Surma Gr
Period:
Neogene
Age Interval:
Miocene
Province:
North East Basins of India, Bangladesh SE
Type Locality and Naming
Named after Surma Basin.
Lithology and Thickness
The unit is subdivided into the Bhuban Fm clayey sandstone and the Bokabil Fm claystone. See those units for details.
Lithology Pattern:
Sandy_claystone
Relationships and Distribution
Upper contact
Conformable with Tipam Gr (Tipam Fm sandstone). There is a local unconformity between its upper Bokabil Fm and the lower Tipam Fm in Sylhet in northeastern Bangladesh.
Regional extent
Garo Hills, Khasi & Jaintia Hills, Tripura Cachar, SE Bangladesh: Assam region of NE Basins thickening into SE Bangladesh geosynclinal basin. Very thin in NW Bangladesh; and Pandua Fm is used there as its coeval unit.
GeoJSON
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Fossils
Age
Miocene to earliest Pliocene
Age Span:
Beginning stage:
Aquitanian
Fraction up in beginning stage:
0.2
Beginning date (Ma):
22.52
Ending stage:
Tortonian
Fraction up in the ending stage:
1.0
Ending date (Ma):
7.25
Depositional setting
Depositional pattern:
Additional Information
Compiler:
Largely copy-pasted from Banglapedia (National Encyclopedia of Bangladesh as compiled by several geologists; http://en.banglapedia.org/index.php/Geological_Group-Formation; 2015)