赤峰撰山子花岗岩年代学、地球化学特征及其成岩动力学背景  

Chronology and Geochemical Characteristics of Zhuanshanzi Granite in Chifeng and Its Diagenetic Dynamics Background

作　　者：孙珍军[1] 孙国胜[2] 于赫楠[1] 向柱 田毅 刘彤[4] 陈旭[4] 李杨[4] Sun Zhenjun Sun Guosheng Yu Henan Xiang Zhu Tian Yi Liu Tong Chen Xu Li Yang(Department of Earthquake Science, Institute of Disaster Prevention Science and I echnotogy ,Beijing 101601 College of Earth Sciences ,Jilin University ,Changchun 130061, China Liaoning Survey Academy of Geology and Mineral Resources, shenyang 110031, China 243 Team of Nuclear Industry, Chifeng 024006, Inner Mongolia ,China)

机构地区：[1]防灾科技学院地震科学系,北京101601 [2]吉林大学地球科学学院,长春130061 [3]辽宁省地质矿产调查院,沈阳110031 [4]核工业二四三大队,内蒙古赤峰024006

出　　处：《吉林大学学报（地球科学版）》2016年第6期1740-1753,共14页Journal of Jilin University：Earth Science Edition

基　　金：河北省高等学校科学技术研究重点项目(ZD2015203);中央高校基本科研业务费资助项目(ZD2015203)~~

摘　　要：撰山子角闪二长花岗岩位于华北克拉通与兴蒙造山带结合部位的中生代构造岩浆活动带，对其开展了主量元素、稀土和微量元素分析以及LA—ICP—MS锆石u—Pb定年等工作，目的在于精确厘定岩体的形成时代和研究其形成的动力学背景。结果表明：花岗岩的LA—ICP—MS锆石U—Pb谐和年龄为（245．8±3．1）Ma（MSWD：3．7，n=17），属早三叠世。岩石地球化学成分特征显示为，其具有高硅（∞（Si02）=71．68％～72．85oA）、富碱（叫（Na20＋K20）=8．98％～9．20％）、高铝（w（A1203）=13．45％～13．77％）、低钙（w（CaO）=0．81％～0．99％）及低TFeO／MgO值（平均值为6．55）的特征，属高钾钙碱性、高分异I型弱铝质花岗岩；稀土配分曲线呈现向右倾斜的配分模式，Eu具有明显的亏损（δEu=0．66～0．68），表明斜长石发生了明显的分离结晶作用；在微量元素原始地幔标准化图谱上呈现清晰的Th、U、La、P富集，Ba、Nb、Ti、Sr、Ta等相对亏损的特征。综合分析认为。撰山子角闪二长花岗岩主要形成于下地壳部分熔融作用，可能有少量的地幔组分加入，其形成于华北板块和西伯利亚板块最终拼合后的后碰撞／后造山伸展作用构造环境。The Zhuanshanzi hornblende monzogranite is located in the the Mesozoic tectonic magmatic active belt which between the North China craton and the Xingmeng orogeny belt. Testing of major elements, rare-earth elements fREEs）, trace elements and LA -ICP -MS zircon U -Pb dating of the hornblende monzogranite have be carried out to accurately determined the forming age and study the dynamics background of the granite, rock. Results show that the LA -ICP- MS zircon U- Pb age of the hornblende monzogranite is （245.8±3.1） Ma. （MSWD=3.7,n=17）, and belongs to the Early Triassic. Geochemically, the granite is characterized by high concentrations of silica （w （SiO2）= 71.68%- 72.85%）, alkali （w（Na20＋K2O）= 8.98%-9.20%）, and alumina （w （Al2O3）=13.45%-13.77%）; low concentrations of calcium （w （CaO）： 0.81%-0.99%） ; and with low values of TFeO/MgO （average is 6.55） , indicating the hornblende monzogranite belongs to high- K, calc-alkaline high differentiation [ type, weak aluminum granite. The granite is enriched in LREE and relatively depleted in HREE （LaN/YbN：21.94- 24.33）, and obvious Eu anomaly （δEu=0.66- 0.68）, which indicates that a large number of the plagioclase fractionation occured during the magmatic processes. In addition, the granite is enriched in Th, U, La and P, and depleted in Ba, Nb, Ti, Sr and Ta, and so on. In summary, the Zhuanshanzi granite is mainly formed by partial melting of crust material, with a few new mantle source composition. It is formed under the extensional tectonic setting in post-collision or post-orogenic stage after the North China plate and Siberia plate＇s eventual collision.

关 键 词：花岗岩 地球化学 LA-ICP-MS锆石U-PB定年 构造环境 撰山子 

分 类 号：P588.12[天文地球—岩石学]