佳木斯地块中部兴东岩群大盘道岩组U-Pb年代学证据

为了查明佳木斯地块中部双鸭山地区出露的兴东岩群大盘道岩组的形成时代及其地质背景，对其主量元素进行了分析，结果表明：该区变质岩岩石化学特征为富铝，原岩可能为砂岩、泥质岩、硅质岩和白云岩夹中基性火山岩，岩石系列属岛弧低钾拉斑玄武岩系列，构造环境可能为岛弧及活动性大陆边缘环境.对大盘道岩组石榴夕线钾长片麻岩进行了锆石LA-ICP-MS U-Pb测年，结果表明佳木斯地块兴东岩群中的火山岩形成时代应大于1000 Ma，因此兴东岩群大盘道岩组形成时代应在中-新元古代.

GEOCHRONOLOGICAL EVIDENCE OF U-Pb FOR THE DAPANDAO ROCK FORMATION OF DONGXING GROUP IN JIAMISI BLOCK

In order to identify the formation age and geological background of the Dapandao rock formation of Xingdong rock group in central Jiamusi block in Shuangyashan area, Heilongjiang Province, the authors analyze the major elements of the formation. The results indicate that the metamorphic rocks in this area are chemically characterized by aluminum enrichment. The protolith are possibly sandstone, argillite, silicalite and dolomite with intermediate-basic volcanic rocks, belonging to island arc and low-K tholeiite series. The tectonic environment might be active island arc and continental margin. The zircon LA-ICP-MS U-Pb dating result for the garnet sillimanite feldspar gneiss of Dapandao formation shows that the volcanic rock of Xingdong rock group in the Jiamusi block should be more than 1000 Ma. Therefore the Dapandao rock formation was formed in the Meso-Neoproterozoic Era.