Identifying Climatic Factors Recorded in a Modern Stalagmite from Shihua Cave, North China

The stalagmite laminae are good indicators of the paleoclimate reconstruction. A better understanding of the variation in drip water is a useful to identify the climatic impacts on the stalagmites formation. The significant annual variation of trace elements in XMG stalagmite (150±1 years) from Shihua Cave, China, has provided chronological markers. Here, the recharge water of XMG were monitored once a month over the period 2015-2018. Its drip rate varies (83-480 sec/drop) with intra- and inter- annual variation depending on the rain frequency and intensity. The rainfall events with the high frequency and low intensity tended to recharge the stalagmite. The dry-wet seasonal variations of discharge, trace elements, growth rate and cave environment were observed. In dry season (September to May next year), Sr/Ca and Mg/Ca of the drip water were increased because of prior calcite precipitation at the slow flow. Especially, Sr/Ca has an obvious anti-correlation with drip rate. Similarly, the growth rate was increasing at low drip rate, which has high calcite saturation index and enough time for more completely CO₂ degassing. Therefore, the majority of the laminae of stalagmite XMG formed in the dry season. In rainy season (June to August),the organic acids of drip water were higher, which result in the formation of annual fluorescent laminae. The results explained the formation mechanism of laminae and the annual cycle in trace elements of stalagmite growing in wet-dry monsoon climate region, which has great potential to reconstruct climate.