摘要:本文对额尔古纳地块北段的富源沟林场含电气石花岗岩体进行了LA-ICP-MS锆石U-Pb同位素定年和岩石地球化学研究。含电气石花岗岩的锆石206Pb/238U年龄加权平均值为458±4 Ma（MSWD = 1.8），表明含电气石花岗岩形成于晚奥陶世初期。岩石地球化学特征表明该花岗岩应为高钾钙碱性系列（K2O = 3.45%～4.83%），铝饱和指数A/CNK＞1.1（1.11～1.28），属强过铝质的S型花岗岩，富集Th、U、Rb、K等元素，相对亏损Sr、Ba、 Nb、Ti、 P、Eu等元素，是同碰撞构造背景下地壳部分熔融的产物。结合前人研究资料和本文数据提出，富源沟林场含电气石花岗岩的形成与额尔古纳地块和兴安地块的碰撞拼贴有关，形成于额尔古纳地块与兴安地块碰撞拼贴作用所引发的碰撞构造背景，由于地缘因素，构造岩浆作用滞后于额尔古纳地块东缘的碰撞拼贴时限，是额尔古纳地块和兴安地块碰撞拼贴的远程效应。
关键词: 晚奥陶世初期/
S型花岗岩/
同碰撞/
地球化学/
额尔古纳地块
Abstract:Zircon U-Pb ages and whole-rock major and trace element date for the Fuyuangoulinchang tourmaline-bearing granites in Mohe County, Heilongjiang Province, NE China were presented in this paper. The petrogenesis of the rocks and its tectonic evolution of the massif were discussed. Zircons from the granites are of magmatic origin based on their cathodoluminescence （CL）images. The 206Pb/238U ages weighted mean age of 458±4 Ma, formed in Upper Ordovician. Chemically, the Fuyuangoulinchang tourmaline-bearing granites in Erguna massif are similar to S-type granites, belonging to the high-K calc-alkaline series. The Fuyuangoulinchang tourmaline-bearing granites have the following characeristics: without hornblende, tourmaline-bearing, A/CNK＞1.11（1.11～1.28）, enriched in Th, U, Rb, K, depleted in Sr, Ba, Nb, Ti, P, Eu, strongly peraluminous. Accordingly, the first magmatic event occurred in the late stage of collision between the Ergun block and Siberia block, and the second magmatic event might have led to the formation of Fuyuangoulinchang tourmaline-bearing granites in response to the southeast ward movement of Xing′an block towards the Ergun block, which had been collaged with the Siberia block. Due to subsequent compression, the crust was thickened and resulted in the remelting of metasands tone and the formation of the Fuyuangoulinchang tourmaline-bearing granites with some features of strongly peraluminous syn-collision S-type granite.
Key words:Upper Ordovician/
S-type granite/
Syn-collisinal/
Geochemistry/
Ergun block
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