辽西地区台子里花岗质片麻岩锆石U-Pb年龄及其地质意义

Zircon U-Pb Age and Geological Significance of the Taizili Granitic Gneiss from Western Liaoning Province

辽西地区台子里发育一套花岗质片麻岩和表壳岩捕虏体的岩石组合,原划定为建平群大营子组,近年的研究将建平群大营子组解体为花岗质深成侵入体和层状岩系。台子里花岗质片麻岩与辽西建平大营子地区叶柏寿片麻岩、曹家烧锅片麻岩具有相似特征。通过对台子里花岗质片麻岩的锆石形态分析和LA-ICP-MS准确定年,确定2 522 Ma的岩浆侵位年龄,代表了大营子组底部花岗质片麻岩的侵位时代为太古宙晚期,是辽西地区太古宙重要的岩浆事件,并为本地区新太古代晚期重要陆壳增生事件提供了重要的年代学信息。

A suit of rock association of granitic gneiss and supracrustal xenoliths, described as the Dayingzi Formation, Jianping Group previously, is widely distributed in the Taizili area in western Liaoning Province. During the research of recent year, the Dayingzi Formation, Jianping Group was disintegrated into granitic＂ plutonic gneiss and layered rock series. This granitic gneiss has similar features as those in the Yebaishou and the Caojiashaoguo gneiss in Dayingzi area. The granitic gneiss could represent the important Archean magma event in western Liaoning Province. The LA - ICP - MS dating method of single particle zircon of granitic gneiss suggests its magma emplacement age is about 2 522 Ma, an significance geological event in the western Liaoning Province. This dating also gives some chronological information for the Late Archean continental crust accretion event in the area.