关键词: 碳－14年龄测定, 同位素年龄测定, 石灰岩, 石笋生长速率

Abstract: The application of radiocarbon dating of speleothems is often limited by "dead carbon" contamination.In this paper we have established a new model to correct contamination of "dead carbon" and determine growth rate of a stalagmite which was collected from Shihua cave, Beijing.Based on the measurements of ¹⁴C activity on 11 samples from the stalagmite, we have found that 5 of the samples have little "dead carbon" contamination and four of the samples contain relatively constant contamination of "dead carbon".The two groups of the samples gives us two linear relationships between natural log of ¹⁴C activity and depth with the same slopes but different intercepts.These data results illustrate that the stalagmite has a relatively constant growth rate and no growth hiatus which are the assumptions of the model.Using the model we have reconstructed the chronology Of the stalagmite and obtained a mean growth rate of 0.042 mm/a.The results are in good agreement with the mean growth rate determined by the annual growth banding and the youngest age measured by ²¹⁰Pb method.

Key words: Carbon-14 dating, Lsotopic age dating, Limestone, Stalagmite growth rate