【摘要】：NE-SW向政和-大埔斷裂帶是華夏板塊內(nèi)部一條重要的斷裂帶,該帶內(nèi)出露大量基性-超基性巖,前人對(duì)于該帶內(nèi)基性-超基性巖的認(rèn)識(shí)一直以來(lái)存在爭(zhēng)議。本論文主要針對(duì)該斷裂帶政和-建甌段基性-超基性巖開(kāi)展鋯石U-Pb年代學(xué)及地球化學(xué)分析,意在厘清基性-超基性巖成因及構(gòu)造屬性,并以此探討華夏板塊新元古代—早古生代構(gòu)造演化。通過(guò)以上研究,本文取得以下主要認(rèn)識(shí):鋯石U-Pb定年顯示,政和-大埔斷裂帶內(nèi)基性巖大多形成于新元古代,其中水吉鎮(zhèn)雙峰式火山巖角閃斜長(zhǎng)片巖原巖形成年齡分別為812±7 Ma,政和斜長(zhǎng)角閃片巖原巖形成時(shí)代725±22 Ma。地球化學(xué)特征表明迪口鎮(zhèn)角閃片巖原巖巖漿來(lái)源于富集型地幔,政和斜長(zhǎng)角閃巖巖漿來(lái)源于相對(duì)虧損的地幔,構(gòu)造判別圖解上前者為板內(nèi)玄武巖,后者具有N-MORB特征。電子探針數(shù)據(jù)表明洋后角閃石巖主要為淺閃石,Re-Os同位素和Sr-Nd同位素特征顯示洋后角閃石巖原巖為巖漿成因,巖漿來(lái)源于富集型地幔,而馬面山蛇紋巖和北歷蛇紋石化橄欖巖為大陸巖石圈殘余地幔橄欖巖。綜和上述特征政和—大埔斷裂帶內(nèi)基性巖形成于新元古代拉張構(gòu)造環(huán)境,而超鎂鐵質(zhì)巖石有的為巖漿成因,有的為殘余的地幔橄欖巖,但其是否為蛇綠巖套還需做進(jìn)一步研究。沿政和-大埔斷裂帶內(nèi)也出露一些中生代的基性巖。鋯石U-Pb定年顯示東游鎮(zhèn)斜長(zhǎng)角閃片巖原巖形成年齡為221±1 Ma。Sr-Nd同位素表明東游鎮(zhèn)斜長(zhǎng)角閃片巖巖漿來(lái)源于富集型地幔,構(gòu)造判別圖解上巖石屬于板內(nèi)拉斑玄武巖。
[Abstract]:The NE-SW Xiangzheng-Tai Po fault zone is an important fault zone in the Huaxia plate, in which a large number of basic-ultrabasic rocks are exposed. In this paper, zircon U-Pb geochronology and geochemistry analysis are carried out for the basic-ultrabasic rocks of Zhenghe and Jianou member of the fault zone, in order to clarify the genesis and tectonic attributes of basic-ultrabasic rocks. The tectonic evolution of Neoproterozoic-early Paleozoic in the Huaxia plate is discussed. Based on the above study, the main conclusions are as follows: the zircon U-Pb dating shows that most of the basic rocks in the Zhenghe-Tai Po fault zone were formed in the Neoproterozoic. The age of formation of the amphibolite schist in Shuiji town is 812 鹵7 Ma, and 725 鹵22 Ma., respectively. The geochemical characteristics indicate that the magma of Dikouzhen hornblende schist originates from the enriched mantle, the Zhenghe and plagioclase amphibolite magma from the relatively depleted mantle. The former belongs to intraplate basalt and the latter is characterized by N-MORB. The electron microprobe data show that the post-oceanic hornblende is mainly composed of shallow-amphibole Re-Os isotopic and Sr-Nd isotopic features, indicating that the post-oceanic hornblende originates from magma, and the magma originates from the enriched mantle. The Mamanshan ophiolite and the northern serpentine peridotite are residual mantle peridotite in the continental lithosphere. The basic rocks in the Zhenghe-Tai Po fault zone were formed in the Neoproterozoic extensional tectonic environment, while the ultramafic rocks were either magmatic or residual mantle peridotite, but whether they are ophiolite suites should be further studied. Some Mesozoic basic rocks were also exposed along the Zhenghe-Tai Po fault zone. The zircon U-Pb dating shows that the age of formation of the amphibole schist is 221 鹵1 Ma.Sr-Nd isotope, indicating that the magma of Dongyou Zhen clinopodiorite schist originated from the enriched mantle, and the tectonic discrimination diagram shows that the rocks belong to intraplate tholeiite basalt.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：P588.12;P542

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