摘要
通过对海南岛花岗岩、变质沉积岩等地壳岩石SmNd同位素的详细剖析,探讨了海南岛的基底性质及其地壳生长史。研究表明:海南岛九所—陵水断裂的南、北经历了不同的构造演化史。断裂以北地壳岩石的εNd(t)分布在3.3至-17.2之间,Nd模式年龄分布在1.2～3.2Ga之间,并在1.4～1.6Ga和2.0Ga形成统计峰值。断裂以北地壳主要以幕式生长形成,太古代时期形成若干陆核(距今3.1～3.2Ga或更早?),1.4～1.6Ga和1.8～2.0Ga为地壳生长的主要时期。断裂以北地壳岩石的SmNd同位素特征和地壳生长史与华夏古陆的相似,其基底是华夏古陆的一部分,断裂以南可能是亲东冈瓦纳(澳大利亚)的裂解块体。
Based on detailed Sm-Nd isotopic analyses of the granitoids and metamorphic sediments in Hainan Island, southern China, the history of crustal growth and the characteristics of the basement of the island were discussed. It was suggested that the crust evolutional history of the terrane to the north of the Jiusuo-Lingshui fault was obviously different from that of the terrane to the south of the fault. The εNd（t） values of the north terrane ranged from 3.3 to 17.2, and Nd model ages ranged from 1.2 to 3.2 Ga, with two age peaks of 1.4-1.6 Ga and 2.0 Ga, in dicating that the accreation of the Precambrian crust was of episodic character. The oldest crustal nucleus might be formed during the Archean （3.1-3.2 Ga ago or older？）, and the periods of 1.4-1.6 Ga ago and 1.8-2.0 Ga ago might be the most important episodes for crustal growth of the north terrane. The Sm-Nd isotopic characteristics revealed that the crustal rocks and the crustal growth history of the north terrane were similar to those of the Cathaysia Block, with the basement being a part of the Cathaysia Block. While the basement of the terrane to the south of the Jiusuo-Lingshui fault might be drifted from the Australian Gondwana.
出处
《地质科学》
CAS
CSCD
北大核心
2005年第3期439-456,共18页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
中国地质调查局1:25万琼海幅区域地质调查和"中国花岗岩重大地质问题研究"(200113900018)项目的部分成果。
关键词
地壳增生
基底
ND同位素
九所-陵水断裂
海南岛
Crustal growth, Basement, Nd isotopes, The Jiusuo-Lingshui fault, Hainan Island
