摘要
Trace elements in speleothem are important proxies of paleoclimate. In recent years, investigation on speleothem Mg/Ca and Sr/Ca ratios has got some important conclusions as follows: 1) Mg and Sr in speleothems derive mainly from overlying soil layer and wall-rock; 2) speleothem Mg/Ca and Sr/Ca ratios are able to indicate paleoclimate, but they should be explained in combination with other indices such as oxygen and carbon isotope ratios; 3) speleothem Mg/Ca and Sr/Ca ratios are influenced by a variety of climatic and environmental parameters including the composition and features of overlying soil layer and wall-rock, interaction between water and rock, advance carbonate deposit, distribution coefficients of Mg and Sr between solution and carbonate etc. Thus their interpretation is multiple depending on the dominant factor; and 4) mineral and crystallization also have certain influences on speleothem Mg/Ca and Sr/Ca ratios. Especially, it is easy to lost Mg and Sr during the transformation from aragonite to calcite, and lead to lower Mg/Ca and Sr/Ca ratios; incorporation of impurity would enhance inhibition of Mg and Sr into calcite lattice.
