黑河市五道沟地区早二叠世A型花岗岩成因

Origin of Early Permian A-Type Granite in the Wudaogou Area,Heihe City

根据岩石学、岩石化学、地球化学及同位素等特征,对黑河市五道沟地区早二叠世碱长花岗岩进行了构造成因研究。该套岩石具高硅、富碱、低钙镁、偏铝质-过铝质特点,且富Rb、Th、K等大离子亲石元素,相对亏损Ba、Sr、P、Ti、Nb等元素,稀土元素具有典型的海鸥式分配样式,总体具有典型A型花岗岩特征;其形成于额尔古纳—兴安地块与松嫩—张广才岭地块挤压拼贴后的伸展环境。黑河市五道沟地区A型花岗岩的最新厘定对该地区晚古生代构造演化的研究及区域成矿规律的探讨具有重要意义。

This study focuses on the tectonic origin of the Early Permian alkali granites in the area of Wudaogou,Heihe based on its petrological,geochemical and isotopic characteristics.These granites are aluminous to peraluminous in composition and high in Si and alkali,but low in Ca and Mg.They are enriched in Rb,Th and K,but depleted in Ba,Sr,P,Ti and Nb.Their REE distributions are of typical gull-type pattern.Overall,they have features of typical A-type granite and were considered to be formed in an extensional environment after collision of Ergun-Xing＇an block with Songnen-Zhangguangcai block.The newly identified Wudaogou A-type granites in the area of Heihe are of great significance to the ongoing study on the Late Paleozoic tectonic evolution and regional metallogenesis.