摘要
分布在贺兰山脉北端的贺兰山群变质杂岩是一套变质程度已达角闪麻粒岩相的孔兹岩系。以往的研究者均认为它的主期变质作用发生在中太古代。本文利用变质岩中矿物的Rb/Sr等时线年龄,同变质花岗岩全岩Rb/Sr等时线年龄及变质岩和花岗岩中锆石^(207)Pb/^(206)Pb年龄值结合地质事实,证明这套变质岩的主期变质作用发生在早元古代。
The metamorphic complex of the Helanshan Group. being situated on the north HeIanshan Range. is a Kho-daliteseries. and the metamorphic grade reached the amphibole granul:te fac:es. It was considered that the main metamorphism of the Helanshan Group took place in the Middle Archean era. In fact, the Rb -Sr mineral isochron of gneiss. Rb - Sr wholerock isochron of the synmetamorphic granites and207Pb/206Pb ages of zircons of various rocks demonstrate that the main metarnorphism of the Helanshan Group took place in the earlyProterozoic era.
关键词
贺兰山群
孔兹岩系
变质杂岩
时代
Chronology of isotope geolgy. North China Massif. Helanshan Group. Khondalite series, granulite facies
