Table 5 Brief descriptions and interpretation of facies types within the fluvial-dominated fluvio-tidal facies association (FA-3)

Facies 3A: Large-scale trough cross-stratified sandstone

Metre-scale trough cross-strata in medium-grained, moderately-sorted sandstone; grains subrounded; bed thickness 20–50 cm; thickness of cross-strata sets > 30 cm; normal grading in cross-strata set; mud-draped foresets with lateral accretion; convolute laminations present locally.

Large-scale trough cross-strata with lateral accretion and mud-draped foresets indicate migration of bars by tidal currents (Bose and Das 1986); convolute laminae indicate liquefaction and fluidization during deposition (Jha et al. 2017).

Facies 3B: Planar cross-stratified sandstone

Lenticular-shaped, medium- to coarse-grained, tabular planar cross-stratified sandstone with locally dispersed pebble layers; thickness of cross-bed sets 10–35 cm; each set records coarse- to medium-grained sandstone near base grading into fine-grained sandstone; thin mud veneers present on foresets.

Downstream migration of 2-D ripples under lower flow-regime (Harms et al. 1982) in channel bar; thin mud veneers indicate tidal fluctuations.