High-precision Laser ~(40)Ar/~(39)Ar dating of Qiongbei volcanic rocks
High-precision Laser ~(40)Ar/~(39)Ar dating of Qiongbei volcanic rocks
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作者：
S. Xiao
晚新生代以来，雷琼地区火山岩频繁大规模喷发。根据K-Ar测年法，将这些火山岩划分为几个火山相。本文采用激光40Ar/39Ar测年法，对琼北地区火山岩进行了精确测年。激光40Ar/39Ar测年结果表明，琼北火山喷发的时间跨度约为1.3~0.052Ma。考虑到视年龄与等时线年龄的差异，建议采用一系列年龄。资料显示，新生代火山岩中普遍存在继承的40Ar*和36ar过量，因此等线年龄更适合作为火山喷发的真实年龄。
Since Late Cenozoic era,volcanic rocks have been frequently and massively erupted in the Leiqiong area. Those volcanic rocks,on the basis of K-Ar dating method,are divided to several volcanic phases. In this paper,laser 40Ar/39Ar dating method is used to test and calculate the accurate time of volcanic rocks in Qiongbei area. The high quality data result by laser 40Ar/39Ar dating method shows that the time spans of eruption of Qiongbei volcanoes are around 1.3～0.052Ma. Considering the differences between the apparent ages and the isochron ages,a series of ages are recommended. As shown as the data,there are widespread inherited 40Ar* and 36 Ar excess in the Cenozoic volcanic rocks,then the isochorn ages are more recommended to be the real ages of the eruptions.