本文選題：揚(yáng)子北緣 + 漢南雜巖　； 參考：《西北大學(xué)》2015年碩士論文

【摘要】：揚(yáng)子地塊北緣空間上向北楔入南秦嶺,東臨巴山弧,西臨龍門山推覆構(gòu)造帶和松藩-甘孜造山帶。大漢山地區(qū)位于揚(yáng)子北緣米倉(cāng)山北麓,區(qū)內(nèi)廣泛發(fā)育一套新元古代基性-酸性侵入雜巖體,它們構(gòu)成漢南雜巖的重要組成部分。此外,新元古代巖漿活動(dòng)還廣泛分布于揚(yáng)子地塊西緣(攀西地區(qū))、東南緣(桂北地區(qū))以及黃陵地區(qū)。目前,由這些巖漿活動(dòng)引出的超大陸構(gòu)造模式和島弧模式之爭(zhēng)掀起了研究熱潮,引發(fā)許多學(xué)者的廣泛關(guān)注。本項(xiàng)研究旨在通過(guò)對(duì)大漢山地區(qū)4個(gè)不同巖石類型的新元古代花崗巖體進(jìn)行野外地質(zhì)調(diào)查、巖石學(xué)、地球化學(xué)、鋯石U-Pb年代學(xué)及Hf同位素研究,確定研究區(qū)新元古代花崗巖類的時(shí)空分布特征、巖漿作用期次、巖石成因及源區(qū)特征,探討這套花崗巖的大地構(gòu)造意義。研究獲得了如下主要進(jìn)展和認(rèn)識(shí)：(1)野外地質(zhì)調(diào)查及巖相學(xué)研究表明,大漢山地區(qū)花崗巖巖體具有多種類型。本項(xiàng)研究包括喜神壩含暗色微粒包體的黑云母花崗巖(GQ)、黃官鉀長(zhǎng)花崗斑巖(NH-7)、紅廟鎮(zhèn)鉀長(zhǎng)花崗巖(XSB和NH-3)及祖師店奧長(zhǎng)花崗巖(EL-1)。各巖體巖石新鮮,未發(fā)生明顯變形和變質(zhì)。(2)通過(guò)詳細(xì)的鋯石原位U-Pb定年工作,獲得喜神壩黑云母花崗巖巖體(GQ)的成巖年齡為886.5±6.8 Ma;黃官鉀長(zhǎng)花崗斑巖巖體(NH-7)的成巖年齡為814±25 Ma；紅廟鎮(zhèn)鉀長(zhǎng)花崗巖巖體中的兩個(gè)樣品(XSB、NH-3)分別獲得了802.1±4.3 Ma和790.5±5.7 Ma的年齡,在誤差范圍內(nèi)這兩個(gè)樣品的年齡基本一致；祖師店奧長(zhǎng)花崗巖巖體(EL-1)的成巖年齡為728±3 Ma。(3)經(jīng)過(guò)系統(tǒng)的地球化學(xué)研究,判斷喜神壩黑云母花崗巖巖體和祖師店奧長(zhǎng)花崗巖巖體具有島弧花崗巖特征,二者具有Nb、Ta、Ti負(fù)異常的地球化學(xué)特征,形成于俯沖擠壓環(huán)境；紅廟鎮(zhèn)巖體和黃官巖體代表伸展構(gòu)造背景下的產(chǎn)物。(4)結(jié)合前人研究成果,提出大漢山地區(qū)新元古代巖漿活動(dòng)可劃分為3個(gè)階段：-880 Ma,代表一期與板塊俯沖匯聚相關(guān)的的島弧巖漿作用,對(duì)應(yīng)本研究的喜神壩黑云母花崗巖巖體；～800 Ma,代表伸展構(gòu)造背景,對(duì)應(yīng)紅廟鎮(zhèn)鉀長(zhǎng)花崗巖巖體和黃官鉀長(zhǎng)花崗斑巖巖體；790Ma之后,發(fā)生另一期俯沖匯聚事件下的島弧巖漿作用,對(duì)應(yīng)于大漢山輝長(zhǎng)巖巖體(790～780Ma)和祖師店奧長(zhǎng)花崗巖巖體。(5)鋯石Hf同位素研究顯示,喜神壩巖體的鋯石εHf(t)值為-25～-3,對(duì)應(yīng)的鋯石兩階段Hf模式年齡(TDM2)集中于2.4Ga；紅廟鎮(zhèn)巖體的鋯石εHf值為-26～-4,對(duì)應(yīng)的鋯石兩階段Hf模式年齡(TDM2)集中于2.2Ga;祖師店巖體的鋯石εHf(t)值為+5.0～-+12.2,對(duì)應(yīng)的兩階段鋯石Hf模式年齡集中于1.1 Ga�？梢钥闯�,喜神壩巖體指示了俯沖背景下古老地殼物質(zhì)的再造；紅廟鎮(zhèn)巖體指示了伸展背景下古老地殼物質(zhì)的再造；而祖師店巖體則指示了新元古代地殼生長(zhǎng)事件。因此,漢南雜巖并非來(lái)自同一源區(qū)同一期次的巖漿作用,代表了新元古代揚(yáng)子北緣地殼演化歷史。(6)綜合區(qū)域大地構(gòu)造,推測(cè)880Ma的巖漿活動(dòng)可能代表了揚(yáng)子北緣對(duì)全球性格林威爾造山運(yùn)動(dòng)最晚期活動(dòng)的響應(yīng)；830～790 Ma的巖漿活動(dòng)可能與Rodinia超大陸裂解相關(guān)；而790～720Ma代表?yè)P(yáng)子北緣與南秦嶺碰撞拼合的時(shí)間。自此以后,揚(yáng)子和南秦嶺拼貼在一起,處于相對(duì)穩(wěn)定的狀態(tài)。
[Abstract]:The northern margin of the Yangtze block is wedged northward in the southern Qinling Mountains, the East is the Bashan arc, the Longmen mountain nappe structure belt and the pine fan Ganzi orogenic belt in the west, and the Da Han Shan area is located at the northern foot of the Yangtze River in the north of the Yangtze River, and a set of Neoproterozoic basic acid intrusive complex is widely developed in the northern margin of the Yangtze River. The magmatic activity is also widely distributed in the western margin of the Yangtze block (Panxi area), the southeast margin (north of Guangxi) and the Huangling area. At present, the controversy over the supercontinental tectonic model and the island arc model caused by these magma activities has aroused a lot of research upsurge, which has caused extensive attention by many scholars. This study is aimed at 4 different rocks in the Great Han mountain area. The Neoproterozoic granitoids of the stone type are investigated in the field, petrology, geochemistry, zircon U-Pb chronology and Hf isotopes, to determine the temporal and spatial distribution characteristics of the Neoproterozoic granitoids in the study area, the stages of magmatism, the petrogenesis and the characteristics of the source area, and to discuss the tectonic significance of the granites. Progress and understanding: (1) the field geological survey and petrographic study show that the granitoid rock mass in the Great Han mountain area has a variety of types. This study includes the dark mica