ENVIRONMENTAL IMPLICATION OF COLOR REFLECTANCE OF DRILL HOLE BDQ0608, KEKE XILI REGION AND ITS INFLUENCING FACTORS

Color reflectance records of the sediment cores taking from the Hole BDQ0608 in a palaeo-lake in Keke Xili region were studied for palaeoenvironmental and palaeoclimatic changes. Although the results of dry and wet samples have similar trend along the sediment profile, their values are of distinct difference. The variation of a^* and b^* values is relatively small, whereas the difference of L^* reaches 22.48. To some extent, the color reflectance of lake sediments may partly indicate their diagenetic environment, as revealed by the visual inspection of lithology of core sediments. The variations of L^* values are mainly related to the changes in contents of total organic carbon (TOC). The correlation between grain size and L^* suggests that sediment environment is certainly a factor to the storage and preservation of total organic carbon, and hence L^* values of sediments could be used as an environment indicator. Compared to other proxies, variations of Ca^*b^* are possibly attributed to the color-causing minerals formed by the oxidation-reduction reaction under the temperature and moisture conditions at that time. Positive correlations between Ca^*b^* values and magnetic susceptibility, TOC and carbonate contents indicate that high values of Ca^*b^* probably reflect a relatively high water level and a warm and wet environment, as confirmed by grain size record.