26/12/2025
📍 AAPG–SPE–EAGE Joint Fieldwork | Sylhet Region
From December 21–24, the AAPG, SPE and EAGE Student Chapters of the Department of Geology, University of Dhaka organized a fieldwork across Jaflong, Tamabil and Jaintiapur (Sylhet) under the guidance of Dr. Anowar Hossain Bhuiyan and Md. Sajjadul Islam Fahim.
🪨 Day 1: We examined the Kopili Shale and Sylhet Limestone. The limestone displayed a clear vertical progression from micritic limestone at the base, through fossiliferous limestone to upper sparitic (crystalline) limestone, reflecting changes in depositional conditions and diagenesis.
🛥️ Day 2: At Tetul Ghat, we studied the Bhuban Formation—a sandstone dominated sequence interbedded with shale, representing a shallow marine to deltaic depositional environment during a marine transgressive phase. We collected shale samples to better understand the Afifanagar deltaic sequence and the transition between shallow marine and deltaic deposits.
🪨 On the return walk, we observed the Bokabil Formation, notable for its heterolithic bedding with alternating sand and shale, indicating deltaic energy fluctuations and also briefly saw the Dupitila Formation, completing our Surma Group observations.
🌍 The Surma Group has major geological significance in Bangladesh. Its Miocene fluvio-deltaic to shallow marine sandstones and shales form the structural backbone of the eastern basin and host the majority of the country’s natural gas reservoirs. In the Surma Basin alone, about 11 out of 28 discovered gas fields account for an estimated ~10.8 trillion cubic feet (TCF) of recoverable gas within the Bhuban and Bokabil formations, making it essential for national energy supply and petroleum exploration.
