本文選題：贛南地區(qū) + 華南地塊　； 參考：《成都理工大學(xué)》2017年碩士論文

【摘要】：贛南地區(qū)在大地構(gòu)造位置上屬于南嶺東西向構(gòu)造巖漿帶的東段,屬于南嶺稀有-有色金屬成礦帶(左祖發(fā),2015)。該區(qū)巖漿活動強烈,部分巖漿巖體呈面狀分布。其中,加里東期和燕山期的巖漿活動最為活躍。區(qū)內(nèi)巖漿巖絕大部分為酸性巖漿巖,基性巖含量極少,零星分布于個別構(gòu)造發(fā)育位置。基性巖墻在區(qū)域上與深大斷裂構(gòu)造關(guān)系緊密,常與區(qū)域內(nèi)的伸展構(gòu)造環(huán)境相關(guān),他們起源于地殼深部(上地�；蛳碌貧�),沿地殼薄弱位置上升到地殼中,在地殼不同層次發(fā)生侵位活動。華南地塊是由西北部的揚子陸塊和東南部的華夏陸塊在新元古代早期沿著江南造山帶拼貼而成,并經(jīng)歷后期多期次構(gòu)造巖漿事件的疊加改造,其中加里東期造山作用就是其中一次非常重要的構(gòu)造事件。但是,目前對華南加里東期構(gòu)造巖漿事件的研究主要集中于花崗巖類,酸性火山巖和基性巖研究程度相對較低。目前發(fā)現(xiàn)的華南加里東期基性巖僅有3例,分別分布于南嶺地區(qū)、云開地區(qū)和武夷地區(qū),年齡主要集中于420-450 Ma之間,但是,基于相關(guān)地球化學(xué)和同位素的研究,目前對這些巖形成的構(gòu)造環(huán)境還存在較大的爭議,有人認(rèn)為他們形成于板內(nèi)環(huán)境,有人認(rèn)為形成于島弧俯沖環(huán)境(Yao et al.,2012;Wang et al.,2013)。本文主要以贛南遂川地區(qū)基性巖墻作為研究對象,開展了詳細(xì)的野外觀察和室內(nèi)巖石學(xué)、地球化學(xué)以及鋯石LA-ICP-MS U-Pb年齡和Lu-Hf同位素等測定分析研究,并對其巖石學(xué)、地球化學(xué)特征、形成時間、巖漿成因及構(gòu)造環(huán)境等有關(guān)問題進行探討�；詭r墻LA-ICP-MS鋯石U-Pb定年法得到Th、U之比介于0.46-1.59之間,可以確定為巖漿成因形成的鋯石。4個樣品的測年結(jié)果為446±6.6Ma(N=30,MSWD=0.55)、431.9±5.7Ma(N=30,MSWD=0.65)、422.3±7.3Ma(N=30,MSWD=0.79)和426.6±6.9Ma(N=20,MSWD=0.52),侵入時代為早古生代志留紀(jì),表明該巖體為贛南地區(qū)加里東運動后期構(gòu)造環(huán)境由擠壓轉(zhuǎn)換為區(qū)域性伸展拉張環(huán)境后的產(chǎn)物。對兩個樣品進行的Lu-Hf同位素分析結(jié)果顯示,初始176Hf/177Hf比值變化范圍較小,對應(yīng)的εHf(t)值都在-4~-0.1之間,全部為負(fù)值,顯示鋯石應(yīng)為殼源巖石重熔作用的產(chǎn)物。鋯石的二階段Hf虧損地幔模式年齡TDM2值介于1424~1670 Ma之間,主要分布在中元古代,指示中元古代時期的新生基性地殼可能是研究區(qū)早古生代加里東期基性侵入巖形成的主要源區(qū)。主量元素特征和微量元素分析結(jié)果顯示,基性巖墻為拉斑玄武巖系列和堿性系列,屬于富鈉基性巖類;TiO2含量較高,其中3個樣品含量大于1%,屬于鈦較高的基性巖類;A/NCK均小于1,屬于準(zhǔn)鋁質(zhì)基性巖類,稀土配分曲線右傾明顯,∑LREE/∑HREE在7.4~8.78之間,顯示樣品輕稀土相對富集,重稀土相對虧損的特征。曲線模式與地幔巖漿型稀土元素曲線模式大致相似,說明巖漿來源與地幔巖漿有密切關(guān)系。這說明早古生代加里東運動末期的巖漿作用是幔源巖漿與中元古代形成的基性地殼共同作用的結(jié)果;早古生代晚期基性巖漿作用以殼源為主。研究區(qū)出露了加里東期同造山期的黑云母二長花崗巖、花崗閃長巖和后造山期黑云母二長花崗巖兩類中酸性巖體。在研究區(qū)同時出現(xiàn)加里東期的酸性和基性兩類侵入巖,說明加里東期侵位巖漿巖由擠壓型酸性巖漸變?yōu)槔瓘埢詭r,反映了該地區(qū)區(qū)域地殼構(gòu)造環(huán)境由早期的擠壓應(yīng)力環(huán)境逐漸變?yōu)楹笃谏煺估瓘埈h(huán)境的演化過程。
[Abstract]:The South Gannan area belongs to the east part of the Nanling East-West tectonic magma belt, which belongs to the Nanling rare nonferrous metal metallogenic belt (Zuo Zufa, 2015). The magma activity is strong and some magmatic rocks are distributed in a face like distribution. Among them, the magma activity in the Caledonian and Yanshan periods is most active. Most of the magmatism in the region is acidic magma. The rock and basic rock content is very small, scattered in a few tectonic development positions. The basic rock wall is closely related to the deep fault structure in the region, often related to the extensional tectonic environment within the region. They originated in the deep crust of the crust (upper mantle or lower crust), rising in the weak position of the crust to the crust, and emplacement activities at different levels of the earth's crust. The Southern China block is made up of the Yangtze block in the northwest and the Huaxia block in the southeast in the early Neoproterozoic Era along the Jiangnan orogenic belt, and experienced the superposition and transformation of the late multistage tectonic magma events. The Caledonian orogeny is one of the most important tectonic events. However, the Caledonian structure in Southern China is present. The study of magmatic events is mainly focused on granitoids, acid volcanic rocks and basic rocks relatively low. There are only 3 Caledonian basic rocks in Southern China, which are found in Nanling, Yunnan and Wuyi areas, mainly between 420-450 Ma, but based on related geochemistry and isotopes. At present, there is still a lot of controversy about the tectonic environment formed by