Abstract
Stalagmites are important archives of the terrestrial paleoclimate during the late Pleistocene and Holocene, and have the advantage of precise dating by U-series methods and lamina counting. In addition, fast-track analysis of milligram-sized carbonate subsamples allows for very high time resolution. Oxygen isotopic age-profiles of stalagmites from caves in south China have provided standard paleoclimatic records that have revealed temporal changes in the intensity of the summer Asian Monsoon. However, quantitative evaluations of temperature and rainfall from stalagmite records are difficult because the stable isotope values and trace element contents in the carbonate fraction are controlled by complex interactions among processes in the atmosphere, in the soil layer, and in the cave. The stalagmite oxygen isotope ratio varies with rainfall intensity, rainfall seasonality, temperature, and evaporation of water, while the carbon isotope ratio reflects the drip rate of water onto the stalagmite, vegetation type, and soil moisture. Another important effect is prior calcite precipitation (i.e., the degree of calcite precipitation from the water before dripping onto a stalagmite), as this factor has a strong influence on the carbon isotope ratio and trace element contents. Despite the complexity of the controlling processes, stalagmite age-profiles from different regions commonly show synchronous changes in isotopic and chemical proxies, especially for certain climatic events such as the B?lling warming. These findings support the existence of a climatic teleconnection in the Northern Hemisphere. Importantly, the age-profiles of isotopic and chemical proxies contain paleoclimatic information. Novel approaches in the field of stalagmite paleoclimatology will enable separation of the effects of temperature and rainfall amount on oxygen isotope values.
