本文選題：富堿斑巖 + 地球化學特征��； 參考：《中國地質大學(北京)》2017年碩士論文

【摘要】：青藏高原東南緣,沿印度板塊與歐亞板塊碰撞邊界的金沙江—哀牢山大斷裂附近,分布著一條NW走向富堿斑巖帶。近年來由該帶內發(fā)現了大量與富堿斑巖具有密切成因聯系的銅金鉬礦床,眾多學者也對該帶的富堿斑巖的成因機制做了相關研究。本文選擇大理地區(qū)的九頂山和寶豐寺巖體為研究區(qū),通過LA-ICP-MS鋯石U-Pb定年法測得九頂山巖體的二長斑巖年齡為35.3±0.2Ma(MSWD=0.43),寶豐寺巖體的二長斑巖年齡為35.6±0.2Ma(MSWD=0.36)。九頂山巖體和寶豐寺巖體富堿斑巖地球化學特征表明:巖石顯示高K2O、高Na2O,和強烈富堿特征,屬高鉀鈣堿性—鉀玄巖系列,顯示過鋁質特征(A/CNK=0.79~1.28)。巖石強烈富集輕稀土元素,輕重稀土分餾明顯((La/Yb)N=8.38~55.50),顯示輕微的Eu負異常(δEu=0.61~0.82),富集大離子親石元素(Rb、Th、U、K),虧損高場強元素,并顯示“TNT”異常。研究區(qū)內的富堿斑巖與云南三江地區(qū)大規(guī)模巖漿作用的同時性和地球化學特征相似,反映它們在構造背景、物質來源和成巖機制上的聯系。區(qū)域構造演化與巖石地球化學特征表明,成巖的巖漿活動與印度板塊和歐亞板塊的碰撞產生的左行走滑有關。研究區(qū)內的樣品屬C型埃達克巖,其富堿巖漿起源于加厚下地殼的熔融作用,并有地幔物質的加入,經歷了較為顯著的殼幔巖漿混合的作用。
[Abstract]:In the southeastern margin of the Qinghai-Tibet Plateau, near the Jinshajiang-Ailaoshan fault along the collision boundary between the Indian plate and the Eurasian plate, there is an alkali-rich porphyry belt with NW strike.In recent years, a large number of copper-gold-molybdenum deposits closely related to alkali-rich porphyry have been found in this zone, and many scholars have also studied the genetic mechanism of alkali-rich porphyry in this zone.In this paper, Jiudingshan and Baofengsi pluton in Dali area are selected as the study area. The age of the second length porphyry of the Jiudingshan rock body is 35.3 鹵0.2 Ma-MSWDU 0.433.The age of the second length porphyry is 35.6 鹵0.2MaMSWD0.3636 by LA-ICP-MS zircon U-Pb dating method.The geochemical characteristics of alkali-rich porphyry rocks in Jiudingshan and Baofengsi pluton show that the rocks are characterized by high K _ 2O, high Na _ 2O and strong alkali-rich, and belong to the high-potassium calc-alkaline _ potash series, showing the characteristics of analuminite (A / CNK _ (0.79) 0.79 ~ (1.28)).The rocks are strongly enriched in light rare earth elements (LREE), and the fractionation of LREE shows a slight negative EU anomaly (未 EU0.61 ~ 0.82), enrichment of the large ion lithophile element RbPe, depletion of high field strength elements, and "TNT" anomaly.The alkali-rich porphyry in the study area is similar to the large-scale magmatism and geochemical characteristics in Sanjiang area, Yunnan Province, reflecting their relationship in tectonic setting, material source and diagenetic mechanism.The regional tectonic evolution and petrogeochemical characteristics indicate that diagenetic magmatic activity is related to the left strike-slip caused by the collision between the Indian plate and the Eurasian plate.The samples in the study area belong to the C type adakite. The alkali-rich magma originated from the melting process of thickened lower crust, with the addition of mantle material, and experienced a relatively significant mixing of crust and mantle magma.
【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】：2017
【分類號】：P597.3;P588.15

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相關期刊論文 前10條

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本文編號：1734835