The color reflectance of marine-terrigenous deposits in LZ908 borehole in south coastal plain of the Laizhou Bay

Color measuring is characterized by high resolution, high efficiency, and low cost. The application becomes increasingly common for tracing sediment sources and climate variation. Borehole LZ908 in the south coastal plain of the Laizhou Bay in northeast China, was used, of which the top 54 m containing all marine facies was focused, to test the feasibility of colorimetry as a climate indicator using visible light reflectance spectra and L^*a^*b^* measurement results. The results show a good correction between lightness and calcium carbonate content in marine-terrigenous deposits; therefore, these deposits can be used as a proxy to study climate changes. Factor-analysis on the first derivative values of the raw visible light reflectance spectra produced three principal factors corresponding to goethite, organic matter, and hematite. Down hole variations in the three factor scores, lightness, calcium carbonate content, and grain size were quite consistent. Moreover, high lightness and low factor scores in goethite, hematite, and organics indicated glacial regression deposits, while low lightness and high factor scores in goethite, hematite, and organics indicated interglacial transgression deposits.