Association of Petroleum Geologists (APG) and Society of Petroleum Geophysicists (SPG), Kolkata Chapter jointly conducted a technical session on 19 March 2018 with the theme “Major Gondwana Basins of India- Problems and Prejudices”. This technical session was attended by all the APG and SPG members of Kolkata Chapter and distinguished retired dignitaries.
Recently the focus of exploration is emphasizing the search for Coal Bed Methane (CBM) and Shale Gas in the Gondwana sequences of the Sedimentary basins of India in addition to exploration of Conventional Hydrocarbon. Hence the technical session was organised to address the various issues related to the exploration of Conventional hydrocarbon, Coal Bed Methane and Shale Gas in Indian sedimentary basins. The lecture was delivered Prof. Dhurjati Prasad Sengupta, Dept. of Geological Sciences, Indian Statistical Institute, Kolkata as an Industry-Academia interaction.
Shri C Mahapatra welcoming Prof. D P Sengupta
ED-Basin Manager and patron APG & SPG Kolkata ChapterProf. D P Sengupta delivering the lecture
Prof. D P Sengupta is an eminent Bio stratigrapher in Dept. of Geological Sciences, Indian Statistical Institute,Kolkata. He has rich experience in the domain of Biostratigraphy of Lower and Upper Gondwana sequences of Indian Basins. He has been working on Gondwana stratigraphy and vertebrate palaeontology with interests inmorphometrics and shape analysis of fossil vertebrates. He has carried out extensive research work; mainly field based on Gondwanas of India and abroad and has erected many new vertebrate taxa and used metamorphic techniques for the first time on Indian Gondwana vertebrate.
The session started with brief presentation about the activities and future plans of APG & SPGKolkata Chapter by Joint Secretary, APG, Kolkata Chapter, Mr G C Deb, DGM (G) and Secretary, SPG, Kolkata Chapter, MrP K Bose, DGM (GP) respectively followed by the lecture & presentation by Prof. D P Sengupta.
The Brief Synopsis of the talk is as follows:
The Gondwana deposits of peninsular India are revisited with the light of new information and ideas. The Gondwana sediments of peninsular India rest on Pre-Cambrian basement and the early Paleozoic deposits are absent in the peninsular part. Some problems and prejudices are inherent to the Indian Gondwanas.
Traditionally, the Gondwana starts with a glacial to fluvio-glacial and glacio-marine Formation called the Talchir. Whether Talchir starts from Carboniferous or Permian-- is the initial question which still remains debatable. The coal regime that followed Talchir is present in all the Permian Gondwana deposits of the southern continents of the world. In fact, the glacial and coaly part with characteristics of Glossopteris-Gangamopteris flora are present in all the Gondwana deposits of India, Australia, Antarctica, South Africa and Argentina.
However, the Triassic ‘Red bed’ that followed Coal-shale-sandstone deposits is not at all restricted in Gondwana. It is a global phenomenon with a global flora and fauna. Continental Triassic sediments, at different parts of peninsular India, differentially fill up the initial rift system that created the Gondwana basins. They also have different fault patterns and sediment loads. Thus, they are not uniform and difficult to correlate among different Gondwana basins of India. On the other hand, overall characteristic lithology (Red Mudstone), flora and particularly, the universal terrestrial fauna make the correlation of Triassic red beds easier in global scale. Thus, during Triassic, Gondwana lost its character as “restricted rift deposits in southern continents”. This creates a problem whether to include Triassic part within Gondwana or not.
In case of the non-marine Jurassic, the story is different for peninsular India. There are very few non-marine Jurassic litho-formations in peninsular India. Most of Indian Jurassics (Peninsular) are marine.
Similarly, in Cretaceous, non-marine sediments of Satpura and that of a small part of Pranhita-Godavari basin, are directly overlying the Gondwanas. Other so called “Cretaceous upper Gondwana” sediments are lying on different basements, but not on Gondwana. They are lithologically different from typical Gondwanas. The flora of Jurassic and Cretaeous, the typical “upper Gondwana flora” is actually a global flora that happened to be present in the “upper Gondwana”.
With all these doubts and indecisive evidences mentioned above, Indian Gondwanas, are still thought to be unified successions with a span of Carboniferous to Cretaceous. However, this concept needs serious rethinking.
President, APG, Kolkata Chapter, Mr. S K Das President, addressing the gathering
SPG, Kolkata Chapter, Mr. S Chakraborty addressing the gathering
APG Jt. Secretary Mr G.C Deb briefing activities of SPG APG, Kolkata Chapter
Secretary Mr P K Bose briefing activities of SPG, Kolkata Chapter
The technical session ended with the concluding remarks of ED-Basin Manager, MBA Basin Kolkataand Patron APG & SPG Kolkata Chapter, Shri ChakradharaMahapatra. He opined that Industry-Academia interaction of such nature is very helpful for ONGC in the long run and more such talks can be organised in future. He urged the participants to discuss and debate ideas, policies& strategies that would allow more comprehensive exploration of the region so as to conclude in a more definitive manner about this region. He also complimented all the SPG and APG members, Kolkata Chapter for organising this technical session.
The session was compered by Ms.Supriya Shukla, Sr. Geophysicist(S), member SPG, Kolkata Chapter and concluded with vote of thanks by Mr.Arun Debasis, Sr. Geologist, member APG, Kolkata Chapter.
Member,SPG Kolkata Chapter, Ms. Supriya Shukla compering the sesion
Member,APG Kolkata Chapter, Mr. Arun Debasis offering vote of thanks