【摘要】：為了更深入的認(rèn)識東昆侖山脈巖漿作用和構(gòu)造演化歷史,本文采用激光剝蝕電感耦合等離子質(zhì)譜儀(LA-ICP-MS)方法對東昆侖山脈中部和東部不同時代的花崗類巖石中鋯石進(jìn)行了系統(tǒng)的微量元素分析。東昆侖山脈晚志留世二長花崗巖和晚二疊世、晚三疊世、早侏羅世花崗巖中絕大多數(shù)鋯石Th/U0.5,鋯石的球粒隕石標(biāo)準(zhǔn)化REE配分曲線均為HREE相對于MREE和LREE富集,并且具有Ce正異常和Eu負(fù)異常,為典型的巖漿鋯石。晚志留世二長花崗巖和晚二疊世、晚三疊世花崗巖鋯石具有低的Ce正異常,高的Eu負(fù)異常;早侏羅世花崗巖鋯石則具有高的Ce正異常,高Nb、Ta含量,低Eu負(fù)異常;晚二疊世花崗巖鋯石還具有高∑REE、Y、Th、U含量;而晚三疊世花崗巖鋯石則在所有樣品中具有最高的Hf含量,是演化程度高的巖漿產(chǎn)物。除此之外,晚志留世、晚二疊世、晚三疊世和早侏羅世樣品中部分鋯石呈現(xiàn)LREE富集,說明它們在巖漿晚期可能遭受LREE富集熱液的改造。根據(jù)鋯石Ti溫度計,計算出所有樣品的結(jié)晶溫度小于800℃,說明它們很有可能形成于富集流體的俯沖帶環(huán)境。結(jié)合前人研究資料和所分析鋯石的U-Pb年齡數(shù)據(jù),對東昆侖山脈中古-中生代多期的構(gòu)造-巖漿事件提供了新的約束:(1)晚志留世二長花崗巖的形成可能與一個小型洋盆的俯沖作用有關(guān),其巖漿源區(qū)是地殼淺部的沉積基底;(2)晚二疊世花崗巖可能是在古特提斯洋向北俯沖過程中由于幔源巖漿使淺層地殼發(fā)生熔融形成;(3)晚三疊世-早侏羅世花崗巖在羌塘和昆侖-柴達(dá)木同碰撞過程形成。
[Abstract]:In order to better understand the magmatic and tectonic evolution history of the Eastern Kunlun Mountains, In this paper, laser denudation inductively coupled plasma mass spectrometer (LA-ICP-MS) is used to analyze the trace elements of zircon in granitic rocks of central and eastern Kunlun Mountains. In the late Silurian monzonitic granite and late Permian, late Triassic and early Jurassic granites in the East Kunlun Mountains, the majority of zircon Th/U0.5, zircon normalized REE partition curves are enriched in HREE relative to MREE and LREE. Ce positive anomaly and negative Eu anomaly are typical magmatic zircon. The zircon of late Silurian monzonitic granite and late Permian, late Triassic granite had low Ce positive anomaly and high Eu negative anomaly, while early Jurassic granite zircon had high Ce positive anomaly, high Nb,Ta content and low Eu negative anomaly. The zircon of late Permian granite also has a high 鈭，

本文編號：2442218