赤峰地区基性岩年代学及其地质意义
发布时间：2019-05-09 14:28
【摘要】：赤峰地区横跨华北板块及兴蒙造山带两大构造单元,本文在野外详细调查的基础上,选取该地区出露的一系列基性岩岩体及岩脉为研究对象,进行详细的岩石学,岩石地球化学及年代学的研究。赤峰南部属华北板块的头道营子地区基性岩体主体为角闪辉长岩,岩石侵入寒武系锦山组结晶灰岩中,通过锆石LA-ICP-MS U-Pb定年,给出368.5±3.1Ma的成岩年龄,为晚泥盆世产物;赤峰北部属兴蒙造山带产出的一系列基性岩脉显示较为强烈的变形作用,其中朝阳沟辉长岩岩脉获得了386.3±3.7Ma的年龄,与中泥盆世就位。赤峰地区白云鄂博-赤峰大断裂两侧基性岩显示出一致的地球化学特征,为拉斑玄武岩系列岩石,贫Si、K,富Mg、Na,富集大离子亲石元素(LILEs,Sr、Ba),相对亏损高场强元素(HFSEs,Nb、Ta、Zr),富集轻稀土,相对亏损重稀土,其源区为富集的岩石圈地幔,岩浆受到一定程度的壳源物质的混染。通过对岩石构造背景分析认为岩石产出于伸展构造背景下,并且受到一定的俯冲消减作用影响或者壳源物质的混染,结合前人研究成果,包含研究区基性岩在内的泥盆岩浆岩呈带状展布于华北北缘,岩浆岩除碱性岩以外,酸性岩及基性岩均有发育,缺失中性成分,类似“双峰式”火成岩,为华北板块与白乃庙弧在晚志留到早泥盆碰撞后伸展环境,此次伸展事件的时限跨越了整个泥盆纪。
[Abstract]:The Chifeng area straddles the North China plate and Xingmong orogenic belt. Based on the detailed field investigation, this paper selects a series of basic rock masses and dikes exposed in this area as the object of study and carries out detailed petrology. Study on petrogeochemistry and chronology. The basic rock mass in the Tongdaoyingzi area, which belongs to the North China plate in the southern part of Chifeng, is mainly hornblende. The rocks intruded into the crystalline limestone of the Jinshan formation of Cambrian system. The diagenetic age of 368.5 卤3.1Ma is given by zircon LA-ICP-MS U-Pb dating. It is a product of late Devonian. A series of basic dikes in the Xingmengmengshan orogenic belt in the northern part of Chifeng show strong deformation, in which the Chaoyang gneiss dike has an age of 386.3 卤3.7Ma, which is in place with the Middle Devonian. The basic rocks on both sides of the Baiyun Obo-Chifeng fault in Chifeng area show the same geochemical characteristics. They are tholeiite series rocks, poor in Si,K, and rich in Mg,Na, rich in large ion lithophile elements (LILEs,Sr,Ba). Relatively depleted high field strength element (HFSEs,Nb,Ta,Zr), enriched in light rare earth, relatively depleted in heavy rare earth, its source region is enriched lithosphere mantle, magma is contaminated by crust source material to a certain extent. Based on the analysis of the tectonic background of the rocks, it is concluded that the rocks occur in the extensional tectonic setting and are affected by subduction and subduction or by the contamination of the crust-derived materials, combined with the previous research results. The Devonian magmatic rocks, including the basic rocks in the study area, are zonal distributed in the northern margin of North China. Apart from alkaline rocks, the magmatic rocks are developed in acidic rocks and basic rocks, lacking neutral composition, similar to "bimodal" igneous rocks. For the extension environment of the North China plate and Bainiao arc after the late Silurian to the early Devonian collision, the duration of the extension event spans the entire Devonian period.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P588.124
本文编号：2472832
[Abstract]:The Chifeng area straddles the North China plate and Xingmong orogenic belt. Based on the detailed field investigation, this paper selects a series of basic rock masses and dikes exposed in this area as the object of study and carries out detailed petrology. Study on petrogeochemistry and chronology. The basic rock mass in the Tongdaoyingzi area, which belongs to the North China plate in the southern part of Chifeng, is mainly hornblende. The rocks intruded into the crystalline limestone of the Jinshan formation of Cambrian system. The diagenetic age of 368.5 卤3.1Ma is given by zircon LA-ICP-MS U-Pb dating. It is a product of late Devonian. A series of basic dikes in the Xingmengmengshan orogenic belt in the northern part of Chifeng show strong deformation, in which the Chaoyang gneiss dike has an age of 386.3 卤3.7Ma, which is in place with the Middle Devonian. The basic rocks on both sides of the Baiyun Obo-Chifeng fault in Chifeng area show the same geochemical characteristics. They are tholeiite series rocks, poor in Si,K, and rich in Mg,Na, rich in large ion lithophile elements (LILEs,Sr,Ba). Relatively depleted high field strength element (HFSEs,Nb,Ta,Zr), enriched in light rare earth, relatively depleted in heavy rare earth, its source region is enriched lithosphere mantle, magma is contaminated by crust source material to a certain extent. Based on the analysis of the tectonic background of the rocks, it is concluded that the rocks occur in the extensional tectonic setting and are affected by subduction and subduction or by the contamination of the crust-derived materials, combined with the previous research results. The Devonian magmatic rocks, including the basic rocks in the study area, are zonal distributed in the northern margin of North China. Apart from alkaline rocks, the magmatic rocks are developed in acidic rocks and basic rocks, lacking neutral composition, similar to "bimodal" igneous rocks. For the extension environment of the North China plate and Bainiao arc after the late Silurian to the early Devonian collision, the duration of the extension event spans the entire Devonian period.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P588.124
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