Abstract:
Sedimentological analysis of upper sandstone unit of Nari Formation was made to assess the environment of deposition with the help of various grain size parameters and thin section studies. West of Karachi Metropolis, the Nari Formation is exposed in the foothills of Pub Range i.e. in the structures of Cape Monze and Pir Mungo anticlines. The thickness of Nari Formation decreases from southwest to northeast. Nari and Gaj formations cropout at the surface with very limited exposures of Eocene rocks. Starting from fold structures in the east the study area ends by a thrust in the west. The Nari Formation consists of sandstone, shale and subordinate limestone. The upper sandstone unit is medium to coarse grained, gritty and present as beds from a few inches to 30 feet in thickness. Many sandstone layers are calcareous, hard` and resistant to weathering, while the others are soft and crumbly. The sandstone varies from quartzarenites to subarkosic and sublithic in composition. The grain size analysis and thin-section studies revealed that the sandstone was deposited in shallow marine through fluviomarine to partly fluvitile environments.
Page(s):
320-327
DOI:
DOI not available
Published:
Journal: Proceedings SPE-PAPG Annual Technical Conference, Volume: 0, Issue: 0, Year: 2005