A marine sediment component interpretation based on diffuse reflectance spectrophotometry from northern South China Sea sediment core MD972148

Abstract

The sediment components of high resolution marine sediment cores are extremely important for revealing past climatic and environmental changes. However, analysis of deep sea sediments presents a number of exceptional challenges, especially for the northern South China Sea (SCS) which receives substantial amounts of suspended sediments from numerous rivers, including both the world's largest river in South China and a small mountain river from southwestern Taiwan. This study applies rapid and low cost color reflectance analysis in combination with multivariate analysis techniques to examine the overall trends of major mineral component variations in sediment core MD972148 from the northern SCS. The first-order derivative (central difference) reflectance data (from 400 to 700 nm) yields five major factors, which accounted for 89.7% of the variance for the input matrix. Collocating with varimax-rotated principal component analysis (VPCA) through SPSS software and comparing with the first-order derivative spectra of known minerals from a laboratory at Kent State University and the USGS library, the three leading factors represent kaolinite, illite + goethite, and hematite. Although the last two factors have no significant correspondences with known minerals, we found these two factors have similar variation patterns with the abundances of the foraminifer species Globigerinoides sacculifer and Globigerina bulloides in the downcore. Our research shows that diffuse reflectance spectrophotometry (DRS) is a useful method for rapidly examining the sediment components. To verify the mechanisms and connections between some sediment components and their color reflectances will require future research.