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

R. J. Azmi ¹

Affiliations
1 Wadia Institute of Himalayan Geology, Dehra Dun - 248 001, IN

Abstract

R. J. Azmi of the Wadia Institute of Himalayan Geology here reports the discovery of small shelly fossils and brachiopods of lower Cambrian affinity from the topmost Rohtasgarh Limestone at Maihar and Rohtas in the Son Valley. This discovery is of importance as it necessitates a revision in the age of the Vindhyan succession. We welcome a discussion on this subject - Ed.

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R. J. Azmi ¹, Deepak Joshi ¹

Affiliations
1 Wadia Institute of Himalayan Geology, Dehra Dun - 248 001, IN

Abstract

No Abstract.

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Kapesa Lokho ¹, D. S. N. Raju ², R. J. Azmi ¹

Affiliations
1 Wadia Institute of Himalayan Geology, 33 GMS Road, Dehra Dun - 248 001, IN
2 MSR Residency, Pragathi Marg, JN Road, Rajahmundry - 53 3103, IN

Abstract

Planktic and benthic foraminifera including uvigerinids are documented from the Upper Bhuban Formation, exposed at Thingdawl village, Kolasib district, Mizoram. The foraminiferal assemblage is poorly preserved and consists of index fossils useful for precise biochronology and interpretation of the depositional environment. A total of ten benthic and six planktic foraminiferal species are described. Six species belong to the genus Uvigerina, four to Ammonia, one species each of Globorotalia, Globigerinoides, Clavatorella, Praeorbulina and two species of the genus Orbulina. Based on lithological and foraminiferal assemblage, middle neritic to upper part of outer neritic paleobathymetry is inferred for the deposition of this part of the Upper Bhuban Formation. The foraminiferal assemblage suggests late Early Miocene to early Middle Miocene, (∼16 Ma) equivalent to planktic foraminiferal zones N8-N9 for the Upper Bhuban Formation.

Keywords

Bhuban Formation, Miocene, Uvigerinids, Foraminifera, Assam-Arakan Basin, Mizoram.

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