speleothem is a secondary mineral deposit formed through chemical and physical processes of minerals in a cave, which includes calcium carbonate, gypsum and other minerals. the water rich in calcium carbonate seeping through cracks in the rocks results in the change of awater temperature and pressure and the transpiration of co2 from the water, causing the saturation and deposit of caco3 in the water. lots of information about ancient climate and ancient environment can be obtained through isotopic analysis on the speleothem.