摘要
通过1∶5万区域地质调查,在内蒙古北山地区小黄山一带早石炭世侵入岩中新解体出片麻状中细粒花岗闪长岩、片麻状细粒二长花岗岩和片麻状似斑状细中粒黑云母二长花岗岩,其中片麻状中细粒花岗闪长岩和片麻状细粒二长花岗岩在空间上紧密伴生。本文研究小黄山一带片麻状花岗岩的形成时代、成因及构造环境。采用锆石LA-ICP-MS U-Pb法在片麻状中细粒花岗闪长岩、片麻状细粒二长花岗岩中分别获得了443.0±1.2 Ma和441.9±1.6 Ma的岩浆结晶年龄,时代为早志留世早期。岩石地球化学分析表明,片麻状中细粒花岗闪长岩和片麻状细粒二长花岗岩均为钙碱性系列岩石,碱度率AR为1.82~2.86,较低,且变化范围小,戈蒂尼指数τ为21.22~64.24(τ>10);岩石富集轻稀土元素及K、Rb、Ba等大离子亲石元素,亏损高场强元素Nb、P、Ti,具有岛弧岩浆岩或造山带岩浆岩的特征。结合前人研究成果综合分析,片麻状中细粒花岗闪长岩和片麻状细粒二长花岗岩形成于岛弧构造环境,是东七一山—公婆泉岛弧带的重要组成部分。
Through a 1∶50000 regional geological survey,gneissic medium-fine-grained granodiorite,gneissic fine-grained monzogranite and gneiss-like intrusive rocks were newly disintegrated in the Xiaohuangshan area of Beishan area,Inner Mongolia.Porphyry medium-fine-grained biotite monzonitic granite,among which gneissic-to-medium-grained granodiorite and gneissic fine-grained monzonitic granite are closely associated in space.The formation age,origin and tectonic environment of gneissic granite in Xiaohuangshan area was studied in this paper.The zircon LA-ICP-MS U-Pb method was used to obtain magma crystallization ages of 443.0±1.2 Ma and 441.9±1.6 Ma respectively in gneissic medium-fine-grained granodiorite and gneissic fine-grained monzogranite.The era is early Silurian.Rock geochemical analysis shows that both gneissic medium-fine-grained granodiorite and gneissic fine-grained monzogranite are calc-alkaline series rocks,with a low alkalinity rate AR of 1.82 to 2.86,and a small range of variation.The Gordini indexτis 21.22~64.24(τ>10);the rock is enriched in light rare earth elements and large ion lithophile elements such as K,Rb,and Ba,and is depleted in high field strength elements Nb,P,and Ti,and has characteristics of island arc magmatic rocks or orogenic igneous rocks.Based on the comprehensive analysis of previous research results,the gneissic medium-fine-grained granodiorite and gneissic fine-grained monzogranite were formed in the island arc tectonic environment and are important componentsof the East Qiyishan-Gongpoquan island arc zone.
作者
胡新茁
杨济远
邓雯
田光昊
孙肖
秦丹鹤
HU Xinzhuo;YANG Jiyuan;DENG Wen;TIAN Guanghao;SUN Xiao;QIN Danhe(Lang Fang Natural Resources Comprehensive Survey Center,China Geological Survey,Langfang 065000,Hebei,China;Hebei Institute of Regional Geological Survey(Geotourism Research Center of Hebei Province),Langfang 065000,Hebei,China)
出处
《地质通报》
CAS
CSCD
北大核心
2024年第6期1059-1071,共13页
Geological Bulletin of China
基金
中国地质调查局项目《内蒙古1∶5万旱山(K47E015013)、小尘包(K47E015014)、望京山(K47E016013)、涌珠泉幅(K47E016014)区域地质调查》(编号:1212011220463)。
关键词
内蒙古北山
小黄山
片麻状花岗质岩石
形成时代
构造环境
岛弧
地质调查工程
Beishan,Inner Mongolia
Xiaohuangshan
gneissic granite rocks
formation age
tectonic environment
island arc
geological survey engineerin
