小兴安岭西北部与永新金矿有关岩浆岩的年代学和地球化学及成矿构造环境

发布时间：2018-06-02 14:19

本文选题：安山岩 + 闪长玢岩　；参考：《现代地质》2017年06期

【摘要】：永新金矿是近年发现的大型蚀变岩型脉状金矿床,闪长玢岩脉等与金矿脉相互穿切并侵入于上盘龙江组火山岩中。锆石LA-ICP-MS U-Pb测年显示,龙江组安山岩结晶年龄为(113.7±1.8)Ma,闪长玢岩结晶年龄为(114.8±1.9)Ma,均形成于早白垩世晚期。二者钠钾含量变化相对较大,相对富铝富铁、钙镁含量中等,从火山岩到脉岩表现为钙碱性向碱性系列过渡特征。火山岩、脉岩与矿石的稀土元素配分曲线有很好的一致性,矿石稀土含量低于岩石。岩石微量元素总体显示Zr、Hf、Nd、U等明显富集,而Nb、Ta、Th、P、Ti等明显亏损。在Sr/Y-Y和(La/Yb)N-(Yb)N图解中,所有样品均落入经典岛弧岩石范围;在Nb-Y、Ta-Yb的构造环境判别图中均处于火山弧岩浆岩区,在(La/Yb)N-δEu变异图上落在壳-幔型岩浆范围。结合矿床稳定同位素及区域金矿时空分布规律等综合特征,认为永新金矿的形成与早白垩世古太平洋板块俯冲所引发的(火山)岩浆活动有关。
[Abstract]:Yongxin gold deposit is a large altered rock type vein gold deposit discovered in recent years. Diorite porphyrite diorite intersects with gold veins and intrudes into the volcanic rocks of the Upper Panlongjiang The zircon LA-ICP-MS U-Pb dating shows that the crystallization age of andesite and diorite-porphyrite are 113.7 卤1.8Maand 114.8 卤1.9Ma. they were formed in late early Cretaceous. The content of sodium and potassium is relatively large, relatively rich in aluminum and iron, and medium in calcium and magnesium. The transition from volcanic rock to dike rock is characterized by a series of transition from calc-alkaline to alkaline. The REE distribution curve of volcanic rock, dike rock and ore is in good agreement, and the rare earth content of ore is lower than that of rock. The trace elements in the rocks generally show that the zirconium HfU and NdCU are obviously enriched, while the NB Ta-Th Pnu Ti is obviously depleted. All samples fall into the classical island arc rock range in the Sr/Y-Y and Lap / YbFN diagrams, and in the tectonic environment discriminant diagram of Nb-Yn Ta-Yb, they are located in the volcanic arc magmatic area, and fall to the crust-mantle magma range on the La / YbN- 未 EU variation diagram. Based on the comprehensive characteristics of stable isotopes of the deposit and temporal and spatial distribution of regional gold deposits, it is considered that the formation of Yongxin gold deposit is related to the (volcanic) magmatic activity caused by the subduction of the Paleo-Pacific plate in the early Cretaceous.
【作者单位】：中国地质大学(北京)地球科学与资源学院;黑龙江省地质调查研究总院;黑龙江省地质矿产局;
【基金】：黑龙江省国土资源厅科研项目“黑龙江省嫩江-黑河构造混杂岩地区成矿规律研究与找矿预测”(201603)
【分类号】：P588.1;P618.51

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