河南洛宁太华岩群斜长角闪岩的锆石^(207)Pb/^(206)Pb和角闪石^(40)Ar/^(39)Ar年龄

^(207)Pb/^(206)Pb Age of Zircon and ^(40)Ar/^(39)Ar of Amphibole from Plagioclase Amphibolite in the Taihua Group, Luoning,Henan,China

运用单颗粒锆石逐层蒸发法和角闪石^(40)Ar/^(39)Ar阶段加热法研究了河南洛宁太华岩群斜长角闪岩的同位素年龄。获得锆石^(207)Pb/^(206)Pb年龄为2675±2 Ma,角闪石^(40)Ar/^(39)Ar坪年龄和等时线年龄分别为2372.98±47.46Ma和2349.10±46.98Ma。锆石^(207)Pb/^(206)Pb年龄代表了斜长角闪岩原岩的形成时代,而角闪石^(40)Ar/^(39)Ar年龄则为其变质时代,与Sm-Nd等时线年龄(2351±103 Ma)相一致。上述年龄数据表明河南洛宁地区太华岩群形成于新太古代,在古元古代遭受过一次角闪岩相变质作用。

The isotopic geological age of plagioclase amphibolite from the Taihua Group in Luoning County,Henan Province,China has been determinated by whole-grain evaporation on single zircon using a double-filement and step-heating 40Ar/39Ar spectra of amphibole. The single-grain zircon 207Pb/206Pb age is 2675±2 Ma and amphi-bole 40Ar/39Ar plateau and isochron ages are 2372. 98 ± 47. 46 Ma and 2349. 10 ± 46. 98 Ma respectively. The former is the crystallization age of plagioclase amphibolite protolith, the later is the metamorphic age and similar to the Sm-Nd isochron age (2351 ± 103 Ma). The isotopic age of plagioclase amphibolite show that the Taihua Group belong to the Neoarchaean and sufferd the amphibole-facies metamorphsm in the Palaoproterozoic subsequently.