摘要
本文提出二元混合体系的端元Sm-Nd模式年龄的计算方法,利用该方法计算二元混合体系两端元的Sm-Nd同位素组成,二端元在混源样品中的重量百分比及地壳残留时间。借助此方法,笔者计算了东秦岭褶皱带基底的Sm-Nd同位素物质组成及形成时代,并讨论了其基底演化过程。研究结果表明,南、北秦岭褶皱带的基底在物质来源和形成时代上存在明显的差别。北秦岭褶皱带基底由 3000Ma和 608Ma两个端元混合组成;而南秦岭褶皱带的基底,则由 1700Ma和 989Ma两个端元混合组成。研究暗示了东秦岭褶皱带存在二次重要的壳幔分异事件,时间分别为989Ma和608Ma。
This paper has put forward a method to obtain Sm-Nd isotopic compositions, weight fractions and model dates of end-members in any binary mixed system. The author has calculated the Sm-Nd isotopic compositions and model dates of the members in the Eastern Qingling Orogenic Belt basement using this method. The results suggest that there is obvious difference in material sources and time of formation between the Southern and Northern Qingling Orogenic Belt basements. The northern basement is composed of two end-members, which formed at 3000 Ma and 608 Ma,While the southern basement at 1700 Ma and 989 Ma. The results also imply that important crust-manlte differential events have occurred at 989 Ma and 608 Ma
出处
《地质科技情报》
CAS
CSCD
北大核心
1991年第4期29-37,共9页
Geological Science and Technology Information
