赤峰地區(qū)基性巖年代學及其地質意義
發(fā)布時間：2019-05-09 14:28
【摘要】：赤峰地區(qū)橫跨華北板塊及興蒙造山帶兩大構造單元,本文在野外詳細調查的基礎上,選取該地區(qū)出露的一系列基性巖巖體及巖脈為研究對象,進行詳細的巖石學,巖石地球化學及年代學的研究。赤峰南部屬華北板塊的頭道營子地區(qū)基性巖體主體為角閃輝長巖,巖石侵入寒武系錦山組結晶灰?guī)r中,通過鋯石LA-ICP-MS U-Pb定年,給出368.5±3.1Ma的成巖年齡,為晚泥盆世產物;赤峰北部屬興蒙造山帶產出的一系列基性巖脈顯示較為強烈的變形作用,其中朝陽溝輝長巖巖脈獲得了386.3±3.7Ma的年齡,與中泥盆世就位。赤峰地區(qū)白云鄂博-赤峰大斷裂兩側基性巖顯示出一致的地球化學特征,為拉斑玄武巖系列巖石,貧Si、K,富Mg、Na,富集大離子親石元素(LILEs,Sr、Ba),相對虧損高場強元素(HFSEs,Nb、Ta、Zr),富集輕稀土,相對虧損重稀土,其源區(qū)為富集的巖石圈地幔,巖漿受到一定程度的殼源物質的混染。通過對巖石構造背景分析認為巖石產出于伸展構造背景下,并且受到一定的俯沖消減作用影響或者殼源物質的混染,結合前人研究成果,包含研究區(qū)基性巖在內的泥盆巖漿巖呈帶狀展布于華北北緣,巖漿巖除堿性巖以外,酸性巖及基性巖均有發(fā)育,缺失中性成分,類似“雙峰式”火成巖,為華北板塊與白乃廟弧在晚志留到早泥盆碰撞后伸展環(huán)境,此次伸展事件的時限跨越了整個泥盆紀。
[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 鹵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 鹵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.
【學位授予單位】：中國地質大學(北京)
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P588.124
本文編號：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 鹵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 鹵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.
【學位授予單位】：中國地質大學(北京)
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P588.124
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