Vertical profiles of some major elements, SiO2-Al2O3 and SiO2-Fe2O3 diagrams, bivariate TiO2-Al2O3 and TiO2-Fe2O3 plots. (a) Vertical profiles of lithologies, total carbon (TC), δ13Corg (‰ vs PDB), total nitrogen (TN), δ15N (‰ vs air), total sulfur (TS), 14C ages, wt% of major elements (SiO2, Fe2O3, Al2O3, TiO2, CaO, MgO, K2O), and major elemental ratios (SiO2/TiO2 and Al2O3/TiO2) in core Mw5S from L. Maruwan, showing the transition between the marine and terrestrial stages via possible brackish conditions (*based on microflora differences at a depth of 60 cm, determined with a DGGE analysis). The raw data are provided in Table 1. (b), (c) Al2O3-SiO2 and Al2O3-Fe2O3 diagrams for L. Maruwan (core Mw5S) and Maruwan-minami (core Ms5S) sediments. Possible end-members of marine and terrestrial major elements are noted on the axes. (d) The similarity of the source rocks of L. Maruwan (core Mw5S, black symbols: R
2 = 0.97 and 0.92) and L. Maruwan-minami (core Ms5S, blue symbols: R
2 = 0.85 and 0.89) was confirmed with bivariate TiO2-Al2O3 and TiO2-Fe2O3 plots.