Sawai Bay Fm
Type Locality and Naming
Named after Sawai Bay section. The lithologic unit ‘nodular clay’, which Jacob and Sastri (1951) identified at Sawai Bay, corresponds to the Sawai Bay Formation.
[Original Publication: Srinivasan, M.S. and Sharma, V. (1973) Stratigraphy and Microfauna of Car Nicobar Island, Bay of Bengal. Jour. Geol. Soc. India, 14, pp. 1-8]
Synonyms: The term ‘Eastern Coast Mudstone’ of Neill Island, used by Singh and Vimal (1974, 1976b) corresponds to the Sawai Bay Formation (Sharma and Srinivasan, 2007).
Lithology and Thickness
Calcareous claystone. Type section mainly comprises of moderately hard, highly calcareous, light to bluish-grey and massive mudstone. Occasional small calcareous concretions are observed in the mudstone giving it a nodular appearance.
Srinivasan and Sarma (1973) divided the formation into two units: a lower Mudstone Member, and an upper Limestone Member.
[Figure 1: Lithology of Sawai Bay section, Car Nicobar, the type section of the Sawai Bay Fm. Upper part of the section is represented by shelly limestone of the Guitar Fm. (modified after Sharma and Srinivasan, 2007)]
Relationships and Distribution
Lower contact
Lower boundary is with the Long Fm
Upper contact
The upper part of the section exposes limestone belonging to the Guitar Fm
Regional extent
The rocks belonging to this formation are widely distributed in Car Nicobar, Chowra, Little Andaman, Long and Neill Islands.
[Figure 1: Detailed geological map of Andaman area (modified after Bandopadhyay 2012) showing locations mentioned in numbers in B. Ghosh et al., 2017, Geo.Soc.London.Memoirs, 47, 95-110)]
GeoJSON
Fossils
Srinivasan and Azmi (1976b) recorded rich assemblage of foraminifera of Globorotalia plesiotumida to Globigerina margaritae Zones.
Age
Depositional setting
Deep waters, Paleobathymetry: (1000-3000 m)
Additional Information