内蒙古二龙包西地区早志留世二长花岗岩地球化学特征及构造环境分析

北山地区早志留世二长花岗岩分布于塔里木板块月牙山-洗肠井构造混杂岩带南侧。通过对岩石学、岩石地球化学特征的研究,认为该岩体为准铝质高钾钙碱性系列;稀土曲线为向右缓倾的"V"型曲线,表现出明显负Eu异常;微量元素中相对亏损Ba、Nb、Sr、P、Ti,富集Rb、Th、Hf等元素,暗示了岩石形成过程中经历了较为明显的斜长石的分离结晶作用。结合区域地质资料及地球化学图解分析,二长花岗岩形成于挤压构造环境,并具有同碰撞花岗岩的特征。

Research on the Geochemical Characteristics and Tectonic Environment of the Early Silurian Monzonitic Granite in Erlongbaoxi Area,Inner Mongolia

The Early Silurian monzonitic granite in the Beishan area was located in the south of the Yueyashan-xichangjin structural melange zone in the Tarim plate.Based on the study of the petrology and the chemistry, the authors hold that the monzonitic granite are the High-K aluminum calcium alkaline rock series, and the REE distribution patterns are characterized by LREE enrichment, right-oblique form and obvious depletion of Eu.the trace elements generally have features of obvious depletion o f Ba、Nb、Sr、P、Ti, enrichment of Rb、Th、Hf.Geochemical characteristics suggested that a strong fractional crystallization of plagioclase existed in the rock formation process.Combined with regional geological setting and geochemical diagram analysis, the monzonitic granite showing the characteristics of the syn-collisional granite, formed in the Compressive tectonic environment.