U-Pb同位素测年新方法--激光烧蚀等离子体质谱法直接测定探针片中锆石和磷灰石年龄

摘要

通过实验研究，笔者确定了激光烧蚀等离子体质谱法直接测定探针片中锆石、磷灰石U-Pb同位素年龄的流程，包括样品制备、矿物成因分析、仪器测试条件和测试过程。该方法最大的优势在于，可在探针片上确定测年矿物的共生组合及地质意义，将测得的年龄与特定地质事件，如变质事件、热液事件等相联系，对年龄数据给予合理的地质解释。利用此方法对一些岩石中的锆石、磷灰石在探针片上进行了测试，与用传统单矿物制靶方法测试的结果在误差范围内一致，表明在探针片上进行含铀矿物原地原位U-Pb测年是完全可行的。%This article introduces an experimental procedure of dating zircon and apatite by laser ablation-multi-ple collector-inductively coupled plasma mass spectrometry using polished thin section , including sample prep-aration, origin analysis of zircon and apatite,and test by LA-MC-ICP-MS . The biggest advantage of this method is that dating Mineral association and the geological significance can be identified in polished thin section, and we can acquire the age by LA-MC-ICP-MS that can be link to particular geological events(such as metamorphic event, hydrothermal event and so on) , accordingly, we should get a reasonable interpretation for experimental re-sults. U-Pb dating of zircon and apatite of some rocks in situ polished thin section were performed by LA-MC-ICP-MS, which are consistent with test result of that dated in mount in the error range, showing U-Pb dating of uranium-bearing minerals in polished thin section is completely feasible.