Fig. 2

a The outcrop of the Unit B salt deposits containing the yellowish K–Mg salt layer above the halite–mud laminae near “Church section” (Manzi et al. 2012). b A close-up image of the highly deformed structure found in the K–Mg salt layer. c, d The fallen rock samples A and B analyzed in this study originated from the yellowish K–Mg salt layer. e–g The polished slabs of the collected samples (K-1 to -3). K-1 and -2 were prepared from Fallen rock A and K-3 from Fallen rock B. The μ-XRF measurements were performed at the areas indicated in red rectangles. The blue rectangle represents the area where thin section picture is shown in Additional file 1: Figure S4. Arrows indicate the orientation of the slabs. h The outcrop of Unit B and Unit C in “Church section”. Unit C consists of shale–anhydrite–halite cycles deposited as a result of the dry–wet alternation in the climate. i A sample taken from cycles 37th to 38th for the biomarker analysis