普通铅同位素演化系统模式

已有的几种普通铅同位素模式仅反映了一些封闭体系铅同位素混合的特殊情况,不便于有效地应用于地质历史时期复杂的地质作用过程。本文应用概率论方法,从理论上分析包括开放体系在内的13种不同系统普通铅同位素混合的23种情况,讨论各种情况下铅同位素资料的地质年代学意义与地质事件发生年代的计算方法,从而建立多阶段铅同位素演化的系统模式。应用读系统模式研究燕山地区的成岩成矿时代,所得结果与其它方法测出的年龄一致。

SYSTEMATIC MODELS OF LEAD-ISOTOPE EVOLUTION

Lead - isotope dating is an important methods of isotope chronology. The known lead - isotope models , which were established in several specific close systems, are hardly to use effectively in geological study. The systematic models of lead - isotope evolution are established in this article. First, twenty three cases of lead - isotope evolution in thirteen different systems, including open systems, are analyzed. Second, the geological dating of each lead - isotope evolution model is discussed. The known lead - isotope models are pan of special models included in the systematic models of lead - isotope evolution. Many data of lead - isotope, which were useless in geological dating before , are valuable in dating of rocks and metal ore - deposits in Yanshan area with the new systematic models. The new lead - isotope ages calculated according to the new systematic models are equal to the ages determined by other isotope - dating methods, which shows the efficiency of the systematic models of lead - isotope evolution.