The Paleocene to Late Eocene Jaintia Group consists of the Tura
Sandstone Formation, Sylhet Limestone, and Kopili Shale, in ascending
order. The Tura Sandstone consists mostly of shallow marine quartz
arenites (Najman et al., 2008), whereas the nummulitic Sylhet
limestones were deposited in shallow marine carbonate environments (Shamsuddin and Abdullah, 1997; Alam et al., 2003). The
predominantly muddy Kopili Shale accumulated in deltaic to shelf or
slope depositional environments