柴北缘绿梁山早古生代花岗岩浆作用与高温变质作用的同时性

被引：34

作者：

孟繁聪

张建新

机构：

[1] 中国地质科学院地质研究所

来源：

岩石学报 | 2008年 / 24卷 / 07期

关键词：

花岗岩; SHRIMP 锆石; 地球化学; 绿梁山; 柴北缘;

D O I：

暂无

中图分类号：

P588.121 [];

学科分类号：

摘要：

采用 SHRIMP 方法获得绿梁山花岗岩的锆石 U-Pb 年龄为430±8Ma（12个测点平均）,所有测点的 Tb/U 比值均大于0.1,该年龄代表花岗岩的形成年龄。同时获得部分具有核-幔结构的继承锆石,其核部年龄为475～460Ma,Th/U 比值为0.01～0.02,为典型的变质锆石,与围岩片麻岩中的锆石类似,反映了花岗岩与片麻岩之间的成因联系。绿梁山花岗岩属于钙碱性系列,SiO2含量为65.63%～74.78%,变化较大,属于过铝质岩石,推测其源岩以沉积岩为主。围岩片麻岩以变质沉积岩为主,可能为花岗岩的主要源岩。花岗岩的(87Sr/86Sr)■为0.71075（t=430Ma）,εNd（430Ma）为-5.5～-4.6,与围岩片麻岩的 Sr-Nd 同位素组成存在较大差别,可能反映了花岗岩形成于高温缺水的环境或者成岩时有地幔物质/年轻地壳物质的加入。花岗岩形成时代与片麻岩变质时代的一致性（430Ma）,反映了它们为同一区域构造热事件的产物,是俯冲陆壳发生热松弛的记录。

引用

页码：1585 / 1594

页数：10

共 23 条

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