NarpuhSandstoneMbr Fm
Type Locality and Naming
The Narpuh Sandstone Member of the Sylhet Fm is named after Narpuh Reserve Forest. Type section is in the Narpuh Reserve forest of the Jainita Hills in Meghalaya. Its thickness is 18 m. [Original Publication: Wilson, G.F., and Metre W.B. 1953: Assam and Arakan, In: Science of Petroleum, vol. 6(1), pp. 119-123]
Synonyms: This is a member of Sylhet Formation, typically developed in the Um Sohryngkew river. Its mappability is similar to that of the Sylhet UmlatodohLimestoneMbr Fm.
Lithology and Thickness
Sandstone. The Narpuh Sandstone Member of the Sylhet Fm consists of ferruginous, medium- to coarse-grained friable sandstone, sometimes white in color and occasionally black near the contact with the Umlatodoh Limestone Member of the Sylhet Fm. Near the base greyish white calcareous grit and occasional thin limestones are present. It is 18 m thick. The variation of thickness of the unit in the Bokajan, Makum, Rajali, Bhekulajan, and Khowang area is from 45.5 m - 115.5 m. It laterally passes into the Tura Fm.
[Figure 1: Paleocene - Lower Eocene sequence of Upper Assam with its subdivisions (after Bharali and Gogoi, 2012)]
Relationships and Distribution
Lower contact
It is conformably underlain by the Sylhet UmlatodohLmsMbr Fm.
Upper contact
It is overlain by the Sylhet PrangLmsMbr Fm.
GeoJSON
Fossils
A sparse microfauna comprising of Orbitolites complanata and Nummulites atacicus.
Age
Depositional setting
Marginal to open marine conditions.
Additional Information