本文選題：長春-延吉增生雜巖帶 + 紅簾石片巖　； 參考：《吉林大學(xué)》2016年碩士論文

【摘要】：位于華北板塊和西伯利亞板塊之間的中國東北及其鄰近地區(qū),處于與太平洋板塊的疊加部位,同時受古亞洲洋和環(huán)太平洋兩大構(gòu)造域的影響,對這一地區(qū)大地構(gòu)造背景的研究具有極高的科學(xué)價值。其中,佳木斯-興凱地塊在空間位置上與俄羅斯遠東、朝鮮和日本等相鄰,在大地構(gòu)造位置上處于中亞-蒙古構(gòu)造域與太平洋構(gòu)造域的疊加部位,可作為研究地體拼貼、兩大構(gòu)造域疊加和轉(zhuǎn)換過程的關(guān)鍵地區(qū)。有關(guān)佳木斯-興凱地塊與華北地塊之間長春-延吉縫合帶的閉合時間和大地構(gòu)造本質(zhì)仍存在爭議。本文以吉林省中部磐石縣煙筒山地區(qū)的紅簾石片巖作為研究對象,通過巖相學(xué),電子探針及鋯石U-Pb同位素年代學(xué)等研究方法來探討紅簾石片巖的形成溫壓條件及原巖時代,并結(jié)合已有的古生物學(xué)資料以及其他年代學(xué)資料來探索佳木斯-興凱板塊和華北板塊的最終閉合時間及其大地構(gòu)造背景。野外地質(zhì)調(diào)查顯示,巖石經(jīng)歷了強烈變形并具有無層序特點,表示該地區(qū)地層可能為構(gòu)造混雜巖,不具備傳統(tǒng)的地層劃分和對比意義;紅簾石片巖呈構(gòu)造透鏡體狀產(chǎn)出于大面積分布的綠片巖中,巖石遭受了強烈的褶曲變形及韌性變形作用。紅簾石片巖典型的變質(zhì)礦物組合為:石英(75%~80%)+多硅白云母(10%)+紅簾石(10%)+石榴石(5%)+長石(5%)。其中白云母可以指示巖石壓力環(huán)境,通過電子探針分析表明,白云母中的Si≥3.305(以氧原子=11為基準(zhǔn)),白云母為多硅白云母,為高壓變質(zhì)作用的產(chǎn)物,可證明其經(jīng)歷高壓反應(yīng)改造。本文利用LA-MC-ICP-MS測年技術(shù)對紅簾石片巖,綠泥石片巖和未變形的長英質(zhì)巖脈四個巖石樣品進行了鋯石U-Pb分析,紅簾石片巖的年齡數(shù)據(jù)顯示:1)最小年齡為233 Ma,顯示原巖年齡為形成與印支期前后;2)峰值為~426Ma,3)峰值為738 Ma的鋯石年齡,對應(yīng)于東北地區(qū)的變質(zhì)結(jié)晶基底年齡;4)最大年齡為1800 Ma的鋯石年齡,為東北地區(qū)存在古老基底的信息。需要指出的是,峰值為233Ma其原巖為三疊系前后,而并不是前人認(rèn)為的二疊紀(jì)或更老。另外,長英質(zhì)巖脈的年齡數(shù)據(jù)顯示,11粒鋯石的加權(quán)平均年齡為217±3 Ma(MSWD=0.37),利用該未變形的長英質(zhì)巖脈可以限定長春-延吉縫合線的下限。本文研究結(jié)果表明,具有一系列特征性增生雜巖的長春-延吉縫合帶是佳木斯-興凱地塊與華北地塊俯沖拼貼形成,并非前人認(rèn)為的索倫-西拉木倫-長春縫合帶的東向延伸,大地構(gòu)造屬性是吉林-黑龍江高壓變質(zhì)帶的南緣。吉林-黑龍江高壓變質(zhì)帶作為東北地區(qū)重要構(gòu)造單元,記錄了古亞洲構(gòu)造域的結(jié)束和古太平洋在晚三疊-早侏羅世西向俯沖開始,標(biāo)志著太平洋板塊俯沖啟動。
[Abstract]:Northeast China and its adjacent areas, located between the North China plate and the Siberian plate, are superimposed with the Pacific plate and are also affected by the two tectonic domains of the Paleo-Asian Ocean and the Pacific Rim. The study of tectonic background in this area is of great scientific value. Among them, Jiamusi Xingkai block is adjacent to the Russian far East, Korea and Japan in space, and is located in the superposition of Central Asia Mongolia tectonic domain and Pacific tectonic domain in the geotectonic position, so it can be used as a collage of the study ground. The two major tectonic domains superimpose and transform the key areas. The closing time and tectonic nature of the Changchun-Yanji suture zone between the Jiamusi-Xingkai block and the North China block are still controversial. In this paper, the authors take the red curtain schist in Yanconshan area, Panshi County, central Jilin Province as the object of study. By means of petrography, electron probe and zircon U-Pb isotopic chronology, the forming conditions of the red curtain schist and the age of the original rocks are discussed. The final closure time and tectonic setting of the Jiamusin-Xingkai plate and the North China plate are explored by combining the available paleobiological data and other geochronological data. The field geological survey shows that the rocks have undergone strong deformation and have the characteristics of no sequence, indicating that the strata in this area may be structural melange, without the traditional stratigraphic division and correlation significance. The red curtain schist occurs in a large area of green schist as a structural lens, and the rock is subjected to strong fold deformation and ductile deformation. The typical metamorphic mineral assemblages of red curtain schist are quartz (75%), polysilicon Muscovite (10%), red curtain (10%), garnet (5%) and feldspar (5%). Muscovite can indicate rock pressure environment. Electron probe analysis shows that Muscovite is the product of high pressure metamorphism with Si 鈮，

本文編號：2062516