| 桑干地区高压麻粒岩中石榴石和斜长石的连续激光
探针40Ar-39Ar等时年龄及其地质意义 |
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| 引用本文： | 胡世玲,郭敬辉,戴橦谟,蒲志平.桑干地区高压麻粒岩中石榴石和斜长石的连续激光
探针40Ar-39Ar等时年龄及其地质意义[J].岩石学报,1999,15(4):40. |
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| 作者姓名： | 胡世玲 郭敬辉 戴橦谟 蒲志平 |
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| 作者单位： | ： 胡世玲 郭敬辉 中国科学院地质与地球物理研究所，北京
100029 |
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| 摘 要： |
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Continuous
laser-probe 40Ar-39Ar age dating on garnet and plagioclase:
constraint to metamorphism of high-pressure basic granulite from Sanggan area, North China
craton. |
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| Abstract: | Continuous laser probe 40Ar-39Ar
technique has been taken to carry out in situ analysis onto the metamorphic garnet and
plagioclase from high-pressure basic granulites in Sanggan area of the North China craton.
Garnet porphyroblasts was formed in the high-pressure granulite facies episode. In the
symplectite assemblage arround garnet, plagioclase is one of the garnet breakdown
products. Ar analysis of garnet porphyroblasts defines an 40Ar-39Ar
isochron which gives out an age of 2510Ma, that indicates the high-pressure granulite
facies metamorphic age. So, the Archaean high-pressure granulite metamorphism has been
confirmed by this age dating. Another 40Ar-39Ar isochron age of
1968Ma has been obtained from Ar data of plagioclase. That should represent the age of
garnet breakdown reaction. The >500Ma gap between the age of high-pressure metamorphism
and garnet breakdown does not support the isothermal decompression P-T path given by
petrological view. The symplectite assemblages are more likely to be formed during another
medium-pressure metamorphism overprint. This conclusion will give a strong constraint on
the crustal evolution of Sanggan area in the North China craton. |
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