Koti Dhaman Fm

Himachal Pradesh-Uttarakhand, Type location is near the Koti Dhaman village in NigaliDhar syncline (Bhargava et al., 1998). [Original Publication: Bhargava, O.N., Singh, I., Hans, S.K., Bassi, U.K. (1998). Early Cambrian trace and trilobite fossils in the NigaliDhar Syncline (Sirmaur district, Himachal Pradesh), lithostratigraphic correlation and fossil contents of the Tal Gr. Himalayan Geology, 19, 89–108].

Fine-grained sandstone. Characterised by medium to coarse-grained arenaceous sediments. In the Nigali Dhar and Korgai synclines it is divisible into two members.

Lower Quartzite Member: It comprises quartzarenite, quartzwacke, oolitic to nonoolitic calcarenite, ortho-conglomerate and minor grey, olive green and red shale in the upper part. The quartzarenite is compact, medium to coarse grained and grey to pale white. The quartzarenite passes into quartzwacke. The conglomerate is polymictic, lenticular and is more common in upper part.

Shale Member: It comprises grey green and reddish-brown shale, thin interbeds of quartzarenite and rare pebble lenses.

Trilobite Redlichia noetlingi, and brachiopods Eoobolus sp., are known from Shale Member (Kumar et al, 1987; Popov et al., 2015). Trilobite traces of Gondwanan affinity i.e., Cruziana salomonis, Cruziana fasciculata, Rusophycus dispar and Rusophycus burjensis are recorded along with Arenicolites isp. and Skolithos isp. from the Lower Quartzite Member (Singh et al., 2020).

The lithounits of the Lower Quartzite Member exhibits cross-bedding, of large scale planar and tabular type, oscillation as well as current ripple marks. Cross-bedding in quartzarenite, rain prints in silly shale, ripple marks in slate and few isolated flute casts are the sedimentary structures preserved.

See Srikantia and Bhargava, 2021; and the correlation chart (fig.6) from (H. Xu, J.G. Meert and M.K. Pandit, Geoscience Frontiers 13 (2022).