these rocks. Some people think they are formed in the internal environment of the plate. Some people think that they are formed in the island arc subduction environment (Yao et al., 2012; Wang et al., 2013). This paper mainly takes the basic rock wall in Suichuan area of South Jiangxi as the research object, and has carried out detailed field observation and indoor petrology, The analysis of ball chemistry and zircon LA-ICP-MS U-Pb age and Lu-Hf isotopes is studied, and its petrology, geochemistry, formation time, magmatism and tectonic environment are discussed. The basic rock wall LA-ICP-MS zircon U-Pb dating method is Th, and the ratio of U to 0.46-1.59 can be determined as the formation of magma genesis. The dating results of.4 zircon samples are 446 + 6.6Ma (N=30, MSWD=0.55), 431.9 + 5.7Ma (N=30, MSWD=0.65), 422.3 + 7.3Ma (N=30, MSWD=0.79) and 426.6 + 6.9Ma (N=20,), and the intrusive age is the early Paleozoic Silurian, indicating that the rock mass was transformed from extrusion to regional extensional stretching environment in the later period of the Caledonian movement in the south of Jiangxi. The Lu-Hf isotopic analysis of the two samples shows that the initial 176Hf/177Hf ratio has a small change range and the corresponding Hf (T) values are all -4~-0.1 and all are negative, indicating that the zircon should be the product of the remelting of the shell source rocks. The TDM2 value of the two stage Hf loss mantle model age of the zircon is between the 1424~1670 Ma, and the main content of the zircon is between the 1424~1670 Ma. It is distributed in Mesoproterozoic, indicating that the new basal crust in the Mesoproterozoic period may be the main source area of the early Paleozoic Caledonian intrusive rocks in the study area. The main element characteristics and trace elements analysis showed that the basic rock wall was the La basalt series and the alkaline series, which belonged to the sodium rich base rock, and the TiO2 content was higher. The content of the 3 samples is more than 1%, which belongs to the high titanium base rock. A/NCK is less than 1. It belongs to the quasi aluminum base rock. The distribution curve of rare earth is right, and the sigma LREE/ Sigma HREE is between 7.4~8.78. It shows that the light rare earth is relatively rich and the heavy rare earth is relative to the loss. The Qu Xianmo formula is similar to the mantle magmatic rare earth element curve pattern. It indicates that the magma source is closely related to the mantle magma. This indicates that the magmatism at the end of the early Palaeozoic Caledonian movement was the result of the joint action of the mantle derived magma and the basic crust formed by Mesoproterozoic, and the primary magmatism of the late Early Paleozoic was mainly the crust source. The study area revealed the two long black mica granite in the eastern period of the Gary period. There are two acidic rocks in rock, granodiorite and post orogenic two feldspar granite. In the study area, there are two types of acid and basic intrusive rocks in the Caledonian period, indicating that the Caledonian emplacement magmatic rocks gradually changed from extruded acid rocks to extensional rocks, reflecting the regional tectonic setting of the region from the early compressive stress ring. The environment gradually evolved into the evolutionary process of extensional extension in later stage.

【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：P542;P588.124

【參考文獻】

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1 左祖發(fā);羅春林;王會敏;劉邦秀;劉春根;徐U，

本文編號：1799287