2014年3月，第20卷，第1期，68-80页 March 2014，Vol.20，No.1，pp.6880
高校地质学报
Geological Journal of China Universities
内蒙古苏左旗北部晚二叠世花岗岩
地球化学特征及意义
陈军林，何雨栗，杨国林，孙柏年，刘珂男
兰州大学地质科学与矿产资源学院，兰州730000
摘要：苏尼特左旗北部晚二叠世花岗岩分布在索伦缝合带北侧，地处西伯利亚板块东南缘古生代陆壳增生区，对这些花岗岩的研究有助于加深对内蒙古中部地区晚古生代构造演化的认识。主微量元素地球化学特征分析结果显示：苏尼特左旗北部晚二叠世花岗岩总体呈富硅、富碱、相对富钠贫钾、贫钙镁的特征，属高钾钙碱性系列。富集LREE和LILE，具明显的销负异常；微量元素相对亏损Nb，Ta，Sr，P，Ti，富集Pb，Hf，Dy等元素。成因类型为高分异的I型花岗岩，产于汇聚板块边缘大陆弧环境，该结果指示索伦缝合带在晚二叠世还未封闭，西伯利亚和华北板块还未完全碰撞拼合，苏尼特左旗北
部地区在晚二叠世可能正处于由板块俯冲向磁撞造山转换的阶段。关键调：I型花岗岩；地球化学；晚二叠世；大陆弧；内蒙古
中图分类号：P588.12
文献标识码：A
文章编号：10067493（2014)01-006813
GeochemicalFeaturesandSignificanceoftheLatePermianGranites
in Northern Sonid Zuoqi, Inner Mongolia
CHENJunlin,HEYuli,YANGGuolin,SUNBainian',LIUKenan
School of Earth Sciences, Lanzhou University, Lanzhou 730000, China
Abstract: The Late Permian granites in northem Sonid Zuoqi occur on the north of the Solonker suture, They are part of the Late Paleozoic suture zone in the southeastern margin of the Siberian plate. Research on the Late Permian granites in this area is helpful to understand the tectonic evolution of the Late Paleozoic in central Inner Mongolia. Major and trace element analyses reveal that the granites are characterized by high silica, high alkali, low magnesium, and low calcium, and the content of NaO is higher than that of K,O. They belong to the high-K cale-alkaline series. The granites are rich in LREE and LILE, and have a negative europium anomaly. Trace elements Nb, Ta, Sr, P, Ti are poorly concentrated and Pb, Hf, Dy, etc, are well concentrated. Petrologic and geochemical characteristics indicate that these rocks are highly fractionated I-type granites, which were produced in a continental arc setting. This result suggest that the Solonker suture had not yet closed, and the Siberian plate had not completely conjoined to the North China plate during the Late Permian. The northem Sonid Zuoqi region might be formed during a transitional stage from subduction to collisional orogeny
Key words: I-type granites; geochemical features; Late Permian; Continental arc; Inner Mongolia
Corresponding author: SUN Bainian, Professor; E-mail: bnsun@lzu.edu.cn 收稿日期：201308-15；修回日期：2013-1204
基金项目：国家重点基础研究发展计划“973”项目（2012CB822003）；高等学校博士学科点专项科研基金（20120211110022）联合资助作者简介：陈军林，1988年生，男，硕士研究生，研究方向为区域地质调查与资源勘查；E-mail:chenjunlin_lzu@163.com
"通讯作者：孙柏年，1955年生，男，教授，研究方向为区域地质学；E-mail:bnsun@zu.edu.cn