摘要
文章对张家川地区的片麻状花岗闪长岩及花岗片麻岩进行了地球化学分析,研究显示,片麻状花岗闪长岩具有的较高Al2O3含量,里特曼指数σ在1.41~1.78;SiO2与P2O5为负相关关系,具有高Sr低Yb的特点,显示Ⅰ型准铝质钙碱性花岗岩的特征。经分析,样品具有岛弧花岗岩地球化学特征。结合区域构造演化,判别其是在早古生代时期商丹洋壳向华北板块俯冲时形成。花岗片麻岩样品SiO2含量主要在71.88~73.81,富集K、Al2O3,里特曼指数σ在0.65~2.00,亏损高场强元素而富集大离子亲石元素,P2O5与SiO2呈正相关关系,显示S型高钾钙碱性、过铝质花岗岩的特征。结合前人所做研究,判别其是在陆-陆碰撞条件下形成。
An integrated study of geochemical analysis of gneiss granitic diorite and granite gneiss in the Zhangjiachuan area is carried out in this paper.The study shows that gneiss granitic diorite has high contents of Al2O3,and the Ritman indexσis between 1.41-1.78;SiO2 and P2O5 are negatively correlated.The samples have high contents of Sr and low contents of Yb,showing the Characteristics of Type-Ⅰ and quasi-aluminous calcium granite.On the whole,the samples have the geochemical-characteristics of arc granitoids.In combination with regional tectonic evolution,it was judged that the samples were formed when the Shangdan-Ocean Crust was subducted to the North-China Plate during the Early Paleozoic.The SiO2 content of granitic gneiss samples is mainly 71.88-73.81,they have high content of K and Al2O3.The Ritman indexσis between 0.65 and 2.00,the samples are characterized by enrichment of large?ion?lithophile?element and depletion of high field-strength elements.There is a positive correlation between P2O5 and SiO2,showing the characteristics of Type-S,high-potassium calcium-alkaline and peraluminous granite.Integrated with previous studies,we propose that the samples were formed under the condition of land-land collision.
作者
白龙峰
黄德志
BAI Long-feng;HUANG Dd-zhi(School of Geosciences and Info-Physics,Central South University,Changsha 410083,P.R.China;Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University),Ministry of Education,Changsha 410083,P.R.China;Hunan Key Laboratory of Nonferrous Resources and Geological Hazards Exploratio,Changsha 410083,P.R.China)
出处
《南方金属》
CAS
2020年第3期8-16,共9页
Southern Metals
