南岭花岗岩类岩石Sm、Nd同位素特征及岩石成因探讨  

Sm-Nd ISOTOPIC CHARACTERISTICS OF GRANITOIDS IN THE NANLING REGION AND THEIR PETRO-GENETIC ANALYSIS

作　　者：袁忠信[1] 张宗清[2] 

机构地区：[1]中国地质科学院矿床地质研究所 [2]中国地质科学院地质研究所

出　　处：《地质论评》1992年第1期1-15,共15页Geological Review

基　　金：国家自然科学基金;项目编号:4880148

摘　　要：根据南岭地区50个岩体79个样品,以及基底构造层岩石26个样品的Sin-Nd同位素特征值讨论了本区陆壳的形成时间及花岗岩类岩石的成因。本区陆壳形成于2101Ma以前,此后大约有2次大规模的地块增生。按照花岗岩类的t_(DM)、Sm/Nd、ε_(Nd)(t)值,以及区域大地构造特征,区内可划分出5个花岗岩分布区。不同地区的花岗岩类具有不同的Sm-Nd同位素特征值,同一地区的花岗岩类岩石及其基底构造层岩石具有相近的Sm-Nd同位素特征值,结合地质构造特征研究可以认为,不同地区花岗岩类的源岩主要就是该区的基底构造层岩石。后者对前者的分布、成因类型,甚至有关的成矿作用具有重要的控制作用。Granitoids are widely distributed in the Nanling region. Their petrogeneticresearch has aroused much interest among many foreign and domestic scholars.Sm-Nd isotopic data of 79 samples from 50 granitoid bodies and 26 samples fromrocks of the basement structural layer in the region were used to study the timeof formation of continental crust and genesis of the granitoids. The resultssuggest that the continental crust of the area was formed 21 00 Ma ago and thatafterwards there occurred aboat 2 Iarge block accretions (1900 Ma--1600 Ma and1300--1100 Ma). According to the data of t_(DM), Sm/Nd and εNd(t), the region can bedivided into 5 areas of granitoids corresponding to 5 regional tectonic units. TheSm/Nd isotopoic values of the granitoids are different for the 5 areas, but thevalues within a specific area are close, and moreover the granitoids and basementrocks in a specific area have similar Sm--Nd isotopic values. From a study ofSm--Nd isotopes and regional tectonics the following conclusion may be drawn:the source rocks of the granitoids in a region are mainly the basement rocks ofthat region. The distribution and mineralization of the granitoids and their petro-genesis are closely related to the age, characteristics and types of the basementrocks.

关 键 词：花岗岩 基底构造层 钐-钕同位素 成岩物质 成因 南岭地区 

分 类 号：P588.121[天文地球—岩石学]