胶东福山—栖霞多金属成矿带成矿岩体成因机制及构造背景  

Genetic mechanism and tectonic settings of the metallogenic granodiorite porphyries from Fushan—Qixia polymetallic metallogenic belt,Jiaodong Peninsula

作　　者：朱学强[1] 秦杰[1] 郭晶[1] 黄永波[1] 王丽娟[1] 王金光[1] ZHU Xueqiang;QIN Jie;GUO Jing;HUANG Yongbo;WANG Lijuan;WANG Jinguang(Shandong Institute of Geological Survey,Jinan,250014)

机构地区：[1]山东省地质调查院,济南250014

出　　处：《地质论评》2022年第6期2033-2052,共20页Geological Review

基　　金：中国地质调查局项目(编号:DD20160044-1);中国地质科学院项目(编号:DD20190009);山东省地质勘查项目(编号:鲁勘字[2018]19号、[2020]63号)的成果。

摘　　要：胶东福山—栖霞多金属成矿带是胶东重要的多金属矿产分布区,与成矿关系密切的主要为燕山期浅成—超浅成的酸性小型斑岩体。关于这些成矿小型斑岩体的形成时代、成因机制及构造背景以及与金矿密切相关的郭家岭岩体之间的关系的研究目前仍存在薄弱之处。笔者等选择香夼岩体、羊虎山岩体,在进行系统的野外地质调查基础上,进行岩石学、岩石化学、年代学等方面研究。结果表明,香夼岩体、羊虎山岩体锆石LA-ICP-MS U-Pb加权平均年龄分别为127.9±0.6 Ma、125.6±0.8 Ma,属于早白垩世。小型斑岩体SiO_(2)含量为62.28%~68.59%,全碱含量为5.50%~9.30%,里特曼指数为1.33~3.38,Al_(2)O_(3)含量为13.52%~14.97%,P2O5含量为0.06%~0.14%,TiO_(2)含量为0.18%~0.6%,Mg^(#)介于30.35~56.70;轻稀土相对富集,具不明显的Eu负异常;富集大离子亲石元素Rb,亏损高场强元素Nb、Ta。岩石类型属于I型花岗岩,同时具有高锶低钇(Adakitic)岩石特征。小型斑岩体与金矿关系密切的郭家岭岩体具有一致的成岩时代,相似的地球化学和Sr、Pb同位素比值,反映小型斑岩体应为郭家岭期岩浆的浅成相。该期岩浆的形成与扬子板块和华北板块碰撞造山晚期增厚的岩石圈拆沉和太平洋板块俯冲的双重构造背景有关。Objectives:The polymetallic metallogenic belt from Fushan—Qixia is an important polymetallic mineral distribution area in Jiaodong Peninsula,and the mineralization is closely related to the ultra-hypabyssal acidic granodiorite porphyries.Methods:The study on the formation age,genetic mechanism and tectonic setting of these granodiorite porphyries and the relationship with Guojialing granite closely related to gold deposit is still weak.In this paper,Xiangkuang granodiorite porphyry and Yanghushan granodiorite porphyry are selected to carry out petrology,petrochemistry,chronology on the basis of systematic field geological survey.Results:The results show that the weighted average ages of zircon LA-ICP-MS U-Pb in Xiangkuang granodiorite porphyry and Yanghushan granodiorite porphyry are 127.9±0.6 Ma and 125.6±0.8 Ma,belonging to the Early Cretaceous.The SiO2 content of granodiorite porphyry is 62.28%~68.59%,the total alkali content is 5.50%~0.30%,the Rietman index is 1.33~3.38,the Al_(2)O_(3)content is 13.52%~14.97%,the P_(2)O_(5)content is 0.06%~0.14%,the TiO_(2)content is 0.18%~0.6%,and Mg#is between 30.35~56.70.Light rare earth elements are relatively enriched with insignificant negative Eu anomaly.Large ion lithophile element Rb is enrichment and high field strong element Nb,Ta are loss.Conclusions:The rock type belongs to Ⅰ-type granite and also has the characteristics of adakitic rock.The granodiorite porphyry has a consistent diagenetic age,similar geochemistry and Sr and Pb isotope ratios with Guojialing granite,which is closely related to gold deposits,reflecting that the granodiorite porphyry should be the shallow facies of the Guojialing magma.The formation of magma in this period is related to the double tectonic settings of thickened lithospheric delamination in late collisional orogenic stage between Yangtze Plate and North China Plate,and subduction of the Pacific Plate.

关 键 词：多金属矿成矿带 臧家庄盆地 斑岩 早白垩世 胶东 

分 类 号：P618.2[天文地球—矿床学]