【摘要】：點(diǎn)蒼山-哀牢山變質(zhì)雜巖帶位于青藏高原東南緣揚(yáng)子板塊與印支板塊的結(jié)合部位。雜巖帶經(jīng)歷了多期構(gòu)造-巖漿-變質(zhì)事件的疊加,帶內(nèi)物質(zhì)組成極其復(fù)雜,是研究古特提斯演化、印度-歐亞板塊俯沖-碰撞-隆升以及漸新世印支地體沿紅河-哀牢山左行走滑側(cè)向擠出的關(guān)鍵地區(qū)。本文對(duì)點(diǎn)蒼山-哀牢山變質(zhì)雜巖帶中、北段戛灑地區(qū)11件花崗質(zhì)巖石進(jìn)行了LA-ICPMS鋯石年代學(xué)和巖石地球化學(xué)分析,研究揭示出新元古代、中三疊世、始新世和漸新世四期不同類型的花崗質(zhì)巖漿活動(dòng)。其中4件花崗質(zhì)巖石中鋯石206Pb/238U加權(quán)平均年齡為780.0±6.3Ma~743.6±6.7Ma,部分巖石內(nèi)發(fā)育有漸新世深熔鋯石;1件花崗質(zhì)片麻巖內(nèi)27顆鋯石的206Pb/238U加權(quán)平均年齡為234.3±2.0Ma;3件花崗斑巖鋯石U-Pb測(cè)年獲得36.67±0.54Ma~33.01±0.39Ma的加權(quán)平均年齡;3件花崗質(zhì)片麻巖/糜棱巖中獲得漸新世(28.58±0.57Ma~24.53±0.29Ma)侵位年齡。巖石地球化學(xué)研究揭示新元古代花崗質(zhì)巖石具有較高的Cu、V、Zn、TiO_2含量及較高鋁指數(shù),A/CNK變化范圍為1.09~1.13,TiO_2含量為0.44~0.60;中三疊世花崗巖具有鈣堿性特征,A/CNK1.0,R1-R2圖解中落入深熔花崗巖范圍內(nèi);始新世花崗巖具有高Sr、Ba、K_2O含量,高Sr/Y、Sr/Nd、Ba/Th比值,低Nd、Na)2O含量的特點(diǎn),巖石中全堿含量為9.2%~10.4%,Sr/Y值為48.8~94.5,Sr/Nd值為30.4~65.3,Ba/Th值為151~358;漸新世花崗巖全堿含量較低變化范圍為3.25~9.03,A/CNK范圍為1.09~1.14,屬富鋁質(zhì)S型花崗巖。花崗質(zhì)巖石野外產(chǎn)狀、鋯石年代學(xué)與巖石地球化學(xué)綜合研究揭示新元古代花崗質(zhì)巖石可能屬揚(yáng)子板塊西緣原特提斯洋俯沖形成的陸緣巖漿弧,印支期造山作用過(guò)程中卷入到雜巖帶內(nèi),新生代區(qū)域性走滑剪切使巖石進(jìn)一步發(fā)生變形和深熔;中三疊世花崗巖為古特提斯洋閉合后揚(yáng)子板塊與印支板塊碰撞后伸展構(gòu)造熱事件的響應(yīng);始新世花崗質(zhì)巖石為印度-亞歐板塊碰撞后伸展背景下地幔上涌交代下地殼進(jìn)而產(chǎn)生的富鉀花崗質(zhì)巖石,且侵位年代由北向南逐漸變新記錄了印度-亞歐板塊匯聚角度的調(diào)整過(guò)程;漸新世花崗質(zhì)巖石為紅河-哀牢山剪切-走滑抬升過(guò)程中變沉積巖、新元古代和晚二疊世-三疊紀(jì)花崗質(zhì)巖石的部分熔融而成。
[Abstract]:The point Cangshan-Ailaoshan metaphorical complex belt is located at the junction of Yangtze plate and Indochina plate in the southeast margin of Qinghai-Xizang Plateau. The complex rock belt has experienced the superposition of multiple tectonic-magmatic-metaphorical events, and the material composition in the belt is extremely complex, which is the key area for the study of the evolution of ancient Tethys, the subduction-collision-uplift of the Indochina-Eurasian plate and the lateral extrusion of the Oligocene Indochina along the left walking and sliding of Honghe-Ailaoshan. In this paper, LA-ICPMS zircon chronology and petrogeochemistry analysis of 11 granitic rocks in the Cangshan-Ailaoshan metamorphic complex belt in the northern section of the North Section have been carried out. The study reveals different types of granitic magmatic activities in Neoproterozoic, Middle Triassic, Eocene and Oligocene. The weighted average age of zircon 206Pb/238U in 4 granitic rocks is 780.0 鹵6.3 Ma~743.6 鹵6.7 Ma, and Oligocene deep melting zircon is developed in some rocks, and the 206Pb/238U weighted average age of 27 zircon in 1 granitic gneiss is 234.3 鹵2.0 Ma. The weighted average age of zircon U-Pb is 36.67 鹵0.54Ma~33.01 鹵0.39Ma. The emplacement age of Oligocene (28.58 鹵0.57 Ma~ 24.53 鹵0.29 Ma) was obtained from three granitic gneiss / mylonite. The study of petrogeochemistry shows that the Neoproterozoic granitic rocks have high Cu,V,Zn,TiO_2 content and high aluminum index, the variation range of A/CNK is 1.09 鈮，

本文編號(hào)：2518164