结合同位素地质年龄，区域对比分析，确认昔格达组属上新世至早更新世沉积。
Isotopic dating and regional stratigraphic correlation indicate that the Xigeda Formation is Pliocene-Early Pleistocene sediment.
地质学家在石笋上钻孔，使用铀衰变成钍的同位素的方法确定它们的年龄。
In this case the geologists drilled into the stalagmites and estimated their age from the way that uranium decays into an isotope of thorium.
尽管我国好多矿床已经测得了大量同位素年龄资料，但这决不等于这些年龄数据均能标定成矿过程中某一地质事件发生的时代。
A lot of isotopic age data of many significant ore deposits in China have been obtained, but a certain geologic event in the mineralization process can not be marked by them.
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