地球化学特征及其地质意义
(1. 中南大学 有色金属成矿预测教育部重点实验室，长沙 410083；
2. 中南大学 地球科学与信息物理学院，长沙 410083)
摘 要: 为了解山东招远原疃金矿区内煌斑岩成因及其形成环境，开展了岩石地球化学研究。结果表明：矿区内煌斑岩SiO2含量为49.29%~52.71%(质量分数)、K2O/Na2O比值范围为1.17~2.91，属钾质钙碱性系列；岩石稀土元素分配型式右倾，具弱负铕异常；Ti、Mn、Cu和Zn等过渡元素富集，Cr和Ni相对亏损。结合煌斑岩K-Ar全岩年龄(102.29~119.34 Ma)，认为本区煌斑岩来源于富集地幔，与早期苏鲁洋板块消减俯冲及太平洋洋壳熔融产生的富集流体均关系密切，其形成与华北克拉通中生代构造体制转折和岩石圈减薄事件有关，是胶东中生代大规模岩浆活动的一部分。
关键字: 原疃；煌斑岩；地球化学；俯冲作用
Yuantuan gold ore district, Shandong Province, China
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
Central South University, Changsha 410083, China;
2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China）
Abstract:To investigate the genesis and forming environment of lamprophyres in Yuantuan gold ore district, the petrogeochemical study was carried out. The results show that the mass fraction of SiO2 changes from 49.29% to 52.71%, the ratio of K2O to Na2O changes from 1.17 to 2.91, belonging to kalium calc-alkaline series. The distribution of REE of samples is right deviation, with slightly negative Eu anomalies. The lamprophyres are characterized by enrichment in transitional elements, such as Ti, Mn, Cu, Zn and depletion in Cr and Ni. Combined with the age of the lamprophyres by K-Ar dating method (102.29−119.34 Ma), it is concluded that the lamprophyres of Yuantuan gold ore district originate from enriched mantle, closely associate with the fluid from early subduction of Sulu Ocean and melting of the Pacific Ocean Crust, and Mesozoic tectonic transition in North China craton and lithospheric thinning events, and it is part of large-scale Mesozoic magma activity of Jiaodong.
Key words: Yuantuan; lamprophyres; geochemistry; subduction
