霍林河地区白音高老组火山岩地球化学特征及构造意义  

Geochemistry and Tectonic Significance of the Volcanic Rocks of Baiyingaolao Formation in Huolinhe Area

作　　者：刘永高 杨海星 LIU Yonggao;YANG Haixing(Inner Mongolia Tenth Geological Mineral Exploration and Development Co.,Ltd.)

机构地区：[1]内蒙古第十地质矿产勘查开发有限责任公司,内蒙古自治区赤峰市024000

出　　处：《现代矿业》2024年第11期46-52,共7页Modern Mining

摘　　要：为研究内蒙古东部霍林河地区白音高老组火山岩的形成年代、岩浆来源及构造背景,对该地区白音高老组火山岩进行锆石U-Pb定年及地球化学分析。采集的6件锆石U-Pb测年样品年龄结果分别为141.7±1.3,140.5±3.5,137.3±2.0,136.4±1.7,135.8±1.6,128.6±1.4 Ma,时代归属早白垩世。地球化学特征揭示,研究区的白音高老组火山岩展现出高硅含量、富含碱铝元素、钙镁铁元素相对匮乏的特点,归类为准铝质至弱过铝质的高钾钙碱性系列火山岩;其稀土元素总量偏高,并伴有不同程度的负铕异常、轻稀土元素(LREE)与重稀土元素(HREE)之间的显著分馏现象;与原始地幔成分相比,研究区火山岩明显富集大离子亲石元素(如Rb、K、B等)以及轻稀土元素,但同时显著亏损高场强元素(Nb、Ta、P、Ti)以及重稀土元素。经分析,该地区的火山岩岩浆主要源自地壳岩石在高温低压条件下的部分熔融过程,并伴随着斜长石与磷灰石的分离结晶作用。结合对该研究区火山岩的年代学、地球化学特征以及区域地质背景的综合分析,可以推断出该地区白音高老组火山岩是在古太平洋板块进行俯冲后撤伸展作用的构造环境下形成的。In order to study the formation age,magma source and tectonic setting of volcanic rocks the Baiyingaolao formation in Huolinhe area,central part of the Greater Khingan Mountains,Zircon U-Pb dating and geochemical analysis of the Baoyinggaolao Formation volcanic rocks in the area.The six zircon U Pb dating samples are 141.7±1.3,140.5±3.5,137.3±2.0,136.4±1.7,135.8±1.6,and 128.6±1.4 Ma,respectively,which belong to the Early Cretaceous.Geochemistry show that the volcanic rocks of the Baiyingaolao formation in the study area are characterized by high silicon,rich alkali aluminum and poor calcium magnesium iron,and are a set of quasi-aluminium-weak peraluminous high potassium calc-alkaline series volcanic rocks.The total amount of rare earth is high with different degrees of light and heavy rare earth fractionation characteristics and negative europium anomaly.Compared with the original mantle,large ion lithophile elements(Rb,K,Ba,K)and light rare earth elements(LREE)are mainly enriched,while high field strength elements(Nb,Ta,P,Ti)and heavy rare earth elements(HREE)are depleted.According to the analysis,the volcanic magma in this area mainly originates from the partial melting of crustal rocks under high temperature and low pressure environment,and is accompanied by the separation crystallization process of plagioclase and apatite.Based on the geochronology,geochemistry,and regional geological data,it is widely believed that the volcanic rocks of the Baoyinggaolao Formation originated in a post-subduction extensional setting,subsequent to the subduction of the Paleo-Pacific plate.

关 键 词：白音高老组 火山岩 地球化学特征 构造背景 

分 类 号：P588.14[天文地球—岩石学] P597.3[天文地球—地质学] P542