大兴安岭绰源地区奥陶系多宝山组-苏呼河组解体及时代探讨

Disintegration and discussion on the time of Ordovician Duobaoshan Formation and Suhuhe Formation in Chaoyuan district of Daxing'anling Mountain

大兴安岭绰源地区出露有呈零星分布的老变质岩系,前人对其归属存在一定的争议。文章通过对该套岩石进行的地层学、岩石学、岩石地球化学特征研究和锆石U-Pb测年,探讨了该套变质岩系的原岩性质、形成环境和区域变质作用。结果表明,原岩主要为一套中酸性凝灰岩、砂岩、粉砂岩、泥岩及其过渡类型的碎屑岩;推测其沉积环境为活动大陆边缘的浅海相或浅海-滨海相;该套地层定年为中下志留统。

The metamorphic rock sequence is exposed sporadically in the Chaoyuan area of Daxinganling Mountains and the formation time controversial.Based on stratigraphy,petrology,rock geochemistry and U-Pb dating age is discussed the original rock property,formation environment and regional metamorphism.The result shows that the original rock is mainly a set of intermediate-acidic tuff,sandstone,siltstone,mudstone and their transitional types of clastic rock deposited under an active continent marginal shallow or shallow-neritic environment.Geological time of the sequence belongs to Middle-Early Silurian Period.