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D. A. Rasheed ¹, C. N. Ravindran ¹

Affiliations
1 Department of Geology, University of Madras, A. C. College Campus, Madras, 600 025, IN

Abstract

A study of the samples from Chokkanadhapuram (79°7'41" : 11°16'2") has revealed the occurrence of the species Bolivinoldes decoratus (Jones) for the first time. The Bolivinoides species found in the area is described and its bio-stratigraphic importance is discussed.

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D. S. N. Raju ¹, B. C. Jaiprakash ¹, C. N. Ravindran ², R. Kalyansunder ², P. Ramesh ²

Affiliations
1 Palaeontology Lab., KDMIPE, ONGC, Dehra Dun-248195, IN
2 Regional Geology Lab., ONGC. No.3, First Lane, Nungambakkam High Road Madras 600034, IN

Abstract

A Major hiatus of varying time span ofiess than 1 Ma to greater than 30Ma encompasses the Cretaceous/Tertiary boundary (KTB) in several parts of the Cauvery, Krishna-Godavari (KG) and other pericratonic basins of India. The succession in the north and northeastern parts of Cauvery basin is apparently continuous, whereas in other areas of this basin, either the sediments of Late Maastrichtian or Middle-Late Maastrichtian or even Middle Campanian-Maastrichtian are unrepresented due to erosion/nondeposition. A north-northeasterly tilt within the Cauvery basin with some tectonic blocks subsiding is inferred during Late Maastrichtian. An additional event of global significance that occured across orvery close to the KTB in KG basin is volcanism within alimited duration of 3.8 to 5.5 Ma equivalent to Deccan volcanism. The succeeding transgression in Paleocene-Early Eocene was in pulses at levels ranging from Zone PI-P7. This hiatus appears to be linked with the rise of a giant hot mantle plume just prior to the eruption of Deccan volcanism during Abathompalus mayaroensis Zone of Latest Maastrichtian around 66.5Ma to 67.5Ma.

Keywords

Stratigraphy, K/T Boundary, Cauvery Basin, Krishna-Godavari Basin.

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kanchan Das Gupta ¹, Pratul Kumar Saraswati ¹, Utz Kramar ², C. N. Ravindran ³, Doris Stuben ², Zsolt Berner ²

Affiliations
1 Department of Earth Sciences, IIT Bombay, Mumbai - 400 076, IN
2 Institute for Mineralogie und Geochemie, Fritz-Haber-Weg 2, 76131 Karlsruhe, DE
3 Regional Geology Laboratories, ONGC, Panvel, Phase I, Mumbai - 410 221

Abstract

The clays of Karai Formation (Uttatur Group) contain well-preserved planktonic and benthic foraminifera of Albian-Turonian age. The pristine tests of planktonic and benthic foraminifera were analyzed for their oxygen isotopic compositions. The δ¹⁸0 values of planktonic foraminifera, comprising Whiteinella archaeocretacea, Marginotruncana sp., Rotalipora reicheli, Praeglobotruacana stephani and Globigerinelloides sp. indicate the maximum near-surface temperatures of 29°C. The bottom water temperature, estimated on benthic foraminifera1 species Gyroidinoides sp., Quadrimorphina sp., Gavelinella sp., Lenticulina sp. and Pleurustomella sp., is about 2. This is in agreement with the palaeoclimatic conditions inferred on fossil assemblages.

Keywords

Palaeotemperature, Stable isotopes, Foraminifera, Cretaceous, Cauvery Basin, TamilNadu.

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