内蒙古营盘湾-东五分子一带的色尔腾山岩群的厘定及地质意义  

Sertengshan Group in Yingpanwan-Dongwufenzi aera,Inner Mongolia: Revision and its geological significance

作　　者：吴新伟[1,2] 徐仲元[1] 

机构地区：[1]吉林大学地球科学学院,长春130061 [2]沈阳地质矿产研究所/中国地质调查局沈阳地质调查中心,沈阳110034

出　　处：《岩石学报》2016年第9期2901-2911,共11页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41272223,41402169);中国地质调查局项目(1212011120709)联合资助

摘　　要：色尔腾山岩群是华北克拉通西部陆块阴山地块早前寒武纪变质基底的主要组成部分,对探讨华北克拉通早前寒武纪基底构造演化有着十分重要的意义。本文根据对营盘湾-东五分子一带的色尔腾山岩群的地质填图、剖面测量、地球化学分析和SHRIMP测年,对色尔腾山岩群的组成、原岩建造、形成环境和形成时代进行了讨论。认为色尔腾山岩群由陈三沟岩组、柳树沟岩组和东五分子岩组组成,陈三沟岩组由灰黑色细粒斜长角闪岩、浅灰色细粒黑云斜长片麻岩夹角闪斜长片麻岩组成;东五分子岩组下段由细粒含石英黑云斜长角闪岩、黑云角闪斜长片麻岩、黑云斜长片麻岩呈韵律产出,顶部为灰白色细粒黑云斜长片麻岩夹薄层磁铁黑云斜长片麻岩,上段为由细粒黑云角闪片岩与浅肉红色黑云长英片麻岩互层,顶部有薄层白色透闪石大理岩;柳树沟岩组以角闪片岩、二云母片岩、二云石英片岩、石榴黑云片岩、黑云母片岩为特征。其原岩总体构成表现为：下部以火山岩为主,上部以碎屑沉积岩和化学沉积岩为主的火山-碎屑沉积建造。火山岩明显富碱,其中酸性火山岩明显富铝、贫镁;具有较高的大离子亲石元素含量、较低的Y和重稀土元素含量;具有轻稀土富集、重稀土亏损的稀土分布形式。地球化学特征与埃达克岩类似,形成于活动大陆边缘的构造环境下。通过对东五分子岩组上部互层产出的细粒长英片麻岩和黑云母片岩分别取样,进行锆石U-Pb SHRIMP测年,分别获得1980±9Ma、1946±16Ma的成岩年龄和1901±15Ma、1893±66Ma的变质年龄。综上所述可以得出,色尔腾山岩群的形成于1.95-1.98Ga之间,是在类似埃达克岩的活动大陆边缘岛弧环境下沉积的,在1.9Ga左右发生碰撞造山而发生变质。Sertengshan Group is an important component of Early Precambrian metamorphic basement in Yinshan Block, which is in the western landmass in the North China Craton. It is significant to study the tectonic evolution of the Early Precambrian North China Craton. According to the geological mapping, profiles, geochemical analysis and SHRIMP dating, this article discussed on the composition, primary rock formation, formation environment and the age of the Sertengshan Group. The author believes that the Sertengshan Group is composed of Chensangou Formation, Liushugou Formation and Dongwufenzi Formation. The Chensangou Formation consists of dark gray fine-grained amphibolite and light gray fine-grained biotite plagiogneiss intercalated with hornblende plagiogneiss. The lower member of the Dongwufenzi Formation consists of fine-grained quartz-bearing biotite plagioclase amphibolite, biotite hornblende plagiogneiss and biotite plagiogneiss, which appear in rhythm. On top is gray fine-grained biotite plagiogneiss gripping thin bedded magnetite biotite plagiogneiss. Fine-grained biotite amphibole schist interbedded with light-flesh-colored biotite felsic gneiss belong to the upper member of Dongwufenzi Formation, there is thin bedded tremolite marble on the top. Liushugou Formation is characterized by hornblende schist, two-mica schist, two mica quartz schist, garnet biotite schist and biotite schist. The original rock has two general features： the lower part is dominated by volcanic rock; the upper part is based on clastic sedimentary rocks and chemical sedimentary rock. Volcanic rock is rich in alkali obviously, and medium acidic volcanic is characterized by relative enrichment in Al and large ion lithophile elements （LILE） and light rare earth elements （LREE）. It is low in Mg, Y and heavy rare earth elements （HREE）. Its geochemical characteristics are similar to adakite, which is formed in tectonic environment of active continental margin. We sampled separately in felsic gneiss and biotite schist, which are

关 键 词：色尔腾山岩群 SHRIMP测年 活动大陆边缘 

分 类 号：P534.3[天文地球—古生物学与地层学] P597.3[天文地球—地质学]