Late Quaternary clay minerals in the inner Lingdingyang of the Pearl River Estuary, southern China: Implications for paleoclimate changes at the provenance

Clay minerals are good indicators of paleoclimate changes , and therefore, clay mineral analysis is commonly used as a powerful tool for paleoclimate reconstruction. In this study, the assemblages and relative contents of clay minerals of the Late Quaternary sediments from the drill core 13-LD-ZK20 in the inner Lingdingyang of the Pearl River Estuary are analyzed. Our results suggest that the clay mineral assemblages are dominated by smectite on an average content of about 49% including illite-smectite mixed-layers clay mineral(R=0), followed by illite, kaolinite and chlorite on average of 20%, 19% and 12%, respectively. The high illite chemical weathering index is mostly greater than 0.4, which signify intense chemical weathering at the provenance. The Late Quaternary deposits of the region can be subdivided into four stages based on the composition of clay minerals and the diagenesis of sediments. It indicates a fluctuated paleoclimate pattern in the Xijiang drainage from warm, cold to warm again. Paleoclimate was unable to be reconstructed with clay minerals for the first stage of Late Pleistocene, due to strong diagenesis. In the second stage, it was warm in the beginning and turned cold by the end of the stage, most likely related to the Last Glacial Maximum. Then the paleoclimate slightly turned warmer in the early third stage. The paleoclimate in the Holocene was warm and humid with short periods of fluctuations.