We tested some geochemical signatures, including the MnO/TiO2 ratio and LaN/CeN ratio, to deduce the depositional environment of the sediments at Site 1179. Among these, diagenetic processes must be taken in to account if the MnO/TiO2 ratio is to be used to estimate the depositional environment, since the early diagenesis can alter the MnO record in the sediments. Diagenetic transformations of Mn with depth were clearly visible in the profiles of manganese abundances in the sediments and pore waters and with the direct observation of the oxidation state of Mn in the sediments by XANES. REE signatures, such as Ce/Ce* or LaN/CeN, can be useful because they are not readily subject to diagenetic effects. However, it is suggested that the Ce/Ce* or LaN/CeN ratio should only be used for siliceous sediments. The presence of MnO2 as a major component in the sediments can cause the lower LaN/CeN ratio, which creates a misleading conclusion for the estimation of depositional environment by the LaN/CeN ratio. The REE signatures and other geochemical data suggest that a variety of materials from continents and volcanic activities were added to biogenic silica to produce the sediments at Site 1179.