辽宁鞍山地区东山杂岩带3.3～3.1Ga期间的岩浆作用——锆石SHRIMP U-Pb定年

3.3-3.1 Ga magmatism in the Dongshan complex, Anshan area, Liaoning, China: Evidence from zircon SHRIMP U-Pb dating

报道了鞍山地区东山杂岩带奥长花岗岩和二长花岗岩的锆石SHRIMP U-Pb年龄。中粗粒奥长花岗岩中岩浆锆石的年龄为3329Ma±22Ma（MSWD=9.6）,存在年龄为3687~3784Ma的残余锆石。细粒奥长花岗岩和二长花岗岩中岩浆锆石的年龄分别为3141Ma±8Ma（MSWD=1.5）和3142Ma±5Ma（MSWD=0.35）。表明约3.3Ga和3.1Ga是鞍山地区2个重要的地壳演化阶段。

This paper reports SHRIMP U-Pb zircon ages of granitoids from the Dongshan complex in the Anshan area, where there are Archean rocks with ages ranging from 3.8 to 2.5 Ga. A medium-coarse-grained trondhjemite sample has a ^207Pb/^206Pb weighted mean age of 3329 ＋ 22 Ma （MSWD=9.6） on magmatic zircons, with inherited zircons of 3687-3784 Ma. Magmatic zircons from fine-grained trondhjemite and adamellite samples have weighted mean ^207pb/^206pb ages of 3141 ＋ 8 Ma （MSWD=1.5） and 3142 ＋ 5 Ma （MSWD=0.35）, respectively. The -3.3 Ga medium-coarse grained trondhjemite was formed by anatexis of 3.8 Ga trondhjerniteic rocks. The 3.14 Ga fine-grained trondhjemite is considered to be a veinlet emanated from the nearby Lishan trondhjemite body with the same age. The 3.14 Ga adamellite cuts the fine-grained trondhjemite and is derived from continental material. Combined with early researches, it is indicated that ～3.3 Ga and ～3.1 Ga are two important crustal evolution stages in the Anshan area.