Ultra-precise Micromilling of Porous Stalagmite Carbonate

High resolution analysis of abrupt climate events is a hot research field. Stalagmites, one of the important archives of paleclimatic records, usually with a growth rate of tens or hundreds of microns per year, have the potential to provide high resolution paleoclimate proxies. Reliable micro-sampling is the key step for stalagmite high resolution analysis. In this paper, technique details for micro-sampling of stalagmite carbonate using a commercial New Wave Technology MicroMill are described. Sample sizes averaging 100 μg were obtained from a 40 μm wide milled path despite the porous nature of the sample and the imperfect laminar structure. Sub-annual sampling resolution was achieved producing sufficient material for trace element and stable isotopic analysis. Key aspects of sample mounting and the optimum MicroMill parameter settings were established. The sample collection technique was perfected and cross contamination of undesired sample material was avoided.