Paleoclimatic interpretation in southern Laizhou Bay since the late Pleistocene: Evidence from groundwater and sedimentary strata

Abstract

Understanding past climatic change and the associated responses of sea level may contribute to the ability to evaluate the relationship between these factors in the future under the background of sea-level changed. Here, we aimed to reveal the climate change and sea-level characteristics of southern Laizhou Bay (SLB) since the late Pleistocene by combining groundwater stable isotopes (2H, 18O and deuterium excess (dexcess)), age dating (14C) and the structural characteristics of sediments from several boreholes. The isotopic proxies for climates demonstrated the depletion of 2H, 18O and dexcess of groundwater recharged in the last glacial period of the late Pleistocene, indicating that the weather was cooler and wetter in the last glacial maximum, while the stable isotopes and dexcess of groundwater were enriched in the Holocene. Several transgressions were revealed through the structural characteristics of boreholes, which also indirectly reflected the large-scale changes of in global temperature. Finally, a conceptual model that describes the evolution of coastal saline groundwater based on the transgression process was proposed based on the sedimentary chronology of strata and groundwater age. These results not only contribute to the study of climate-related sea-level change since the late Pleistocene but also provides a theoretical explanation for the mechanism by which coastal saline groundwater forms.