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Kantimati G. Kulkarni ¹, V. D. Borkar ¹, Tejashree Petare ¹

Affiliations
1 Palaeobiology Group, Agharkar Research Institute, G.G. Agarkar Road, Pune – 411 004, IN

Abstract

Well preserved flask shaped borings belonging to ichnogenus Gastrochaenolites Leymerie, (1842) are being reported from the Kalyanpur Limestone Member (Pliocene) of Dwarka Formation, Jamnagar district, Kathiawar Region, Gujarat. The ichnofauna consists of Gastrochaenolites ampullatus Kelly and Bromley, G. cluniformis Kelly and Bromley, G. lapidicus Kelly and Bromley, G. orbicularis Kelly and Bromley, G. ornatus Kelly and Bromley, G. torpedo Kelly and Bromley, G. turbinatus Kelly and Bromley, and Gastrochaenolites isp. Though individuals of groups other than bivalves are known to create Gastrochaenolites-like borings, these borings were evidently emplaced by bivalves alone, confirmed by the presence of bivalve casts in some of the specimens. This hardground suggests an intraformational break in deposition.

Keywords

Bioerosion, Gastrochaenolites, Neogene, Pliocene, Kathiawar, Gujarat.

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Kantimati G. Kulkarni ¹, V. D. Borkar ¹, Tejashree J. Petare ¹

Affiliations
1 Geology and Palaeontology Group, Agharkar Research Institute, G. G. Agarkar Road, Pune-411004, IN

Abstract

An ichnoassemblage from the Fort Member, Jaisalmer Formation, occurring in a hill north of the city of Jaisalmer is described. It comprises Arenicolites tenuis isp. nov., Bichordites isp., Planolites isp., Rhizocoralliurn irregulare Mayer, Rhizocorallium jenense Zenker, Taenidium serpentinurn Heer and Thalassinoides isp. Overall paucity of repichnia in an ichnoassemblage vis-a-vis noticeable dominance of domichnia and fodinichnia implies abundance of detrital nutrients. Host rocks yielding this ichnoassemblage are current bedded calcarenite showing fine shell hash along current beds and clayey limestones with presence of small, lenticular storm bed intercalations. They suggest near-shore, moderate-to strong-energy marine conditions rich in organic nutrients, supporting inferences drawn on the basis of trace fossils. The beds containing this ichnoassemblage are assigned ages ranging from Bathonian to Callovian, and hence considered here Middle Jurassic.

Keywords

Trace Fossils, Fort Member, Middle Jurassic, Jaisalmer, Rajasthan.

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Kantimati G. Kulkarni ¹, Satarupa Bhattacharjee ¹, V. D. Borkar ¹

Affiliations
1 Geology Group, Agharkar Research Institute, G.G. Agarkar Road, Pune - 411 004, IN

Abstract

Idiomorphic clionid borings were discovered on some of the oyster shells occurring in limestone intercalations within the Claystone Member of the Chhasra Formation (Burdigalian, Miocene), Kachchh, Gujarat. Epoxy resin was injected in a fragmentary shell of Crassostrea gingensis, which subsequently was completely dissolved in dilute hydrochloric acid. Examination of artificial casts of borings, thus obtained, revealed presence of three ichnospecies of Entobia. An open camerate system with long, cylindrical chambers is diagnostic of E. catenifomis, while camerate system of E. laquea consists of lace-like network of small, globose, equidimensional chambers. Entobia isp. A shows limited exploratory threads and small irregularly distributed apertures. Entobian borings suggest clear, well-Illuminated, shallow, sublittoral waters with little sediment input. However, proliferation of these borings is not very extensive in the limestone intercalations under consideration, suggesting that the spell of nondeposition must have been short. It is interesting to note that out of seven oyster species known from the Miocene strata of Kachchh, clionid borings were observed on only two species viz., Hyotissa hyotis and Crassostrea gingensis.

Keywords

Miocene Oysters, Bioerosion, Entobia, Kachchh, Gujarat.

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Kantimati G. Kulkarni ¹, V. D. Borkar ¹

Affiliations
1 Geology Group, Agharkar Research Institute, G.G. Agarkar Road, Pune 411 004, IN

Abstract

No Abstract.

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Kantimati G. Kulkarni ¹, V. D. Borkar ¹

Affiliations
1 Agharkar Research Institute, G .G. Agarkar Road, Pune - 411 004, IN

Abstract

Only three ichnoforms are recorded from the Cuddapah Supergroup so far. Two of them were described from the Gulcheru Quartzite without specific determination, while the third, identified as Planolites sp. was discovered near Nagarjuna Sagar. The claim that the so called horizontal burrows from the Gulcheru Quartzite resemble ichnogenus Arthrophycus is incorrect, as in reality they are trace fossils of 'inorganic origin', referable to the forms Rlzysonetron or Manchuriophycus. Also, the pock marks constituting 'vertical and inclined burrows' from the Gulcheru Quartzite are, in fact, a weathering feature. Hence, the opinion that these 'trace fossils' are useful for local correlation is not tenable. Planolites sp. reported from the Nagarjuna Sagar area is now identified under the specific name R beverleyensis (Billings). The sandstone sequence yielding Planolites sp. was traditionally believed to be a part of the Srisailam Formation. There was a suggestion that it may be considered as belonging to the Banganapalle Sandstone of Kurnool Group, in view of the occurrence of Planolites sp. and intercalations of shales and limestones, Since the sediments in question are not laterally continuous with any outcrop of the Kurnool Group, it is suggested here that it be recognised as a separate lithostratigraphic entity and correlated with Banganapalle Sandstone.

Keywords

Trace Fossils, Cuddapah Supergroup, Proterozoic, Guvvalacheruvu and Maddimadugu Areas.

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Amruta R. Paranjape ¹, Anand S. Kale ², Kantimati G. Kulkarni ³

Affiliations
1 Geology and Palaeontology Group, Agharkar Research Institute,G.G. Agarkar Road, Pune 411 004, IN
2 Bharat Petro Resources Ltd, Maker Towers, Cuffe Parade, Mumbai 400 005, IN
3 Geology and Palaeontology Group, Agharkar Research Institute, G.G. Agarkar Road, Pune 411 004, IN

Abstract

No Abstract.

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