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M. H. Basavaraju ¹, B. S. Pundeer ¹

Affiliations
1 KDMIPE, ONGC Ltd., Dehra Dun- 248001, IN

Abstract

The Gondwanas of Upper Assam are locally divided in to Lower Gondwana and Upper Gondwana based on the subsurface electro-logs, lithology and palynofossil assemblages The Lower Gondwana is dominated by rich radlal monosaccate genera viz Phcatipollenites sp , Parasaccites sp , Potomeisporites sp , Virkkrpollenites sp along with trilete spores of Microbaculispora sp and Microfoveolanspora sp and dated as Early Permian age These palynoassemblages are closely cornparabie with those recorded from the Krishna-Godavari Basln, Cauvery Basln, South Rewa Basln, Satpura Basan and Jayanth coal fields which are considered as equivalents of Talchlr Forrnatlon The occurrence of Lezosphaeridia in the Early Permian sediments indicates a marine Influence during the deposition of tbe sediments The Early Cretaceous sediments of Upper Gondwana contains mainly of Tricolpites sp , Phcifera senonicus, Ornamentifera sentosa, Cyclinospora reduncus, Staplinisporites sp , Cicatncosisporites sp , Classopollis sp , and Callralosporites sp indicating an Aptian-Albian age The equivalent palynoassemblages are reported from the Cauvery and krihshna-Godavari Basins.

Keywords

Palynostratigraphy, Gondwana sediments, Dhansirl valley, Assam.

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M. H. Basavaraju ¹, B. S. Pundeer ¹

Affiliations
1 Regional Geological Labs, ONGC Ltd., Sivasagar - 785 640, IN

Abstract

The occurrence of Lower Gondwana palynoassemblage has been recorded from the subsurface sediments of an exploratory well Dergaon-A in Dhansiri Valley of Assam-Arakan Basin. The recorded palynoassemblage includes rich radial monosaccate genera Potoneisporites sp, Parasaccites sp, Plicatipollenites sp, Virkkipollenites sp, associated with the trilete spores viz. Microfoveolatispora sp, Microbaculispora sp, along with acritarch Leiosphaeridia sp. These palynofossils are correlatable with those recorded from the Talchir Formation of South Rewa Basin, Jayantia coal field, Cauvery Basin and Krishna Godavari Basin. Occurrence of Leiosphaeridia indicate that the sediments appears to be deposited under marine conditions.

Keywords

Palynofossils, Monosaccate, Permian, Assam-Arakan Basin, NE India.

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