飞秒激光剥蚀-等离子体质谱原位微区Rb-Sr同位素年代学

Rb-Sr同位素定年法是一种应用广泛的同位素地质年代学方法。常规的Rb-Sr同位素定年方法是利用全岩或矿物经过化学消解、离子交换树脂纯化等化学前处理，使用质谱仪测定Rb和Sr同位素比值，计算Rb-Sr同位素等时线年龄。由于87Rb和87Sr的同质异位素叠加，样品需经过复杂的化学前处理过程，但该方法费时耗力，对操作人员有极高的要求。另外，岩石矿物也可能是不同期次形成的，颗粒可能存在包裹体和环带，这样获得的Rb-Sr年龄可能是混合年龄而不具有地质意义，因此需要发展更精细的微区Rb-Sr同位素年代学方法。本研究拟利用飞秒激光剥蚀系统结合串联四极杆等离子体质谱的多四极杆质量分析器和碰撞反应池优势，建立高精度高分辨度Rb-Sr同位素原位微区定年方法，研制Rb-Sr同位素定年微区分析参考物质，最终建成可为国内外同行服务的分析平台。

Rb-Sr isotope dating is a widely used method of isotope geochronology. The conventional Rb-Sr isotope dating method is to determine the ratio of Rb and Sr isotopic and calculate the isochron age of Rb-Sr isotope by using the whole rock or mineral after chemical pretreatment such as chemical digestion and ion exchange resin purification. Due to the superposition of 87Rb and 87Sr isobars, the samples need to go through a complex chemical purification process, but this method is time-consuming and labor-intensive, requiring skilled technique for operators. In addition, the rocks and minerals may be formed at different times, and the particles may contain inclusions or growth zoning, so the Rb-Sr isochron age obtained may be of mixed age and have no geological significance, so it is necessary to develop a in situ and micro-analysis Rb-Sr isotope geochronology method. This study intends to use the femtosecond laser ablation system combined with the advantages of multi-quadrupole mass analyzer and collision reaction cell in tandem inductively coupled plasma mass spectrometry to establish high precision high resolution in situ micro-analysis of the Rb-Sr isotope dating method, prepare the Rb-Sr isotope micro-analysis reference material, and finally build an analysis platform that can serve domestic and foreign peers.