内蒙古科尔沁右翼前旗玛尼吐组火山岩年代学及岩石地球化学特征  

Chronology Characteristics and Rock Geochemical Characteristics of the Volcanic Rocks in Manitu Formation in Horqin Right Wing Front Banner in Inner Mongolia

作　　者：张力强[1] 陈彪[1] 曹元宝[1] 王江辉[1] 黄忠军 陈广宇[1] 孙浩[1] 张钧贵 

机构地区：[1]武警黄金第四支队

出　　处：《现代矿业》2017年第3期16-20,共5页Modern Mining

基　　金：中国地质调查局地质调查项目(编号:12120115041901)

摘　　要：大兴安岭中南段科尔沁右翼前旗地区广泛分布有玛尼吐组中—基性火山岩,结合相关岩石样品分析结果,对该区玛尼吐组火山岩年代学及岩石地球化学特征进行了详细分析。研究表明:(1)火山岩LA-ICP-MS锆石U-Pb加权平均年龄为(137.3±1.5)Ma,表明该类岩石形成于早白垩世初期;w(SiO_2)44.25%~63.45%,属中—基性岩;w(K_2O)/w(Na_2O)平均为1.01,为钾质岩石;(2)玛尼吐组火山岩形成于板内环境,即为古生代俯冲碰撞结束后(局部大洋残存至中生代)统一的板块内部活动所形成的火山岩,亲火山弧的地球化学特征更多的是古生代板块俯冲作用的残留,而非由太平洋板块俯冲引起。上述分析对于进一步研究大兴安岭地区,尤其是大兴安岭中南段中生代火山岩提供了可靠依据。Intermediate-basic volcanic rock of Manitu formation is widely distributed in Horqin Right Wing Front Banner in the middle-south section of Greater Khingan Mountains. Combing with some related analysis results of the rock samples of the area,the chronology characteristics and rock geochemical characteristics of the volcanic rocks in Manitu formation in the area are discussed in depth. The results show that：（1）the LA-ICP-MS zircon U-Pb weighted average age is（ 137. 3 ± 1. 5） Ma,which indicated that the volcanic rocks is formed in the early stage of Early Cretaceous Epoch; w（ SiO_2） is from 44. 25% to63. 45%,which show that the the volcanic rocks is belongs to intermediate-basic volcanic rocks; the average value of w（ K_2O）/w（ Na_2O） is 1. 01,which show that the volcanic rocks is belongs to potassic rocks;（2）the volcanic rocks of Manitu formation is formed in the intraplate environment,that is to say,the volcanic rocks is formed by the uniform plate internal activities after the end of the Paleozoic subduction collision（ the local ocean is residual to the Mesozoic Era）,the rock geochemical characteristics close to volcanic arc is formed under the action of the residual of the Paleozoic plate subduction,rather than caused by the subduction of Pacific plate. The above analysis results can provide reliable basis for studying the Mesozoic volcanic rocks of Greater Khingan Mountains,especially for the middle-south section of Greater Khingan Mountains.

关 键 词：玛尼吐组 火山岩 年代学 岩石地球化学特征 构造环境 

分 类 号：P588.14[天文地球—岩石学]