Bindhyachal Pandey; S.K. Mishra; D.N. Tiwari; J.P. Gautam
The Cauvery Basin of south India is an ideal reference section for the study of the marine Cretaceous (Aptian-Maastrichtian) sediments. The basin received more than 5500 m thick mixed siliciclastic and calcareous sediments in the course of intermittent phases of marine transgressions/regressions during Aptian-Maastrichtian time. The three microfacies-grainstone, packstone, and wackestone - have been broadly identified in the Campanian-Maastrichtian sediments of the Ariyalur Group of the Cauvery Basin. An attempt has been made here to use the distinctive features of these three microfacies and contained diverse bioclasts for the reconstruction of the physicochemical conditions to unravel the depositional history of this part of the Cauvery Basin, southern India. The facies analysis depicts a shallow marine (maximum depth 10 m) environment with an uninterrupted deepening from the Campanian to Middle Maastrichtian terminating into a basinal conditions during the Late Maastrichtian. The basin was well oxygenated with an average temperature (26°-28°C) of the Cretaceous sea and normal palaeosalinty range (30%-35%). These Campanian - Maastrichtian sediments are deposited on a carbonate ramp setting extending from the inner ramp to the marginal outer ramp. © 2021 Palaeontological Society Of India. All rights reserved.
Turonian (Late Cretaceous) Heterodont Subfamilies: Lucininae, Eriphylinae and Opinae (Bivalvia: Veneroida) from the Narmada Basin, central India
(Palaeontological Society Of India, 2021) A.K. Jaitly; Susheel Kumar; Bindhyachal Pandey; J.P. Gautam; Deep Narayan Tiwari
Eight species belonging to the genera/subgenera Lucina, Parvilucina (Microloripes), Callucina, Eriphyla (Lyapinella), Crassatellina and Opis of the three subfamilies Lucininae, Eriphylinae and Opinae have been reported here from the Turonian (Late Cretaceous) of Narmada Basin, India. Out of these, the two species Crassatellina minuta and Opis reticulata have been newly created. The overall characters of the subfamily Opinae, the genus Callucina and the subgenus Eriphyla (Lyapinella) have also been reviewed here. © 2021 Palaeontological Society Of India. All rights reserved.