Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

U. B. Mathur ¹, S. C. Pant ¹

Affiliations
1 Regional Palaeontological Laboratory, Geological Survey of India, Jaipur 302015, IN

Abstract

Morphologically unidentifiable bone fragmenls from Jurassic of Jaisalmer (Raja-sthan) and Infratrappean of Kutch (Gujarat) were recently identified to be dinosaurian by their histological examination under petrographic microscope. This was feasible because the tissue structure of dinosaur bones is different from other contemporaneous vertebrates. It is characterised by the occurrence of dense Haversian systems of many generations in greater part of cortex. The note deals with the structure of Haversian System, its mode of occurrence and the methodology for identifying dinosaur bone fragments. It is hoped that the knowledge of bone histology will help in the discovery of new horizons and localities in India where only a few occurrences are known so far.

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U. B. Mathur ¹, S. Srivastava ¹

Affiliations
1 Regional Palaeontological Laboratory, Geological Survey of India (Western Region), Jaipur, IN

Abstract

Theropod and sauropod dinosaur teeth are being described for the first time from Lameta Group (Upper Cretaceous) of Kheda District, Gujarat. Carnosaurian teeth show megalosaurid characters and are placed in Majungasaurus (Megalosaurus) crenatissimus and (?) Megalosaurus. Five morphological types of (?) Megalosaurus teeth have been distinguished which vary from laterally compressed flattened cones to recurved ones having serrations on anterior/posterior margins and directed either at right angles or obliquely to the margins. The sauropod dinosaur teeth are tentatively placed in Titanosaurus and described as a new species viz., (?) Titanosaurus rahioliensis.

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D. M. Mohabey ¹, U. B. Mathur ¹

Affiliations
1 Geological Survey of India, Ahmedabad 380014, IN

Abstract

New occurrences of well-preserved dinosaur eggs have been found in the Lameta sediments near Dohad in Panchmahals district, Gujarat. The new localities lie 90 km east of the well-known Balasinor-Rahioli belt, which has the distinction of being one of the few dinosaur nesting sites in the world. The dinosaur eggs are spherical and have nodose ornamentation. Two types of egg shells have been distinguished on the basis of their microstructure. The egg shelIs have affinity towards sauropod types and are comparable to those of Kheda Type-B.

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D. K. Pandey ¹, Tej Bahadur ¹, U. B. Mathur ¹

Affiliations
1 Department of Geology, University of Rajasthan, Jaipur - 302004, IN

Abstract

Neogene-Quaternary sedimentary basin of Saurashtra along the northwestern coast of India is of great interest for its importance in sea-level and palaeoclimatic studies. Lithostratigraphically, the lithic-units have been grouped into Gaj, Dwarka, Miliolite, Chaya, Katpur and Mahuva Formations in ascending order. Present paper deals with stratigraphic distribution and depositional environment of individual sections of the Chaya Formation. With the addition of a new member, the Chaya Formation now consists of three members; viz. Okha Shell Limestone Member, Aramda Reef Member and Porbandar Calcarenite Member.

Keywords

Chaya Formation, Lithostratigraphy, Biota, Depositional Environment, Coastal Saurashtra, Gujarat.

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U. B. Mathur

Abstract

No Abstract.

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U. B. Mathur ¹

Affiliations
1 A-25, Malviya Nagar, Jaipur - 302 017, IN

Abstract

No Abstract.

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D. K. Pandey ¹, U. B. Mathur ², Rakesh Singh ¹, Tej Bahadur ¹

Affiliations
1 Department of Geology, University of Rajasthan, Jaipur - 302 004, IN
2 Department of Geology,University of Rajasthan, 2A-25, Malaviya Nagar, Jaipur - 302 017, IN

Abstract

Chaya Formation (Late Pleistocene-Holocene) of Dwarka-Okha area in Saurashtra peninsula, Gujarat, is subdivided into the lower Okha Shell Limestone Member and the upper Aramda Reef Member. A ca 1.5m thick succession of coral-alga1 lithofacies of Aramda Reef Member that has been radiometrically dated at Woods Hole Oceanographic Institute, U.S.A. to 41.2-18.3 ka, is exposed in a well section near Mithapur (district Jamnagar), and is described here. The environmental conditions during Late Pleistocene are also discussed.

Keywords

Coral-Algal Sediments, Palaeo-Environment, Chaya Formation, Mithapur, Gujarat.

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U. B. Mathur ¹, D. K. Pandey ¹

Affiliations
1 Department of Geology, University of Rajasthan, Jaipur - 302 00, IN

Abstract

High precision Acceleration Mass Spectrometry (AMS) dates of corals, gastropods and smaller foraminifers from a coral-algal stratigraphical sequence, exposed 2.73-4.20 m above the present msl, near Mithapur on Dwarka-Okha coast, have been reported in the present paper. The age ranges from ca. 41.2 to 18.3 ka BP. The mineralogy, petrology and δ¹³C values of the samples indicate that the dates are reliable within the limitations of the dating method. Confirmatory U/Th dating will, however, be useful to strengthen the conclusion. Since the samples are from the intraplate area of the Saurashtra Peninsula, the present position of 41.2 and 18.3 ka old sea level recorders cannot be explained by a large-scale uplift. At the same time, they cannot be taken as the records of the sea level stands of ∼40 ka and ∼18 ka BP, as the generally accepted data suggest very low sea level stands of the periods. Therefore, an epeirogenetic model is to be evolved that satisfactorily explains not only the presence of -40 ka corals and stratigraphically superposed younger ∼18 ka sediments, but also the corals of 118-176 ka BP and 6 ka BP ages that co-exist at low altitudes at Mithapur. For this we need to generate more reliable dates of the area and integrate them with the geological and geophysical information.

Keywords

Late Pleistocene, Coral, AMS Dating, Sea Level Changes, Saurashtra, Gujarat.

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