| 迁安紫苏花岗岩的~(40)Ar/~(39)Ar年龄谱 |
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| 引用本文： | 桑海清,王松山,胡世玲,裘冀.迁安紫苏花岗岩的~(40)Ar/~(39)Ar年龄谱[J].岩石学报,1988,4(4). |
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| 作者姓名： | 桑海清 王松山 胡世玲 裘冀 |
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| 作者单位： | 中国科学院地质研究所，中国科学院地质研究所，中国科学院地质研究所，中国科学院地质研究所 北京 100011，北京 100011，北京 100011，北京 100011 |
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| 摘 要： | 对采自河北省迁安县水厂地区的紫苏花岗岩中的黑云母和紫苏辉石进行了~(40)Ar/~(39)Ar年龄测定,分别给出了18.7亿年和19.6亿年的~(40)Ar保存年龄。这两种矿物的年龄谱的视年龄的梯度变化表明,紫苏花岗岩形成后是缓慢冷却的。3.9亿年左右的一次热事件,造成了放射成因~(40)Ar的丢失。根据热历史和封闭温度的研究,从27亿年(侵入到该区紫花岗岩中的花岗闪长岩的锆石U-Pb年龄)到19.6亿年,紫苏花岗岩岩体的抬升速率为6.5m/Ma,但从19.6亿年到18.7亿年,其抬升速率高达111m/Ma,具有明显的构造抬升作用。
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| 关 键 词： | ~(40)Ar/~(39)Ar年龄谱 缓慢冷却 ~(60)Ar保存年龄 抬升速率 紫苏花岗岩 |
~(40)Ar/~(39)Ar AGE SPECTRUM OF QIANAN CHARNOCKITE |
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| Sang Haiqing Wang Songshan Hu Shiling Qiu Ji.~(40)Ar/~(39)Ar AGE SPECTRUM OF QIANAN CHARNOCKITE[J].Acta Petrologica Sinica,1988,4(4). |
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| Authors: | Sang Haiqing Wang Songshan Hu Shiling Qiu Ji |
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| Abstract: | The cbarnockite samples were collected from Sbuichang area of Qianan county, Hebei Province, China. Previously, they yielded a Rb/Sr whole rock age of 2.65Ga and an U/Pb zircon age of 2.73Ga. Some scholars thought that the charnockitcs belong to the migmatic bodies.
The ~(40)Ar/~(39)Ar step heating experiment performed on biotite and hypersthene yielded two age spectra, and gave two ~(40)Ar preserved ages of 1.87Ga and 1.96Ga respectively. The two complex age spectra show that the charnockites underwent a thermal perturbation at low temperature interval. The diversified dates by different dating methods indicate that the charnockite slowly cooled down since emplacement. The charnockitc plutons had an uplift rate of 6.5m/Ma from 2.70Ga to 1.96Ga, while the uplift rate rose up to 111m/Ma from 1.96Ga to 1.87Ga.
The orogeny of 1.96Ga had universal significance not only in Shuichang and eastern Hebei, but also for the whole North China Block. |
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| Keywords: | ~(40)Ar/~(39)Ar age spectra Slow cooling ~(40)Ar preserved age Uplift rate Charnockite |
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