Table 2. Sedimentary facies and depositional environments for the investigated Hiraiso Formation.

Facies labels correspond to Kashiyama & Oji (2004), Facies Ha′ was, however, not recognised by those authors and is added in this study.

Facies	Description	Depositional environment
S	Well-sorted, massive, thick-bedded, light grey, sandstones.	Upper shoreface
Ha′	Swaley, cross-bedded, fine grained, thick sandstones and very fine-grained, sandstones, separated by thin (mm-size), dark grey, silt laminations. The thicker, fine-grained sandstone beds frequently contain large (up to 7 cm) bivalves orientated perpendicular to bedding.	Lower shoreface
Ha	Hummocky cross-stratified, thick, fine-grained sandstones with randomly orientated invertebrates forming basal lenses. Sandstones alternate with thin beds of bioturbated siltstone (mm-scale).	Lower shoreface-offshore transition
Hb	Hummocky cross-stratified, thick, fine-grained, occasionally graded upward sandstones with randomly orientated invertebrates and rip up mud clasts forming basal lenses. Sandstones alternate with thick beds of bioturbated, dark grey, siltstones. Plant debris can be common on sandstone bedding surfaces.	Offshore transition
Hc	Parallel- and hummocky cross-stratified, sandstones that occasionally exhibit upward grading. Asymmetrical ripples common on bedding surfaces. Sandstones also exhibit convolute bedding. Sandstones separated by beds of bioturbated, dark grey siltstones.	Offshore transition
Hd	Parallel laminated and massive sandstones alternating with siltstones. Both sandstone and siltstone beds are typically bioturbated, but thicker sandstone beds are only bioturbated towards the bedding surface. Sandstones also exhibit asymmetrical ripples.	Offshore transition-distal offshore
He	Banded alternations of sandstones and bioturbated siltstones. Sandstones commonly exhibit asymmetrical ripples on bedding surfaces or convolute bedding.	Distal offshore
Ms (Osawa Fm.)	Banded alternations of unbioturbated grey sandstones and dark grey siltstones. Sandstones typically have surfaces with small asymmetrical ripples.	Basin