Dharagad Gr
Period:
Paleoproterozoic
Age Interval:
(ca 1800 Ma)
Province:
N.India Lesser Himalaya
Type Locality and Naming
Himachal Pradesh-Uttarakhand, Deoban Basin, Tons Valley of Himachal Pradesh and Uttarkhand.
Lithology and Thickness
Sandstone and Volcanics. It comprises white to pale white quartzite, meta-siltstone and phyllite with interstratified tholeiitic volcanics.
Lithology Pattern:
Fine-grained sandstone
Relationships and Distribution
Lower contact
Unconformable with Larji Gr (?; would not fit the age assignments; unless due to fault – see age discussion below).
Upper contact
Conformable with the Tiontar Fm.
GeoJSON
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Fossils
Discovery of trace fossils in the Dharagad terrain led Rai et al. (1997).
Age
Paleoproterozoic. The whole rock dating of the volcanics by Nd–Sm method gave an age of 2540 ± 90 Ma age (Bhat and LeFort, 1992), which according to Miller et al. (2000) is ‘meaningless’ as 207Pb/206Pb dates on single zircon occurring in these volcanics, indicate 1800 ± 13 Ma age (Miller et al., 2000). Discovery of trace fossils in the Dharagad terrain led Rai et al. (1997) to assign a Cambrian age to the entire Dharagad Gr, which militates against the Paleoproterozoic radiometric age of the interstratified volcanics. The younger age interpretation to the entire Dharagad Gr arose due to non-recognition of the Skolithos-bearing horizon as a separate entity, which is quite distinct from the Dharagad arenites and these two have tectonic contact. Pending better age control, temporarily placed here below the latest Proterozoic Damtha Gr with a fit to the 1800 Ma age
Age Span:
Beginning stage:
Statherian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
1,800.00
Ending stage:
Statherian
Fraction up in the ending stage:
0.2
Ending date (Ma):
1,760.00
Depositional setting
Marine environment.
Depositional pattern:
Additional Information
Compiler:
O.N. Bhargava & Birendra Singh.