granite (GQ), the Yellow official potassium long granite porphyry (NH-7), the potassium feldspar granite (XSB and NH-3) of the red temple town and the ancestor division granitic granite (EL-1). The body rock is fresh, without obvious deformation and metamorphism. (2) through the detailed zircon in-situ U-Pb dating, the age of diagenesis of the biotite granitoid granite rock mass (GQ) is 886.5 + 6.8 Ma, and the age of diagenesis of the Huang Guan potassium long granite porphyry rock mass (NH-7) is 814 + 25 Ma, and two samples (XSB, NH-3) in the potash granite rock mass of the red temple town are divided. The age of 802.1 + 4.3 Ma and 790.5 + 5.7 Ma is not obtained. The age of the two samples is basically the same in the range of error; the age of the diagenesis of the AUD granitic granite (EL-1) is 728 + 3 Ma. (3) through systematic geochemical study. It is determined that the rock mass of the black mica granite and the Oracle granite rock of the Heisan dam are island arc granite. Rock characteristics, two of which have the geochemical characteristics of Nb, Ta, Ti negative anomalies, formed in the subduction and extrusion environment; the red temple rock mass and the Huang Guan rock mass represent the product of the extensional tectonic setting. (4) the Neoproterozoic magmatic activity in the Great Han mountain area can be divided into 3 stages: -880 Ma, representing the first stage and the subduction and convergence of the plate subduction. The related island arc magmatism corresponds to the biotite granite rock mass of the joy God dam of this study; to 800 Ma, representing the extensional tectonic setting, corresponding to the red temple granite rock mass and the Yellow official potassium long granite porphyry rock mass; after 790Ma, the island arc magmatism under another subduction event occurs, corresponding to the Great Han mountain gabbro rock mass (790). (5) the zircon Hf isotopes of the zircon. (5) the zircon Hf (T) value of the zircon is -25 to -3, and the corresponding zircon two stage Hf mode age (TDM2) is concentrated in 2.4Ga; the zircon - Hf values of the red temple rock mass are -26 to -4, the two phase of the zircon is concentrated in the ancestor Dian Yan The zircon epsilon Hf (T) value of the body is +5.0 to -+12.2, and the corresponding two stage zircon Hf mode age is concentrated at 1.1 Ga., it can be seen that the Xinshen dam rock indicates the reengineering of ancient crustal material under the subduction background, and the red temple rock mass indicates the reengineering of ancient crustal material under the extensional background, while the zutodian rock mass indicates the Neoproterozoic crust growth. Therefore, the Hannan complex does not come from the same stage of magmatism in the same source area and represents the evolution history of the northern margin of the Neoproterozoic Yangtze River. (6) comprehensive regional tectonics, and it is presumed that the magmatic activity of 880Ma may represent the response of the northern margin of the Yangtze to the most advanced activity of the orogenic movement of the global character Lin Wei, and 830~790 Ma of magma activity. The movement may be associated with the Rodinia supercontinental fragmentation, while 790 ~ 720Ma represents the time of collision and integration of the northern margin of the Yangtze and southern Qinling Mountains. Since then, the Yangtze and southern Qinling Mountains collages together in a relatively stable state.

【學(xué)位授予單位】：西北大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P588.121;P597.3

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